.
IMPORTANT:
Now is the time to go back over every
joint using MEDIUM or THICK CA.
Don't be stingy here - the integrity of
your wing depends upon strong glue
joints. Glue BOTH sides of EVERY
joint, even the aileron servo lead tube.
BE ABSOLUTELY POSITIVE THE SHEAR WEBS ARE BONDED TO BOTH THE TOP AND BOTTOM SPARS.
8.
Cut, fit and glue a bottom center sheet between the trailing edge sheet and the rear spar.
9.
a. On both ends of the wing panel cut off and sand flush any excess materials.
b. Although the leading edge is pre-shaped, it should be blended into the leading edge sheet and the ribs with a long
sanding block. Trim and sand the overhanging portion of the trailing edge sheets flush with the trailing edge.
c. Sand the top center sheets smooth. Cut a 3/4" square or round access hole in the top center sheet as shown on the
plan.
Left Wing Panel
10.
Repeat steps 2 through 9 to build the left wing panel. BE CAREFUL, DO NOT BUILD TWO RIGHT OR TWO LEFT WING
PANELS.
Joining The Wing Panels
11.
a. Trial fit the two wing panels with the 1/8" laser cut plywood dihedral brace
installed between the main wing spars. Be certain that the dihedral brace
is not preventing the panels from making solid contact with each other at
the center. If necessary, trim or sand the dihedral brace for a snug fit. The
2° dihedral per wing panel will automatically be built-in by the dihedral
brace. If you want to check the angle, place the wing on the table so that
one side sits flat, and the other is raised. The bottom of the raised wingtip
should be about 1-7/8" above the surface of the table. A variation of up to
1/2" either way is acceptable and will not affect flight performance. Most
important is to have a tight joint at the wing center with no gaps.
b. Use epoxy (either SIG 5-MINUTE or SLOW-CURE) to join the two wing
panels. Apply glue generously to the end ribs and the dihedral brace. Work some glue into the slot in each wing
root. Carefully slide the wing halves into place and hold in place with tape or pins. Wipe away any excess epoxy that
oozes from the center joint with a paper towel or a rag dampened with isopropyl alcohol. Before the glue cures,
make sure that the leading and trailing edges of both panels are perfectly aligned and that there is no built-in twist.
Let cure.
Completing The Wing
12.
a. While you still have access through the bottom of the wing, check the glue joint around the wing hold-down blocks
and the dihedral brace. If necessary, apply another coat of epoxy to the joints.
b. Finish installing the bottom wing center sheets using pieces cut from 3/32"x4"x36" balsa.
c. After the glue on the center section sheets has cured cut two 3/16"x1/2" slots in the bottom leading edge sheet at
the W-3 wing rib in both right and left wing panels. Glue the four 3/16"x3/16"x36" forward spars in these slots and in
the bottom of all of the ribs. When the glue has cured, sand the forward spars flush with the tip ribs.
d. Glue the laser cut lite-ply wingtip to the outboard end of both wing panels.
e. Give the wing a final sanding. Sand just enough to take off any prominent high spots or bumps. Excessive sanding
will distort the airfoil shape.