Owner manual
will leave material for adjusting the fit of the cowl to
the fuselage. Cut the cowl front 1/8" [3mm] outside
the molded-in cutline as well.
❏ 3. Cut out a small corner from the molded-in lip on
the left side of the front of the cowl top and from the
right side of the front of the cowl bottom. Use a bar
sander with coarse sandpaper to true the edges of
all three cowl parts. Securely tape the three pieces of
the cowl together with masking tape.
❏ 4. Cut eight 3/4" [19mm] cowl mounting blocks
from the 3/8" x 3/8" [9.5 x 9.5mm] basswood stick
leftover from the tail cone mounting blocks and the
servo mounts in the wing. Securely glue the cowl
mounting blocks to the front of the fuselage 1/16"
[1.6mm] from the outer edge to allow for the
thickness of the cowl.
❏ 5. Position the cowl and slip the spinner over the
crankshaft. Note the small balsa sticks that have been
tack glued to the front of the fuselage to align the cowl.
See how the cowl fits the fuselage and spinner. There
are three things to look for: 1) whether or not the spinner
is centered in the front of the cowl; 2) the spacing
between the spinner backplate and the cowl; 3) the fit of
the cowl to the fuselage.The fit should already be “pretty
close,” but now you have to trim and fit the cowl as
necessary until you get a finished fit. Start by noting
where the aft edge of the cowl needs to be trimmed so
the spinner will be centered. If the spinner is off to the
right side of the cowl, the cowl will need to be shifted
over more toward the right.To achieve this, trim the right
side of the aft edge of the cowl. Remove the cowl and
trim as necessary—if much material has to be removed
use curved-tip scissors, but when you start “zeroing in”
on the fit use a bar sander with 80-grit sandpaper.
❏ 6. Once the front of the cowl has been centered on the
spinner, it is time to trim the aft edge of the cowl front to
get an even gap between the back plate of the spinner
and the cowl. Use a bar sander to trim the cowl front as
necessary to achieve the desired fit. Note that trimming
the back of the cowl top and bottom (as done in step 4)
will “steer” the cowl in the correct direction so the spinner
is centered, but trimming the back of the cowl front will
change the spinner gap (between the back plate of the
spinner and the front of the cowl). Take your time and
proceed slowly to get a good fit.
❏ 7. Once cowl alignment has been achieved,
remove the cowl and separate the three pieces. Use
coarse sandpaper to thoroughly sand the inside
and outside of the cowl around the seams so glue
and filler will adhere. Tape the cowl back together.
Use thin and medium CA to permanently glue the
parts together.
❏ 8. Remove the masking tape and refit the cowl to
the fuselage. Make any final trim adjustments
necessary for a good fit between the cowl and the
fuselage and between the cowl and the spinner.
❏ 9. Use coarse sandpaper to thoroughly roughen the
inside of the cowl along the seams between the three
pieces.Use an epoxy brush to apply 30-minute epoxy all
the around the seams, then lay strips of 3/4" [20mm]
fiberglass cloth along the seams. Brush the epoxy
through the glass cloth while brushing the glass cloth
down to the plastic. Allow the epoxy to harden.
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