Radio Control System Installation 2003/05

ast month in this series I gave you a basic
introduction—from an informational and identification
standpoint—that would enable you to purchase your
first Radio Control (RC) system. This month I will take
you from the shipping box to the model aircraft. The
discussion will cover the installation aspects of a typical RC
system.
Dual Conversion and Narrow Band: There are two terms I didn’t
discuss last month which have been brought to my attention by
several reader letters (remember, the ones I asked for?).
With regard to RC receivers, “dual conversion” is a technique
in which the receiver operates at two lesser frequencies besides
the operating frequency. The basic dual-conversion receiver
employs two crystals rather than one. Because of the “extra” level
of conversion, these receivers can be made more selective and
more immune to certain interference situations.
The basic dual-conversion receiver will, by nature, be slightly
larger in size, weigh a little more, and be slightly more expensive
than a single-conversion receiver. There is nothing wrong with
single conversion, and several lines of RC receivers have used that
type of circuitry successfully for many years. However, most
receiver labels these days will identify the product as “dual
conversion.”
Along these same lines you will see the expression “narrowband”
performance. When we obtained our 50 RC channels in
1982, we were committed to operate in a much “tighter” channel
environment. Older RC channel separation was 80 kilohertz
(kHz), and our new channels were placed at a narrow spacing of
20 kHz. To meet the new demand (at the time) required
considerable improvements in the RC electronic circuitry.
That is past us now and anything you can purchase today will
almost exclusively be “narrow band,” meaning that it will operate
safely with an adjacent channel operating next to you on the
flightline.
Batteries and Charging: The first thing you have to do after
unpacking your new RC system is charge the batteries that power
the system. I wrote about this last month. RC transmitters are
usually powered by eight AA-size battery cells, and the typical
airborne pack (the pack that goes inside the model) has four cells
Radio Control
Hitec Neon three-channel components set up for electricpowered
flight: receiver (top left); two servos (top center);
battery pack capable of powering electric motor and RC
system (right); Castle Creations Pixie-14 ESC, which takes
engine throttle servo’s place in this application (bottom).
Components supplied with Laser 6 system: four servos (top left),
receiver (middle left), battery pack (middle right), switch harness
(below pack), aileron extension cable (at bottom).
The Hitec Laser 6 is a basic four-channel-function system
capable of operating ailerons, rudder, elevator, throttle.
The Hitec RCD Neon FM three-channel RC system is a
good first radio. The transmitter is in the background.
24 MODEL AVIATION
lSystem ■ Bob Aberle
receivers—all of
dual-conversion
circuitry: (from
top to bottom)
Futaba R127DF,
Airtronics 92745,
Hitec 3500.
RC system as it would typically be installed in trainer. Author made mock-up to show how components are placed and mounted. Red
area simulates wing location. (This is not to any particular scale.)
Front portion of model’s fuselage looking aft. Engine is up front,
followed by fuel tank, airborne battery pack, receiver, switch
harness, three servos.
The heart of the RC system: receiver (left), switch/charging jack
(center), servos (on right). Nylon ties help organize bundles of
cables.
Close-up of typical glow-fueled engine. Fuel tank has been
simulated. It should be positioned as close to engine as possible
to maintain good fuel draw.
Installation
May 2003 25
Typical RC
26 MODEL AVIATION
The on/off placard is important!
Typical control-surface hinges using Sonic-Tronics light hinges.
Knife slots are cut into balsa surfaces. Hinges are inserted into
slots on halves, then a drop of cyanoacrylate glue holds hinge in
place.
At the tail of the model, separate control horns are used for the
elevator- and rudder-control attachments. Vertical fin and rudder shown hinged. At right is typical controlhookup
hardware: control horns (top), clevises and threaded
adjustment rods (center), wire and keeper that attach to servo
output arms (bottom).
If you fly with aileron control, the servo for that function is
usually mounted in the wing. An aileron extension cable may be
needed to reach RC receiver located inside fuselage.
Close-up of three servos. Location of output arms are staggered
so control rods won’t interfere with one another.
May 2003 27
One side of rudder on a tail-dragger, showing how control rod is
attached to horn. Rudder moves as does tail wheel.
Four-cell airborne battery box (left) holds AA alkaline cells.
Typical four-cell Ni-Cd rechargeable battery pack is on right.
Charging RC transmitter, receiver battery pack directly.
Charging receiver or airborne battery pack by going through
charging jack located on power switch harness assembly. Green
LED lit on charger indicates that it is charging battery properly.
Cable on other side of switch goes to receiver.
(usually AA, but they can be smaller).
In some of the inexpensive and basic
systems, you may have to use
nonrechargeable alkaline battery cells. If
you do, purchase at least a dozen cells and
insert them into the transmitter and receiver
battery boxes. Be careful to observe the
battery polarity (positive [+] and negative
[–]).
Most RC systems will be provided with
rechargeable batteries. The majority will be
the Nickel Cadmium (Ni-Cd) variety. To a
lesser degree, you may be supplied with
Nickel Metal Hydride (NiMH) batteries.
As a beginner you won’t have to be
concerned with the type of battery because
the manufacturer will have thoughtfully
provided the correct companion battery
charger. That charger will usually be a wallplug
type transformer with two cables
exiting the case (small black box). The
transformer plugs into any 115VAC
electrical outlet.
One cable exiting the transformer gets
plugged into the charging jack located on
the side, bottom, front, or rear of the
transmitter case. The connectors for the
transmitter and receiver are different, so
there will never be any confusion about
which cable goes where.
On the receiver side there are two
possibilities for charging your batteries. In
one case you physically unplug the battery
pack from the switch harness and plug the
charger cable directly into the battery. On
some of the more deluxe RC systems, the
switch harness includes a charging jack.
When this is provided, you don’t have to
unplug the battery pack. Just plug the cable
into the charging jack, which is an integral
part of the switch-harness assembly. But to
do this will normally require that you
remove the wing so you have access to that
cable, which is located inside the fuselage
radio compartment.
Some manufacturers make these
charging jacks so they can be mounted on
the side of the model’s fuselage, such that
they protrude to the outside. With that kind
of arrangement you can plug in the charger
cable from the exterior of the fuselage
without the need to gain access to the radio
compartment inside the aircraft.
