RE: [ATM] Carbon Fiber for Spider Vanes

["Donald Good" <donald.good@comcast.net>]

I don't think there is any ? of a fragile CF spider breaking.  It will
break.  But a CF spider is only fragile if it is poorly made.  As Shane
Santi of Dream - Telescopes & Accessories wrote earlier, a properly made CF
piece is both light and strong and not fragile.  (BTW, Peter, I don't think
Shane was saying that you said "five times", only that he frequently hears
such unqualified claims being made.)  And making a composite part is highly
qualified.  Shane mentioned a couple of factors: Manufacturing techniques
(hand layup, vacuum bagging), materials (CF, Kevlar, E-glass, S-glass), and
design (fiber/resin ratio).  Of course there are other factors in each
category, each contributing to the desired properties of the part.  Some,
others have mentioned.  Additional factors are:

Manufacturing techniques: pre-pregs, heat curing
Materials: hybrid fibers such as CF/Kevlar mixes, different resin systems
for different fibers and operating temperatures 
Design: fiber fabric weave patterns, fiber tows (unidirectional bundles),
layer orientations (e.g. 0-45-90) and composition (different fabrics and/or
different fibers).
Knowledge: which factors affect which properties
Experience: ability to operate equipment and put it all together properly
Safety: Resins are generally toxic, fibers fragments can cause damage to
skin and lungs

If you do not have experience with composites, find someone who does who is
willing to help.
Clear skies
Don

> -----Original Message-----
> From: atm-bounces@atmlist.net 
> [mailto:atm-bounces@atmlist.net] On Behalf Of Rod Shea
> Sent: Monday, April 04, 2005 3:58 PM
> To: Peter; atm@atmlist.net
> Subject: Re: [ATM] Carbon Fiber for Spider Vanes
> 
> In past postings, the ? of a fragile CF spider breaking has 
> been raised.  I have been looking into this, and plan drop 
> testing the whole sec assembly with a dummy secondary, to 
> find out if the sec would break loose with rough handling.
> 
> Rod
> 

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