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8.
Join the bottom sheeting, spar, and trailing edge using the same technique as above.
9.
When the longer parts are complete, pin the trailing edge as accurately as you can over
the plans.
Note:
Building over the plans is not strictly necessary. If you are building
over the plans, trust the components. The parts are correct!
10.
Mark the middle of the center piece and
use that line in conjunction with the
plans to locate and pin the bottom sheet.
11.
Draw a centerline across the bottom
wing sheeting, then draw two more lines
exactly 3 cm (1.181”) to either side of
center. These will exactly locate the
inside edge of the R1 ribs and help align
them when installing them. (Thanks,
Glidermang!)
12.
Pin the center piece and trailing edge to
the board.
13.
Slip one R9 and one R4 rib into the
trailing edge on both sides of the wing
and pin them on line at 90 degrees vertical
to the board to serve as spacers for the
bottom sheet. Do Not pin through the bottom sheet.
14.
Slip the bottom sheeting underneath the ribs, and use your straight edge to press the
bottom sheeting against the notches in the bottom of the ribs and against the center piece.
Pin the bottom sheeting into place with the pins located to the rear of the bottom sheet.
15.
Once the three pieces (bottom sheet, centerpiece, and TE) are pinned and marked, check
for square and flat then glue the bottom sheeting, center piece and trailing edge together
at the center piece. Thin CA works well here.
Spar and Ribs
The internal main spar is built up inside the top and bottom sheeting. It’s constructed of two 3
mm (~1/8”) square carbon fiber rods spaced 3 mm (~1/8”) forward of the trailing edge of the
bottom sheeting joined by a balsa sheer web. Of primary concern is aligning the bottom carbon
fiber spar with the bottom spar cap. If it is not aligned precisely, the pre-cut notches in the ribs
will not fit correctly. (See Fig. 15, next page)
To build the center section spar:
1.
Locate the spar parts: the two square carbon fiber spars and the spar sheer web that you
glued up in the
Wing Preparation
section.
2.
Rough up the sides of each square carbon fiber spar with sandpaper to remove any mold
release and provide more surface area for the glue to reach. Carbon fiber dust is nasty
stuff! Wear a mask and sand outdoors if possible.
3.
Place a carbon fiber spar on the bottom sheet approximately 3 mm (~1/8”) forward of the
back of the bottom sheeting.
Figure 14: Wing Center Piece Marked at Center
