Preflight; Charge The Batteries; Balance The Propeller; Find A Safe Place To Fly - GREAT PLANES Piper J-3 Cub Instruction Manual

❏ 3. If one wing always drops when you lift the model, it
means that side is heavy. Balance the airplane by adding
weight to the opposite, lighter wing tip. Note: An airplane
that has been laterally balanced will track better in loops
and other maneuvers.
Balancing your Model
Note: This section is VERY important and must NOT be
omitted! A model that is not properly balanced will be
unstable and possibly unflyable.
❏ 1. The balance point (C.G.) is located 4" [103mm] back
from the leading edge of the wing against the fuselage.
Balance your Piper Cub using a Great Planes C.G. Machine
Airplane Balancer (GPMR2400) for the most accurate
results. This is the balance point at which your model should
balance for your first flights. After initial trim flights and when
you become more acquainted with your Piper Cub, you may
wish to experiment by shifting the balance up to 3/8" [9.5mm]
forward or backward to change its flying characteristics.
Moving the balance forward may improve the smoothness
and stability, but the model may then require more speed for
takeoff and may become more difficult to slow for landing.
Moving the balance aft makes the model more agile with a
lighter, snappier "feel." In any case, please start at the location
we recommend. Do not at any time balance your model
outside the recommended range.
❏ 2. With the airplane on the balance stand, the wing
attached to the fuselage, all parts of the model installed
(ready to fly), and an empty fuel tank, lift up the tail as
necessary to level the stab. Release the model, and
observe the tail of the aircraft. If the tail drops, the model is
"tail heavy" and you must add weight* to the nose to
balance the model. If the nose drops, it is "nose heavy" and
you must add weight* to the tail to balance the model.
Note: Weight may be added by using Great Planes
(GPMQ4485) "stick-on" lead weights.
* If possible, first attempt to balance the model by changing
the position of the receiver battery. If you are unable to
obtain good balance by doing so, then it will be necessary
to add weight to the nose or tail to achieve the proper
balance point.
At this time check all connections including servo horn
screws, clevises, servo cords and extensions. Make sure you
have installed the nylon retainer on the Screw-Lock Pushrod
Connector and the silicone retainers on all the clevises.

Charge the Batteries

Follow the battery charging procedures in your radio
instruction manual.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 the Propeller

Carefully balance your propellers before flying. An
unbalanced prop is the single most significant cause of
vibration. Not only may engine mounting screws vibrate out,
possibly with disastrous effect, but vibration may also
damage your radio receiver and battery. Vibration may
cause your fuel to foam, which will, in turn, cause your
engine to run lean or quit.
We use a Top Flite Precision Magnetic Prop Balancer
(TOPQ5700) in the workshop and keep a Great Planes
Fingertip Balancer (GPMQ5000) in our flight box.
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Find A Safe Place to Fly

We strongly suggest that the best place to fly is an AMA
chartered club field. Ask the AMA or your local hobby shop
dealer if there is a club in your area and join. Club fields are
set up for R/C flying and that makes your outing safer and
more enjoyable. The AMA address and telephone number
are in the front of this manual. If a club and flying site are not
available, find a large, grassy area at least 6 miles away
from houses, buildings and streets and any other R/C radio
operation like R/C boats and R/C cars. A schoolyard may
look inviting but is too close to people, power lines and
possible radio interference.

Ground Check the Model

Inspect your radio installation and confirm that all the control
surfaces respond correctly to the transmitter inputs. The
engine operation must also be checked by confirming that
the engine idles reliably, transitions smoothly and rapidly to
full power and maintains full power, indefinitely. The engine
must be "broken-in" on the ground by running it for at least
two tanks of fuel. Follow the engine manufacturer's
recommendations for break-in. Make sure that all screws
remain tight, that the hinges are secure and that the prop is
on tight.

Range Check Your Radio

Whenever you go to the flying field, check the operational
range of the radio before the first flight of the day. First,
make sure no one else is on your frequency (channel). With
your transmitter on, you should be able to walk at least 100
feet (30 meters) away from the model and still have control.
While you work the controls, have a helper stand by your
model and tell you what the control surfaces are doing.
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PREFLIGHT

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