IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com
Edition: Model Aviation - 2003/06
Page Numbers: 46,47,48,49,50,51,53,54,55,56,57
IN THE PREVIOUS installments—
the second and third, in the April and
May issues—I discussed the basic
Radio Control (RC) system, the
selection process, and basic installation
in a model aircraft. This month I’ll get
into the operation of an RC system.
More detailed information using a basic
training model will be provided in
following months, including the
assembly and flying aspects.
For the purpose of this presentation,
let’s assume we have that RC modelaircraft
mock-up (containing the RC
airborne components) from the previous
article sitting in front of us on our
workbench. The RC transmitter is
nearby. To get familiar with your new
RC system you are encouraged to
operate it at home, try the various
controls, and even pretend you are
flying the model! Allow yourself to get
the feel of it.
Before turning on that transmitter,
think for a moment about your location.
If you are operating from your home
shop or garage, the
important thing to
consider is whether there
might be an RC flying
field in the immediate
area. You would be wise
to check this out before
turning on your
transmitter for the first
time. Keep in mind that
two identical RC
channels can easily
interfere with one
another.
As a precaution, you
can operate your RC
transmitter for relatively
short periods with the
antenna fully collapsed.
By doing this you are
able to operate your RC
system for checkout
purposes, but the
transmitted signal will be greatly
reduced. Extended use of the transmitter
with the antenna collapsed might cause
overheating and damage to the output
stages.
A cardinal rule of RC operations is
to turn on your transmitter, then turn on
the receiver (airborne pack). Use the
reverse order when shutting down the
system; turn the receiver off first and
the transmitter off last. (The transmitter
goes on first and off last.)
If you turn the receiver on first,
without any signal being broadcast from
the transmitter, it is possible for the
servos to jitter (dither) or even drive to
an extreme control position and stall out
the servo motor. In this condition you
would have excess battery drain and
might even damage a servo motor or
gear.
Make sure your transmitter and
receiver battery packs have been
charged properly. The supplied dualoutput
battery charger should always be
employed prior to operating the system.
The amount of charge placed on these
batteries by an RC system dual-output
charger is at a low enough level that
they can’t be overcharged.
The general rule is to charge
transmitter and receiver battery packs
overnight, or at least for 10 hours. The
only problem you might experience is if
you charge for less than 10 hours. As I
have already stated, never attempt to
just put back into a battery what you
think you took out. Several charging
sessions for only an hour or two can
quickly lead to a battery that has little, if
any, charge remaining. That is an
invitation to potential control problems
in flight.
Most RC transmitters will have a
meter, an LCD (Liquid Crystal Display)
voltmeter, or color indicator lights that
inform you of your batteries’ charge
status, and some even provide an
audible alarm when the battery needs to
be recharged. The airborne battery
Radio Control
System
Operations
Hitec Laser 6 is typical four-channel-function-control
RC transmitter. Antenna mast is collapsed to short
section, to which channel-number flag is attached.
Shortening antenna greatly reduces transmitted
power, making transmitter safer to operate for tests in
shop and permitting convenient range check
outdoors. If you can get receiver to operate to roughly
50-100 feet from transmitter while antenna is
retracted, you will have out-of-sight range once model
is in air and antenna is fully extended.
■ Bob Aberle
In foreground is model mock-up with all RC-system components in
place. In back is RC transmitter with antenna mast almost fully
collapsed into case.
46 MODEL AVIATION
needs extra monitoring while at the flying
field; we will get into that in the installment
about flying.
Now that we have the batteries charged and
we know the sequence for turning on the
power, one of the first steps on a new RC
airborne installation is to determine that all
controls operate from the proper control sticks
on the transmitter. The order in which each
servo cable plugs into the RC receiver makes
the difference. For our initial training purposes
we will employ only three channel functions,
such as rudder, elevator, and engine/motor
(throttle) control. That will involve three
servos for a fuel-powered model or two servos
and an Electronic Speed Control (ESC) for
electric power.
With the transmitter and receiver powered
up, move the rudder control stick, which will
be on the right side (or right control-stick
assembly) on a three- or four-channel-function
transmitter. Rock this stick side to side (left to
right) and observe the rudder on the model (or
mock-up in this case). The rudder should move
when you operate the control stick. If, say, the
elevator moves when you move the rudder
stick on the transmitter, you have to change the
servo plug at the receiver.
I wish I could simply tell you that
connector position one at the receiver is
always rudder, two is elevator, etc.
