ilar method is also used for the aileron horns.
Servo choice: The elevators can travel more than 50
degrees, and it is up to you whether you want to use this
throw or not. The throw defines the kind of servo. If you are
going to use the maximum throw for 3D manoeuvres, we
definitely recommend digital servos like JR8411, or even
better the 8511/8611. It is not just that the torque of a stan-
dard servo is not enough - it is the play in the gears which
could cause problems centering, and high speed flutter
might be the result.
When using the powerful digital servos and larger throws
we highly recommend that you use our Composite-ARF
phenolic servo arms, designed for this kind of aircraft and
included in the kit (see photo). These must be fixed to the
standard (25 mm/1” Ø) plastic output arms supplied with
the servo with 2 small sheet-metal screws each. Rough up
the bottom surface of the C-ARF servo arm and the top
surface of the standard servo arm. With servos installed,
centre the standard servo arms (using your R/C) at 90° to
the btm. surface of the stabs.
Then glue the phenolic C-ARF arms in place with a couple
of drops of thick CA, making sure they are centred on the
servo arm bolt in the shaft and also at 90° to the stab sur-
face. Finally remove them from the servo and secure the
phenolic arms to the standard plastic arms with at least 2 of
the very small (2.2mm Ø x10) sheet metal screws provided
in the kit. Make up the linkages from the 45mm long M3
threaded rods, with 2 quicklinks and 2 x M3 locknuts for
each stab. Don’t forget to ‘Loctite’ the quick-link and lock-
nut on one end of each linkage. Do NOT use ball-links on
the servo arms or the control-surface horns, because they
will twist the servo arm/horn and cause flutter. This is a
solid experience and you should consider it a FACT.
The last job is to fit the M3 stab retaining bolts. Look inside
the stabs and you will see the small plywood reinforcement
plates between the spar sleeve and the bottom surface of
the stab. Mark the bottom of both stabs in the centre of this
plywood. Install the aluminium tube into 1 stab, and drill a
2.4mm hole right through the stab surface, the plywood
plate, sleeve and into the 20mm aluminium tube. The cen-
tre of the hole should be about 34mm from the trailing edge
of the stab. Thread the hole with an M3 tap and secure it
with an M3 x 16 bolt. To be really safe, you can glue an M3
blind nut inside the stab spar tube, with some 30 minute
epoxy and micro-balloons. Wax or oil the bolt first!
Fit both stabs to the fuselage, check that they fit tightly to
the fuselage at the roots, and then drill the hole in the other
stab and spar tube, thread as before, and secure with
19
(above) Shows C-ARF servo arm
glued and screwed onto standard
25mm diameter servo output arm.
(below) M3 blind nut glued into
elevator spar tube.
(above) Shows the stab retaining
bolt, with clear tape over it to pre-
vent it coming out in flight. The
small pieces of tubing stop the
quick-links from opening.
(below) Elevator horn alignment
template from scrap plywood. Line
is hinge axis. Use for both elevators
to ensure same throws.