88 M ODEL AVIATION
ToMoRRoW IS the big day! The
weather man has promised sunshine and a
light breeze. The club instructor will be at
the field at 9 a.m. You’re ready—at least
you think you are!
It feels as though it’s been a long
time since you approached the club
members at the mall show—but it really
hasn’t. Some of the first questions you
asked seem kind of silly now, but you
appreciate how politely the members
handled them.
The “How fast? How high? How far
away can you control it? How much does
it cost?” questions soon gave way to more
relevant issues.
The show that piqued your interest
featured everything—ultralight Indoor
models, Control Line (CL), and Radio
Control (RC). You were afforded an
excellent opportunity to compare the
many aspects of aeromodeling. It also
allowed you to do a “wallet check,” to see
how this newfound activity could fit in
your budget.
Trips to the hobby shop and club
meetings followed, along with the myriad
relevant questions that developed as you
prepared the model.
Let’s do a “home preflight check”
before you go out to the field!
Free Flight (FF): This is tough to cover in
a column—most of what you need to do
will occur at the site. You’ve probably
test-glided the model, or put in a few
winds to see how it might fly. But the real
test is when it’s checked by a club
member.
You can check for obvious warps and
misalignment of the surfaces, but
tweaking the flying surfaces may be
required. You remember this because at
the mall show, the modeler would breathe
on a wingtip and twist it a bit between
flights, or place a small shim of wood
under the wing or stabilizer.
By now you understand that
“trimming” is an essential part of the
flight; once you release the model, it’s at
the mercy of the elements and your
preparation.
Check to make certain you have the
equipment you need. This will vary
widely according to the type of model—
whether it is Hand-Launch, Indoor,
Rubber, etc.
Make certain your AMA number and/or
your name and address are on—or in—the
model (Indoor models are excluded).
That’s an AMA Safety Code requirement.
It may make the difference between whether
or not you get the model back when you hook
a boomer of a thermal.
Control Line: You have the lines and
handle. That’s a requirement, since most
CL models make poor FF models.
It was touch-and-go for a while when
you bought the lines, because you
weren’t certain what length or diameter
to use. It was also a concern when you
learned you had to finish the lines with
the attachment clips.
Fortunately, the club member you
contacted sent you in the direction of the
AMA Competition Regulations.
That was also confusing at first, since
the CL section had more than a dozen
different charts!
Then you realized your trainer wasn’t a
Speed model, a Combat model, or a Rat
Race model. That’s why the suggestion to
use your model weight and engine size,
and select the lines from the Precision
Aerobatics chart made sense.
Hopefully your instructor will pull-test
the system for you. Like a chain, the system
is only as strong as the weakest link.
You have spare propellers, glow plugs,
fuel, and a charged glow-plug battery. You
also have protection for your fingers for
when you start the engine, a fuel filler, and
an assortment of screwdrivers, wrenches,
etc.
Look at the model. The alignment is
good—no warps. The bellcrank moves
freely, but is not loose. A tug on the
elevator suggests the hinges are anchored.
The rudder is angled toward the outside
of the circle (to the right, if you are flying
counterclockwise).
The engine has the amount of rightthrust
shown on the plans, and is firmly
mounted to the firewall. The pushrod to
the elevator is supported in several places
along its length, to prevent flexing.
You’ve hooked up the lines to the
leadouts, and adjusted the handle so the
elevator is in a neutral position when the
handle is straight in your hand. Your
instructor will certainly look at these items
at the field, but you want to be prepared.
You’re not real certain about the
amount of movement in the elevator. The
plans weren’t specific about that. And the
bellcrank had several holes to choose
from, as did the control horn attached to
the elevator.
The laws of physics indicate that moving
the pushrod out from the pivot point of the
bellcrank would give you greater throw;
moving the control-horn end closer to the
elevator would increase the throw.
The problem is how much elevator
movement is correct? Err on the low
side—too much elevator movement will
cause an oversensitive, erratic model.
Too little elevator movement, and you
may not be able to do maneuvers—but at
least you won’t overcontrol.
Making certain that you have balanced
the model correctly is important.
Many CL models use slight rearward
position for the leadout guides near the
wingtip. This is a kind of insurance to
maintain line tension.
