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Composite-ARF YAK 55SP (3m span)
No glue joint needs to be stronger than the materials that it
is attached to, as it would just result in increased weight for
no advantage. The landing gear is a well proven design,
taken from our 3.3m Yak, and the slight flexibility helps to
smooth any less-than-perfect landings. Do not change or
modify it, as the results would only be negative. We had
plenty of time and experience to engineer the strength
needed in this area - and we did !
The motordome, firewall and molded exhaust system tun-
nel are a fully integral parts of the fuselage, and provide
plenty of strength for any engines up to 170cc on the mar-
ket today. See the Engine Installation section for details of
engine and setting thrust angles.
The Stabilisers:
The stab parts are also vacuum bagged sandwiched. The
rudder and the elevator control surfaces are hinged with
4mmØ tubes, fitted through phenolic hinge bearing plates
which are jig-installed during manufacture for perfect align-
ment.
The rudder and elevator design allows for at least 45
degrees throw. For the Yak it is mandatory that the tail area
is extraordinarily light weight, so the stab is designed for one
powerful digital servo installed in each half. All the structural
parts are preinstalled. The horizontal stabs are mounted with
one 20mm aluminum tube and one 10mm carbon anti-rota-
tion pin each.
Servo Screws:
Fix all the servos into the milled plywood servo mounts
using the 2.9 Ø sheet metal screws provided in the kit, not
the standard screws normally supplied with servos by the
servo manufacturer. This is because all the holes in our
milled servo mounts are 2mm diameter, due to our CNC
manufacturing process, and this is too big for the normal
screws.
All stabiliser and aileron servos must be secured into 6mm
thick plywood mounts, and we have included plywood dou-
blers for you to add in any places where there is only 1
layer of 3mm plywood present.
Take Care:
Composite sandwich parts are extremely strong, but fragile at the same time. Always keep in
mind that these contest airplanes are designed for minimum weight and maximum strength in
flight. Please take care of it, especially when it is being transported, to make sure that none of
the critical parts and linkages are damaged. Always handle your airplane with great care, espe-
cially on the ground and during transport, so you will have many hours of pleasure with it.
techsupport@composite-arf.com
(above) The lightweight fin-post
has the phenolic rudder hinge
posts already installed and aligned
at the factory. The corresponding
tubes are also installed in the rud-
der for the hinge tube.
(below) The elevator and rudder
hinging uses 4mm diameter tubes,
inside phenolic hinge posts that
are factory-installed and aligned.
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