Message-ID: <3A7AF5CD.611068DB@qwest.net>
Date: Fri, 02 Feb 2001 10:00:45 -0800
From: Curtis Krouse <kc16@qwest.net>
To: lancair.list@olsusa.com
Subject: Re: 320FB Wing closeout chapter
References: <80.660158a.27ac14e0@aol.com>
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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Jim,

Is your wing tip incidence within the limits with the misaligned
condition?  Have you done the prefit on the stub wing skins?

If you haven't bonded the stub wing skins on, then you are in a good
situation.  If I'm remembering correctly, the most important thing to do
is get the leading edge aligned.  You'll need to bolt down the main spar
and torque the nuts to insure that you have all the play out of the
front spar.  Then when you align the stub wing skins concentrate on the
leading edge.  Make sure you get it aligned so that when you sight down
the leading edge of the wing, the stub wing is in alignment.  Whatever
you end up with at the trailing edge is what needs to be corrected.  I
suspect that you have some twist in your main spar that needs to be
addressed.  OR...you may have something along the main spar where they
attach that will cause the twist, like a drop of dried epoxy.  Check to
make sure that the mating surfaces of your main spar are smooth and free
of any buggers.

Once all that is done, I would contact someone at Lancair support. 
Especially if you have a SFB kit.  If you have a SFB kit....all that
prealignment and fitting has been done already and I would be very
hesitant to start reshaping ribs.  Building up the wing rib can cause
some really nasty problems when you attempt to bond the wing skin on. 
Also, it will cause the dimensions of the trailing edge channel to widen
which will make it difficult to get a good clean gap where the flap is. 
It's like a chain of events that could cause you a lot of extra work. 
Imagine the work that you would have if you raised a straight line over
an 11 ft distance.  The leading edge of the bottom wing skin will be out
of alignment all the way out to the wing tip.  Once you correct that you
will have a misalignment with the bonding point at the spar which will
show as a ridge unless you use a truck load of filler.  Then the
problems it can cause with sealing the gas tanks could be a real pain
too.  I'd rethink the building up and cutting down of the ribs.  Of
course, if you have the slow build kit, then most of my opinion is
invalid.

My suggestion would be to make sure that you have a good mating of the
front spars, align the leading edge of the stub wing skins, determine if
the wing tip incidence is correct, then see how much wing twist that you
have at the BL50 rib.  Once that dimension is determined I would call
Lancair support to find out the best way to cure the twist.  That
solution may be a lot better than building up and cutting ribs.  You may
have to apply a bunch of weight to the trailing edge and then apply heat
to a certain location on the front spar and let the twist settle out
that way......but I would urge you to call the support for the best
suggestion.

I wouldn't leave the twist in and put tension on the aft spar bracket
either.  The wing may not care.....but I bet the bracket would over a
period of time.  And if that bracket failed in flight....you could be in
some serious trouble.

I hope this has helped.

Curtis Krouse

> Thanks Curtis ... that's the kind of info/advice I'm looking for. Actually I
> haven't bonded the stub wing skins on yet. This may give me options I
> otherwise may not have. Likely I'll build up on the wing rib and cut down
> some on the stub wing rib.
> 
> What'da you think?
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