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Composite-ARF Yak 55 (2.1m/83")
M3 nuts for each stab, as shown in the photos.
The clevise should be positioned in the servo
arm hole about 25mm from the servo centre,
and on the elevator horn it should be on the 4th
or 5th hole out from the elevator 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.
'Loctite' the quick-link and lock-nut on at least
one end of all linkages. Add a couple of short
lengths of silicone tube over all clevises to pre-
vent them opening accidentally in flight.
Of course you will also need to cut out a corre-
sponding rectangular shape in fuselage for the
back of each servo as they will project into the
fuselage by about 20mm (3/4"). See photo right.
The stabs are secured to the carbon tube using
two M3 bolts, screwed thru' the bottom surface
of the stabs, into T-nuts that you must glue
inside the carbon tube. There is a small plywood
reinforcing plate inside the stab that the bolts will
pass thru', and the centre of this is 85mm from
the root.
Apply some masking tape to the bottom of the
stabs and mark the centreline of the stab tube
on it. Fit the carbon tube into one stab, and drill
a Ø 2.4mm hole 100mm out from the root of the
stab, thru' the bottom surface, the ply reinforce-
ment, the fibreglass sleeve and the bottom of
the carbon tube. Tap the hole M3. Remove the
carbon tube and glue in the M3 T-nut, using a
thick mixture of 5 minute epoxy and micro-bal-
loons, with the M3 bolt temporarily in place to
ensure alignment. Wax or oil the bolt first !
You will need to grind or file the sides of the T-
nuts a little so that they will fit inside the carbon
tube.
Fit both stabs tightly to the fuselage, and then
drill the hole in the other stab and spar tube,
thread and glue in the T-nut as before. Counterbore the holes in the bottom surface of the stabs
for the boltheads so that they fit almost flush with the bottom surface of the stabs, and put a piece
of clear tape over the bolt-heads for flight.
Note: Try to always leave the stab tube fixed in one stab, and never remove that one bolt, as it
is tricky to find the right position for the stab tube again if it is removed from both stabs!
techsupport@composite-arf.com
(above) Make slots in the fuselage for the
back of the servos. You can glue the socket
on the end of the elevator extension lead
into the fuselage as shown here.
(below) Location of the hole in the underside
of the stabs for the spar securing bolts.
The stabs are secured onto the carbon tube
spar using M3 bolts, into cut-down M3 T-nuts
that are glued into the ends of the tube with
epoxy and micro-balloons.
17
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