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RE: [PSUBS-MAILIST] Reverse engineering



Uh-Oh, this is the famous plastic coke bottle question again. Take one of those and fill it with compressed air, and you will find it withstands hundreds of psi. But take it underwater with you on a scuba dive (external pressure) and it will collapse before you know it. External pressure resistance is NOT calculated from internal pressure resistance. They are two entirely different things.
 
I'm afraid the "formula" for external pressure is actually a number of pages worth, because it depends on lots of variables like diameters, length, material, etc., etc. You can readily calculate the depth rating of cylinders and speres, but anything else is hard. I'll send you scans of all the formulas off list, and the spreadsheet on PSUBS automates the same calculations.
 
"Reverse engineering" is something quite different. That refers to taking something apart and creating the design from the finished product, rather than building a product from a design. When I was an engineering student in Argentina, one of my colleagues worked at a tank factory. His assignment was to take the fire control circuitry from a Leopard II tank (purchased from Germany) and figure out the design so replicas could be built without paying the royalties.
 
cheers,
 
- Alec
-----Original Message-----
From: Floridarobots@aol.com [mailto:Floridarobots@aol.com]
Sent: Tuesday, December 04, 2001 8:29 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Reverse engineering



Question.....  What is the formula to calculate reverse engineering on a pressure hull ?  

If a Co2 tank is rated for say 1000 PSI of outward pressure from the inside, what would it be rated for  as far as pressure from the outside ? Sorry if this sounds like a dumb question, Im not sure if there is a calculation for this....
Tom