Balance The Model (C.g.); Balance The Model Laterally - GREAT PLANES Waco YMF-5 Instruction Manual

Balance the Model (C.G.)

At this stage the model should be in ready-to-fly condition
with all of the systems in place including the prop, cowl, and
pilot figure(s).
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1. 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 5-1/4" [133mm] back from
the leading edge of the wing. Note: It is permissible to fly the
airplane with the C.G. up to 7/16" [11.1mm] forward or 5/8"
[15.9mm] aft of this mark, but for the first flights set the C.G.
for the recommended location. Do not fly outside of the listed
C.G. range!
To ensure a successful fi rst fl ight, fl y your Waco YMF-
5 set up only according to the C.G. and control surface
throws specifi ed in this manual. The throws and C.G. are
not arbitrary, but have been determined through extensive
testing and accurate record-keeping. This provides you
with the best chance for success and enjoyable fi rst fl ights
that should be surprise-free. Additionally, the throws and
C.G. shown are true, real data which will allow the model to
perform in the manner in which it was intended when fl own
by a pilot of the skill level for which it was intended. DO
NOT OVERLOOK THESE IMPORTANT PROCEDURES.
A model that is not properly setup will be dangerous,
unstable, and possibly unfl yable.
`
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2. With all parts of the model installed (ready to fly) and
an empty fuel tank, put your fingers on the balance points
you just marked and suspend the model from these points.
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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 using a glow engine.
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 structure around 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 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

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1. With the wings 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.
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