Great Planes Spitfire 40 Kit - GPMA0179 - Manual (Page 35)

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3. 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 3-3/4" back from the leading edge where the wing
meets the fuse as shown in the sketch and on the wing plan.
This is the point at which the model should balance for your first
flights. After initial trim flights and when you become more
acquainted with your Spitfire, you may wish to experiment by
shifting the balance up to
1/2" forward or 3/8" 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.
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4. 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.
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5. Position the model on a Great Planes C.G. Machine ™ , or
manually 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 “stick-on” weights
(GPMQ4485, not included).
*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 the transmitter and receiver
batteries the night before you go flying, and at other times as
recommended by the radio manufacturer.
Balance the propellers carefully 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 the radio
receiver and battery. Vibration may cause the 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.
Since you have chosen the Spitfire we assume that you are an
experienced modeler. Therefore, you should already know
about AMA chartered flying fields and other safe places to fly. If
for some reason you are a relatively inexperienced modeler,
and have not been informed, 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.
If you are not thoroughly familiar with the operation of R/C
models, ask an experienced modeler to inspect your radio
installation and confirm that all the control surfaces respond
correctly to transmitter inputs. The engine operation must also
be checked by confirming that the engine idles reliably and
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 all screws remain tight, that the hinges are secure
and that the prop is on tight.
Ground Check the Model
Find a Safe Place to Fly
Balance the Propeller
Charge the Batteries
Check all connections including servo arm screws, Faslinks,
clevises and servo wires. Make sure you have installed the
silicone retainers on all the clevises.
PREFLIGHT
35