DIY glass fibre plenum chamber? Bad idea?

[Dick Brewster]

From: DemonTSi at aol.com
Date: Wed, 11 Feb 1998 01:35:10 EST 

In a message dated 98-02-10 22:32:33 EST, kv at us.ibm.com writes:

>....

> I worked with kevlar a bit this past semester in school and was kinda
> disappointed because it wasn't all that "it was cracked up to be." We had a
> plate consisiting of 30 layers of pre-preg uniderectional kevlar (laid up in a
> criss-cross fashion...each layer rotated 45degrees relative to previous layer)
> and it couldn't stop a 9mm...albeit it was shot from point blank range. 
> Anywayz, for this application (the intake plenum), I think the use of good
> 'ole, everyday carbon fiber is more than enough. And it sure will look cool
> too. 

>Van

For Kevlar to work as armor it needs room to move to absorb the
energy of the projectile. Well laid up, many layer, 45 degree
cris cross is exactly the wrong way to do it because it make a
rigid structure that can't move enough to absorb the energy of
the projectile so the Kevlar fibres get cut and/or pushed aside
as the projectile whizzes through.  Kevlar has little if any
advantage in a composite structure unless is is very skillfully
used in combination with other composites.

Most homebrew and small shop composites aren't designed and
fabricated well enough to take full advantage of glass'
properties, let alone carbon. but if you are using carbon for its
appearance, then at least you are being honest with yourself. 
Take care in the mounting, most failure I have seen on composite
housings, covers and decorative structures could have been
prevented by proper mounting. Obviously, if a failure can cause
composite bits to fall of on the engine side of the aircleaner,
its worth some extra care.

Cheers