Great Planes Yak-55M 50-55cc Sport / 3D ARF - GPMA1230 - Manual (Page 31)

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19. Cycle your receiver battery pack (if necessary) and
make sure it is fully charged.
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20. If you wish to photograph your model, do so before
your fi rst fl ight.
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21. Range check your radio when you get to the fl ying fi eld.
FLYING
The Yak-55M is a great-fl ying model that fl ies smoothly and
predictably. The Yak-55M does not, however, possess the self-
recovery characteristics of a primary R/C trainer and should
be fl own only by experienced R/C pilots.
Fuel Mixture Adjustments
A fully cowled engine may run at a higher temperature than
an un-cowled engine. For this reason, the fuel mixture should
be richened so the engine runs at about 200 rpm below peak
speed. By running the engine slightly rich, you will help prevent
dead-stick landings caused by overheating.
CAUTION (THIS APPLIES TO ALL R/C AIRPLANES): If,
while fl ying, you notice an alarming or unusual sound such
as a low-pitched “buzz,” this may indicate control surface
fl utter. Flutter occurs when a control surface (such as an
aileron or elevator) or a fl ying surface (such as a wing or
stab) rapidly vibrates up and down (thus causing the noise).
In extreme cases, if not detected immediately, fl utter can
actually cause the control surface to detach or the fl ying
surface to fail, thus causing loss of control followed by an
impending crash. The best thing to do when fl utter is detected
is to slow the model
immediately by reducing power, then
land as soon as safely possible. Identify which surface
fl uttered (so the problem may be resolved) by checking all
the servo grommets for deterioration or signs of vibration.
Make certain all pushrod linkages are secure and free
of play. If it fl uttered once, under similar circumstances
it will probably fl utter again unless the problem is fi xed.
Some things which can cause fl utter are; Excessive hinge
gap; Not mounting control horns solidly; Poor fi t of clevis
pin in horn; Side-play of wire pushrods caused by large
bends; Excessive free play in servo gears; Insecure servo
mounting; and one of the most prevalent causes of fl utter;
Flying an over-powered model at excessive speeds.
Takeoff
Before you get ready to takeoff, see how the model handles
on the ground by doing a few practice runs at
low speeds
on the runway. Hold “up” elevator to keep the tail wheel on
the ground. If necessary, adjust the tail wheel so the model
will roll straight down the runway. If you need to calm your
nerves before the maiden fl ight, shut the engine down and
bring the model back into the pits. Top off the fuel, then check
all fasteners and control linkages for peace of mind.
Remember to takeoff into the wind. When you’re ready, point
the model straight down the runway, hold a bit of up elevator
to keep the tail on the ground to maintain tail wheel steering,
then gradually advance the throttle. As the model gains
speed decrease up elevator, allowing the tail to come off the
ground. One of the most important things to remember with
a tail dragger is to always be ready to apply
right rudder to
counteract engine torque. Gain as much speed as your runway
and fl ying site will practically allow before gently applying up
elevator, lifting the model into the air. At this moment it is likely
that you will need to apply more right rudder to counteract
engine torque. Be smooth on the elevator stick, allowing the
model to establish a
gentle climb to a safe altitude before
turning into the traffi c pattern.