Almost all charging will be done at home
in your shop, and presumably the wing will
have been removed for transportation and
storage purposes. The external fuselage
charging jack will come into play later,
when you learn to use field-type batterycapacity
testers or when the need arises for a
quick field charge.
It is important for you to determine that
your charger is working properly before you
leave it unattended. Each wall-plug
transformer will have two colored lightemitting
diodes (LEDs); they may be red,
green, or red and green! When you
successfully connect a charger cable, that
LED should glow to let you know that the
charging has started. If you are charging
both batteries, you should have two
glowing LEDs.
Photos courtesy the author Graphic Design by Lydia Whitehead
Typical RC connectors. On left is Futaba J connector on end of
servo cable. Black is normally used for negative battery wire.
Red, or positive, lead wire is in the center. On the right is a white
wire for signal function. Next are mating halves of a Hitec
connector. Red positive lead is still in center. Hitec uses yellow
for third, or signal, lead. At extreme right is mating set of Deans
three-pin connectors—the only connectors you can easily solder.
They are popular with do-it-yourself modelers.
Most receivers have connector block on one end to which all
servos and battery power plug in. Shown is servo cable plugged
into Channel-1 function; two-wire cable plugs into battery input
connector at other end.
Each servo comes with extra output arms, mounting hardware.
Supplied rubber grommets (four for each servo!) must be
pressed into mounting flanges of servo. Brass eyelets are
pressed into grommets from lower side of servo.
Antenna is affixed with small nylon tie to top of vertical fin. Never
connect antenna to movable surface since constant motion will
quickly break off wire.
Mounting screw is passed through eyelet, grommet from top
side.
28 MODEL AVIATION
The first time you charge your new
battery packs, you are advised to leave
them on charge for a full 24 hours. After
that, it is normal to leave the charger on
overnight. These batteries have been
designed to take hundreds and hundreds of
recharging cycles. Most batteries will
provide several years of regular service
without degrading in performance.
Because your RC-system charger
operates on such a low level, nothing will
really happen if you forget and leave a
charger on for, say, 48 hours. In the same
regard, don’t play the “I’ll put back in
what I took out” game; that is, you use the
RC system for two hours, so you recharge
it for only two hours. Don’t even think of
doing that!
The battery chemistry is such that it
must be on charge for a period of at least
10 hours each time. If you plan on flying
the next day, put the charger on the night
before. If you don’t fly the next day
because of bad weather and a week goes
by, charge it again. When in doubt, charge
again; it can’t hurt, but it sure can help!
One final caution: when charging,
make sure you plug your charger into a
115VAC outlet that remains on all the
time. Let’s say you choose an outlet that is
operated by a switch near the door to your
shop. As you exit the shop for the night
and turn off the overhead lights, you may
have also turned off your charger. The
next day you go flying and your model
crashes after the first or second flight
because the batteries were never charged.
The subject of batteries is extremely
important to the RC system’s operation.
As I progress in this series I will feed you
more information about battery-capacity
testing at home and at the flying field.
Connectors and Wiring Polarity: Your
RC transmitter is a self-contained unit that
you hold in your hands. On the aircraft
side you have a series of components that
must be installed or mounted inside the
aircraft fuselage, then all of those
components must be connected so you
have an operating airborne RC system.
That interconnecting is done with
“connectors.” They allow you to make and
break electrical connections without
needing to solder wire; the manufacturer
has already done the soldering and/or
mechanical wire crimping for you.
Years ago, types of connectors varied
considerably from manufacturer to
manufacturer. One brand would not work
with or fit into another brand. In many
cases the wire color coding was different,
as was the order of polarity. Things have
become more standardized throughout the
industry, but the best advice I can give you
when starting out is never mix or match
different brands of connectors.
If you purchased a Futaba RC system,
use only Futaba components and Futaba
connectors. The same goes for the charger
and charging cables I just discussed. Use
only the charger that was supplied with
May 2003 29
your system. For now, while you are
getting started, use the components as
supplied. You may make exceptions to this
rule as you gain experience.
Most connectors have keyways or slots
that permit them to be connected only one
way. Wiring convention used by most of
the RC industry today has the positive (+)
pin or wire in the center of a basic threepin
connector.
Battery power circuits use two wires,
and the servo cables have three wires. By
having the positive wire in the center, if
you are actually able to plug a connector in
backward, the circuit will be incomplete.
Nothing would work, but at least nothing
would be short-circuited and blow out.
Basic RC Component Installation: The
components that make up your airborne
RC system include the receiver, servos,
battery pack, switch harness, and an
aileron extension cable if you are using
aileron control (on the wings of your
aircraft). You will need a servo for each
control function: rudder, elevator, aileron
(if applicable), and engine throttle. That is
typical for a fuel-powered model.
If you were flying an electric-powered
airplane, the throttle servo would be
May 2003 31
replaced with an Electronic Speed Control
(ESC). You plug the ESC cable into the
same throttle port (connector) on your
receiver as you would a throttle servo.
Operating the throttle control stick on
your transmitter would then vary the
motor’s speed.
Not to complicate the initial story, but
most ESCs, intended for the smaller-size
electric-powered models, contain an
internal Battery Eliminator Circuit (BEC).
It will allow you to use one battery pack to
power your model’s motor and your RC
system (on a shared basis). I’ll write more
about this when I get into electricpowered
models.
Placement of the RC components
involves a couple of considerations. Most
important, these radio parts add weight to
your model. The components’ location can
affect your aircraft’s center of gravity
(CG) or balance point. An improperly
balanced model (too tail-heavy or noseheavy)
is not going to fly well, or at all.
Another consideration is the length of the
cables supplied with the various
components. Failure to arrange them in a
logical order can leave you with cables
that are too short or too long.
Traditionally, the RC battery pack is
placed up front, just behind the engine and
fuel tank. Most basic aircraft designs have
shorter nose lengths and longer tail
lengths, hence the need for more weight
forward. Your battery pack will probably
be the heaviest weight in the system. You
can put that weight to the best possible
advantage while attempting to achieve the
correct balance.
Working your way back from the
model’s nose, the item behind the battery
pack should be the throttle servo, which
must be mechanically connected to the
engine carburetor. If you have an electricpowered
aircraft, the ESC should be
located in roughly the same area as the
throttle servo. After this we should be
approximately at the position of the
wing’s leading edge (the front of the
wing).
