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Composite-ARF YAK 55SP (3m span)
tage, if you set in about 10% NEGATIVE aileron differential
in your transmitter program. This means that the 'down'
throw needs to be about 10% more than the up throw.
Why? Because the axis of the hinge is not at the centreline
of the aileron, so it moves slightly in and out when it trav-
els, and the aileron gets a little "bigger" in surface area
when moving up, and "smaller" when moving down. This is
why you have to set the negative differential in your trans-
mitter to compensate for the size changing. 10% is a good
starting point, and you will find out the exact setting during the first flights, doing fast vertical rolls
and watching the fuselage rolling in a perfect line. You can set it perfectly, this is guaranteed.
The bottom slot needs some explanation, too. The cut line is exactly in the correct position so
that the aileron slides under the wing skin smoothly. If the cut was a few mm forward or back, it
would not work properly. So, make sure that the lip is not damaged, and that the aileron slides
under this lip perfectly. It will NOT lock at any time, as long as the lip is not damaged. If damage
occurs to the lip, you can cut off 2-3 mm, but you should never need to cut off more than this.
The wings are already set-up with servo mounts milled in the plywood ribs, and a milled servo
access hatch for the outer servos, and we recommend a pair of high-torque digital servos (eg:JR
DS8511 or 8611) in each wing. Our servo covers and milled plywood mounts make installation,
and exchange if necessary, very quick and easy and provide a rock solid servo mounting and
linkage system.
The wings are attached to the fuselage with the 4
threaded aluminium dowel anti-rotation pins, with
4 plastic nuts inside the fuselage. If the aluminium
dowels come loose in the wing, the wing will slide
outwards, away from the fuselage, and the main
spar tube will definitely break. So take great care
to inspect the glue joints of these anti-rotation
dowels in the wing REGULARLY. Excessive vibra-
tions or hard shocks can cause the glue joints to
weaken or break. Monitor these joints whenever
you assemble your plane before flying it. Never
forget to tighten the nuts inside the fuselage. Please DO
NOT modify these attachment dowels in any way, their per-
fect function is proven for many years.
The Fuselage:
The fuselage is also made in negative moulds, and is all
constructed using TAVS technology. All the loadbearing
internal parts are installed during manufacture, to ensure
accurate location and reduce your assembly time. The
fibreglass tubes in the wings and stabs to receive the spar
tubes, and the anti-rotation dowels, are already installed.
There is no need to even check the incidences - you can be
assured that these are already set in the moulds so that no
adjustment is necessary.
The landing gear mount is strong and doesn't need any
extra reinforcement. The fuselage is extremely light weight,
and the gear loads need to be led into the structure gently.
techsupport@composite-arf.com
(above) The internal wing struc-
ture, showing the carbon roving
and cloth reinforcement.
(below) The wing root, showing
the 50mm Ø 6061 alloy wing tube
and the aluminium anti-rotation
dowels in the root rib.
5
Centreline of hinge axis
Phenolic control horn
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