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From: dil@mace.cc.purdue.edu (Perry G Ramsey)
Newsgroups: sci.space.shuttle
Subject: Re: For All Mankind [was Re: center engine out]
Summary: Don't snicker at RP-1
Message-ID: <5633@mace.cc.purdue.edu>
Date: 27 Sep 90 14:32:46 GMT
References: <7294@eos.UUCP> <3498@syma.sussex.ac.uk> <15953@wpi.WPI.EDU> <1096@tsdiag.ccur.com>
Distribution: sci.
Organization: Department of Earth and Atmospheric Sciences
Lines: 28

In article <1096@tsdiag.ccur.com>, davet@tsdiag.ccur.com (Dave Tiller N2KAU) writes:
> 
> I'm pretty sure it burned LOX and (hee..hee) Kerosene! Really...
> -- 
> David E. Tiller         davet@tsdiag.ccur.com  | Concurrent Computer Corp.

RP-1 is nothing to snicker at.  Hydrogen is light and has a high Isp,
but it has very poor volumetric efficiency (a fancy way to say it takes
up a lot of space.)  If the Saturn first stage had been hydrogen powered,
the fuel tanks would have been a lot larger (I can gen some more reliable 
numbers if anyone is interested, but 5 or 6 to 1  is about right.)  
Take a look at a cutaway of the external tank and see how much is
for the liquid hydrogen.  Or better yet, look at cutaways of the
S-IC and S-II.  The difference in fuel tank size is very apparent.
RP-1 is the booster fuel in the Delta and Atlas, which are still the
most reliable launch vehicles around.
Hydrogen makes sense for upper stages, but using it to boost from
the ground is not so great.

There have been proposals to switch the Shuttle to hydrocarbons,
usually liquified natural gas (methane), or liquified petroleum gas
(propane), both for volumetric efficiency and ease of handling.
Imminently sensible proposals, IMHO.
-- 
Perry G. Ramsey           Department of Earth and Atmospheric Sciences
perryr@vm.cc.purdue.edu   Purdue University, W. Lafayette, IN USA
dil@mace.cc.purdue.edu    We've looked at clouds from ten sides now, 
			  And we REALLY don't know clouds, at all.