SIG Four-Star 120, Building And Flying Instructions, Page: 12 / 30

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FUSELAGE CONSTRUCTION
Fuselage Subassemblies
Before starting fuselage construction, there are a few subassemblies that should be built and set aside until needed. This
is done to avoid interruptions during the flow of fuselage construction.
32.
a. Glue together the two die-cut 5/32" plywood F-1 pieces using Kwik-Set epoxy or
slow CA. Use a heavy weight of some kind to hold the two pieces perfectly flat
while drying.
b. Mark the vertical center line and thrust line on the F-1 assembly using the cross-
section on the plan as a guide.
c. The engine mount included in the kit will fit most of the 1.20-size four-stroke
engines on the market. Positon the engine mount (or another mount of your
choice) on F-1, mark the location of the mounting holes, then drill them out with a
3/16" drill bit.
33.
a. Lightly hammer four 6-32 blind nuts into the back of F-1. Pull the blind nuts into their final position by bolting the
engine mount to the front of F-1 using four 6-32 x3/4" socket head bolts. Apply medium or slow CA around the
edges of the blind nuts to hold them in place. Be careful not to get any glue in the threads!
b. Position your engine on the mount far enough forward for the propeller to clear the fuselage "cheeks", mark the
engine mounting holes, then drill at each of the marks. If you plan on using the four #8 x1" sheet metal screws
provided in the kit, use a 9/64" dia. drill bit. The sheet metal screws are self-tapping and won't loosen from engine
vibration. If you prefer, machine screws can be substituted, but you'll have to drill and tap the mount.
34.
Temporarily bolt the engine to the
mount so you can locate the best spot
on F-1 for the throttle pushrod to exit
and line up with your engine's
carburetor control arm. A 2-56 solder
clevis is provided in the kit to attach the
flexible cable pushrod to the engine's
carburetor. The solder clevis should
work well for 2-stroke engines, but most
4-stroke engines may require a different
type of connector. Remove the engine
and engine mount, and drill at the mark
with a 9/64" dia. drill bit.
35.
a. Glue the two die-cut 5/32"
plywood landing gear mounts
together with epoxy or slow CA.
Again, weight the assembly
down until dry.
b. Carefully center the aluminum
landing gear over the landing
gear mount and mark the
location of the mounting holes
through the three holes in the
landing gear. Remove the mount
and drill at the marks with a
13/64" drill bit.
c. Lightly hammer three 8-32 blind
nuts into the holes and secure
them with medium or slow CA.