Balance the Model (C.G.)
At this stage the model should be in ready-to-fly condition with
all of the systems in place including the engine, landing gear,
and the radio system.
❍
1. Use a felt-tip pen or 1/8"-wide tape to accurately mark the
C.G. on the bottom of the wing on both sides of the fuselage.
The C.G. is located 3-3/4" [95mm] back from the leading edge
of the wing.
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2. With the wing attached to the fuselage, all parts of the
model installed (ready to fly) and an empty fuel tank, place the
model on a Great Planes CG Machine, or lift it at the balance
point you marked.
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3. If the tail drops, the model is “tail heavy” and the battery
pack and/or receiver must be shifted forward or weight must be
added to the nose to balance. If the nose drops, the model is
“nose heavy” and the battery pack and/or receiver must be
shifted to the rear or weight must be added to the tail to balance.
If possible, relocate the battery pack and receiver to minimize or
eliminate any additional ballast required. If additional weight is
required, nose weight may be easily added by using a “spinner
weight” (GPMQ4645 for the 1 oz. weight, or GPMQ4646 for the
2 oz. weight). If spinner weight is not practical or is not enough,
use Great Planes (GPMQ4485) “stick-on” lead. A good place to
add stick-on nose weight is to the firewall. Begin by placing
incrementally increasing amounts of weight on the fuselage
over the firewall until the model balances. Once you have
determined the amount of weight required, it can be
permanently attached. If required, tail weight may be added by
cutting open the bottom of the fuselage and gluing it
permanently inside.
Note: Do not rely upon the adhesive on the back of the lead
weight to permanently hold it in place. Over time, fuel and
exhaust residue may soften the adhesive and cause the weight
to fall off. Use #2 sheet metal screws, RTV silicone or epoxy to
permanently hold the weight in place.
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4. IMPORTANT: If you found it necessary to add any weight,
recheck the C.G. after the weight has been installed. Also, if you
found it necessary to move any radio components, make sure
it is securely re-installed inside the fuselage.
Balance the Model Laterally
❍
1. With the wing level, have an assistant help you lift the
model by the engine propeller shaft and the bottom of the
fuselage under the TE of the fin. Do this several times.
❍
2. If one wing always drops when you lift the model, it means
that side is heavy. Balance the airplane by adding the
necessary amount of stick-on weight to the other wing tip. An
airplane that has been laterally balanced will track better in
loops and other maneuvers.
PREFLIGHT
Identify Your Model
No matter if you fly at an AMA sanctioned R/C club site or if you
fly somewhere on your own, you should always have your
name, address, telephone number and AMA number on or
inside your model. It is required at all AMA R/C club flying sites
and AMA sanctioned flying events. Fill out the identification tag
at the center section of this manual and place it on or inside
your model.
Charge the Batteries
Follow the battery charging instructions that came with your
radio control system to charge the batteries.You should always
This is where your model should balance for your first flights.
Later, you may wish to experiment by shifting the C.G. up to
1/4 " [6mm] forward or 1/4 " [6mm] back to change the flying
characteristics. Moving the C.G. forward may improve the
smoothness and stability, but it may then require more speed
for takeoff and make it more difficult to slow for landing.
Moving the C.G. aft makes the model more maneuverable,
but could also cause it to become too difficult for you to
control. In any case, start at the location we recommend and
do not at any time balance your model outside the
recommended range.
More than any other factor, the C.G. (center of gravity or,
balance point) can have the greatest effect on how a model
flies, and may determine whether or not your first flight will
be successful. If you value this model and wish to enjoy it for
many flights, DO NOT OVERLOOK THIS IMPORTANT
PROCEDURE. A model that is not properly balanced will
be unstable and possibly unflyable.
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