The wing usually covers the model’s
“RC compartment.” When you remove the
wing (be it located on the top or bottom of
the fuselage), you are able to access this
section. The front portion of this
compartment is where the RC receiver is
generally installed. Behind the receiver (in
roughly the middle of the space) is a good
place for the power (on/off) switch and the
charging jack. The rudder and elevator
servos go toward the aft portion of the
compartment.
Some modelers locate the throttle servo
back at this position (shown on the mockup).
If they do, they must run a control rod
back forward to the engine throttle. With
this kind of arrangement, all the servo
cables (and the ESC cable for electric
power) can easily reach the mating
connector block on the receiver.
If you are using aileron control, it’s a
good idea to first plug an aileron extension
cable into the receiver. The other end of
this extension can pass up toward the wingmounted
aileron servo. When you attach the
wing before flying, that aileron servo must
be connected to the extension cable. In the
same regard, you must disconnect the
aileron servo cable from the extension cable
when you remove the wing for
transportation or storage.
The remaining installation involves
running control rods back to the rear or tail
surfaces of the aircraft. The output of the
rudder servo up front must be connected to
the movable rudder at the model’s tail, and
the elevator servo output must be connected
to the elevator control surface in the rear.
More details of these control-rod hookups
will be discussed in the installment dealing
with model assembly.
Most aircraft have a tail-dragger
configuration, in which the model’s tail
rests on the ground. A tail wheel is attached
to the rudder and moves with the rudder to
steer or maneuver the aircraft when it is
taxiing on the ground. As you will learn,
aircraft that do not have groundmaneuvering
capability are usually hand
launched.
The other popular aircraft configuration
is the tricycle landing gear (trike gear). In
this arrangement the aircraft sits relatively
level on two rear-mounted main wheels and
a single nose, or forward, wheel. That nose
wheel is mechanically connected to the
rudder servo such that the aircraft can be
steered while on the ground. Trike gear is
probably the easier configuration for the
rank beginner to handle and learn, but
hooking up the nose-wheel steering can
prove more complex.
The last, but important, item of concern
is deploying the receiver antenna wire
properly. Each modern RC receiver has a
wire antenna measuring approximately 40
inches that exits its case. The smaller the
aircraft, the harder it is to “deploy” this
antenna wire properly.
The time-honored method is to run the
antenna wire from the receiver directly to
the outside of the fuselage (through a smalldiameter
hole), then out to the rear of the
aircraft where it can be attached to the top
of the vertical fin or the tip of the stabilizer.
The antenna should never be attached to
a movable tail surface such as the rudder or
elevator; the constant flexing could
eventually break the wire. Under no
circumstances should you reduce the
antenna wire’s length. To do so might
detune the output stage of your receiver and
greatly reduce radio range. Several
excellent reduced-size antennas are
available for use with the smaller models; I
will get to that later. For now the beginner
should concentrate on using the full-length
antenna.
These wire receiver antennas can pick
up more than received radio signals; they
can pick up, for instance, electrical noise
generated by the motors inside the servos.
Keeping this in mind, it is important that
you keep away from the servo actuators
when routing your antenna wire to the rear
of the aircraft. Try to get the antenna
outside and away from these noise
generators.
RC System Mock-Up: To put everything
in the proper physical size and location, I
have included a mock-up of a typical
airborne RC system. It is laid out exactly as
the RC equipment would be installed in
your aircraft. Keep it as a reference for RCmodel
installations.
May 2003 33
I have reached another cutoff point. By
now you should have a good idea of what to
buy and how to install it in your aircraft.
Next month I’ll take up the subject of RCsystem
operation. From there this series will
go into selecting and assembling an Almost
Ready-to-Fly, or ARF, trainer, how to fuel
and start your engine, and how to make that
all-important first flight.
Please keep writing in with your
questions addressed to “From the Ground
Up” in care of Bob Hunt, Box 68,
Stockertown PA 18083; E-mail:
[email protected]. We try to think of
everything, but there will be missed items or
ones with which you have concern. Model
Aviation wants this series to grow! 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
Polk’s Hobbies
698 S. 21st St.
Irvington NJ 07111
(973) 351-9800
Fax: (973) 351-9700
[email protected]
www.polkshobby.com

ast month in this series I gave you a basic
introduction—from an informational and identification
standpoint—that would enable you to purchase your
first Radio Control (RC) system. This month I will take
you from the shipping box to the model aircraft. The
discussion will cover the installation aspects of a typical RC
system.
Dual Conversion and Narrow Band: There are two terms I didn’t
discuss last month which have been brought to my attention by
several reader letters (remember, the ones I asked for?).
With regard to RC receivers, “dual conversion” is a technique
in which the receiver operates at two lesser frequencies besides
the operating frequency. The basic dual-conversion receiver
employs two crystals rather than one. Because of the “extra” level
of conversion, these receivers can be made more selective and
more immune to certain interference situations.
The basic dual-conversion receiver will, by nature, be slightly
larger in size, weigh a little more, and be slightly more expensive
than a single-conversion receiver. There is nothing wrong with
single conversion, and several lines of RC receivers have used that
type of circuitry successfully for many years. However, most
receiver labels these days will identify the product as “dual
conversion.”
Along these same lines you will see the expression “narrowband”
performance. When we obtained our 50 RC channels in
1982, we were committed to operate in a much “tighter” channel
environment. Older RC channel separation was 80 kilohertz
(kHz), and our new channels were placed at a narrow spacing of
20 kHz. To meet the new demand (at the time) required
considerable improvements in the RC electronic circuitry.
That is past us now and anything you can purchase today will
almost exclusively be “narrow band,” meaning that it will operate
safely with an adjacent channel operating next to you on the
flightline.
Batteries and Charging: The first thing you have to do after
unpacking your new RC system is charge the batteries that power
the system. I wrote about this last month. RC transmitters are
usually powered by eight AA-size battery cells, and the typical
airborne pack (the pack that goes inside the model) has four cells
Radio Control
Hitec Neon three-channel components set up for electricpowered
flight: receiver (top left); two servos (top center);
battery pack capable of powering electric motor and RC
system (right); Castle Creations Pixie-14 ESC, which takes
engine throttle servo’s place in this application (bottom).
