Message-ID: <001501bfdad0$182cb8a0$f8b188ce@pavilion>
From: "J. N. Cameron" <toucan@The-I.net>
To: "Lancair List" <lancair.list@olsusa.com>
Subject: Door stiffening
Date: Tue, 20 Jun 2000 10:56:25 -0500
Mime-Version: 1.0

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Here's an excerpt from an e-mail I sent recently to Skip Slater (ES
builder); thought it might have more general interest, given the recent
discussion on doors:

Another problem with the door is that the gas strut exerts a mighty
upward and outward force on the top right (aft) corner of the door,
particularly when it's shut.  In the manual they kind of wave a hand at this
and say something about adding several plies to the frame channel to stiffen
it.  It won't work.

    Before I started my first plane, I got a little kit from Aircraft Spruce
or somebody that was a sort of introduction to fiberglass technique.  As a
learning demo, they had you lay up a 4- or 6-ply glass sheet, maybe 3" by
12".  Then, using the same number of plies, they had you lay up the same
size sandwich of 2- or 3-ply glass, half an inch of foam, then the other 2
or 3 plies.  The former is very whippy and flexible, and remains so even if
you increase it to 8- or 10-ply.  The latter, however, can be put across the
corner of a table and will bear my full weight without flexing.  Sorry if
this is all obvious to you, but the application to the ES door is to form a
1/2" or 3/4" foam piece inside the door stiffener, particularly at that
corner where the strut attaches, then add about a 4BID layup over it,
forming a foam sandwich.  I had no trouble with that corner after stiffening
it like that.  I think next time I'll do it all around, except where the
latches need to go through the stiffener.  I think with the foam sandwich
method you don't need carbon, but it will help keep the weight of the door
down.  For as little area as is involved, the cost shouldn't be significant.
It's interesting, though, that on my first ES the door stiffener was carbon,
and this time they sent me an e-glass one.

I wonder if the new, pricey FB door will have sufficient stiffening to avoid
the door-bulge problems?

Jim Cameron,  ES builder


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