Great Planes Spitfire 40 Kit - GPMA0179 - Manual (Page 37)

The Great Planes Spitfire is a great flying semi-scale sport
model that flies smoothly and predictably, yet is mildly
aerobatic. The Spitfire does not, however, possess the self-
recovery characteristics of a primary R/C trainer and should
only be flown by experienced RC pilots. The Spitfire is limited
only by your abilities and imagination.
Have Fun!
Takeoff on “high” rates if you have dual rates on your transmitter
– even if you are taking off in a crosswind. For all models it is
good practice to gain as much speed as the length of the
runway will permit before lifting off. This will give you a safety
margin in case the engine quits. When you initially advance the
throttle and the tail begins to lift, the Spitfire will begin to turn to
the left (due to the torque of the engine – a characteristic of all
taildraggers). Be prepared for this by applying sufficient right
rudder to keep the Spitfire running straight down the middle of
the runway (or flying field). The left turning tendency will
decrease as the plane picks up speed. Be sure to allow the tail
to rise off the ground before lifting the model into the air.
Depending on the surface you are taking off from, you will need
to apply little or no up elevator until flying speed is reached.
Don’t hold the tail on the ground with too much up elevator, as
the Spitfire will become airborne prematurely and may stall.
When the plane has gained enough flying speed to safely lift
off, gradually and smoothly apply up elevator and allow the
model to climb at a shallow angle (do not yank the model off the
ground into a steep climb!).
We recommend that you take it easy with your Spitfire for the
first several flights, gradually “getting acquainted” with this great
sport model as your engine gets fully broken-in. If you feel as
though you have your hands full, keep this one thing in mind:
pull back on the throttle stick to slow the model down. This
will make everything happen a little slower and allow yourself
time to think and react. Add and practice one maneuver at a
time, learning how the Spitfire behaves in each. For smooth
flying and normal maneuvers, use the low rate settings as listed
on page 34. This low rate elevator setting is intentionally very
soft and smooth, and was selected specifically to provide a
smooth, fluid flight performance overall.
Sometime well before it’s time to land you should climb your
Spitfire to a safe altitude and cut the throttle to an idle and
check out the model’s low speed characteristics. Do this a few
times so you know what to expect upon landing.
When it’s time to land, fly a normal landing pattern and
approach. Keep a few clicks of power on until you are over the
runway threshold. For the first few landings, plan to land slightly
faster than stall speed and on the main wheels, as this is the
easiest way to land your Spitfire. Later, with a little practice you
will find you can make slow 3-point landings.
Have a ball! But always remember to think about your next
move and plan each maneuver before you do it. Impulsively
“jamming the sticks” without any thought is what gets
most fliers in trouble rather than lack of flying skill.
FLIGHT TRIMMING
Note: The following article has been reprinted in part for
future reference and also as a guide for your flight instructor or
experienced flying partner to help you with trimming your
model. If further information is required, please contact your
local hobby dealer, local flying club or call Great Planes at
(217) 398-8970.
A model is not a static object. Unlike a car, which you can
only hunt left or right on the road (technically, a car does yaw in
corners, and pitches when the brakes are applied), a plane
moves through that fluid we call air in all directions
simultaneously. The plane may look like it’s going forward, but it
could also be yawing slightly, slipping a little and simultaneously
climbing or diving a bit! The controls interact. Yaw can be a
rudder problem, a lateral balance problem or an aileron rigging
problem. We must make many flights, with minor changes
between each, to isolate and finally correct the problem.
The chart accompanying this article is intended to serve as
a handy field reference when trimming your model. Laminate it
in plastic and keep it in you flight box. You just might have need
to consult it at the next contest! The chart is somewhat self-
explanatory, but we will briefly run through the salient points.
First, we are assuming that the model has been C.G.
balanced according to the manufacturer’s directions. There’s
nothing sacred about that spot — frankly, it only reflects the
balance point where a prototype model handled the way the
guy who designed it thought it should. If your model’s wing has
a degree more or less of incidence, then the whole balance
formula is incorrect for you. But, it’s a good ballpark place
to start.
The second assumption is that the model has been balanced
laterally. Wrap a strong string or monofilament around the prop
shaft behind the spinner, then tie the other end to the tail wheel
or to a screw driven into the bottom of the aft fuse. Make the
string into a bridle harness and suspend the entire model
inverted (yes, with the wing on!). If the right wing always drops,
sink some screws or lead into the left wing tip, etc. You may be
surprised to find out how much lead is needed.
At this point the model is statically trimmed. It’s only a
starting point, so don’t be surprised if you wind up changing it
all. One other critical feature is that the ailerons must have their
hinge gap sealed. If shoving some Scotch tape or Monokote
into the hinge gap to prevent the air from slipping from the top
of the wing to the bottom, and vice-versa, bothers you, then
don’t do it.
To achieve the maximum lateral trim on the model, the hinge
gap on the ailerons should be sealed. The easiest way to do
this is to disconnect the aileron linkages, and fold the ailerons
as far over the top of the wing as possible (assuming they are
top or center hinged). Apply a strip of clear tape along the joint
line. When the aileron is returned to neutral, the tape will be
invisible, and the gap will be effectively sealed. Depending on
how big the ailerons are, and how large a gaping gap you
normally leave when you install hinges, you could experience a
20 percent increase in aileron control response just by this
simple measure.
Your first flights should be to ascertain control centering and
control feel. Does the elevator always come back to neutral
after a 180° turn or Split-S? Do the ailerons tend to hunt a little
after a rolling maneuver? Put the plane through its paces.
APPENDIX
Landing
Flying
Takeoff
37