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On Fri, 19 Apr 1996, Alan B. Chapman wrote:
> internal pressure to external pressure 200:1. In flight your tank is
> still holding 200 bar but the external pressure may be as low as 0.5 bar
> making the ratio 400:1.
Nooooooo! Please stop it! That's it! I lost my temper on this one!
(this is the physicist in me talking)
Pressure is an absolute measurment (measured relative to an absolute
zero). If you follow you reasoning than the ratio of pressures for a
spacecraft is infinit (which would imply infinitly thick walls!).
It's true but the ratio is not what counts. The varition of pressure seen
by the walls of the cylinder is 0.5% ie 200/201. This is not enough for
you cylinder to even yawn about.
THE REASON IS: if something goes wrong with your full cylinder inside
the plane your taking 400 people down with you. And I'm not even thinking
about what wold happen in a crash with your full cylinders under all
these passengers. The cost of an extra visual inpection is nothing
compared to these even remote eventualities. Why is this not obvious???
[\]
|
=================================================================^^(_)^^^^^^^^^
Roger Lacasse "I found the meaning of life!
Foster Radiation Laboratory, It's in the eyes of my wife and kids."
McGill University, Office: (514) 398-7025
3559 University street, Fax: (514) 398-7022
Montreal, Qc., Canada. e-mail: roger@ph*.mc*.ca*
H3A 2B1 http://spiff.physics.mcgill.ca/scuba.html
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