Great Planes Extra 300S 60 Kit - GPMA0236 - Manual (Page 43)

Note: The balance and control throws for the Extra
300S have been extensively tested. We are confident
that they represent the settings at which the Extra 300S
flies best. Please set up your model to the
specifications listed above. If, after you become
comfortable with your Extra 300S, you would like to
adjust the throws to suit your tastes, that's fine. Too
much throw can force the plane into a stall or snap roll,
so remember, “more is not better.”
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. Accurately mark the balance point on the top of the
wing on both sides of the fuselage. Use thin strips of tape
or a felt-tip pen to make the marks. The balance point
(C.G.) is located 4-1/8" back from the leading edge as
shown in the sketch and on the wing plan. Balance your
Extra 300S using a Great Planes C.G. Machine
™ Airplane
Balancer (GPMR2400) for the most accurate results. Hint:
Reference the full-size wing plan to help you locate the
proper balance point. 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 Extra 300S, you may wish to experiment by shifting
the balance up to 3/8" forward or back to change the
flying characteristics. Moving the balance 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 balance aft makes
the model more agile with a lighter, snappier “feel” and
often improves knife-edge capabilities. In any case, please
start at the location we recommend and do not at any
time balance your model outside the recommended
range.
❏ 2. With the wing attached to the fuselage, all parts of the
model installed (ready to fly) and an empty fuel tank, hold
the model upside-down with the stabilizer level.
❏
3. Lift the model at the balance point. If the tail drops
when you lift, 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: Nose weight may be easily
installed by using a “spinner weight” or gluing lead weights
to the firewall. Tail weight may be added by using Great
Planes (GPMQ4485) “stick-on” lead weights. Later if the
balance is O.K., you can open the fuse bottom and glue the
weights in permanently.
* If possible, first attempt to balance the model by changing
the position of the receiver battery and receiver. 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.
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.
Charge the Batteries
At this time check all connections including servo arm
screws, faslinks, clevises and servo cords. Make sure you
have installed the nylon retainer on the Screw-Lock
Pushrod Connector on the throttle pushrod at the servo
arm and the silicone retainers on all the clevises.
PREFLIGHT
4-1/8" at Root
BALANCE YOUR MODEL
We recommend the following control surface throws:
Note: The throws are measured at the widest part of the
elevators, rudder, and ailerons. Adjust the position of the
pushrods at the control/servo horns to control the amount of
throw. You may also use the ATV's if your transmitter has
them but the mechanical linkages should still be set so the
ATV's are near 100% for the best servo resolution (smoothest,
most proportional movement).
High Rate Low Rate
ELEVATOR: 1-1/4" up 3/4" up
1-1/4" down 3/4" down
RUDDER: 2-1/2" right 1-1/2" right
2-1/2" left 1-1/2" left
AILERONS: 5/8" up 1/4" up
5/8" down 1/4" down
Note: If your radio does not have dual rates, then set the
control surfaces to move between the high rate and low
rate throws.
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