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Composite-ARF Yak 55 (2.1m/83")
techsupport@composite-arf.com
Rudder
The rudder is hinged to the fin using the Ø 2mm wire (sup-
plied) which passes thru' the 3 phenolic hinge posts that are
factory-installed and aligned. File a point on one end of the
wire, and a short 90° bend on the other end and push it
through the tube in the rudder from the bottom, capturing the
3 phenolic hinges on the way. Don't forget to secure the bent
end of the wire with some strong tape for flight.
Trial fit the double-sided phenolic rudder horn in the slot that
is already milled in the base of the rudder, and mark the part
that will be glued in. Remove it, mask the parts that will be
exposed, and scuff the centre part on both sides with coarse
sandpaper. Cover the slot area on both sides of the rudder
with waxed plastic parcel tape, as mentioned in the
Stabiliser section above. Cut thru' the tape to expose the
slots in the rudder. Glue in place with 30 min. or slow (not 5
minute !) epoxy and microballoons mix, making sure that it
is centred in the rudder. The front edge of the phenolic horn
should be flush against the back of the balsa false leading-
edge inside the rudder. Remove the plastic tape
from the rudder and horn when the glue is hard.
Servo: The rudder is a large surface on the Yak
which definitely needs a hi-torque power servo
of at least 12kg torque, and we recommend the
digital JR/Graupner 8511/8611/8811, or Futaba
S9351, for this very important control surface.
The servo is installed in a CNC milled compos-
ite mounting plate, which is then glued across
the fuselage just behind the back end of the
exhaust tunnel as shown here. Position the top
surface of the mounting plate 35mm (1.6")
above the bottom of the fuselage, so that the
pull-pull wires pass underneath the rear fuse-
lage bulkhead. If you are using a larger and
heavier motor than the DA-50, you should install
the rudder servo mount as far back as possible
to help with setting the correct CG.
If using a full-length pipe, then you will need to
cut and extend the muffler tunnel, and the rud-
der servo mount will need to be raised by
approx. 80mm to clear it. In this case the position of the slots for the pull-pull cables to exit the
fuselage will change from the ones shown here.
To prepare the mount, glue the ply plate to the bottom of the balsa with CA and mount the servo
with the Ø 2.9 x 13mm screws provided, not the standard ones that come with the servo. The
composite balsa stiffening rails are glued into the milled slots under the front and back of the
plate with thin CA. Depending on the exact location of the servo mount you may need to sand
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