Horizontal Stabiliser - Composite-ARF SPARK Instruction Manual

Composite-ARF SPARK

Horizontal Stabiliser

The one-piece stab is factory-finished for you. It
is secured to the fuselage by a 6mm carbon
dowel at the front, that fits into an 8mm carbon
tube in the fuselage, and a pair of M4 Allen bolts
at the back - which screw into threaded metal
inserts that have been laminated to the fuselage
sides. The phenolic control horns are glued in
place, and jig-aligned, and even the cutouts for
the servos are started to save you a little time.
The stabiliser is quite thin and will only accept a
15mm thick 'wing-mount type' servo if you want
it to fit completely flush. The servo should have
at least 4 kg torque and a strong, slop-free, gear
train. Therefore we also highly recommend the
Graupner/JR DS 3328/3301 for this application.
Make up the servo mounts from 2 layers of the
milled 3mm Liteply pieces, with a layer of the
1.5mm thick ply strip glued to the bottom if nec-
essary to match to exact height of your servos.
Laminate them all together with thin CA, and
then file the slot thru' the 1.5mm ply (if used) to
make sure the servo fits absolutely flush against
the upper skin of the stab. Sand a small groove
in the top of the mounts for the servo extension
cable exit. Screw the wing-mount brackets of the
servos to the mounts using the small Ø 2.2 x
10mm sheetmetal screws supplied in the hard-
ware packs, and sand off any excess that comes
thru' the top surface of the mounts. Then remove
the screws and apply 1 very small drop of thin
CA to all of the screw holes - which will harden
the wood around the edges of the hole to give a
more secure fixing. Use this technique on all
screw fixings into Liteply throughout the plane.
Note: The aileron servo mounts are made up in
exactly the same way, if you are also using JR
DS3328 or 3301 wing-mount type servos.
Fit a JR heavy duty servo arm to each servo,
and centre them now with your R/C so that they
will be at 90 degrees to the bottom surface of the
stab. Apply masking tape to the bottom surface
of the stab and mark on the lines of the linkages,
in line with the elevator horns and exactly paral-
lel to the fuselage centreline.
There are factory-made cutouts in the underside of the stab for the servos, but these will proba-
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(above) Shape the servo mounts to fit against
the rear spar in the stab.
(below) Align servo output arm carefully with
the phenolic elevator horn, parallel to the
fuselage centreline.
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