Unfortunately no two RC manufacturers use
the same convention or order. The rudder and
elevator functions will generally be on the first
and second position, with the throttle on the
third.
So if your rudder stick is operating the
elevator, swap those first two connectors at the
receiver terminal block. Try the rudder stick
again; the rudder will most likely operate
properly. Try the elevator control stick in an
up-and-down motion, and the elevator will
probably respond. If it doesn’t, you must try
other connector positions on your receiver
until the control-stick command operates the
correct control function.
Try the throttle control on the transmitter.
This will be located on the left-side controlstick
assembly (on a four-channel transmitter)
June 2003 47
Finger points to transmitter power switch.
Always turn on transmitter power first and
turn receiver on second.
Failure to turn on receiver power for your model only after you have turned on
transmitter power could lead to jammed control rods and broken servo gears.
Charge transmitter and receiver battery packs using supplied system dual-output
charger overnight—at least 10 hours. More time won’t hurt. Do not try to put back in the
battery what you think you took out. In this simulated photo, wall-plug transformer was
not plugged into 115VAC outlet.
The three servos operating rudder, elevator, engine throttle are plugged into receiver
connectors 1, 2, 3 respectively. If transmitter rudder stick operated elevator servo, you
would unplug one of three connectors and try another location until rudder responded
properly. At other end of connector block is power input plug from switch harness.
Photos by the author Graphic Design by Lydia Whitehead
or on the rear of the transmitter case for a three-channel transmitter.
For a glow-fueled model you will be using a third servo to operate
the engine carburetor (throttle device). In this instance, it will be
obvious when you move the transmitter throttle stick that the throttle
servo is responding. It won’t be as obvious when using electric power
because the ESC is substituted for a servo, but we will get more into
that next month.
Now we have the control surfaces and throttle operating from the
correct control sticks on the transmitter. The next important thing to
check is the direction of the servo movement. We are going one step
further in our basic checkout procedure.
Move the transmitter rudder-control stick fully to the right side
while observing the rudder’s position on the mock-up (simulated
aircraft in this case!). The rudder should be deflected to the right, which
would produce a right turn in the aircraft. As you move the control
stick from the neutral position to the extreme position (such as full
right), the rudder operates in direct proportion to your stick deflection.
This proportional control allows you to impart any amount of rudder
control to the aircraft, depending on how far you deflect the control
stick.
Let’s say that the rudder moved to the left when you applied right
rudder stick at the transmitter; that means it is hooked up backward,
which could easily crash your model on its first flight. Almost all
modern RC transmitters have a servo-reversing switch for each control
function. In this case, flip the rudder-reversing switch to the opposite
position.
48 MODEL AVIATION
Finger holds rudder-control stick over on transmitter, and rudder
is hard over at aircraft (mock-up) end. It means rudder is moving
in correct direction; applying right rudder at transmitter results in
right rudder at aircraft.
If you had found rudder control reversed, you could have easily
flipped rudder channel servo-reversing switch, available on most
RC transmitters. This Hitec Laser 6 has servo-reversing switches
accessed from inside battery compartment.
On three-channel Hitec, servo-reversing switches are located at
lower rear corner of case. If rudder had worked backward, you
would just flip “CH-1” switch from “NORM” to “REV” (reverse).
Rear of Hitec three-channel transmitter showing throttle channel
lever located away from case edge, which would be the idle
position.
Pointer indicates left-side control-stick assembly, and
specifically that throttle stick is in uppermost position, which is
for high, or maximum, engine speed (power).
Now move the control stick to the right,
and the rudder should move to the right.
Follow this same procedure, and check to
make sure that the elevator moves up when
you are pulling back on the elevator control
stick.
Check the engine throttle control. With the
throttle-control stick in the uppermost
position, the engine carburetor should be set
for full open, which will provide full, or
maximum, power. At the bottom throttlecontrol-
stick location, the carburetor should
be almost fully closed, which will provide a
low idle speed. On a three-channel
transmitter, with the throttle-control lever
located on the rear of the case, convention
usually dictates that moving the lever to the
outside of the case is high throttle and moving
the lever toward the inside (pulling it toward
you) is the idle position.
On some of the lesser-function RC
transmitters (such as the three-channel
variety), it is possible to see servo-reversing
switches on the first two channels but not on
the throttle channel. If this is your problem, it
will require special attention. On a glowfueled
model, you simply move the throttle
control-rod location from one side of the
servo output arm to the other. That will
reverse the direction of the control. It gets
more complicated in the case of electric
power; let’s leave that for next month.
