Great Planes SPAD XIII EP WWI Parkflyer ARF - GPMA1143 - Manual (Page 20)

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Balance the Model (C.G.)
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1. At this stage the model should be in ready-to-fl y condition
with all of the systems in place including the motor, landing
gear, radio system, battery, and all hatches. Place the battery
in the battery compartment but do not connect it.
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2. Use a felt-tip pen or 1/8" [3mm]-wide tape to accurately
mark the C.G. on the bottom of the top wing on both sides
of the fuselage. The C.G. is located 2-1/8" [54mm] back
from the leading edge of the wing.
This is where your model should balance for the fi rst
fl ights. Later, you may wish to experiment by shifting
the C.G. up to 1/8" [3mm] forward or 1/8" [3mm] back
to change the fl ying characteristics. Moving the C.G.
forward may improve the smoothness and stability, but
the model may then require more speed for takeoff and
make it more diffi cult to slow for landing. Moving the C.G.
aft makes the model more maneuverable, but could also
cause it to become too diffi cult to control. In any case,
start at the recommended balance point and do not at
any time balance the model outside the specifi ed range.
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3. With all parts of the model installed (ready to fl y) and a
battery pack in place (do not connect it), place your fi ngers
on the marks you made and balance the model.
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4. If the tail drops, the model is “tail heavy” and the battery
pack 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 must be shifted aft or weight must be
added to the tail to balance.
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5. Using a felt-tip pen, mark the position of the battery
pack in the battery compartment. This will help eliminate trim
changes or unwanted surprises each time that you change
the battery. When using different capacity batteries, you may
have to re-balance your plane and place an additional mark
in the battery compartment. Install the 2" [50mm] piece of
hook & loop material in the battery tray.
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6. If additional weight is required, use Great Planes
(GPMQ4485) “stick on” lead. A good place to add stick-
on nose weight is to the fi rewall (don’t attach weight to the
cowl—it is not intended to support weight). Begin by placing
increasing amounts of weight on the top of the fuse over the
fi rewall 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 fuse and gluing it permanently inside.
IMPORTANT: If you found it necessary to add any weight,
recheck the C.G. after the weight has been installed.
Balance the Model Laterally
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1. With the wing level, lift the model by the motor shaft
and the bottom of the fuse under the TE of the fuse. Do this
several times.
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2. If one wing always drops when you lift the model, it means
that side is heavy. Balance the airplane by adding weight
to the other wing tip. An airplane that has been laterally
balanced will track better in loops and other maneuvers.