Mailing List lml@lancaironline.net Message #6718
From: <BOBPAS26@aol.com>
Subject: IV-P Main Wing Skin Trimming
Date: Fri, 15 Sep 2000 22:56:20 EDT
To: <lancair.list@olsusa.com>
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A fellow builder that we share tips with asked yesterday how we trimmed the
inside edge of the main wing skins. It occured to me that others might
appreciate the technique I used. It;s very simple, accurate and quick.

You'll need two pieces of flat aluminum flashing about 6" wide and long
enough to extend beyond the leading and trailing edge of the wing to
establish the trim line for the inside edge of the wing skins. This aluminum
is available at Home Depot, or similar places--cheap.

Square off the two pieces of the flashing long enough to extend about 3-4
inches beyond the leading and trailing edge of the wing. Place one piece on
the top near the inner edge of the skin and hold one up against the bottom
skin parallel to the top strip. Carefully align the edges closest to the
fuselage, drill and cleco the two pieces of flashing together just beyond the
trailing edge. I did the inside edge first, then aligned the front edges,
then added a couple more clecos along the back edge of the aluminum just
beyond the flap trailing edge (you do need the flaps installed and locked in
the retracted postion for all work on the fairings) You'll have a sandwich of
two aluminum strips with the wing between and a top and bottom inside edges
that are parallel and perpendicular to the top of the wing. Then go to the
front and pull the alumimum forward so the clecos are close to the trailing
edge but not distorting the aluminum. Check the inside edge alignment at the
front, slide the sandwich in or out along the wing to where you want to
mark/cut, ensuring that both the top and bottom skins extend at least a bit
all along the cut line. Then tape or cleco the aluminum temporarily to the
wing and scribe your cut/trim line. There will be a slight gap along the
outboard edge of the aluminum flashing that covers the bottom skin because of
the wing taper--it won't affect the straight inside edge appreciably, but you
could shim it equally along the span if you're a perfectionist. After doing
one wing, carefully take the sandwich off and use it to do the other wing--it
will align to the other side of the flashing. I marked the aluminum and wing,
and drilled a couple of alignment holes for clecos through the aluminum and
wing skin just inside the innermost rib (had about 1/4" to play with there)
so I could re-establish the trim line after installing the fairings to butt
up against the wing skin and adding micro to make a smooth mate. After
sanding to the required contour, I slipped the flashings back on to the
original position, re-marked the join line and cut through the micro to
separate the wings and fuselage/fairings. Worked well.

Bob P
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Please send your photos and drawings to marvkaye@olsusa.com.
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