.
f.
Fill in between the lower stringers, over the wing saddle with 1/8" sheet balsa.
g.
Notch the fuselage and epoxy the plywood tail wheel bracket mount F12 in place.
h.
Inset 1/8"x3/4"x2-3/8" plywood cowl mount inserts into the fuselage side at
location shown on the plan.
i.
Shape the fuselage with a knife and sanding block to the cross-sections shown
on the plan. You will need the cowl to get the shape of the nose area just right for
a good fit.
5.
Cowling
The cowling should be assembled and fitted to the fuselage before the fuselage is covered and painted. Careful shaping of
the nose is necessary to achieve a good fit. Butyrate dope thinner, MEK or cyanoacrylate adhesives can be used to
assemble the cowl.
Note: Read about an Optional Cowl Reinforcement Method below before starting.
a.
Cut away the excess plastic around the lower air exit flange at the rear of both cowl halves.
b.
Tape the cowling halves together and try a preliminary fit of the- match to the fuselage. If the cowl fits the fuselage too
loosely, remove a little width by sanding down the seam between the two halves. Sand very lightly.
c.
Untape the cowl when the fit is satisfactory. Hold the plastic joiner strip in place
on the inside of one half. Leave half of tne joiner strip extending over the edge so
as to lap onto the other cowl half when it is attached. Using a small, pointed
brush, flow a few drops of thinner under the edge of the strip. It will spread along
the seam by capillary action. Don't let the thinner get under your finger, it will
leave a finger print.
Read section 16, "Sanding And Painting
Plastic Parts", before sanding the cowl
surface.
d.
Hold the cowl halves tightly together. Use strips of masking tape to hold the
opposite side (top or bottom) from which you will be gluing first. Flow thinner into
the seam from the inside. Squeeze and hold together any parts of the seam not
closed. Allow to dry. Remove the masking tape and join the halves on the other
side. Allow to dry thoroughly.
e.
Even up the back edges of the cowl with a sanding block.
f.
Scrape and sand the seam to take out any rough spots or flaws. Do not use
coarse sandpaper that will cut deep scratches in the plastic. The deep scratches
may later open up wider when dope is applied. Use medium paper and finish
carefully with fine paper, sanding down enough to have a smooth, scratch-free
surface. Low spots in the seam can be filled with Sig Epoxolite putty. Don't put on
too much Epoxolite and expect to sand away the excess later. Epoxolite dries
very hard and must be worked into the final desired shape before it hardens.
Epoxolite can easily be shaped with your finger and/or a single edge razor blade.
Dip them in water occasionally to keep the Epoxolite from sticking to them.
g.
Cut out the 3 air intake openings in the front of the cowl using the patterns on the fuselage plan front view for the exact
size and location. Mark the openings on the front of the cowl. Drill a series of holes about 1/8" in diameter around the
inside of the marks - have the holes almost touching each other. Cut through the bits of plastic between each of the drilled
holes with a knife and break out the part to be removed. Once the preliminary openings are made, the edges can be
trimmed to exact shape with an X-Acto knife.
h.
Cut out the backs of the side scoops to provide more exit space for the engine cooling air. The most important factor in
cooling a fully cowled engine is to keep a constant stream of fresh, cool air moving thru the cowling by having more exit
area than incoming area. Inadequate exit space can cause the heated air to be trapped in the cowl, which causes the
engine to overheat.