Each lap flown by a CL model has an
upwind, downwind, and two crosswind
portions, which happen in rapid succession!
If you don’t maintain line tension, you
won’t maintain control. Slack lines are no
lines at all!
It’s important to remember that a wellbuilt
and well-trimmed CL model will be a
delight to fly. Some critics suggest that
anything can fly as CL if you put a big
enough engine on it! This is not true.
No matter what type of CL model you
are considering, take proper care in setting
it up to allow it to fly safely, efficiently,
and pleasurably.
Radio Control: Don’t call it “remote
control!” Actually it is, and so is CL, but
with RC you are substituting a radio signal
for steel lines.
Early RC models were FF models
occasionally interrupted by a radio signal.
Now the radio signal must be retained
generally throughout flight, to prevent
servo movement and a subsequent “hard
landing.”
As you prepare for your flight, many of
the same elements in FF and CL are
required. Your flight box needs spare
Bob Underwood
N e w c o m e r s
Box 40, St. Peters MO 63376
Welcome to
the group
who are pilots
with their feet
on the ground!
propellers, plugs, and other “stuff.”
You’ve charged (or are charging) the
transmitter and receiver servo batteries.
You’ve tugged on all the surfaces, checked
for warps and alignment, balanced the model
for the 10th time (without fuel, of course!),
and watched as the nose dipped slightly.
Remember that nose-heavy models fly
sluggish; tail-heavy models fly once!
You’re not ready yet! Go back and check
each screw holding a servo arm on a servo. Is
there a keeper on each of the clevises? Are
they locked in place? Are all the mounting
screws in place, holding the servos? Are they
firm, but not crushing the rubber grommet?
Is the receiver and battery mounted
loosely in foam? Is the fuel-tank cap tight,
and are the fuel lines firmly in place on
the tubing?
As do your CL brethren, you need to
check the control-surface throw. You may
have a system with dual rates on the
elevator, ailerons, and rudder.
If so, make sure you let your instructor
know if you have set them, and which
direction the switch moves to activate the
different rates!
As with CL, the surface movement is
controlled by the position of the clevis in
the servo arm and the control horn. Out on
the servo arm and in on the horn creates
more control movement.
Don’t go to extremes. Hopefully your
instructions will provide the typical setup.
While you are thinking about it, hook up
the ailerons and place the wing in position on
the model. Turn on the radio system and
stand behind the model. Move the elevator
stick toward the bottom of the transmitter and
make certain the elevator moves upward.
The ailerons are next. When you move
the stick to the right, does the right aileron
move up and the left aileron move down?
That’s what they should do.
The same right-left movement is
needed for the rudder.
Last is the throttle. Is the barrel in the
intake wide open when the stick is moved
toward the top of the transmitter?
All of this may sound elementary, but
it’s amazing how many times even oldtimers
end up with the ailerons going the
wrong way in relation to the movement of
the transmitter stick.
This often happens because the modeler
set the directions while facing the nose of the
model, rather than standing behind the tail.
You’re ready. You have your AMA
membership card and/or the card for the
club. You packed your creature
comforts—sunglasses, water, a snack. A
hat with a brim is helpful, to keep the sun
and your hair out of your eyes.
It’s not a bad idea to pack a small
notebook and a pen or pencil. There will
probably be some thoughts you’ll want to jot
down. These may be observations you make
about the event, or those of the instructor.
Some individuals don’t feel a degree of
apprehension for the first flight, but most
do. Each new model is a new experience.
That’s true for the old-timer as well.
Your instructor probably feels a degree
of concern too—it’s your equipment being
tested!
Although the preflight will help to
reassure that you have done a good job
building and preparing the model, there
are still many problems that can develop
or are undetectable.
If something is found that suggests
the model should not be flown, and it
cannot be corrected at the field, be
patient. Fix the problem and try again
later.
Happy first flight! Welcome to the group
who are pilots with their feet on the
ground! Start building your list of aviation
sayings that are true for all of us:
“He who stalleth, shall falleth.”
“Two things are useless: the air above
you, and the runway behind you.”
“One law Congress can’t repeal is the
law of gravity.”
“For every takeoff, there is at least one
landing.”
“Takeoffs are optional—landings are
mandatory.”
There are many more! What sayings
have you learned? MA
