90° square. Fix the servos into the mounts with
the Ø 2.9 x 13mm screws, and place them on
the hatch covers to check that the servo arms
are in the centre of the slots milled in the hatch
covers, and aligned with the aileron horns. Don’t
forget to allow for the extra thickness of the phe-
nolic servo horns that will be fixed onto the servo
discs. You may need to make the slots in the
servo hatch covers a little wider, by 1mm or so.
Tack glue the servo mounts to the hatch covers
with CA, then remove the servos and reinforce
the glue joints between the servo mount and the
servo cover plate with slow (min. 30 minute)
epoxy and milled fibre, with a nice glue fillet all
around. These are important joints!
Centre the servos using your R/C and fit the
phenolic servo arms to the servo output discs
using the same method as for the rudder servo.
Secure with at least 2 small bolts and nuts each.
Secure the completed hatch covers to the wing
with 4 sheet-metal screws, Ø 2.9 x 10mm.
Finally make up the linkages from the M3 x
45mm threaded rods supplied, with 2 clevises
and 2 x M3 locknuts for each.
Important:
The clevise should be on the
inner
hole of the servo extension arm, and on the
aileron horn it should be on the
outer hole
from
the aileron surface - to maximise the mechanical
advantage and reduce any chance of flutter.
With your transmitter throws set at maximum
(125%) this will still allow even the hi-rate/3D
throws mentioned at the end of the manual.
Please do
not
use the outer hole on the servo
arm, and do
not
reduce the throws electronical-
ly in your transmitter !
Don’t forget to ‘Loctite’ the clevise
and lock-nut on one end of each link-
age, and fit short lengths of tube to
prevent clevises from opening acci-
dentally. Do NOT use single-sided
ball-links on the phenolic horns,
because they will twist the servo arm
and cause flutter. This is a solid
experience and you should consider
it a FACT.
Composite-ARF Yak 55
(2.1m/83”)
21
(above) Make sure you thoroughly sand and
clean all the plywood parts before gluing the
servo mounts onto the hatch covers, and
make a nice fillet of epoxy on all joints.
