Top Flite TOPA0305 Part 2 User Manual

Page 25

BUILD AND FIT THE COWL TO THE

FUSELAGE

1. Cut the molded ABS cowl left side, right

side, and front along the cutlines (seen from the

inside). Cut a notch in the top of the right cowl half

and the bottom

of the left cowl half so the lap joints

do not interfere. On the aft edges

of the right and

left cowl sides, cut about 1/8" aft of the cutlines.

This gives you a little extra material to work with

you can accurately fit the cowl to the fuse. Cut the
openings in the front of the cowl. If you have one,
use a rotary hand tool with a cutting burr followed
by a sanding drum. Sand the edges

so they are

straight and even.

2. Thoroughly sand all areas that are to be

glued, including a 1/2" strip along the inside edges
of the cowl, so the fiberglass reinforcement tape
will stick.

3. Tape the cowl together with masking tape.

Test fit the cowl to the fuse. Glue the seams with
thin CA.

Test fit the die-cut 1/8" plywood cowl rings

on the firewall. If necessary, sand the edges of the
cowl rings

so they are inset from the edges of the

balsa fuselage sides approximately 1/16". Glue the
cowl rings to the firewall.

5. With the engine mounted, fit the cowl to the

fuselage. Mark the high spots on the aft edge of the
cowl where you need to remove material

so it

accurately fits the fuselage and aligns with the
backplate of your spinner. At first the cowl will be
too long but as you zero-in on the fit, place the
backplate of your spinner on your engine to help
you align the front of the cowl. This is a cut-and-fit

procedure that takes a little time, but it's one of
those areas where you can really show your
craftsmanship. Take your time and remove small
amounts of material at a time.

Note:

the head of the engine, the needle valve or

carburetor interferes with the cowl, remove them
for the time being.

6. Test fit eight 1/2" x 1/2" x 5/8" maple cowl

mount blocks in the notches in the cowl ring.
Sand the blocks

so they match the shape of the

cowl. Glue them in place. Mark the center

of each

cowl mount block on the fuselage. Test fit the cowl

to the fuselage to make sure none of the blocks

interferes with the cowl.

Securely tape the cowl to the fuselage. Using

the marks as a guide, drill 1/16" holes through the
cowl and the cowl mount blocks 1/4" in front of the
aft edge of the cowl. Hint: After you drill each hole,
screw in a #2

x 3/8" screw to keep the cowl

accurately aligned as you proceed.

8. Remove the cowl and enlarge the holes

the cowl

only

with a 3/32" drill bit.

9. Test fit the cowl to see how it fits. Use #2 x

3/8" screws to hold it in place.