The next item to concern ourselves with is
the position of the trim levers for each channel
function. On most RC transmitters there are
levers adjacent to the control stick (for rudder,
elevator, and throttle) that when moved can
impart a certain small amount of control
adjustment for trimming purposes while the
aircraft is in flight. These levers usually have
a ratchet-type device that produces a clicking
sound when moved; this is done to prevent
unwanted movement of the trim levers.
The full movement of a trim lever will
usually impart approximately 15% of the full
control throw. Digital trim is being employed
on some of the more sophisticated RC
transmitters, in which case the traditional
lever is replaced by a push-button switch.
There will be more about that when we get
into the advanced radio systems, at a much
later date.
For each new model you are advised to
turn on the transmitter and receiver, then
position the rudder and elevator trim levers
for the middle or center position. With the
throttle control stick in the high or full-power
position, move the throttle trim lever to the
uppermost position.
At this point you might observe, with your
hands off the transmitter control sticks, that
your rudder and/or elevator are/is not exactly
at the neutral control position(s). If that is the
case you must adjust your control rods, which
presumably have adjustable clevises on at
least one end. By screwing the clevis in or
out, you are changing the length of the control
rods, hence the position of the control surface
(rudder or elevator).
With the throttle stick at full power and the
throttle trim at the uppermost position, your
engine carburetor should be full open. Again,
adjusting the clevis will make this happen.
Moving the throttle control stick all the way
down should make the carburetor opening
almost fully closed. This will provide a low
idle speed. At this point, if you move the
throttle trim lever to the lower position, the
June 2003 49
Looking inside typical glow-fueled model engine’s carburetor
with throttle barrel at full open for full, or maximum, power.
Looking inside the carburetor barrel, this time it is almost
completely closed off to produce low or idle speeds.
Each primary channel function (rudder, elevator, throttle on
three-channel radio; aileron, rudder, elevator, throttle on fourchannel
radio) has own trim-lever adjustment. Shown is rudder
trim lever set in middle position; rudder itself is exactly at
neutral.
Pointer indicates that throttle trim lever is at uppermost position;
throttle control stick is all the way up at full throttle. When you
bring that stick all the way down, the engine should be at idle.
Bringing throttle trim lever down at that point will completely
close carburetor and stop engine
50 MODEL AVIATION
Pointer shows black plastic keeper that prevents control-rod wire end from falling off servo output arm. Output arm screw is securely
in place. Without this screw, servo output arm might fall off. Which hole you select on servo output arm affects amount of control
throw obtained.
Pull on elevator to make sure hinges are secure!
Simple receiver antenna attachment on top of fixed vertical fin.
Pass wire through one hole, out the other. Leave remainder of
antenna wire hanging off rear of aircraft. Don’t cut off any
antenna wire!
Transmitter neck strap attached to hook and eye on Airtronics
Radiant transmitter. Strap goes around pilot’s neck and supports
transmitter case, leaving both hands free to grip and operate
transmitter control sticks.
Adjustable clevis attached to top hole of elevator control horn.
Spring device is slid up over clevis and acts as safety “keeper.”
It will prevent clevis from opening. If you detach clevis, you can
rotate it on its threaded rod, which will allow you to adjust
elevator position. Which hole you select on control horn will
provide different amounts of control throw.
June 2003 51
Use nylon tie to attach antenna wire to top of fixed vertical fin.
E-Cubed R/C short antenna rod can be substituted for long
receiver antenna wire, but at loss of roughly 15% radio range.
Rear of Radiant; trainer cable is plugged into special jack. Same
goes for other transmitter, which gets other end of cable.
Airtronics Radiant transmitter (L) and trainer cable used to
connect two RC transmitters. Student holds one transmitter and
instructor holds other. Instructor can hit switch and take primary
control of model at any time.
To hold medium to large model’s wing to
fuselage, use at least six No. 64 rubber
bands—three on each side, crisscrossed.
Above: FMA Co-
Pilot sensor on
bottom of aircraft
fuselage. This selfstabilizing
device
will return model
to level attitude
when you take
your hand off
control sticks.
Left: Close-up of
Co-Pilot sensor.
carburetor, if mechanically set properly, will
completely close and the engine will stop
running.
Mechanically adjusting the carburetor
control linkage can take extra patience. More
advanced RC transmitters have electronictype
dial-up adjustments that make carburetor
settings easy, but I want to keep everything
simple for the moment.
