Great Planes Ultimate 3D E-Performance ARF - GPMA1546 - Manual (Page 23)

23
Balance the Model (C.G.)
More than any other factor, the C.G. (balance point)
can have the greatest effect on how a model fl ies, and
may determine whether or not your fi rst fl ight will be
successful. If you value this model and wish to enjoy it for
many fl ights, DO NOT OVERLOOK THIS IMPORTANT
PROCEDURE. A model that is not properly balanced will
be unstable and possibly unfl yable.
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, and the radio system. Temporarily install the battery
pack in place for balancing purposes.
❏
1. Use a felt-tip pen or 1/8" [3mm]-wide tape to accurately
mark the C.G. on the underside of the top wing, at the center
where the two top wing panels are joined. The C.G. is located
3-5/16" [84mm] back from the center LE of the top 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 3/8" [9.5mm] 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.
❏
2. With all parts of the model installed (ready to fl y) and
battery installed, place the model on a Great Planes CG
Machine, or lift it at the balance point you marked.
❏
3. If the tail drops, the model is “tail heavy” and the battery
pack must be shifted forward to balance. If the nose drops, the
model is “nose heavy” and the battery pack must be shifted aft
to balance. If possible, relocate the battery pack and receiver
to minimize or eliminate any additional ballast required.
The Ultimate Biplane EP ARF is designed so that additional
weight should not need to be added for balancing purposes.
Changing to a lighter (1250mAh) or heavier (2100mAh)
battery pack will shift the balance point from the forward
position to the aft position, or vice-versa. Moving the battery
pack on the battery tray will make smaller changes in the
C.G. position.
❏
4. IMPORTANT: If you found it necessary to add any
permanent weight for balancing purposes, recheck the C.G.
after the weight has been installed.
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
fuse under the TE of the fi n. 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 weight
to the other wing tip. An airplane that has been laterally
balanced will track better in loops and other maneuvers.