(1) Plywood Electric Motor Mount
(1) Balsa Triangle Stock
(4) M4 x 25mm Socket-Head Bolts
(4) M4 x 20mm Socket-Head Bolts
(4) M4 Blind Nuts
(4) M4 Flat Washers
(4) M4 Lock Washers
(2) Velcro
®
Straps
(1) Electric Motor, ESC, Prop, Lipo Battery (not furnished)
❑
37) Note that the firewall portion of the laser-cut plywood
motor mount is adjustable fore and aft to accommodate
different length motors. In this step, we will adjust the motor
mount for your particular electric motor. For the RASCAL 110,
we need a total distance from the back of the plywood motor
mount box to the motor’s thrust washer to end up exactly 6".
This distance allows the cowling to fit properly.
a) Assemble your motor according to the manufacturer's
instructions. Then carefully measure the distance from
the back of the mounting plate to the front of the thrust
washer (the "thrust washer" is where the back of the
propeller will be located).
b) Subtract the measurement taken in the previous step a)
from 6". The result is the distance you need to locate the
front of the firewall from the back of the plywood motor
mount box.
(With the motor we are using in these
photos, the motor measurement is exactly 3". So 6"
minus 3" = 3". We will set our firewall at 3" from the back
of the mount. Your result may be different depending on
your motor.)
c) Carefully measure and mark the distance determined in
the previous step from the back edge of the motor mount
box towards the front. Do this along side each of the
adjustment slots on both sides of the box.
d) After you have all the slots marked, move the firewall
until you have the front of the firewall lined up with the
marks. Make sure you end up with the firewall straight
and square in the box. If it is not, recheck your marks
and adjust as necessary.
e) Tack glue the firewall in place. Recheck once more to
make sure that the front of the firewall is at the correct
distance from the back of the motor mount box. That
distance plus the length of your motor must equal 6".
When satisfied it is correct, glue the firewall securely to
the rest of the motor mount box. Make sure to soak in
some CA along all the edges.
❑
38) A set of four M4 x 25mm socket-head bolts, M4 blind
nuts, and M4 flat washers are provided for attaching the
plywood electric motor mount to the firewall. The firewall has
been laser etched with the four locations for mounting bolts.
Look closely and you will find four small etched dots on the
firewall with the correct spacing to match the holes in the back
of the plywood motor mount.
a) Using a 1/16" drill pilot holes through the firewall at the
four etched locations. Then switch to a 1/4" dia. bit to
drill out the four holes to the final size to accept the blind
nuts.
b) Install the M4 blind nuts in the back of the firewall. You
will need to reach in through the fuselage to the front of
the plane. This can be made a lot easier by inserting a
1/8" dia. dowel (7" to 8" long) through the hole from the
18