Index Home About Blog
From: Henry Spencer <>
Subject: Saturn history (was Re: Apollo Block I...)
Date: Wed, 28 Aug 1996 13:15:41 GMT

In article <> Michael Walsh <> writes:
>There were severe cultural clashes between NASA Marshall and GD Convair.
>In particular, Marshall was adamantly opposed to the Centaur and Atlas
>requirement for the tanks to be pressurize to maintain structural integrity...

Balloon tanks just seem to have trouble getting respect.  The USAF was
equally skeptical; a large part of the reason why they were adamant about
needing a second ICBM program -- Titan -- was that they wanted to have a
workable ICBM in the pipeline when (as a lot of them expected) GD's balloon-
tank Atlas failed.

The most amusing part of this is that Marshall themselves ended up
building a system which requires tank pressurization for structural
integrity!  The shuttle ET's LOX tank must be pressurized during filling,
otherwise it buckles.  (It wasn't *meant* that way, of course...!)

>Also, you seem to be ignoring the fact that the six engine RL-10 SIV stage was
>a precursor to the SIV-B stage that used the J-2 engine.  All of the
>information obtained from the earlier stage would be fed directly into
>SIV-B development which was done by the same Douglas design team.

Oh, I agree that without the S-IV, developing the S-IVB would have been 
harder and would have needed more testing.  It might even have been useful
to build a subscale demonstrator and run it through some ground testing.
My point is that developing one flight-ready stage would have been cheaper
and easier than developing two -- the *total* cost of the S-IV and S-IVB
exceeded that needed to go direct to the S-IVB.
 ...the truly fundamental discoveries seldom       |       Henry Spencer
occur where we have decided to look.  --B. Forman  |

From: (Henry Spencer)
Subject: Re: Mercury Atlas Question
Date: Sun, 5 Dec 1999 20:21:55 GMT

In article <>,
Michael J. Gallagher  <> wrote:
>>...without pressure in its tanks, an
>>Atlas would collapse under its own weight, even on the ground ....
>That's _after_ it's fueled, right, and its strong enough to stand
>under its own weight empty?

Nope, not even under its own weight empty.  Except when it's in the
special tension frame used in the factory, an Atlas has to be pressurized
AT ALL TIMES, period.

>I'm thinking of Atlases put on display at
>museums (including the one in Ottawa, which I saw in October); are
>they ok on their own, or is some structural reinforcing put in when
>the engines are ripped out?

They need either pressurization or some sort of internal support.  When I
saw the one in Ottawa -- which admittedly was a number of years ago --
there was a compressor chugging away in the background.  I think there are
some museum Atlases which have been filled with foam or something like
that, but I don't know details.
The space program reminds me        |  Henry Spencer
of a government agency.  -Jim Baen  |      (aka

Index Home About Blog