them into the flaps until the holes for the clevises are
7 - 8mm in front of the leading edge of the flap.
Especially if you want to connect the servos together
on a Y-lead and use a single channel it is important
to have the horns in identical positions on both flaps.
Make a small template from scrap plywood and an
old drill bit to copy the position of the first flap horn
to the other flap, as shown here. Tack glue both
horns in place with a small drop of thick CA. File
matching slots (approx. 6 x 12mm) in the trailing
edge of the wing for the horn & linkage to pass thru’.
Carefully prepare the inside of the wing skins where
the mounts will be glued in place. Insert the ply servo
mounts (only) into the wing, and hold them at an
angle so that you can insert the servos and screw
them into place thru’ the hatches. Just 2 servo
screws is enough for trial fitting. Twist the mounts
vertical again, push them forward to make contact
with the wing spar, and set the angle of the servo
arm parallel to the flap horns. Tack in place with a
drop of thick CA. Make up the linkages from your
preferred hardware - we used M3 threaded rod and
steel clevises, and they will need to be approx.
100mm long, clevise pin-to-pin.
NB:
To obtain the best mechanical advantage (and
holding power) for the flaps you must set your servo
throws to the maximum possible and fit the clevise
into a hole on the servo arm as close as possible to
the servo centre !
Connect the linkages to the hole approx. 10mm from
the centre of the servo horn, with the servo horns
angled approx. 45° forward for
the ‘up’ flap position, and check
the flap travel by hand. You
only need 40° - 45° max. travel
for landing. When you are sat-
isfied with both flap travels,
carefully remove the servos
and permanently glue the
mounts into place with slow or
30 min. epoxy and micro-bal-
loons, making sure they are se-
cured to the wing spar.
Also glue the flap horns se-
curely to the inside surface of
the flaps, inserting the glue on
the end of a thin stick.
Fox Composites Co., Ltd.
11
(below) Completed flap servo installa-
tion in right wing, at the outboard side
of the hatch, with flap in the fully down
(‘landing’) position, and the servo arm
angled backwards at about 45°.
(above) Ply mounts secured with a fillet
of epoxy/micro-balloons all around.
(below) Flap servo installed in left wing,
at inboard side of hatch, using the 12mm
longer plywood mount supplied.
