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From: (Henry Spencer)
Subject: Re: (CM+LM+0.7*S-III)/STS??
Date: Tue, 3 Aug 1999 22:21:39 GMT

In article <7o7l33$snb$>,
John Topley <> wrote:
>> ...(Despite impressions otherwise, Apollo was
>> pretty conservatively run, and only two major items used technology that
>> was considered new and poorly understood... although that didn't stop them
>> from having trouble in some other areas.)
>Out of interest Henry, what were those two major items?

Why am I not surprised that someone asked? :-)

1. The CM heatshield had to be considerably larger than any existing
design, and also had to survive a rather more energetic reentry than had
yet been tried, and the scaling laws for heatshields were not fully
understood at the time.  (Flight tests showed that the final design was
serious overkill, as expected.)

2. Supercritical storage of helium for tank pressurization, used in the LM
descent stage, had never been done before, but the weight savings were
large enough to make it compelling nevertheless.  (The ascent stage used a
more conservative design, but its tanks were so much smaller that this
didn't hurt too badly.)

Oh yes, the source for this is Owen Maynard, who was there.
The good old days                   |  Henry Spencer
weren't.                            |      (aka

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