GREAT PLANES Piper j-3 cub Instruction Manual page 16

3. Trial fit the dihedral brace between the main spars of
the wing. Sand the edges of the dihedral brace if necessary
to get it to fit without forcing the spars apart.
4. IMPORTANT: Use a good quality non-brittle epoxy
for this task, such as Great Planes Pro 30-minute Epoxy.
Place waxed paper on the work surface and mix up a batch
of epoxy. Apply it to the top and bottom of the dihedral brace,
the spar joiners, the spars, spar ends and the ends of both
TE's. Apply plenty of epoxy, to fully fill all voids at the center
of the wing. Slide the spar joiners and the dihedral brace
into one wing panel first. Slide the other wing panel into
place and wipe off any excess epoxy. Immediately proceed
to the next step.
5. Block up each wing panel 5/8" (1/2" for the clipped
wing) as measured from the work surface to the bottom of rib
#7. Carefully align the spars and the TE of both wing panels.
Clamp the spar joiners to the spars and wipe off any excess
epoxy with a paper towel. Allow the epoxy to fully harden
before disturbing the wing and removing the clamps.
Wipe out any excess epoxy in the holes in the forward main
spar joiner.
6. Securely glue the remaining four 1/16" balsa vertical
grain shear webs to the front and back sides of the main
spar joiners between the #2 and #3 ribs.
7. Install the two #1B ribs as shown in the photo. The top
surface of each rib should be flush with the top surface of
the spars.
8. Round off one end of each 1/4" x 3" hardwood Wing
Dowel (DOWEL017). Slightly chamfer the other end of each
dowel. Slide the chamfered end of both dowels into the wing
and securely glue them to both spar joiners with either thick
CA or epoxy.
9. Install the two #1A ribs as shown in the photo. The top
surface of each rib should be flush with the top surface of
the spars.
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