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From: J Shepherd <jms@fe*.ed*.ac*.uk*>
Subject: Re: Blow and Go---out of context/Appology to J. Kellon
To: Richard Pyle <deepreef@bi*.bi*.ha*.or*>
Cc: techdiver@terra.net
Date: Sat, 9 Mar 96 12:19:54 GMT
	This seems pretty clear;

	There are reasons to reduce your ambient pressure as quickly as
possible to speed up degassing, and there are reasons to make your
pressure changes as slow as possible to control bubble dynamics.

	Since there are mathematical models available for both; why
doesn't someone whose head hasn't rejected it's maths implant (like mine
has) try to formulate an ideal medium between the two?

	It would be worth noting that firstly, neither of these models
will be perfect, but they are the best that we have, so why not throw
some numbers around. Secondly, making the same assumptions for both
models may require altering them. For instance, if the compartment
algorithms are based on statistics, they will include the creation of
and removal of bubbles in their planned stops, and they would need to be
re-jigged to remove that assumption. You could then look for the optimum
ascent rate to prevent bubble establishment and growth whilst
depressurising as fast as possible; and have a predictive model for dive
planning.

	I won't dive it, and I guess no-one else would, but we'd have
some numbers to play with. The principles are about as clear as they're
going to be without all of us going home with a serious physics
textbook.

	Incidentally; a long lost memory - didn't NASA try using diving
based theory to safely decompress it's astronauts to .2 Bar O2 for EVA?
And it didn't work well? Wouldn't that discrepancy be explained in terms
of the 'new' model?

	Cheers,

	Jason

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