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We recommend that you take it easy with your Extra 300 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 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 Extra behaves in each.
For smooth flying and normal maneuvers, use the low rate
settings as listed on page 41. High rate elevator may be
required for crisp snap rolls and spins. For good knife-edge
performance forward fight speed is the key.
Sometime well before it's time to land you should climb your
Extra 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.
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 your 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 Extra. 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. Happy Landings!
APPENDIX
FLIGHT TRIMMING
A model is not a static object. Unlike a car, which 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 your 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.
Flight
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-degree turn or Split-S? Do the ailerons tend to hunt a little
after a rolling maneuver? Put the plane through its paces.
Control centering is either a mechanical thing (binding servos, stiff
linkages, etc.), an electronic thing (bad servo resolution or dead-
band in the radio system), or C.G. (aft Center of Gravity will make
the plane wander a bit). The last possibility will be obvious, but
don't continue the testing until you have isolated the problem and
corrected it.
Let's get down to the task of trimming the model. Use the
tachometer every time you start the engine, to insure consistent
results. These trim flights must be done in calm weather. Any
wind will only make the model weathervane. Each "maneuver" on
the list assumes that you will enter it dead straight-and-level. The
wings must be perfectly flat, or else the maneuver will not be
correct and you'll get a wrong interpretation. That's where your
observer comes in. Instruct him to be especially watchful of the
wings as you enter the maneuvers.
Do all maneuvers at full throttle. The only deviation from this is if
the plane will be routinely flown through maneuvers at a different
power setting.
45
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