Components supplied with Laser 6 system: four servos (top left),
receiver (middle left), battery pack (middle right), switch harness
(below pack), aileron extension cable (at bottom).
The Hitec Laser 6 is a basic four-channel-function system
capable of operating ailerons, rudder, elevator, throttle.
The Hitec RCD Neon FM three-channel RC system is a
good first radio. The transmitter is in the background.
24 MODEL AVIATION
lSystem ■ Bob Aberle
receivers—all of
dual-conversion
circuitry: (from
top to bottom)
Futaba R127DF,
Airtronics 92745,
Hitec 3500.
RC system as it would typically be installed in trainer. Author made mock-up to show how components are placed and mounted. Red
area simulates wing location. (This is not to any particular scale.)
Front portion of model’s fuselage looking aft. Engine is up front,
followed by fuel tank, airborne battery pack, receiver, switch
harness, three servos.
The heart of the RC system: receiver (left), switch/charging jack
(center), servos (on right). Nylon ties help organize bundles of
cables.
Close-up of typical glow-fueled engine. Fuel tank has been
simulated. It should be positioned as close to engine as possible
to maintain good fuel draw.
Installation
May 2003 25
Typical RC
26 MODEL AVIATION
The on/off placard is important!
Typical control-surface hinges using Sonic-Tronics light hinges.
Knife slots are cut into balsa surfaces. Hinges are inserted into
slots on halves, then a drop of cyanoacrylate glue holds hinge in
place.
At the tail of the model, separate control horns are used for the
elevator- and rudder-control attachments. Vertical fin and rudder shown hinged. At right is typical controlhookup
hardware: control horns (top), clevises and threaded
adjustment rods (center), wire and keeper that attach to servo
output arms (bottom).
If you fly with aileron control, the servo for that function is
usually mounted in the wing. An aileron extension cable may be
needed to reach RC receiver located inside fuselage.
Close-up of three servos. Location of output arms are staggered
so control rods won’t interfere with one another.
May 2003 27
One side of rudder on a tail-dragger, showing how control rod is
attached to horn. Rudder moves as does tail wheel.
Four-cell airborne battery box (left) holds AA alkaline cells.
Typical four-cell Ni-Cd rechargeable battery pack is on right.
Charging RC transmitter, receiver battery pack directly.
Charging receiver or airborne battery pack by going through
charging jack located on power switch harness assembly. Green
LED lit on charger indicates that it is charging battery properly.
Cable on other side of switch goes to receiver.
(usually AA, but they can be smaller).
In some of the inexpensive and basic
systems, you may have to use
nonrechargeable alkaline battery cells. If
you do, purchase at least a dozen cells and
insert them into the transmitter and receiver
battery boxes. Be careful to observe the
battery polarity (positive [+] and negative
[–]).
Most RC systems will be provided with
rechargeable batteries. The majority will be
the Nickel Cadmium (Ni-Cd) variety. To a
lesser degree, you may be supplied with
Nickel Metal Hydride (NiMH) batteries.
As a beginner you won’t have to be
concerned with the type of battery because
the manufacturer will have thoughtfully
provided the correct companion battery
charger. That charger will usually be a wallplug
type transformer with two cables
exiting the case (small black box). The
transformer plugs into any 115VAC
electrical outlet.
One cable exiting the transformer gets
plugged into the charging jack located on
the side, bottom, front, or rear of the
transmitter case. The connectors for the
transmitter and receiver are different, so
there will never be any confusion about
which cable goes where.
On the receiver side there are two
possibilities for charging your batteries. In
one case you physically unplug the battery
pack from the switch harness and plug the
charger cable directly into the battery. On
some of the more deluxe RC systems, the
switch harness includes a charging jack.
When this is provided, you don’t have to
unplug the battery pack. Just plug the cable
into the charging jack, which is an integral
part of the switch-harness assembly. But to
do this will normally require that you
remove the wing so you have access to that
cable, which is located inside the fuselage
radio compartment.
Some manufacturers make these
charging jacks so they can be mounted on
the side of the model’s fuselage, such that
they protrude to the outside. With that kind
of arrangement you can plug in the charger
cable from the exterior of the fuselage
without the need to gain access to the radio
compartment inside the aircraft.
Almost all charging will be done at home
in your shop, and presumably the wing will
have been removed for transportation and
storage purposes. The external fuselage
charging jack will come into play later,
when you learn to use field-type batterycapacity
testers or when the need arises for a
quick field charge.
It is important for you to determine that
your charger is working properly before you
leave it unattended. Each wall-plug
transformer will have two colored lightemitting
diodes (LEDs); they may be red,
green, or red and green! When you
successfully connect a charger cable, that
LED should glow to let you know that the
charging has started. If you are charging
both batteries, you should have two
glowing LEDs.
Photos courtesy the author Graphic Design by Lydia Whitehead
Typical RC connectors. On left is Futaba J connector on end of
servo cable. Black is normally used for negative battery wire.
Red, or positive, lead wire is in the center. On the right is a white
wire for signal function. Next are mating halves of a Hitec
connector. Red positive lead is still in center. Hitec uses yellow
for third, or signal, lead. At extreme right is mating set of Deans
three-pin connectors—the only connectors you can easily solder.
They are popular with do-it-yourself modelers.
Most receivers have connector block on one end to which all
servos and battery power plug in. Shown is servo cable plugged
into Channel-1 function; two-wire cable plugs into battery input
connector at other end.
Each servo comes with extra output arms, mounting hardware.
Supplied rubber grommets (four for each servo!) must be
pressed into mounting flanges of servo. Brass eyelets are
pressed into grommets from lower side of servo.
Antenna is affixed with small nylon tie to top of vertical fin. Never
connect antenna to movable surface since constant motion will
quickly break off wire.
Mounting screw is passed through eyelet, grommet from top
side.
28 MODEL AVIATION
The first time you charge your new
battery packs, you are advised to leave
them on charge for a full 24 hours. After
that, it is normal to leave the charger on
overnight. These batteries have been
designed to take hundreds and hundreds of
recharging cycles. Most batteries will
provide several years of regular service
without degrading in performance.
Because your RC-system charger
operates on such a low level, nothing will
really happen if you forget and leave a
charger on for, say, 48 hours. In the same
regard, don’t play the “I’ll put back in
what I took out” game; that is, you use the
RC system for two hours, so you recharge
it for only two hours. Don’t even think of
doing that!