If you were dealing with a real model with a
glow-fueled engine, at this point it would be
appropriate to take it outside and run up the
engine a few times. This would allow you to
fine-tune the carburetor settings for the
various throttle control stick and trim-lever
positions.
A guest author will write an article about
fueled engine operation and the necessary
support equipment (fuel type, fuel pump,
starter battery, starter motor, propeller size,
tank size, fuel lines, muffler, etc.) within the
next few months.
How much control throw or control
excursion do you need for your first few
flights? Model-aircraft manufacturers and
model designers who publish plans in
magazines usually provide guidelines for your
initial flights. They may suggest one-inch
rudder throw or travel on either side of the
neutral position and half-inch elevator control
on either side of neutral.
If you don’t get a recommendation, ask a
friend who has more experience than you do
or use the one-inch rudder and half-inch
elevator for starters. It is probably better to
have a little more than less control for that
first flight. Once you get past that point, your
instructor (hopefully you will have one!) will
correct the control throws as necessary to
make life easier for you as you learn to fly
and solo.
Making adjustments to increase or
decrease control throws (control-surface
movements) is generally handled by the
selection of the hole position on the servo
output arm and the control horn on the control
surface. Moving the clevis attach point from
the outside control-horn holes to the inside
will cause increased throw. The same can be
done (if more convenient) at the servo output
arm. Moving from the outside hole closer in
to the servo-output-arm hub will prompt a
decrease in control throw.
June 2003 53
Never forget to make safety checks on your
model. Do this before your first flight and on a
regular basis thereafter. One of the most
common problems is failing to properly attach
the control-surface hinges. Hinge choices and
their installation will be the subject of a future
article.
For now, no matter what type of hinge you
use, physically pull on the control surface to
make sure it is secured properly.
Throughout the years, I can’t tell you how
many rudders or elevators I’ve pulled off of
beginners’ models before a first flight. You can
have the best radio system and the best model
in the world, but if a rudder or elevator falls off
in flight you will have no model at all!
In the same regard, make sure that all of
your control-rod clevises, or whatever
connectors you employ, are locked in place.
Small keepers can be purchased to slip over the
clevis so it can’t separate. Other types of
“keepers” prevent a Z-bend wire end from
dropping off of a servo output arm.
Also make sure you have that single screw
in place holding the output arm to the servo
hub. I’ve seen many output arms fall off in
flight, only to result in major crashes. The
radio and aircraft worked fine, but those pilots
were beaten by a single missing screw (known
as single-point failure).
Most trainer-type models’ wings are held to
the fuselage with a few rubber bands. You
shouldn’t be too casual with what looks like a
simple task; don’t use a couple of leftover
rubber bands. Most average to larger models
should use the standard No. 64 rubber bands.
The smaller models, such as park flyers, can
use lighter-weight No. 33 size. You can find
these rubber bands in quantity (bags or boxes)
at the larger stationery stores (such as Staples
and Office Max).
Each model should employ approximately
six rubber bands to hold down a wing. Use a
cross pattern, such as front left dowel to right
rear dowel (three and three). Although
seemingly wasteful, use new rubber bands
each time you go to the flying field; it’s cheap
insurance.
Every RC receiver will have an antenna
wire, which is usually roughly 40 inches long,
exiting its case. On larger models you will
have plenty of room to “hang” or stretch out
this length of wire. On the smaller models you
may end up with a considerable excess length
that has to trail off the rear of the model. Don’t
54 MODEL AVIATION
cut any of this antenna wire off! Your receiver
is tuned for that specific length. Making the
antenna shorter can have a serious effect on
your RC performance. Most important, the
range of radio operation might be reduced.
As you get into the hobby, you will learn
that special shortened antenna rods can be
substituted for the full length of wire. A
primary source for these antennas is Eclectic
Electric Necessities, or E-Cubed R/C
(www.ecubedrc.com). Several models are
available, down to as short as 11⁄2 inches in
length. Radio reception is said to only be
reduced by 15%. However, you will be
required to cut off the existing antenna close to
the receiver case, then solder the wire from the
new rod to the remaining wire stub. For now
I’d prefer that you stick with the supplied, fulllength
antenna.
Antenna routing, or locating in the fuselage
then out to the tail, is most important. If you
get too close to such noise generators as a
servo (the motor inside) or an ESC, you might
see interference in the form of jittery controls
or reduced radio range.
