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.
Make sure that the control horns are glued into the ailerons properly. The hole in the phenolic
horn for the quick-link needs to be exactly perpendicular to the hinge axis line, and in this
manual we show you a simple way to ensure that the horns in all pairs of control surfaces will be
identical, making it easy to set up your R/C for accurate flying manoeuvres.
The wings are already set-up with servo covers and hatch-
es for 2 servos per aileron, and we recommend a pair of
high-torque servos, like the JR D8411, in each wing. Our
servo covers and milled plywood mounts make both instal-
lation, 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 fuse-
lage, 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 vibrations or
hard shocks can cause the glue joints to weaken or break.
Monitor these joints whenever you set up your plane. 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 to receive the wing spar tube, the
stab spar tubes, and the holes and reinforcement plates for 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. No glue joint
needs to be stronger than the materials that it is attached to, as it would just result in increased
weight for no advantage. The landing gear is a fairly flexible design, which works very much like
Composite-ARF Extra 300SX
(2.6m span)
techsupport@composite-arf.com
5
Centreline of hinge axis
Phenolic control horn
