SIG Four-Star 120, Building And Flying Instructions, Page: 10 / 30

.
Aileron Servo Installation
The ailerons on the Four-Star 120 are operated by two servos mounted
separately in each wing panel (see "RADIO REQUIREMENTS" earlier on in these
instructions).
25.
Cut two hatch rails from the special-cut 1/4"x1/2"x12" basswood stick provided in
the kit. Glue the hatch rails in place, flush with the bottom edge of the W-2 and W-
3 wing ribs. The hatch rails provide a seat for the aileron hatch and a flat surface
for attaching the covering material.
26.
a. The die-cut 1/16" plywood hatch may require some trimming or sanding for
a perfect fit on the hatch rails. With the hatch in place, drill four holes
through both the hatch and the hatch rails (at each corner of the hatch)
with a 1/16" drill bit.
b. Remove the hatch, then redrill the four holes in the hatch with a 3/32" drill
bit. The hatch is held in place with four #2 x 3/8" sheet metal screws. Be
sure to mark each hatch so you can tell later which hatch goes with which
wing panel!
27.
a. Since servos come in many sizes, you need to make a custom servo tray
from lite-ply and basswood to fit your particular servo. Cut a hole in the die-
cut lite-ply aileron servo mount to fit your particular servo. The forelaft
dimension of the hole should be about 1/16" larger than the length of your
aileron servo.
b. Cut two 3/8" sq. x4" basswood servo rails (from tile 27" long piece provided
in the kit) and glue them to the aileron servo mount flush with the front and
rear edges of the hole.
c. If necessary, trim or sand the edges of the servo mount until it fits snugly in
position between the ribs. Trial fit the mount, but don't glue it in yet.
28.
Carefully position the servo on the mount so that the outer hole of the servo arm
is lined-up with the control horn on the aileron. The goal here is to keep the
aileron push rod wire parallel to the wing ribs (and the airflow). Mark the 4 servo
mounting holes, then fas.ten the servo to the aileron servo mount using either the
screws provided with the servo or long wood screws (#2 x3/4", not provided in
kit).