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Composite-ARF YAK 55SP (3m span)
installed at the back of the inner phe-
nolic mount and the other in the outer
mount. For the ultimate response fit
three x JR 8511/8611 or 8711/8811
servos.
Futaba: We strongly recommend that
you only install 3 servos, not 2. Either
3 x S9351's or 3 of the larger S9152's,
and special phenolic mounting plates
are included for these.
Servo Mounting
Secure the servos to the phenolic
plates (without using the rubber grom-
mets and brass ferrules) as shown,
using the supplied M3 x 12mm allen
bolts, washers and M3 lock-nuts.
Align the servo cases exactly parallel
to each other using a steel ruler on the
servo case sides.
The inner servos should be installed
with the output shafts towards the
leading edge of the wing, and the outer
servo is installed with the output shaft
closest to the trailing edge.
The phenolic plates are isolated from
the ribs using the grommets and brass
ferrules originally supplied for fitting
into the servos, as shown here. Fit
them into the milled semi-circular
cutouts around the edges of the phe-
nolic mounts. You will need a couple of
extra grommets and ferrules for this.
Servo Arms
It is mandatory to use full metal servo
arms for the aileron controls, and we
always use the SWB double-loc arms
(shown here).These arms clamp onto
the servo output shaft with no lost movement (play) at all. We used 1.5" arms on the rear two
servos, and a single 1" arm on the front inner 'ganged' servo.
Whichever make of metal arms you use, chose the lengths carefully to provide full deflection
throws without having to electronically reduce the end-points, to ensure the highest torque and
mechanical advantage.
If using the SWB arms you will need to reduce the thickness of the 1.5" arms a little at the end
so that the supplied aluminium clevises fit without binding, and this is easily done on a belt
sander (see photo on page 16). The 1" SWB arms used for the front (ganged) inner servo are
(above) Dual inner aileron servos installed in the pheno-
lic mounts provided, 'ganged' together with metal servo
servo arms using the hardware provided in the kit.
(below) The single outer servo installed in the phenolic
mount, and screwed to the plywood rib.
(below) Back view of the inner ganged servos, showing
the lock-nuts that secure the servos , and the grommets
and brass ferrules fitted around the perimeter of the
mounting plate. Note that the 1.5" SWB arm has been
sanded a little for a good fit of the clevise.
21
techsupport@composite-arf.com
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