The battery chemistry is such that it
must be on charge for a period of at least
10 hours each time. If you plan on flying
the next day, put the charger on the night
before. If you don’t fly the next day
because of bad weather and a week goes
by, charge it again. When in doubt, charge
again; it can’t hurt, but it sure can help!
One final caution: when charging,
make sure you plug your charger into a
115VAC outlet that remains on all the
time. Let’s say you choose an outlet that is
operated by a switch near the door to your
shop. As you exit the shop for the night
and turn off the overhead lights, you may
have also turned off your charger. The
next day you go flying and your model
crashes after the first or second flight
because the batteries were never charged.
The subject of batteries is extremely
important to the RC system’s operation.
As I progress in this series I will feed you
more information about battery-capacity
testing at home and at the flying field.
Connectors and Wiring Polarity: Your
RC transmitter is a self-contained unit that
you hold in your hands. On the aircraft
side you have a series of components that
must be installed or mounted inside the
aircraft fuselage, then all of those
components must be connected so you
have an operating airborne RC system.
That interconnecting is done with
“connectors.” They allow you to make and
break electrical connections without
needing to solder wire; the manufacturer
has already done the soldering and/or
mechanical wire crimping for you.
Years ago, types of connectors varied
considerably from manufacturer to
manufacturer. One brand would not work
with or fit into another brand. In many
cases the wire color coding was different,
as was the order of polarity. Things have
become more standardized throughout the
industry, but the best advice I can give you
when starting out is never mix or match
different brands of connectors.
If you purchased a Futaba RC system,
use only Futaba components and Futaba
connectors. The same goes for the charger
and charging cables I just discussed. Use
only the charger that was supplied with
May 2003 29
your system. For now, while you are
getting started, use the components as
supplied. You may make exceptions to this
rule as you gain experience.
Most connectors have keyways or slots
that permit them to be connected only one
way. Wiring convention used by most of
the RC industry today has the positive (+)
pin or wire in the center of a basic threepin
connector.
Battery power circuits use two wires,
and the servo cables have three wires. By
having the positive wire in the center, if
you are actually able to plug a connector in
backward, the circuit will be incomplete.
Nothing would work, but at least nothing
would be short-circuited and blow out.
Basic RC Component Installation: The
components that make up your airborne
RC system include the receiver, servos,
battery pack, switch harness, and an
aileron extension cable if you are using
aileron control (on the wings of your
aircraft). You will need a servo for each
control function: rudder, elevator, aileron
(if applicable), and engine throttle. That is
typical for a fuel-powered model.
If you were flying an electric-powered
airplane, the throttle servo would be
May 2003 31
replaced with an Electronic Speed Control
(ESC). You plug the ESC cable into the
same throttle port (connector) on your
receiver as you would a throttle servo.
Operating the throttle control stick on
your transmitter would then vary the
motor’s speed.
Not to complicate the initial story, but
most ESCs, intended for the smaller-size
electric-powered models, contain an
internal Battery Eliminator Circuit (BEC).
It will allow you to use one battery pack to
power your model’s motor and your RC
system (on a shared basis). I’ll write more
about this when I get into electricpowered
models.
Placement of the RC components
involves a couple of considerations. Most
important, these radio parts add weight to
your model. The components’ location can
affect your aircraft’s center of gravity
(CG) or balance point. An improperly
balanced model (too tail-heavy or noseheavy)
is not going to fly well, or at all.
Another consideration is the length of the
cables supplied with the various
components. Failure to arrange them in a
logical order can leave you with cables
that are too short or too long.
Traditionally, the RC battery pack is
placed up front, just behind the engine and
fuel tank. Most basic aircraft designs have
shorter nose lengths and longer tail
lengths, hence the need for more weight
forward. Your battery pack will probably
be the heaviest weight in the system. You
can put that weight to the best possible
advantage while attempting to achieve the
correct balance.
Working your way back from the
model’s nose, the item behind the battery
pack should be the throttle servo, which
must be mechanically connected to the
engine carburetor. If you have an electricpowered
aircraft, the ESC should be
located in roughly the same area as the
throttle servo. After this we should be
approximately at the position of the
wing’s leading edge (the front of the
wing).
The wing usually covers the model’s
“RC compartment.” When you remove the
wing (be it located on the top or bottom of
the fuselage), you are able to access this
section. The front portion of this
compartment is where the RC receiver is
generally installed. Behind the receiver (in
roughly the middle of the space) is a good
place for the power (on/off) switch and the
charging jack. The rudder and elevator
servos go toward the aft portion of the
compartment.
Some modelers locate the throttle servo
back at this position (shown on the mockup).
If they do, they must run a control rod
back forward to the engine throttle. With
this kind of arrangement, all the servo
cables (and the ESC cable for electric
power) can easily reach the mating
connector block on the receiver.
If you are using aileron control, it’s a
good idea to first plug an aileron extension
cable into the receiver. The other end of
this extension can pass up toward the wingmounted
aileron servo. When you attach the
wing before flying, that aileron servo must
be connected to the extension cable. In the
same regard, you must disconnect the
aileron servo cable from the extension cable
when you remove the wing for
transportation or storage.
The remaining installation involves
running control rods back to the rear or tail
surfaces of the aircraft. The output of the
rudder servo up front must be connected to
the movable rudder at the model’s tail, and
the elevator servo output must be connected
to the elevator control surface in the rear.
More details of these control-rod hookups
will be discussed in the installment dealing
with model assembly.
Most aircraft have a tail-dragger
configuration, in which the model’s tail
rests on the ground. A tail wheel is attached
to the rudder and moves with the rudder to
steer or maneuver the aircraft when it is
taxiing on the ground. As you will learn,
aircraft that do not have groundmaneuvering
capability are usually hand
launched.
The other popular aircraft configuration
is the tricycle landing gear (trike gear). In
this arrangement the aircraft sits relatively
level on two rear-mounted main wheels and
a single nose, or forward, wheel. That nose
wheel is mechanically connected to the
rudder servo such that the aircraft can be
steered while on the ground. Trike gear is
probably the easier configuration for the
rank beginner to handle and learn, but
hooking up the nose-wheel steering can
prove more complex.
