Great Planes Ultra Sport 60 Kit - GPMA0420 Pages 28-48 - Manual (Page 15)

the throttle on the downwind leg of the landing approach.
This will automatically help to bleed off some of the speed.
If your ULTRA SPORT 60 is built straight and true, you'll
find that you can really flare it out for slow, nose-high, full-
stall landings without fear of tip stalling.
Have a ball! Butalways stay in control and fly in a safe
manner.
GOOD LUCK AND GREAT FLYING!
SEE THE FULL LINE OF GREAT PLANES
AIRPLANES AND ACCESSSORIES AT YOUR
HOBBY DEALER.
WE HOPE YOU WILL SELECT ANOTHER
"GREAT PLANE" AS YOUR NEXT PROJECT.
THANK YOU!
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 simulta-
neously. The plane may look like it's going forward, but it
could also be yawing slightly, slipping a little and simultane-
ously 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 primary
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 bal-
anced 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 me-
chanical thing (binding servos, stiff linkages, etc.), an elec-
tronic 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 yourobserver 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...
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