Mailing List lml@lancaironline.net Message #701
From: Ed Armstrong <ed@testelectronics.com>
Subject: fiberglass and carbon fiber
Date: Thu, 1 Oct 1998 16:13:15 -0700
To: Lancair [Lancair.List@Olsusa.Com] (E-mail) <lancair.list@olsusa.com>
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A while ago I wrote: That means that the body of my plane is going to take
up most of the stress, and my longeron is not going to do much of anything.
Any one have a word of encouragement for me?

Now that I thought about this more, I realize that the longeron is not
supposed to be structurally used for load carrying. I think we are just too
familiar with things needing frames, and the whole idea behind composite
construction is to reduce framework by making the surface strong. The wings
are flat and need spars to keep them from bending, but the fuselodge is big
and round like a pipe. A pipe is a strong shape, yes it is a pipe with a
hole cut in the side for the canopy cover, but it is still a strong shape.
I imagine this as kind of unibody construction. The whole body acts to
support forces. If you look under the longeron the whole body is carbon
fiber over honeycomb material. As we all know, the carbon fiber has a very
strong tensile strength and the honeycomb keeps it from bending. We all
know how this 90% of forces on the surface and 10% of the forces inside
theory works. If you look inside the firewall, you can see, the load forces
are distributed evenly across all of this. I think the wooden strips are
probably just for vibration dampening, and conveniently double for mounting
the old style canopy. I think all the calculations being done on these wood
strips are not applicable because they are neglecting to add in the support
offered by the body design.

Regards,
Ed
Watsonville CA.
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