The last, but important, item of concern
is deploying the receiver antenna wire
properly. Each modern RC receiver has a
wire antenna measuring approximately 40
inches that exits its case. The smaller the
aircraft, the harder it is to “deploy” this
antenna wire properly.
The time-honored method is to run the
antenna wire from the receiver directly to
the outside of the fuselage (through a smalldiameter
hole), then out to the rear of the
aircraft where it can be attached to the top
of the vertical fin or the tip of the stabilizer.
The antenna should never be attached to
a movable tail surface such as the rudder or
elevator; the constant flexing could
eventually break the wire. Under no
circumstances should you reduce the
antenna wire’s length. To do so might
detune the output stage of your receiver and
greatly reduce radio range. Several
excellent reduced-size antennas are
available for use with the smaller models; I
will get to that later. For now the beginner
should concentrate on using the full-length
antenna.
These wire receiver antennas can pick
up more than received radio signals; they
can pick up, for instance, electrical noise
generated by the motors inside the servos.
Keeping this in mind, it is important that
you keep away from the servo actuators
when routing your antenna wire to the rear
of the aircraft. Try to get the antenna
outside and away from these noise
generators.
RC System Mock-Up: To put everything
in the proper physical size and location, I
have included a mock-up of a typical
airborne RC system. It is laid out exactly as
the RC equipment would be installed in
your aircraft. Keep it as a reference for RCmodel
installations.
May 2003 33
I have reached another cutoff point. By
now you should have a good idea of what to
buy and how to install it in your aircraft.
Next month I’ll take up the subject of RCsystem
operation. From there this series will
go into selecting and assembling an Almost
Ready-to-Fly, or ARF, trainer, how to fuel
and start your engine, and how to make that
all-important first flight.
Please keep writing in with your
questions addressed to “From the Ground
Up” in care of Bob Hunt, Box 68,
Stockertown PA 18083; E-mail:
[email protected]. We try to think of
everything, but there will be missed items or
ones with which you have concern. Model
Aviation wants this series to grow! 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
Polk’s Hobbies
698 S. 21st St.
Irvington NJ 07111
(973) 351-9800
Fax: (973) 351-9700
[email protected]
www.polkshobby.com

ast month in this series I gave you a basic
introduction—from an informational and identification
standpoint—that would enable you to purchase your
first Radio Control (RC) system. This month I will take
you from the shipping box to the model aircraft. The
discussion will cover the installation aspects of a typical RC
system.
Dual Conversion and Narrow Band: There are two terms I didn’t
discuss last month which have been brought to my attention by
several reader letters (remember, the ones I asked for?).
With regard to RC receivers, “dual conversion” is a technique
in which the receiver operates at two lesser frequencies besides
the operating frequency. The basic dual-conversion receiver
employs two crystals rather than one. Because of the “extra” level
of conversion, these receivers can be made more selective and
more immune to certain interference situations.
The basic dual-conversion receiver will, by nature, be slightly
larger in size, weigh a little more, and be slightly more expensive
than a single-conversion receiver. There is nothing wrong with
single conversion, and several lines of RC receivers have used that
type of circuitry successfully for many years. However, most
receiver labels these days will identify the product as “dual
conversion.”
Along these same lines you will see the expression “narrowband”
performance. When we obtained our 50 RC channels in
1982, we were committed to operate in a much “tighter” channel
environment. Older RC channel separation was 80 kilohertz
(kHz), and our new channels were placed at a narrow spacing of
20 kHz. To meet the new demand (at the time) required
considerable improvements in the RC electronic circuitry.
That is past us now and anything you can purchase today will
almost exclusively be “narrow band,” meaning that it will operate
safely with an adjacent channel operating next to you on the
flightline.
Batteries and Charging: The first thing you have to do after
unpacking your new RC system is charge the batteries that power
the system. I wrote about this last month. RC transmitters are
usually powered by eight AA-size battery cells, and the typical
airborne pack (the pack that goes inside the model) has four cells
Radio Control
Hitec Neon three-channel components set up for electricpowered
flight: receiver (top left); two servos (top center);
battery pack capable of powering electric motor and RC
system (right); Castle Creations Pixie-14 ESC, which takes
engine throttle servo’s place in this application (bottom).
Components supplied with Laser 6 system: four servos (top left),
receiver (middle left), battery pack (middle right), switch harness
(below pack), aileron extension cable (at bottom).
The Hitec Laser 6 is a basic four-channel-function system
capable of operating ailerons, rudder, elevator, throttle.
The Hitec RCD Neon FM three-channel RC system is a
good first radio. The transmitter is in the background.
24 MODEL AVIATION
lSystem ■ Bob Aberle
receivers—all of
dual-conversion
circuitry: (from
top to bottom)
Futaba R127DF,
Airtronics 92745,
Hitec 3500.
RC system as it would typically be installed in trainer. Author made mock-up to show how components are placed and mounted. Red
area simulates wing location. (This is not to any particular scale.)
Front portion of model’s fuselage looking aft. Engine is up front,
followed by fuel tank, airborne battery pack, receiver, switch
harness, three servos.
The heart of the RC system: receiver (left), switch/charging jack
(center), servos (on right). Nylon ties help organize bundles of
cables.
Close-up of typical glow-fueled engine. Fuel tank has been
simulated. It should be positioned as close to engine as possible
to maintain good fuel draw.
Installation
May 2003 25
Typical RC
26 MODEL AVIATION
The on/off placard is important!
Typical control-surface hinges using Sonic-Tronics light hinges.
Knife slots are cut into balsa surfaces. Hinges are inserted into
slots on halves, then a drop of cyanoacrylate glue holds hinge in
place.
At the tail of the model, separate control horns are used for the
elevator- and rudder-control attachments. Vertical fin and rudder shown hinged. At right is typical controlhookup
hardware: control horns (top), clevises and threaded
adjustment rods (center), wire and keeper that attach to servo
output arms (bottom).
If you fly with aileron control, the servo for that function is
usually mounted in the wing. An aileron extension cable may be
needed to reach RC receiver located inside fuselage.
Close-up of three servos. Location of output arms are staggered
so control rods won’t interfere with one another.
May 2003 27
One side of rudder on a tail-dragger, showing how control rod is
attached to horn. Rudder moves as does tail wheel.
Four-cell airborne battery box (left) holds AA alkaline cells.
