The Ultimate 40 bottom wing is built as one piece.
D 1. Use 30-minute epoxy to glue together the die-cut 1/8"
plywood ribs R-5 and R-6.
TWO WARPED SPARS INSTALLED
THIS WAY WILL RESULT IN A
STRAIGHT WING
D 1. Pin the die-cut 3/32" balsa ribs R-1 in position over
the main spar.
Note: The jig tabs should be contacting the plan. Use
small T-pins to pin the aft jig tabs to the building board
over their location on the plan.
HOLD KNIFE AT AN ANGLE
WHEN CUTTING APART
LEADING EDGE
D 2. The shaped and notched balsa wing LE and TE are
fastened together by thin strips of balsa. Separate them by
cutting with a hobby knife, as shown in the sketch above.
TWO WARPED SPARS INSTALLED
THIS WAY WILL RESULT IN A
WARPED WING
D 2. Match sets of 1/4" x 3/8" x 24" balsa wing spars so
any warps will counteract each other.
D 3. Trim the end of two main spars to the angle shown
on the plan. Use 6-minute epoxy to glue the ends of
the main spars together. Before the epoxy cures, use the
cross-pinning technique (see sketch above) to pin the main
spars against the building board.
D D 3. Center the LE vertically on the front of the ribs with
each rib inserted in its respective notch. Use a straightedge
to check that the LE is straight before gluing it in position.
D D 4. Cut the LE at the root as shown on the plan. Save
the piece you cut off for the wing center section.
D 5. Repeat the process to install the other LE.
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