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From: giles@ucf-cs.UUCP
Newsgroups: net.columbia
Subject: Re: Fire after Discovery Shutdown?
Message-ID: <1372@ucf-cs.UUCP>
Date: Mon, 9-Jul-84 13:01:45 EDT
Article-I.D.: ucf-cs.1372
Posted: Mon Jul  9 13:01:45 1984
Date-Received: Wed, 18-Jul-84 02:34:04 EDT
References: <2344@decwrl.UUCP>
Organization: University of Central Florida
Lines: 36

(1):  Yes, there was a small hydrogen fire in the tail of the orbiter after
      the aborted launch.  Fire suppression equipment in the rear of
      the orbiter put it out without difficulty.

(2):  That water may have been the sound suppression system in action.  I
      have not seen the entire launch sequence on tape yet, so I can't say
      that was the source of the water for sure.

      The sound suppression system, for those joining us late, is required
      because the launch pad is a giant slab of concrete.  Apparently the
      old Saturn Vs had a relatively quiet ignition; when the SRBs of the
      Shuttle ignite, a *very* strong shock wave leaves the engines, hits
      the pad, and bounces straight back into the ET and orbiter.  (Note:
      this was not anticipated, in part because the SRBs had not been fired
      on the launch pad, as the SSMEs had.)

      According to one of my former professors (who monitored air quality 
      during the launch) NASA determined that the most dangerous point of
      STS-1 occured just a few seconds after launch -- when this echo was
      reverbating throughout the orbiter and ET.  In fact, they found a 
      four-foot reinforcement rod bent in the orbiter's nose.  Add this to
      the well documented "walk" of the orbiter across the launch pad and
      Young & Crippen had an interesting couple of seconds.

      Anyway, instead of rebuilding the launch pads (out of nice fireproof
      soundabsorbing materials) NASA decided to dump a couple of tons of
      water between the Shuttle and the pad.  The general idea is that the
      acoustical energy will be spent breaking the water drops into water
      vapor, instead of the Shuttle system into a giant fire-cracker.  
      I recall that there was quite a bit of debate at the time over the
      usefulness of this approach, but it apparently has worked.


Bruce Giles
{decvax, duke}!ucf-cs!giles		university of central florida
giles.ucf-cs@Rand-Relay			orlando, florida 32816