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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
  
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