The best idea is to get the antenna wire
outside the fuselage as soon as possible, then
route the long wire up to the top of the fixed
vertical fin or out to the tip of the stabilizer. I
generally drill two holes in the stabilizer tip or
top of the vertical fin, and pass the antenna
wire in one hole and out the other. I don’t like
to place any real tension on the antenna wire
because it might eventually break. Nor do I
favor attaching the antenna wire to any
moving surface, such as the elevator or rudder;
the constant flexing motion could eventually
break the wire.
With every new airplane and new radiosystem
installation, you must run a prescribed
range check to make sure you have adequate
control when the aircraft gets hundreds of feet
away from you in the air.
The best way to do that is to collapse the
transmitter antenna as much as it will go. If it
retracts all the way into the case, leave a few
inches sticking up above the top of the case.
By doing this, you will greatly reduce your
transmitter’s transmitting power, which will
allow a simulated range check, but at a much
shorter distance.
Turn on the transmitter then the receiver.
Operate all of the control functions. Have a
friend hold the aircraft and walk away from
you. You will be holding the transmitter and
moving, say, the rudder control stick hard
every few seconds. At the aircraft end you
should see the rudder move positively to your
exact commands.
A point will be reached where the control
surface will start to get nervous or jittery. A
little beyond that point the radio may even
stop working (the control surface locks or
simply doesn’t move). The exact point at
which that happens can vary between 50 and
100 feet. The exact distance can be determined
from your RC-system operation manual or by
contacting the manufacturer directly.
If you only get 10 feet or so, you have a
problem. It might be in the radio itself, the
batteries might not be charged, or the antennawire
routing might be too close to a servo. No
matter what the problem, it must be resolved
June 2003 55
before you attempt a first flight.
It’s a good idea to run such a check at your
local flying field. Get a club member or a
local flier to coach you through this process
the first time around. Remember to obtain the
frequency-control pin for your channel
number before you turn on your transmitter!
Since fueled engine vibration and
electrical noise generated by electric motors
can have an effect on radio range, run the
same transmitter-antenna-collapsed range
check while running your fueled engine or
electric motor. If everything is okay, you
should be able to obtain the same range
regardless of whether the engine/motor is
running or not.
On most four-channel RC transmitters
with dual control-stick assemblies, there is a
hook and eye located in roughly the center of
the front panel. This bracket accepts a neck
strap that many RC manufacturers supply with
their systems. You put the strap around your
neck and attach it to the hook and eye on the
transmitter case. The strap helps support the
case, leaving your fingers free to grip or
operate both control-stick assemblies.
Complete transmitter support trays are also
available. Their use is quite common with the
RC pilots throughout Europe. The tray is
supported by a neck strap, then the RC
transmitter is placed into the tray. Longerlength
control sticks are usually substituted.
The pilot can grip them, making it feel more
like flying a full-scale aircraft. I encourage
you, as a new flier, to keep it simple and resort
to these support devices later, as you gain
experience.
I almost forgot to mention that most RC
transmitters provide certain adjustment for
control-stick length and spring tension. You
can read about how to do this in your
operating manual. It is strictly a matter of
preference; I rarely change a factory controlstick
setting on any of my transmitters.
There are several items you should be aware
of as you begin your flight training. They will
be the subject of articles in the near future, as
you absorb all of the details of this wonderful
hobby.
56 MODEL AVIATION
One such item is a “trainer cable.” Many
RC transmitters have trainer jacks or
connectors and trainer-operated switches. You
can purchase the cable as an accessory item
from your RC-system manufacturer. You must
have the same brand of RC system, and it is
helpful, though not imperative, that you have
the same model of RC transmitter.
The idea is to plug this 6- to 10-foot cable
between the two transmitters. Only one
transmitter will actually send the signals or
control commands to the aircraft. Your
instructor holds one transmitter and you hold
the other. You will be in control of your
aircraft, but if you get into a situation that
might prompt a crash, the instructor holds onto
a long-handled switch and instantly takes over
control of the model. This is considered a
better technique than having the instructor grab
the transmitter from you each time you get into
trouble.
We have recently seen several selfstabilizing
devices come onto the hobby
market. The one that comes to mind is the
FMA Direct Co-Pilot, which I reviewed in the
August 2002 Model Aviation (pages 77-79).
This device uses an infrared sensor, located on
the bottom of the fuselage, to sense and
maintain level flight.
Let’s say you make a turn and the aircraft
starts to spiral and descend. Just take your
fingers off the control sticks, and the Co-Pilot
will almost instantly return your model to level
flight. This is where the term “self-stabilizing”
comes from.
