[AR] Centaur (was Re: Re: Human Rated Hydrogen Tanks...)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Mon, 1 Jul 2019 20:42:33 -0400 (EDT)
On Fri, 28 Jun 2019, Anthony Cesaroni wrote:
Frank once said that he'd really like to get back to the original
Centaur tank sidewall thickness instead of the heavier modern one...
What was the justification for increasing the wall thickness again?
IIRC, the wall thickness was reduced during the development of the
original vehicle design. It was thicker in the very first flight
vehicle(s) from what I understand.
If I've understood correctly (a quick look doesn't find a single reference
with all the details, so this is an attempt to pull the bits together, but
it may not be entirely right)...
The very first flight Centaur had 10-mil (10/1000in) sidewalls... but the
LH2 tank split open near max q, a very embarrassing failure eventually
traced to differential-thermal-contraction problems.
The ensuing design scrub increased the thickness to 14 mil temporarily to
increase the margins. (Congressional reaction to the failure of #1 had
been very negative...)
Once some successful flights were achieved, they backed off to 12 mil for
production Centaurs -- that was the number Frank cited as the "original"
thickness in his talk at Space Access 2012.
And the modern Centaurs have 20-mil walls as a result of higher tank
pressure, partly because of the elimination of the boost pumps and partly
because of the desire (for some missions) to reduce venting losses during
long coast periods. (Frank said that getting productive use out of the
boiloff gas -- burning it for power generation and tank settling -- makes
venting more acceptable and hence permits keeping tank pressure lower.)
Henry
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