Great Planes U-Can-Do 3D 60 ARF - GPMA1270 - Manual (Page 22)

At this stage the model should be in ready-to-fly condition
with all of the systems in place including the engine, landing
gear, covering 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. The C.G. is located 4-7/8"
[124mm] back from the leading edge of the wing.
❏
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 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.
❏
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.
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.
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.
NOTE: Checking the condition of your receiver battery pack
is highly recommended. All battery packs, whether it's a
trusty pack you've just taken out of another model, or a new
battery pack you just purchased, should be cycled, noting
the discharge capacity. Oftentimes, a weak battery pack can
be identified (and a valuable model saved!) by comparing its
actual capacity to its rated capacity. Refer to the instructions
and recommendations that come with your cycler. If you
don't own a battery cycler, perhaps you can have a friend
cycle your pack and note the capacity for you.
Charge the Batteries
Identify Your Model
PREFLIGHT
Balance the Model Laterally
Plane is balanced correctly when
the bottom of the fuse is horizontal.
4-7/8"
[124mm]
This is where your model should balance for your first
flights. Later, you may wish to experiment by shifting the
C.G. up to 3/8" [9mm] forward or 1/2" [13mm] back to
change the flying characteristics. 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.
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