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From: peterb@pbear.UUCP
Newsgroups: net.columbia
Subject: Re: Speculation III
Message-ID: <900006@pbear.UUCP>
Date: Fri, 7-Feb-86 22:35:00 EST
Article-I.D.: pbear.900006
Posted: Fri Feb  7 22:35:00 1986
Date-Received: Tue, 11-Feb-86 07:22:52 EST
References: <1955@pur-phy.UUCP>
Lines: 36
Nf-ID: #R:pur-phy:-195500:pbear:900006:000:1708
Nf-From: pbear!peterb    Feb  7 22:35:00 1986


/* Written  4:50 am  Feb  4, 1986 by pur-phy!piner in pbear:net.columbia */
/* ---------- "Speculation III" ---------- */

   I have seen the NASA films on the right SRB and there is no doubt
that the fuel burned through the skin. However, I still have doubts
about this causing the explosion the destroyed the Challenger.
   The reason is this, the external tank contains LIQUID H2 and O2.
In order for the burning solid fuel to rupture the ET, it would first have
to burn through the ET insulation. This insulation is holding liquid H2
at around 20 degrees Kelvin. That's cold. The insulation has to
have a huge R value. After you burn through that, you still have to
get through the aluminum tank. That tank contains liquid. Try this
experiment. Take a paper cup and fill it with water. Now take a propane
torch, and try burning a hole through the bottom. What happens? The
water boils but the cup does not burn. If indeed the SRB "torch"

 . . . . . . .

Ok, this is true. But there are other things that can fail causing the
"instant" explosion that was seen.

From my memory, The ET's weight was reduced, and pressure biasing was
used to provide the surface rigidity not provided by the lighter structure.

This pressure bias exists between the feul/oxidizer tanks, and the skin of
the ET. So if you take your blowtorch to a presurized can that contains
cyrogenic fluids. Between the extreme temperature differentials, and the
internal prerssure, the surface metal will flow and finally rupture.

Once ruptured, the rigidity of the tank is reduced, and so is the resonance
of it. This could be the ''secondary'' cause of the ET explosion that you
were looking for.

Peter Barada
ihnp4!ima!pbear!peterb