Great Planes Piper J-3 Cub 20 Kit - GPMA0158 - Manual (Page 19)

______BUILD THE FUSELAGE SIDES_____
D D 5 Glue the die-cut 3/32" balsa lower fuselage
doubler and upper fuselage doubler to the inside of one
of the fuselage sides The lower fuselage doubler must
align at the front and bottom edges The upper fuselage
doubler must align with the fuselage side at the front and at
the aft top edge.
D D 1 Pin or tape the fuselage plan to a flat work surface
and cover it with waxed paper Trial fit the die-cut 3/32"
balsa main fuselage side, lower front fuselage side and
aft upper fuselage side together as shown in the plans
Sand as necessary to achieve a good fit then pin the sides
over the plans Glue the side pieces together with thin CA
Wipe off any excess CA with a paper towel before it cures
D D 6 Glue the die-cut 3/32" balsa aft fuselage doubler
in place The doubler should match up with the front
corner made by the main fuselage side and the aft upper
fuselage side and line up with the top edge of the aft
upper fuselage side
D 7 Repeat steps 5 and 6 adding the doublers to the
inside of the other fuselage side Be sure to make a right
and a left side.
D D 2 Pin the die-cut 3/32" balsa cabin top to the plan
Cut three cabin posts from the 3/32" x 5/16" x 24" balsa
stick and pin them into position Glue the cabin posts and
cabin top to the fuselage side with thin CA Also sand off
the die-cut bumps on the lower front fuselage side so that
the edges are flush with each other.
D D 3 Remove the fuselage side from the plans and
inspect the glue joints for gaps, filling where necessary with
thick CA.
D 4 Repeat steps 1 -3 for the other fuselage side When
completed, place both sides together and sand the edges
where necessary to make the pieces identical Designate a
right and a left side at this time Mark the sides to avoid
building two "rights" or two "lefts" in the following steps
Sand the inside and outside of both fuselage sides with
150-grit sandpaper
D 8 Use the die-cut 3/32" balsa aft fuselage top as a
gauge to position the die-cut 3/32" balsa cabin doubler.
The bottom of the cabin doubler should be above the
fuselage side by the thickness of the aft fuselage top The
aft edge of the vertical slot in the cabin doubler should be
flush with the aft edge of the cabin and the top edge must
be flush with the top of the cabin side Once you have
determined its exact location, glue it to the cabin with thin
CA Glue a doubler to both the right and left fuselage sides.
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