Typical four-cell Ni-Cd rechargeable battery pack is on right.
Charging RC transmitter, receiver battery pack directly.
Charging receiver or airborne battery pack by going through
charging jack located on power switch harness assembly. Green
LED lit on charger indicates that it is charging battery properly.
Cable on other side of switch goes to receiver.
(usually AA, but they can be smaller).
In some of the inexpensive and basic
systems, you may have to use
nonrechargeable alkaline battery cells. If
you do, purchase at least a dozen cells and
insert them into the transmitter and receiver
battery boxes. Be careful to observe the
battery polarity (positive [+] and negative
[–]).
Most RC systems will be provided with
rechargeable batteries. The majority will be
the Nickel Cadmium (Ni-Cd) variety. To a
lesser degree, you may be supplied with
Nickel Metal Hydride (NiMH) batteries.
As a beginner you won’t have to be
concerned with the type of battery because
the manufacturer will have thoughtfully
provided the correct companion battery
charger. That charger will usually be a wallplug
type transformer with two cables
exiting the case (small black box). The
transformer plugs into any 115VAC
electrical outlet.
One cable exiting the transformer gets
plugged into the charging jack located on
the side, bottom, front, or rear of the
transmitter case. The connectors for the
transmitter and receiver are different, so
there will never be any confusion about
which cable goes where.
On the receiver side there are two
possibilities for charging your batteries. In
one case you physically unplug the battery
pack from the switch harness and plug the
charger cable directly into the battery. On
some of the more deluxe RC systems, the
switch harness includes a charging jack.
When this is provided, you don’t have to
unplug the battery pack. Just plug the cable
into the charging jack, which is an integral
part of the switch-harness assembly. But to
do this will normally require that you
remove the wing so you have access to that
cable, which is located inside the fuselage
radio compartment.
Some manufacturers make these
charging jacks so they can be mounted on
the side of the model’s fuselage, such that
they protrude to the outside. With that kind
of arrangement you can plug in the charger
cable from the exterior of the fuselage
without the need to gain access to the radio
compartment inside the aircraft.
Almost all charging will be done at home
in your shop, and presumably the wing will
have been removed for transportation and
storage purposes. The external fuselage
charging jack will come into play later,
when you learn to use field-type batterycapacity
testers or when the need arises for a
quick field charge.
It is important for you to determine that
your charger is working properly before you
leave it unattended. Each wall-plug
transformer will have two colored lightemitting
diodes (LEDs); they may be red,
green, or red and green! When you
successfully connect a charger cable, that
LED should glow to let you know that the
charging has started. If you are charging
both batteries, you should have two
glowing LEDs.
Photos courtesy the author Graphic Design by Lydia Whitehead
Typical RC connectors. On left is Futaba J connector on end of
servo cable. Black is normally used for negative battery wire.
Red, or positive, lead wire is in the center. On the right is a white
wire for signal function. Next are mating halves of a Hitec
connector. Red positive lead is still in center. Hitec uses yellow
for third, or signal, lead. At extreme right is mating set of Deans
three-pin connectors—the only connectors you can easily solder.
They are popular with do-it-yourself modelers.
Most receivers have connector block on one end to which all
servos and battery power plug in. Shown is servo cable plugged
into Channel-1 function; two-wire cable plugs into battery input
connector at other end.
Each servo comes with extra output arms, mounting hardware.
Supplied rubber grommets (four for each servo!) must be
pressed into mounting flanges of servo. Brass eyelets are
pressed into grommets from lower side of servo.
Antenna is affixed with small nylon tie to top of vertical fin. Never
connect antenna to movable surface since constant motion will
quickly break off wire.
Mounting screw is passed through eyelet, grommet from top
side.
28 MODEL AVIATION
The first time you charge your new
battery packs, you are advised to leave
them on charge for a full 24 hours. After
that, it is normal to leave the charger on
overnight. These batteries have been
designed to take hundreds and hundreds of
recharging cycles. Most batteries will
provide several years of regular service
without degrading in performance.
Because your RC-system charger
operates on such a low level, nothing will
really happen if you forget and leave a
charger on for, say, 48 hours. In the same
regard, don’t play the “I’ll put back in
what I took out” game; that is, you use the
RC system for two hours, so you recharge
it for only two hours. Don’t even think of
doing that!
The battery chemistry is such that it
must be on charge for a period of at least
10 hours each time. If you plan on flying
the next day, put the charger on the night
before. If you don’t fly the next day
because of bad weather and a week goes
by, charge it again. When in doubt, charge
again; it can’t hurt, but it sure can help!
One final caution: when charging,
make sure you plug your charger into a
115VAC outlet that remains on all the
time. Let’s say you choose an outlet that is
operated by a switch near the door to your
shop. As you exit the shop for the night
and turn off the overhead lights, you may
have also turned off your charger. The
next day you go flying and your model
crashes after the first or second flight
because the batteries were never charged.
The subject of batteries is extremely
important to the RC system’s operation.
As I progress in this series I will feed you
more information about battery-capacity
testing at home and at the flying field.
Connectors and Wiring Polarity: Your
RC transmitter is a self-contained unit that
you hold in your hands. On the aircraft
side you have a series of components that
must be installed or mounted inside the
aircraft fuselage, then all of those
components must be connected so you
have an operating airborne RC system.
That interconnecting is done with
“connectors.” They allow you to make and
break electrical connections without
needing to solder wire; the manufacturer
has already done the soldering and/or
mechanical wire crimping for you.
Years ago, types of connectors varied
considerably from manufacturer to
manufacturer. One brand would not work
with or fit into another brand. In many
cases the wire color coding was different,
as was the order of polarity. Things have
become more standardized throughout the
industry, but the best advice I can give you
when starting out is never mix or match
different brands of connectors.
If you purchased a Futaba RC system,
use only Futaba components and Futaba
connectors. The same goes for the charger
and charging cables I just discussed. Use
only the charger that was supplied with
May 2003 29
your system. For now, while you are
getting started, use the components as
supplied. You may make exceptions to this
rule as you gain experience.
Most connectors have keyways or slots
that permit them to be connected only one
way. Wiring convention used by most of
the RC industry today has the positive (+)
pin or wire in the center of a basic threepin
connector.
Battery power circuits use two wires,
and the servo cables have three wires. By
having the positive wire in the center, if
you are actually able to plug a connector in
backward, the circuit will be incomplete.
