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Composite-ARF YAK 55SP (3m span)
Wings
The wings are 95% finished at the factory, and
have already been installed on your fuselage
to set the alignment. Dual phenolic aileron
horns are already pre-installed for you at the
factory. Slide the wings onto the 50mm diam-
eter alloy wing tube, and fit the 4 plastic wing
retaining nuts onto the M6 threaded alumini-
um wing dowels. Each aileron has 2 or 3 ser-
vos (depending on your servo choice) fitted
into cnc milled phenolic mounting plates that
are screwed into the cutouts in the inner and
outer plywood ribs. For easier access we
have included a milled servo hatch to fit in the
recess over the outer servo position, and you
will need to mill the slot in it to suit the exact
position of your chosen servo arm.
Wing Tube
The wing tube is a 50mm Ø T6 alloy, which
slides inside a fibreglass sleeve in each wing,
and it should be 1035mm (38.5") long. Please
check the length to make sure that it passes
through the inner plywood ribs in each wing,
that are about 355mm (14") from the root, oth-
erwise the wing could fail in flight.
Servo Choice
If you chose to use only 2 servos for each
aileron then one of these must be installed in
the rear position of the inner phenolic mount,
and the other in the outer phenolic
mount. Any slight mis-match of the ser-
vos will not cause servo damage dam-
age due to the slight torsional flexibili-
ty of the large ailerons.
If fitting 3 servos for each aileron, then
the inner pair are ganged together as
shown in the photos here. Fitting 3
powerful servos to each aileron does
make the snaps a little 'crisper', and if
you chose lower power digitals, like
the JR8411 or Futaba S9152/S9351
then you must install 3 servos per
wing.
JR/Graupner: 2 x 8511/8611's are
quite sufficient for each aileron, as
used in the prototype. Even better is a
pair of 8711/8811 servos - one
techsupport@composite-arf.com
(above) Each aileron is controlled by two or
three servos installed in phenolic mounts that
are screwed to the plywood ribs in the wing. (2
x JR 8511 servo set-up shown here)
(below) Included in the kit are phenolic servo
mounting plates for both JR and Futaba servos.
(below) Phenolic servo mounts and 3 x JR 8511
servos installed in the milled cutourts in the wing
internal structure.
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