Great Planes Stuka Ju-87 60 ARF - GPMA1340 - Manual (Page 28)

At this stage the model should be in ready-to-fly condition
with all of the systems in place including the engine, landing
gear, and the radio system.
❏
1. Use a felt-tip pen or 1/8" wide tape to accurately mark
the C.G. on the top of the wing on both sides of the fuselage.
The C.G. is located 4" [102mm] back from the leading edge
of the wing along the side of the fuselage.
❏
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.
❏
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.
weight, or GPMQ4646 for the 2 oz. 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 at the base of 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.
❏
4. IMPORTANT: If you found it necessary to add any
weight, recheck the C.G. after the weight has been installed.
❏
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.
❏
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.
Balance the Model Laterally
This is where your model should balance for your first flights.
Later, you may wish to experiment by shifting the C.G. back from
the leading edge of the wing, up to 4-7/16" [113mm] to change
the flying characteristics. The forward C.G. for this model is
3-3/4" [95mm] back from the leading edge of the wing and the
rearward C.G. is 4-7/16" [113mm]. Moving the C.G. forward may
improve the smoothness and stability, but it 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 for
you to control. In any case, start at the location we recommend
and do not at any time balance your model outside the
recommended range.
More than any other factor, the C.G. (balance point) can have
the greatest effect on how a model flies, and may determine
whether or not your first flight will be successful. If you value this
model and wish to enjoy it for many flights, DO NOT
OVERLOOK THIS IMPORTANT PROCEDURE. A model that is
not properly balanced will be unstable and possibly unflyable.
Balance the Model (G.G.)
These are the recommend control surface throws:
High Rate Low Rate
ELEVATOR: 5/16" [7.9mm] up 3/16" [5mm] up
5/16" [7.9mm] down 3/16" [5mm] down
RUDDER: 1-1/8" [28mm] right 3/4" [19mm] right
1-1/8" [28mm] left 3/4" [19mm] left
AILERONS: 1-1/16" [27mm] up 3/4" [19mm] up
1-1/16" [27mm] down 3/4" [19mm] down
FLAPS: 1-1/2" [38mm] down 1" [25mm] down
IMPORTANT: The Great Planes Stuka has been extensively
flown and tested to arrive at the throws at which it flies best.
Flying your model at these throws will provide you with the
greatest chance for successful first flights. If, after you have
become accustomed to the way the Stuka flies, you would like to
change the throws to suit your taste, that is fine. However, too
much control throw could make the model difficult to control, so
remember, “more is not always better.”
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