Re: ATM Carbon vs. Glass fiber for tube

["Dave Pitou" <dpitou@ix.netcom.com>]

Mark wrote:

> There are rolls of 48" wide cork sheeting about 1/8-1/4" thick available
> at a local hardware store, and I was considering laying up fiberglass on
> that, over some kind of form for roundness.  Would cork (being light)
> make a good inner layer?  I understand the stiffness comes from the dual
> tube construction of the two layers of glass/carbon/kevlar...
> 
In general the ideal material to seperate the structural layers should be
very light, very stiff in the radial direction, and make a strong bond to
the cloth layers in tension, compression, and shear. I haven't used cork
before, but it could work OK. It's not as stiff as you would like, but
it'll be easy and cheep to work with. I would try a test piece first to
check for stiffness and adhesive strength. Clamp one end of the test piece
and pull hard on the other end. Watchout for delamination between the cork
and the fiber on the side facing away from you. In my experience the
Kevlar/epoxy bond is weaker than either glass/epoxy or carbon/epoxy, so use
glass for the test piece at least. 

Dave