The stabilisers should be
controlled by a full-size
servo of minimum 8kg
torque (eg: JR8311,
8411, or Futaba equiva-
lent). We strongly advise
fitting the best servo you
can here, and a digital
type of at least 8kg gives
peace-of-mind!
Adjust the size of the
cutout in the milled 6mm
liteply servo mount to fit
your servo, and screw it
in place, with the open
end of the cutout towards
the bottom of the fuse-
lage - again using allen-
head sheetmetal screws
to make it easier to re-
move the servo later.
Centre the servo with
your Tx, and fit a heavy-
duty servo arm onto the
output shaft at 90° to the servo case. The servo mount fits vertically between the 2 bulkheads in
front of the Fin position, with the servo output arm on the centreline of the fuselage, projecting
thru’ the factory-milled slot in the top of it.
Trial fit the mount and servo, and adjust the mount as necessary. Prepare all surfaces for gluing
properly. We find that the easiest way to glue the mount in place is with the fuselage upside-down
in a cradle, and connected to the yoke with the final linkage to ensure correct alignment. Tack glue
the mount (and servo) in place with 2 small drops of thick CA first, then carefully remove the servo
with a short ‘L-shaped’ allen wrench - and securely bond the mount to both bulkheads and the
upper surface of the fuselage with a slow epoxy and milled fibre mixture.
Re-install the servo, and refit the M3 or 4 x 40 pushrod linkage as shown. Fit the clevise as close
to the servo arm centre as possible, and use at least 100% servo travels to maximise the me-
chanical advantage. You will need to file a narrow slot in the base of the fin to clear the linkage later.
NB:
Do
NOT
use a single-sided ball-link to connect the elevator linkage to the Yoke - it could
cause twisting and dangerous flutter !
There is plenty of space between the stab servo and the top of the thrust-tube, but you can sili-
cone glue a thin ply shield to the bottom of the servo, and cover it with aluminium tape if you are
worried about heat. Check carefully that the bottom of the fibreglass stab yoke does not touch the
top of the outer thrust tube in the elevator ‘up’ position.
During gear installation be careful to route the elevator servo extension cable as far away from the
(hot) thrust tube as possible, and we strongly recommend that you additionally protect them by
wrapping the cables with self-adhesive aluminium tape and fixing them securely to the sides of the
fuselage. This also applies to the servo extension cable for the rudder servo.
Fox Composites Co., Ltd.
18
(above) Completed stab and rudder linkages, with Ø 7mm fin
joiners glued into fuselage. Heavy duty plastic servo arm used on
stab servo, with M3 clevise on 2nd hole. Slot in fuselage under
rudder allows easy connection of clevise onto stab yoke, and reg-
ular safety inspection. Note that rear fin joiner is offset, and a slot
must be filed in back of fin base to clear stab linkage.
