posite orientation in the 2 wings so that you can Y-lead
them together and use a single Rx channel for opera-
tion as shown in the photos here. If you want to use a
single Rx channel for operating the two flap servos you
must fit them both in the same orientation (as shown in
these photos), but it is quite tricky to make the linkages
and horns exactly the same to obtain identical throws !
It is certainly
much
easier to use a ‘Matchbox’ (or equiv-
alent) on one servo so that you can reverse them, and
adjust centres and end points to match each other per-
fectly, and in this case you can install the flap servos in
'mirror-image' (like the aileron servos).
The rectangular-shaped servo mounts are made up by
gluing the 6mm milled balsa part to the underside of the
milled ply part with thick CA. Don't forget to make a
'Left' and 'Right' servo mount ! Sand the inside of the
slots to fit your chosen servos if necessary, 33mm wide
for the 3301 or 3328 types. Trial fit the mounts in the
servo bays, and sand a slight curve on the balsa to
match the wing shape. Adjust the length of the 2 tabs
that project forward on each mount to so that they touch
the front spar, and that the back edges of the mounts
are exactly parallel with the leading edge of the
ailerons/flaps.
Carefully sand and prepare the inside surface of the
wing skin where the mounts will be glued in place later.
With the mounts temporarily installed in the wing (but
NOT glued in place), accurately mark the positions of all
4 servos. Fit the aileron servos as far towards the wing
tip as possible, and the flap servos as close to the wing
root as possible. Remove the mounts and screw the
servos in position with small self-tapping screws. The
flap servos should be packed up off the mounts with
scrap 1.5mm ply strips to give extra clearance for the
servo arms. You can trim and sand off the 'normal'
servo mounting tabs on one side of the 3301 or 3328
wing servos, and fix them using the wing-mounting tabs
- or file slots in the plywood mounts if you prefer.
Centre the aileron servos now, using your Tx, and fit
short servo arms at 90° to the servos case as shown.
Centre the Flap servos also, and then fit the servo arms
angled backwards by 2 splines/approx. 15 degrees (to-
wards the flaps). Before gluing the mounts into the
wing, file a 8mm wide and 8mm deep slot on the un-
derside of each mount for the flap linkages as shown,
exactly in line with the servo arms. Now glue both com-
pleted servo mounts into the wing, using 30 minute
epoxy and micro-balloons mixture and making sure that
the front tabs are also glued to the wing spar.
Fox Composites Co., Ltd.
11
(above) Glue the 2 milled parts to-
gether with thick CA or epoxy to make
servo mounts (left wing shown).
(below) Completed mount for right
wing, ready to be glued in. Note ply
packers for flap servo, grooves in top
surface for servo cables and clearance
slot underneath for flap linkage.
Bottom view showing clearance slot at
back, and chamfer at front, for flap
linkage and servo arm. Make these be-
fore gluing the mounts into the wing!
slot for linkage
