Re: Unmanned test dives

[John Brownlee <jonnie@chronic.lpl.arizona.edu>]

	I have a question.

	Often times, we hear about 'viewport failures,' and I am curious
exactly what failure is being discussed. For example, it is possible to
build the best conical viewport in the world with annealed and lapped
surfaces, and weld the viewport cell into the hull poorly. Popped welds
lead to premature crushing. 
	Aren't we presuming, more times than not, that it is the design
that is the problem, and not the implimentation? This goes double for
testing with high pressure and temperature cycling. I'm not talking as
much about the guys who try to build 1 atm. 300' boats with window glass,
but the 'in-betweens' on the engineering spectrum. 
	How about cycling, then. How have those among us with sucessful
boat hulls done their cycle testing? I used a test rig at the university I
attended to test my viewport, eventually to destruction after some
non-destructive tests. Anyone else?

							John

John Brownlee
Lunar and Planetary Lab
University of Arizona
jonnie @ lpl . arizona . edu