Top Flite TOPA0905 - Manual (Page 38)

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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 upside-down on a Great
Planes CG Machine, or lift it upside-down 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 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, nose weight may be easily added
by using a “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, use
Great Planes (GPMQ4485) “stick-on” lead. A good
place to add stick-on nose weight is to the firewall
(don’t attach weight to the cowl—it is not intended to
support weight). Begin by placing incrementally
increasing amounts of weight on the bottom of the
fuse 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 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, 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.
Balance the Model Laterally
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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 fin. 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.
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
on the decal sheet 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 flying, and at other
times as recommended by the radio manufacturer.
Balance Propellers
Carefully balance your propeller and spare propellers
before you fly. An unbalanced prop can be the single
most significant 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 flight box.
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 flying
with batteries that are only partially charged. This is where your model should balance for the
first flights. Later, you may wish to experiment by
shifting the C.G. up to 3/8” [10mm] forward or 3/8”
[10mm] back to change the flying 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
difficult to slow for landing. Moving the C.G. aft
makes the model more maneuverable, but could
also cause it to become too difficult to control. In
any case, start at the recommended balance
point and do not at any time balance the model
outside the specified range.
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