Carl Goldberg GPMA1960 Gentle Lady Glider ARF - Manual (Page 12)

12
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 engine or
brushless motor, landing gear, and the radio system (and
battery pack if applicable).
1. Use a felt-tip pen or 1/8" [3mm]-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 3-5/8" [92mm] 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 1/4" [6mm] forward or 1/2" [13mm] back to
change the fl ying characteristics.
2. With the wing attached to the fuselage and all parts
of the model installed (ready to fl y), place the model on a
Great Planes CG Machine, or lift it at the balance point you
marked, using your fi ngertips.
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 aft 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, use Great Planes (GPMQ4485) “stick-on”
lead. A good place to add stick-on nose weight is at the front
of the radio compartment. Begin by placing incrementally
increasing amounts of weight on the fuse over this area
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.
Note: Do not rely upon the adhesive on the back of the lead
weight to permanently hold it in place. Over time, the weight
may fall off. Use #2 sheet metal screws, RTV silicone or
epoxy to permanently hold the weight in place.
4. IMPORTANT: If you found it necessary to add any weight,
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 nose 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. A glider that has been laterally
balanced will track better in fl ight.
FLYING
CAUTION (THIS APPLIES TO ALL R/C AIRPLANES):
If, while fl ying, you notice an alarming or unusual sound
such as a low-pitched “buzz,” this may indicate control
surface fl utter. Flutter occurs when a control surface
(such as an aileron or elevator) or a fl ying surface (such
as a wing or stab) rapidly vibrates up and down (thus
causing the noise). In extreme cases, if not detected
immediately, fl
utter can actually cause the control
surface to detach or the fl ying surface to fail, thus
causing loss of control followed by an impending crash.
The best thing to do when fl utter is detected is to slow
the model immediately by reducing speed, then land as
soon as safely possible. Identify which surface fl uttered
(so the problem may be resolved) by checking all the
servo grommets for deterioration or signs of vibration.
Make certain all pushrod linkages are secure and free
of play. If it fl uttered once, under similar circumstances
it will probably fl utter again unless the problem is fi xed.
Some things which can cause fl utter are; Excessive
hinge gap; Not mounting control horns solidly; Poor fi t
of clevis pin in horn; Side-play of wire pushrods caused
by large bends; Excessive free play in servo gears or
insecure servo mounting.
Try to fi nd an experienced pilot to help you with your fi rst fl ights.
Although the Gentle Lady is very easy to fl y, an experienced
pilot can save you a lot of time and possible aggravation by
helping you get your model in the air smoothly.