T
HE foam cutting process leaves some
very fine “threads” on the surface of the
core. In most cases, they can be removed by
rubbing the cores with your fingers. In some
cases, you might need to
very lightly
sand
the core with a fresh piece of 400 grit sandpa-
per.
Be careful not to change the shape of
the core or gouge the wing.
You do not need
to remove any of the foam itself, just the
threads. It is a good idea to support the wing
in its foam “cradle” anytime you are working
on it.
You may want to remove the threads from
the surface of the foam cradles so they don’t
accidentally end up in some glue joint later.
Next, using a sharp knife, trim off the ragged trailing edge of
the core. The trailing edge should be about
1
⁄
32
" thick when
you are done.
W
HEN the glue is dry, examine the wing
skins. Generally, you will find that one
side is smoother and more even than the
other. This will be the outside of the skin.
Mark the inside with a felt tip pen so you
won’t get it mixed up later. Use a good flat
sanding block (we prefer the aluminum “T”
bar as shown) and 120 grit sandpaper to
remove any excess glue. Finish sand with 320
grit. For best results, clean off all of the balsa
dust with a brush attachment on a vacuum
cleaner. We also wipe the skins with a
painters tack rag.
When the skins are smooth, trim them to
shape as shown on the plans. The dimen-
sions shown are slightly oversize to allow for trimming later.
Mark the skins “upper right”, “lower left” etc. on the inside of
the skins
Mark the inside of the skins
Sand off excess glue
Sand smooth
Clean off balsa dust
Trim to size
Phoenix
Page 7
Wing Construction
Sand wing skins
Remove “threads”
Trim trailing edge
Clean up foam cores
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