21
2.75" [70mm]
Great Planes
C.G. Machine
❏
2. With the wing attached to the fuselage, all parts of the
model installed (ready to fl y) and an empty fuel tank, place
the model upside-down on a Great Planes CG Machine, or
lift it upside-down at the balance point you marked.
❏
3. If the tail drops, the model is “tail heavy.” If possible, move
the battery pack and/or receiver forward to get the model to
balance. If the nose drops, the model is “nose heavy.” If possible,
move the battery pack and/or receiver aft. If the receiver and/
or battery cannot be moved, or if additional weight is still
required, nose weight may be easily added by using “spinner
weight” (GPMQ4645 for the 1 oz. [28g] weight, or GPMQ4646
for the 2 oz. [57g] weight). If spinner weight is not practical or
is not enough, or if tail weight is required, use Great Planes
“stick-on” lead (GPMQ4485). To fi nd out how much weight is
required, place incrementally increasing amounts of weight on
the bottom of the fuselage over the location where it would be
mounted inside until the model balances. A good place to add
stick-on nose weight is to the fi rewall. Do not attach weight to
the cowl—this will cause the mounting screws to open up the
holes in the cowl. 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:
If mounting weight where it may be exposed to fuel
or exhaust, do not rely upon the adhesive on the back to
permanently hold it in place. Over time, fuel and exhaust
residue may soften the adhesive and cause the weight to fall
off. Instead, permanently attach the weight with glue or screws.
❏
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 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.
PREFLIGHT
Identify Your Model
No matter if you fl y at an AMA sanctioned R/C club site or if
you fl y 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 fl ying sites
and AMA sanctioned fl ying events. Fill out the identifi cation
tag on page 23 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
charge your transmitter and receiver batteries the night before
you go fl ying, and at other times as recommended by the
radio manufacturer.
CAUTION:
Unless the instructions that came with your
radio system state differently, the
initial
charge on
new
transmitter and receiver batteries should be done for 15
hours
using the slow-charger that came with the radio
system
. This will “condition” the batteries so that the next
charge may be done using the fast-charger of your choice.
If the initial charge is done with a fast-charger, the batteries
may not reach their full capacity and you may be fl ying with
batteries that are only partially charged.
Balance the Propellers
Carefully balance your propeller and spare propellers before
you fl y. An unbalanced prop can be the single most signifi cant
cause of vibration that can damage your model. Not only
will engine mounting screws and bolts loosen, possibly with
disastrous effect, but vibration may also damage your radio
receiver and battery. Vibration can also cause your fuel to
foam, which will, in turn, cause your engine to run hot or quit.
We use a Top Flite Precision Magnetic Prop Balancer
(TOPQ5700) in the workshop and keep a Great Planes
Fingertip Prop Balancer (GPMQ5000) in our fl ight box.
