Great Planes SU-31 3D ARF - GPMA1412 - Manual (Page 48)

48
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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 Sukhoi SU-31 1.60 ARF is a great-fl ying model that fl ies
smoothly and predictably. The Sukhoi SU-31 1.60 ARF 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 overpowered 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.
Flight
For reassurance and to keep an eye on other traffi c, it is a
good idea to have an assistant on the fl ight line with you. Tell
him to remind you to throttle back once the plane gets to a
comfortable altitude. While full throttle is usually desirable for
takeoff, most models fl y more smoothly at reduced speeds.
Take it easy with the Sukhoi SU-31 1.60 ARF for the fi rst
few fl ights, gradually getting acquainted with it as you gain
confi dence. Adjust the trims to maintain straight and level
fl ight. After fl ying around for a while, and while still at a safe
altitude with plenty of fuel, practice slow fl ight and execute
practice landing approaches by reducing the throttle to see
how the model handles at slower speeds. Add power to see
how she climbs as well. Continue to fl y around, executing
various maneuvers and making mental notes (or having your
assistant write them down) of what trim or C.G. changes may
be required to fi ne tune the model so it fl ies the way you like.
Mind your fuel level, but use this fi rst fl ight to become familiar
with your model before landing.
Landing
To initiate a landing approach, lower the throttle while on the
downwind leg. Allow the nose of the model to pitch downward
to gradually bleed off altitude. Continue to lose altitude, but
maintain airspeed by keeping the nose down as you turn onto
the crosswind leg. Make your fi nal turn toward the runway (into
the wind) keeping the nose down to maintain airspeed and
control. Level the attitude when the model reaches the runway
threshold, modulating the throttle as necessary to maintain
your glide path and airspeed. If you are going to overshoot,
smoothly advance the throttle (always ready on the right
rudder to counteract torque) and climb out to make another
attempt. When you’re ready to make your landing fl are and
the model is a foot or so off the deck, smoothly increase up
elevator until it gently touches down. Once the model is on the