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The Yak 54 EP ARF is a great-flying model that flies
smoothly and predictably. The Yak 54 EP ARF does not,
however, possess the self-recovery characteristics of a
primary R/C trainer and should be flown only by experienced
R/C pilots.
CAUTION (THIS APPLIES TO ALL R/C AIRPLANES): If,
while flying, you notice an alarming or unusual sound
such as a low-pitched "buzz," this may indicate control
surface flutter . Flutter occurs when a control surface (such
as an aileron or elevator) or a flying surface (such as a
wing or stab) rapidly vibrates up and down (thus causing
the noise). In extreme cases, if not detected immediately,
flutter can actually cause the control surface to detach or
the flying surface to fail, thus causing loss of control
followed by an impending crash. The best thing to do
when flutter is detected is to slow the model immediately
by reducing power, then land as soon as safely possible.
Identify which surface fluttered (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 fluttered
once, under similar circumstances it will probably flutter
again unless the problem is fixed. Some things which can
cause flutter are; Excessive hinge gap; Not mounting
control horns solidly; Poor fit 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 flutter; Flying an over-
powered model at excessive speeds.
If you have access to a smooth, paved runway, we suggest
using it to takeoff, especially for the first few flights. Position the
Yak 54 EP ARF onto the runway pointed into the wind. Slowly
advance the throttle stick to half throttle leaving the elevator in
the neutral position. As the tail rises off the ground, slowly
increase throttle and apply a bit of up elevator to lift the model
into the air. As you become accustomed to the takeoff
characteristics of the Yak 54 EP ARF, they can be performed
quickly, only requiring five to ten feet of runway until the model
is airborne.
If you do not have access to a smooth runway, the Yak 54 EP
ARF can be hand launched. For the first flight, it is a good
idea to have someone launch the airplane for you. This
allows you to keep your hands on the radio sticks and
correct any trim problems that are present.
Have the person launching the Yak 54 EP ARF hold the plane
by the fuselage just below the canopy. Throttle up to full power,
and have your helper give the plane a gentle underhanded
toss at about 30° angle upward into the wind. The high thrust
FLYING
Takeoff
to weight ratio will allow the plane to accelerate to flying speed
almost instantly. Climb to a comfortable altitude and throttle
back to a lower power setting.
For reassurance and to keep an eye on other traffic, it is a
good idea to have an assistant on the flight 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 fly more smoothly at reduced speeds.
Take it easy with the Yak 54 EP ARF for the first few flights,
gradually getting acquainted with it as you gain confidence.
Adjust the trims to maintain straight and level flight. After
flying around for a while, and while still at a safe altitude with
plenty of battery charge, practice slow flight 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 fly 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 fine tune the model so it flies
the way you like.
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 final 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 flare 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 runway and has lost flying
speed, hold up elevator to place the tail on the ground,
regaining tail wheel control.
One final note about flying your model. Have a goal or flight
plan in mind for every flight. This can be learning a new
maneuver(s), improving a maneuver(s) you already know, or
learning how the model behaves in certain conditions (such
as on high or low rates). This is not necessarily to improve
your skills (though it is never a bad idea!), but more
importantly so you do not surprise yourself by impulsively
attempting a maneuver and suddenly finding that you've run
out of time, altitude or airspeed. Every maneuver should be
deliberate, not impulsive. For example, if you're going to do
a loop, check your altitude, mind the wind direction
(anticipating rudder corrections that will be required to
maintain heading), remember to throttle back at the top, and
24
Flight
Landing
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