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Re: [PSUBS-MAILIST] hull thickness technical help needed

David, (I think, you don't sign your posts)
No heartbreak here, I happen to love composites...there's a little outfit out in Mojave California, (Scaled Composites I believe :), that's been doing some pretty amazing things for awhile now. In fact, they'e been showcasing for decades now composites absolute best feature.......it's super high strength to weight ratio.
What if you could build a composite 1 atm sub hull that could submerge 50 cf to 1000 m, and the shell itself would weigh a mere pound.
Would you still require 3,200 lbs of weight to reach neutral buoyancy? What would this weight consist of? I don't believe good ole Archimedes there will let us get away with that so fast.
So composites is ruled out as a favorable material for 1 atm submersibles by simple physics is it not?
If you are to pursue a 1 atm submersible hull utilizing composites, you must do so by acknowledging and accepting the responsibilities and pitfalls of experimentation with the budget and resources of an individual. 

Personally....me copy what been done already! :)
It is the intention of this forum to promote safely operated and successful psubs. Be prepared to receive feedback that you may not be expecting nor desire to hear. This is a veritable gold mine but, you have to learn to mine it. 

Best of luck to you

Joe






From: DrewBane1@aol.com
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] hull thickness technical help needed
Date: Wed, 18 Oct 2006 16:23:42 EDT
Hate to be a heart breaker but might be onto the information im looking for. 
Been talking to the engineers at work and one of which has a clue as to
where i might find the design specs
on a vacuum chamber they designed a few years back and the technical info to 
be able to calculate hull thickness. As far as repairing frp and weeping
hulls, this sounds more like a poor construction using old polyester resins not 
the epoxy vinyl ester that is commonly used on todays pressure vessels.  OK
here is some insight on frp pipe, 24" dia. 3/4" wall frp pipe is rated for 100 
psi internal pressure, test pressure is 150 psi, max test pressure is 225
psi.
There is a 10 x's safety margin on the pipe pressure and DOW claims their
resins achieve a 16 x's safety margin and yes they do take into consideration 
constant pulsing and hammering of the pipe as well as temps of 180' and
chemicals that would eat your steel subs alive. (no offense to steel lovers) For those that think frp will give them greater styling advantages, this is only true for ambient subs shape will still play an important role on a 1 ATM sub 
in frp. When i get the information for  calculating thickness for a vacuum
chamber I will share it freely with  those that love composites.....






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