Great Planes Piper J-3 Cub 40 Kit - GPMA0160 - Manual (Page 20)

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1. Use a sanding block to sand off any excess epoxy on
the top and bottom of the spars in the center of the wing.
Also lightly sand both the tops and bottoms of each rib to
remove any glue bumps or other irregularities.
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2. Mark a centerline on one of the 1/16" x 3" x 14-7/8"
balsa Center Sheets (CUB4W14) lay the sheet against the
back edge of the leading edge sheeting and mark the edge
of the sheet on the ribs and spars. Remove the sheet and
apply thick CA to the ribs and spars. Press the sheeting
down and hold it in place until the glue sets.
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3. Slide a second piece of top center sheeting up against
the first piece and glue it in place. Cut a third piece to fill the
gap between the second piece and the TE and glue it in
place. Save the scrap from the third piece.
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4. Use a 2-1/2" diameter circle template or the outline drawn
on the plans as a guide for cutting a smooth radius at each
corner of the top center sheeting as shown in the photo. Sand
the edges smooth with a piece of fine (220 grit) sandpaper. Use
extreme caution to avoid cutting into the spars!
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5. Trim a piece of the 1/16" x 3" x 14-7/8" center wing
sheeting to fit between the spar and the bottom LE
sheeting. It also must fit between the first two #3 ribs as
shown in the photo.
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6. Glue the remaining piece of center wing sheeting
behind the spar and use the scrap left over from the top of
the wing to fill in to the TE. This sheeting also must fit
between the first two #3 ribs. Cut out between the #1B ribs
for access to the aileron servo.
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7. Cut the Cap Strips from the 1/16" x 1/4" x 30"
(CUB4W15) balsa sticks to fit between the LE sheeting and the
TE sheeting, and glue them to the top of each exposed rib.
Install Center Sheeting
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