Top Flite TOPA0310 - Manual (Page 33)

washer) should be 7-7/16". Most glow engines will
require an “extension box” made from 1/4" Plywood
(not included). For ignition engines and large glow
engines some modelers prefer to mount the box (if
required) to a vibration isolation mount such as the
Great Planes Vibration Isolation Plate (GPMG2000,
not included).
Skip the following two steps if you are not building an
extension box.
Materials required for extension box: sheet of 1/4"
5-ply birch plywood, 1/2" balsa triangle stock, and
1/2" x 1/2" basswood.
❏ 3. To determine the length to make the extension
box, measure the distance from the back of the
mount to the front of the drive washer. Subtract that
distance from 7-7/16". That’s how long the extension
box must be. In the case of the O.S. Gemini 160
shown here, the box must be 2-3/4" long.
❏ 4. Build the extension box from 1/4" birch
plywood (not included) using 30-minute epoxy.
Reinforce the inside corners of the box with triangle
stock (not included). If using a Great Planes Isolation
Mount, be certain the box will fit on the mount and
will not interfere with the grommets.
Refer to this photo for the following three steps.
❏ 5. Mount your engine to the box using the
appropriately sized screws and blind nuts (not
included). Make the back of the box from 1/4"
plywood and glue it inside the back of the box, flush
with the back edge of the box sides. Mark reference
lines on all four sides of the box that align with the
crankshaft on the engine. Some engines have “tick
marks” that indicate the centerline.
❏ 6. Make reinforcement rails from 1/2" x 1/2"
basswood (not included) and glue them around the
base of the box. Position the box on the firewall in
alignment with the tic marks, then
temporarily
secure the box to the firewall with #6 x 1" screws (not
included). The box will be permanently glued to the
firewall after the fuse is sheeted.
Let’s temporarily mount the fuel tank before sheeting
the front of the fuse.
❏
7. Determine the height of the fuel tank in relation
to the carb on your engine. The fuel tank should be
positioned, so that when half full, the fuel level is
even with your carburetor. If necessary, build a
fuel
tank mount from the 1/8" x 4-3/8" x 5-3/4" plywood
fuel tank floor and leftover 1/4" x 3/8" basswood as
shown on the plan. Use screw eyes (not included) or
something similar to secure the tank, then glue the
assembly into position. In the case of the model
shown in the manual (using the O.S. Gemini 160), no
fuel tank floor was required due to the low positioning
of the carburetor. Removable balsa rails were used to
secure the tank. Position your fuel tank and drill holes
for routing the fuel lines. Later, the vent line will be
connected to the pressure tap (or connected to a
drain tube in the case of the Gemini as no tank
pressure is required) and the fuel line will be
connected to a Great Planes Easy Fueler Fuel Filler
Valve (GPMG4160, not included).
Note: Do not
permanently mount the tank until after you have
hooked up the throttle.
Mount the stab and fin
❏ 1. Cut two 7-1/4" long pieces from the 1/2" x 24"
balsa tri stock. Use a fine razor saw to make saw cuts
in the tri stock so you can bend it to the stab saddle,
then securely glue both pieces to the saddles. Where
necessary, carefully trim the tri stock even with the
stab saddles.
❏ 2. Place the stab in the stab saddle. Take
measurements and make marks with a ballpoint pen
to center the TE of the stab in the saddle. Place a
weight on top of the stab to hold it down and keep it
from shifting.
Note: Before continuing, plan the routing of your
throttle pushrod, as this may have an effect on
fuel tank location.
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