Message #44

Date: Nov 16 1999 15:43:49 EST
From: (David E. Munday)
Subject: Re: Fabric Wrinkling

I think I'd check to see what the dimensions of the spars are.  If
yours bends enough to wrinkle and others don't it sounds like you're
getting more deflection than is normal.  That could be bad.  The
standard spar is 3/4 inches thick.  See if yours is thinner or if
yours may be a box spar rather than a simple plank.

On Sun, 14 Nov 1999 07:22:56 -0500, "Darrel Morisse"
<> wrote:

>>> I asked a few days ago if it's normal for the wing fabric to wrinkle
>>> slightly outboard of the strut attach points, but got no answer.  Is this
>>> normal?
>>By "strut attach points," I'm assuming you mean the wire attach points.
>Sorry.  My error.  Should have said landing wire attach points.  My fingers
>were keeping a secret what was going on in my brain.
>>Second, is it wrinkled all the time, or does only show up in flight (or,
>>conversely, does it show up on the ground and disappear in flight)?  The
>>load pattern changes when a plane transitions from ground to flight.
>Also should have said that it wrinkles in flight, not on the ground.
>Wrinkles from the area of the attach points outboard.  This is an indication
>that the spars are bending slightly and I was curious if this is normal in
>the Flybaby.  My Kitfox wings bend quite a lot under load but since it's a
>high wing I can't see if they're doing any wrinkling or not.
>>Wouldn't hurt to pull of some inspection panels and take a quick look
>>inside, just for peace of mind.  A small flashlight and a mirror on a
>>stick will let you look for loose braces, etc.
>>Ron Wanttaja
>I had a pretty good look around and all looks to be in order from what I can
>see.  Even though the airplane was built 30 years ago, it was very well done
>and I'm confident in it's structural integrity.  Some new rag on the wings
>sure won't hurt though, but that's gonna have to wait awhile until after I
>get this new Kitfox flying, which I anticipate around Y2K time.  Building
>the panel now, all else is pretty much done.
>Thanks for the help,
>Deep Thought
>"Ever wonder why Kamikaze pilots wore helmets?"

David E. Munday                         E-mail:
Dept. of Mechanical Engineering         Web:
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