Nothing would work, but at least nothing
would be short-circuited and blow out.
Basic RC Component Installation: The
components that make up your airborne
RC system include the receiver, servos,
battery pack, switch harness, and an
aileron extension cable if you are using
aileron control (on the wings of your
aircraft). You will need a servo for each
control function: rudder, elevator, aileron
(if applicable), and engine throttle. That is
typical for a fuel-powered model.
If you were flying an electric-powered
airplane, the throttle servo would be
May 2003 31
replaced with an Electronic Speed Control
(ESC). You plug the ESC cable into the
same throttle port (connector) on your
receiver as you would a throttle servo.
Operating the throttle control stick on
your transmitter would then vary the
motor’s speed.
Not to complicate the initial story, but
most ESCs, intended for the smaller-size
electric-powered models, contain an
internal Battery Eliminator Circuit (BEC).
It will allow you to use one battery pack to
power your model’s motor and your RC
system (on a shared basis). I’ll write more
about this when I get into electricpowered
models.
Placement of the RC components
involves a couple of considerations. Most
important, these radio parts add weight to
your model. The components’ location can
affect your aircraft’s center of gravity
(CG) or balance point. An improperly
balanced model (too tail-heavy or noseheavy)
is not going to fly well, or at all.
Another consideration is the length of the
cables supplied with the various
components. Failure to arrange them in a
logical order can leave you with cables
that are too short or too long.
Traditionally, the RC battery pack is
placed up front, just behind the engine and
fuel tank. Most basic aircraft designs have
shorter nose lengths and longer tail
lengths, hence the need for more weight
forward. Your battery pack will probably
be the heaviest weight in the system. You
can put that weight to the best possible
advantage while attempting to achieve the
correct balance.
Working your way back from the
model’s nose, the item behind the battery
pack should be the throttle servo, which
must be mechanically connected to the
engine carburetor. If you have an electricpowered
aircraft, the ESC should be
located in roughly the same area as the
throttle servo. After this we should be
approximately at the position of the
wing’s leading edge (the front of the
wing).
The wing usually covers the model’s
“RC compartment.” When you remove the
wing (be it located on the top or bottom of
the fuselage), you are able to access this
section. The front portion of this
compartment is where the RC receiver is
generally installed. Behind the receiver (in
roughly the middle of the space) is a good
place for the power (on/off) switch and the
charging jack. The rudder and elevator
servos go toward the aft portion of the
compartment.
Some modelers locate the throttle servo
back at this position (shown on the mockup).
If they do, they must run a control rod
back forward to the engine throttle. With
this kind of arrangement, all the servo
cables (and the ESC cable for electric
power) can easily reach the mating
connector block on the receiver.
If you are using aileron control, it’s a
good idea to first plug an aileron extension
cable into the receiver. The other end of
this extension can pass up toward the wingmounted
aileron servo. When you attach the
wing before flying, that aileron servo must
be connected to the extension cable. In the
same regard, you must disconnect the
aileron servo cable from the extension cable
when you remove the wing for
transportation or storage.
The remaining installation involves
running control rods back to the rear or tail
surfaces of the aircraft. The output of the
rudder servo up front must be connected to
the movable rudder at the model’s tail, and
the elevator servo output must be connected
to the elevator control surface in the rear.
More details of these control-rod hookups
will be discussed in the installment dealing
with model assembly.
Most aircraft have a tail-dragger
configuration, in which the model’s tail
rests on the ground. A tail wheel is attached
to the rudder and moves with the rudder to
steer or maneuver the aircraft when it is
taxiing on the ground. As you will learn,
aircraft that do not have groundmaneuvering
capability are usually hand
launched.
The other popular aircraft configuration
is the tricycle landing gear (trike gear). In
this arrangement the aircraft sits relatively
level on two rear-mounted main wheels and
a single nose, or forward, wheel. That nose
wheel is mechanically connected to the
rudder servo such that the aircraft can be
steered while on the ground. Trike gear is
probably the easier configuration for the
rank beginner to handle and learn, but
hooking up the nose-wheel steering can
prove more complex.
The last, but important, item of concern
is deploying the receiver antenna wire
properly. Each modern RC receiver has a
wire antenna measuring approximately 40
inches that exits its case. The smaller the
aircraft, the harder it is to “deploy” this
antenna wire properly.
The time-honored method is to run the
antenna wire from the receiver directly to
the outside of the fuselage (through a smalldiameter
hole), then out to the rear of the
aircraft where it can be attached to the top
of the vertical fin or the tip of the stabilizer.
The antenna should never be attached to
a movable tail surface such as the rudder or
elevator; the constant flexing could
eventually break the wire. Under no
circumstances should you reduce the
antenna wire’s length. To do so might
detune the output stage of your receiver and
greatly reduce radio range. Several
excellent reduced-size antennas are
available for use with the smaller models; I
will get to that later. For now the beginner
should concentrate on using the full-length
antenna.
These wire receiver antennas can pick
up more than received radio signals; they
can pick up, for instance, electrical noise
generated by the motors inside the servos.
Keeping this in mind, it is important that
you keep away from the servo actuators
when routing your antenna wire to the rear
of the aircraft. Try to get the antenna
outside and away from these noise
generators.
RC System Mock-Up: To put everything
in the proper physical size and location, I
have included a mock-up of a typical
airborne RC system. It is laid out exactly as
the RC equipment would be installed in
your aircraft. Keep it as a reference for RCmodel
installations.
May 2003 33
I have reached another cutoff point. By
now you should have a good idea of what to
buy and how to install it in your aircraft.
Next month I’ll take up the subject of RCsystem
operation. From there this series will
go into selecting and assembling an Almost
Ready-to-Fly, or ARF, trainer, how to fuel
and start your engine, and how to make that
all-important first flight.
Please keep writing in with your
questions addressed to “From the Ground
Up” in care of Bob Hunt, Box 68,
Stockertown PA 18083; E-mail:
[email protected]. We try to think of
everything, but there will be missed items or
ones with which you have concern. Model
Aviation wants this series to grow! 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
Polk’s Hobbies
698 S. 21st St.
Irvington NJ 07111
(973) 351-9800
Fax: (973) 351-9700
[email protected]
www.polkshobby.com