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From: brad@dcc1.UUCP (labasst)
Newsgroups: net.columbia
Subject: Re: More Challenger Theories
Message-ID: <192@dcc1.UUCP>
Date: Fri, 7-Feb-86 12:39:38 EST
Article-I.D.: dcc1.192
Posted: Fri Feb  7 12:39:38 1986
Date-Received: Sun, 9-Feb-86 06:23:29 EST
References: <152800003@uiucuxc> <152800004@uiucuxc> <2924@ut-ngp.UUCP>
Reply-To: brad@dcc1.UUCP (labasst)
Organization: DeKalb Community College, Clarkston GA
Lines: 45

In article <2924@ut-ngp.UUCP> kjm@ut-ngp.UUCP (Ken Montgomery) writes:
>> The SRB's burn from the bottom up.  The position of the flame front should
>> be directly calculatable by NASA.  The key question is:  Would the flame
>> front be near that joint at that point in the flight.
>> [Michael Gardner]
>
>This is not correct.
>The SRB fuel is pierced all the way down the long axis by a star-shaped
>hole.  Burning occurs on the surface thus formed.  Side note: the hole is
>star-shaped to keep the surface area, and thus the burn rate, relatively
>constant over the burn time.  A cylindrical hole would, as the SRB burned,
>increase in surface area.
>
>[Ken Montgomery]

   Ken, you have the right idea but your information isn't completely 
correct either. I have a copy of a shuttle manual ( missing title page
so I can't name the source) which says.


      The high thrust level during lift-off of the Shuttle
      results from an 11-point-star propellant
      configuration in the forward segment. After lift-off,
      thrust is reduced by the total burnout of the star
      points (at 62 seconds into flight) to constrain
      flight dynamic pressure. Thrust then gradually
      increases because of the design of the burning
      cavity. When the flame surface of the burning
      propellant reaches the liner surface, the thrust
      again starts to decay and continues to decay until
      burnout (about 10 seconds later).


   I wish I had the original source for this since it covers
all the shuttle systems in easy to read language with just
enough detail.

Brad Beach  ...!gatech!dcc1!brad

-- 
I did my own thing and now I have to undo it.
                                   
                                  Brad Beach     
                        ...!gatech!dcc1!brad      <=   Funny, this doesn't 
                                                          look like me.