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Composite-ARF Yak-55 SP (2.6m span)
Fuel Tank Base, Rudder Servo
Plate and Throttle servo mount
The rudder servo plate, fuel tank base and throttle servo
mount are assembled from a combination of CNC milled
plywood and composite-balsa parts that have been lami-
nated both sides with glasscloth, and vacuum-bagged, at
the factory. This material gives exceptional strength with
low weight and is more than adequate for this structure - so
please don't modify it in any way.
Throttle Servo Mount
Assemble the throttle servo mount from the milled plywood
parts, which clip together with interlocking tabs to make this
easy. Glue the milled plywood parts together with thin CA,
and then reinforce all joints with 30minute epoxy and milled
fibre. Trial fit the servo and determine the position to get a
nice straight linkage to the carburettor, without touching the
main undercarriage legs. Mark the position of the servo arm
and cut a slot in the cockpit base for it.
The mount is held in place using 2 x M3 blind nuts, as
shown, and two M3 x 12mm bolts and washers from the
underside of the cockpit floor. Please glue a small scrap of
3mm plywood under the cockpit floor to reinforce it and pre-
vent the bolt heads pulling through the composite material.
Unless you have a very short screwdriver, you will find it
easier to drill a hole through the side of the fuselage (which
will be covered by the wing root) to access the bolt or screw
holding the servo arm onto the servo shaft. Make up the
throttle linkage from the M3 all-thread, stop nut and quick -
links that are included in the hardware bag.
Note that all DA motors need quite a lot of servo throw to
get the full throttle range, so make sure you can fit a long
output arm on the servo. The photo on page 25 also shows
the throttle linkage in place.
Rudder Servo Mount
The rudder servo mounting plate is also assembled from
interlocking milled plywood and composite balsa sheet
parts, as shown in the photos below. See also the photos in
the Rudder section.
Tack the assembly together with thin CA, and then reinforce
all joints with a mixture of 30 minute epoxy and milled fibre.
Mark the exact centre of the cockpit floor and trial fit the
mount to be sure it is centrally positioned. Do not glue it in
place until you have completed the fuel tank base and
checked that the 2 parts fit together properly and are
techsupport@composite-arf.com
Finished in 1.5 hours
(above) Throttle servo location
shown here. The mount is fixed
down to the cockpit floor with M3
bolts and blind nuts.
28
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