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1) There are four sets of “cross-hairs” etched on the front of
the plywood firewall to mark the locations of the mounting holes
for the Maxx Products #ACC3958 Motor Mount. To install this
mount on the firewall you will need to purchase (4) 4-40 x 1/2”
Socket-Head Bolts, (4) #4 Flat Metal Washers, and (4) 4-40 Blind
Nuts. Drill the four mounting holes with a 9/64” or #27 drill bit.
NOTE: If you are using a different mount, line your mount up on
the firewall according to the horizontal and vertical thrust lines that
are etched in the plywood. Then drill appropriate holes where
needed for your mounting bolts.
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2) Install the blind nuts on the back of the firewall. The best
method is to use one of your mounting bolts, with a flat washer
on it, from the front side of the firewall to “draw” the blind nut into
the back side. Keep tightening the bolt until the prongs of the blind
nut are completely locked into the plywood. After you get all four
blind nuts in place, apply a little glue around the flanges of the
blind nuts to keep them from coming loose. Be careful not to get
any glue in the threads of the blind nuts.
HELPFUL HINT: It’s never easy putting a blind nut on the backside
of the firewall of a pre-built model. Here’s a handy trick! Take a
stick of scrap balsa wood - 1/4” sq. x 10”-12” long works well in
most cases - and put a piece of doubled-up tape (any kind) on the
end, and then stick the blind nut to the tape. With this stick you
can reach inside the nose of the airplane and hold the blind nut in
position while you screw in the mounting bolt from the front of the
firewall. If the model structure doesn’t allow a straight shot at the
location, cut an angle on the end of the stick to allow you to hold
the blind nut at the correct angle.
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3) Additional holes are needed in the firewall to allow air to flow
back inside the fuselage to cool the battery and the ESC in flight.
We recommend drilling three new 3/8” dia. holes in the lower part
of the firewall, as shown in the photo. These three new holes, in
addition to the laser-cut hole that is already in the firewall, should
provide enough cooling air flow to keep the battery pack and ESC
cool in flight. An electric drill with a 3/8" dia. drill bit is the simplest
way to make these new holes.
Note: If using the plastic Maxx Products #ACC3958 Motor Mount,
we recommend that you also make a new 7/8" dia. hole right at
the intersection of the thrust lines, as shown, which will be directly
behind the motor mount. This hole will allow air that flows into the
front of the plastic mount to continue on back into the fuselage,
where it will eventually exit the airplane near the tail. This will keep
the motor cool in flight.
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4) The cooling air must have a place to exit the fuselage. There
is an opening already cut in the fuselage bottom wood for this pur-
pose. You will have to remove the white covering material to open
this hole. The hole is located approximately 11-1/2" from the end
of the fuselage - see photo. You should be able to easily make
out the edges of the hole by sight and feel. Using a sharp new
blade in your hobby knife, carefully cut the covering away over the
hole. After removing the covering, seal and toughen the edges of
the bare balsa wood with a coat of Thin CA glue.
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5) Bolt your motor and mount to the firewall. Use thread lock
compound (not supplied) on all the bolt threads.
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6) Install your Speed Controller (ESC).
a) Solder appropriate connectors (not supplied) to the battery
leads of your ESC.