[AR] Re: tank frost (was Re: LH2.... Density)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Sun, 23 Jun 2019 12:44:08 -0400 (EDT)
On Sun, 23 Jun 2019, Uwe Klein wrote:
At least with polyurethane (I think that's right) spray-on foam
insulation, the cold-side cells will cryopump/cryoevacuate down
initially. But over time (days to weeks), atmospheric gas will diffuse
through the cell walls...
What happens if you put the insulation on the inside? :-)
Then it has to take compressive loads from tank pressure, which makes it
heavy. The Saturn V third stage's LH2 tank had internal insulation, and
you'll see occasional discussions of all the advantages that had, but
rarely any mention of it being quite a bit heavier than the second stage's
external insulation. Considering that LH2 has a problem with its tanks
being heavy anyway, this is an unwelcome extra...
Henry
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