between the dual phenolic elevator horns using the M3 x
20mm allen bolts and lock-nuts provided in the hardware
pack. Add a drop of Loctite for extra safety.
It is allowed to fit a single-sided ball-link onto the metal
servo arms to adjust the line of the linkage if necessary -
but you
must not
fit a ball-link to a single-sided phenolic or
plastic servo arm.
Static balance
Because the Yak elevators have very large counterbal-
ances, it does help to reduce loads on the servos if you add
15 - 20 grams of lead into each one, inserted through a
small hole drilled as shown, and epoxies into place.
Throws
If you need more travel on the elevators than the factory
assembly allows (about 40°) you will need to increase the
length of the slots in the composite/balsa ‘false’ leading
edge of the elevators with a small file. The outer 2 slots in
particular will need to be longer, and you can extend them
almost right out to the composite skin. Unfortunately it’s not
possible for us to mill these slots longer during manufacture
- as the L.E. spar would fall apart on the CNC milling table.
However, this is a very quick job with a Permagrit file, or
similar (see photos right), and you can easily achieve 50
degree throws if you wish.
Rudder
The rudder is completely finished at the facto-
ry, with the dual phenolic rudder horns glued
in, and the phenolic hinge posts aligned and
secured - ready to accept the Ø 4mm brass
hinge tube. Fit the brass tube in the same way
as for the elevators, sanding a small chamfer
on one end to ease insertion - and tape the
lower end in place before flight.
Assemble the tray from the milled parts and
install the servos and phenolic arms outside
the model, as shown. Lightly sand all compos-
ite balsa milled parts first, and glue together
with thin CA. Add the 3mm thick plywood
strips underneath each servo rail, cut from the
12mm wide ply strips provided. Then reinforce
all joints with 30 minute epoxy. The length and
angles at both front and back can be sanded,
if necessary, to fit exactly between the back of
the muffler compartment and the bulkhead at
the back of the cockpit opening (see photo
below).
Composite-ARF YAK 55SP
(3m span)
17
(above) Insert 15-20 grams of lead
thru’ a hole into the front of the
counter-balance of each elevator.
(below) You can increase available
throws by lengthening the slots in
the leading edge of the elevators,
especially the 2 outer slots.
(above/below) Assemble the rudder tray with
thin CA, as shown, with the plywood strips glued
underneath with epoxy.