Simulators are an extension of video
games. They operate from a personal computer
(PC) and use a transmitter case and control
sticks instead of the traditional mouse. You
view the aircraft’s flight on the PC monitor
and input controls via the transmitter box.
These simulators have become quite refined in
recent years and offer considerable realism,
making it easier to learn some of the basic
control maneuvers. The use of simulators will
be the subject of a separate Model Aviation
article in the near future.
After all of this, you are ready to go out to the
flying field and make your first flight. Well,
almost ready. We haven’t discussed a specific
first-time model. It is important to learn how to
assemble it (in the case of an Almost Readyto-
Fly, or ARF, type of model) and install the
necessary RC equipment, and then you can
head out to the field for that first flight.
Next month I’ll introduce you to electricpowered
flight. It’s my specialty, and I have
used it exclusively for many years. I’ve had
considerable success training new RC pilots
using this form of power.
My intention in succeeding articles in this
series is to select an electric-powered ARF,
assemble it, show how to operate it, then get
you out for that first flight. After that I have a
simple-to-construct, original-design electricpowered
sailplane to include. The idea will
be to teach you “scratch building” from
magazine plans in its simplest form. All of
the radio and electric power equipment
from your ARF will be transferred to the
scratch-built model. You will also receive
the all-important flying instructions.
June 2003 57
I recognize that not everyone in our hobby
likes or wants electric power, so guest
authors/experts will write articles for this
series to include such topics as assembling
and flying glow-fueled ARFs and basic
building techniques and covering skills that
everyone needs to know, regardless of what
power source you choose. We hope to get into
model kit building as well.
Other types of models will be explored
that do not employ RC, yet can be equally
enjoyable to fly (such as Control Line, Free
Flight, rubber power, and Hand-Launched
Gliders). That’s what this series is all about.
Please write in with your questions and
suggestions to “From the Ground Up” in care
of Bob Hunt, Box 68, Stockertown PA 18083;
E-mail: [email protected]. That is most
important to us. MA
Bob Aberle
Sources:
RC Systems
Airtronics Inc.
1185 Stanford Ct.
Anaheim CA 92805
(714) 978-1895
[email protected]
www.airtronics.net
Castle Creations
18773 W. 117th St.
Olathe KS 66061
(913) 438-6325
Fax: (913) 438-1394
www.castlecreations.com
FMA Direct
5716A Industry Ln.
Frederick MD 21704
(800) 343-2934
Fax: (301) 668-7619
[email protected]
www.fmadirect.com
Futaba Corporation of America:
Great Planes Model Distributors
Box 9021
Champaign IL 61826-9021
(800) 637-7660 or (217) 398-6300
[email protected]
www.futaba-rc.com
GWS:
Balsa Products
122 Jansen Ave.
Iselin NJ 08830
(732) 634-6131
www.balsapr.com
and
Horizon Hobby Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.horizonhobby.com
Hitec RCD
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
JR Remote Control:
Horizon Hobby Inc.
Multiplex USA:
Hitec RCD
and
Royal Hobby Distributors
8295 Tujunga Ave.
Sun Valley CA 91352
(818) 771-1003
www.multiplexrc.com
Tower Hobbies
Box 9078
Champaign IL 61826-9078
(800) 637-6050
www.towerhobbies.com
Batteries
SR Batteries Inc.
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
Batteries America
2211-D Parview Rd.
Middleton WI 53562
(800) 308-4805
[email protected]
www.batteriesamerica.com
Maxx Products International
815 Oakwood Rd. Unit D
Lake Zurich IL 60047
(847) 438-2233
Ordering only: (800) 416-MAXX (6299)
Fax: (847) 438-2898
www.maxxprod.com/
Hardware:
Carl Goldberg Products Inc.
Box 818
Oakwood GA 30566
(678) 450-0085
Fax: (770) 532-2163
www.carlgoldbergproducts.com
Du-Bro Products
Box 815
Wauconda IL 60084
(800) 848-9411
Fax: (847) 526-1604
www.dubro.com
Sonic-Tronics Inc.
7865 Mill Rd.
Elkins Park PA 19027
(215) 635-6520
Fax: (215) 635-4951
[email protected]
www.sonictronics.com
Sullivan Products
1 N. Haven St.
Box 5166
Baltimore MD 21224
(410) 732-3500
Fax: (410) 327-7443
www.sullivanproducts.com