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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: net.columbia
Subject: Re: SRB vs liquid
Message-ID: <6374@utzoo.UUCP>
Date: Fri, 7-Feb-86 17:50:53 EST
Article-I.D.: utzoo.6374
Posted: Fri Feb  7 17:50:53 1986
Date-Received: Fri, 7-Feb-86 17:50:53 EST
References: <615@uwvax.UUCP>
Organization: U of Toronto Zoology
Lines: 17

> ...was implied that due to NASA budget restrictions, SRBs were used
> when liquid fuel was better/safer.

Liquid fuel is better in that it gives higher performance and makes
prolonged re-use simpler.  As for safety, the one important difference
is that liquid fuels are much more controllable.  Once a solid rocket
is lit, there is little you can do except point the exhaust in the
right direction and cross your fingers.  (Well, one exception:  you
can stop combustion of some solid fuels by reducing chamber pressure;
the only practical way to do this is to blow the nozzle off.  Solid-
fuel ICBMs do this to get precise cutoff times.)

I think NASA's preference was mostly on grounds of performance and re-use.
I could be wrong.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry