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From: joels@tekred.UUCP (Joel Swank)
Newsgroups: net.columbia
Subject: Speculation on cause of ET rupture
Message-ID: <447@tekred.UUCP>
Date: Tue, 11-Feb-86 13:07:15 EST
Article-I.D.: tekred.447
Posted: Tue Feb 11 13:07:15 1986
Date-Received: Thu, 13-Feb-86 19:44:55 EST
References: <1955@pur-phy.UUCP> <900006@pbear.UUCP>
Organization: Tektronix, Beaverton OR
Lines: 22

>    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"

I was watching the CBS news this morning. An 'expert' said that
the rupture in the tank was most likely caused by the stress caused
by the exhaust from the burn-through pushing the SRB sideways against
the structures that hold the SRBs to the tank, rather than any blow-torch
effect burning it. This makes more sense because the burn-through seemed
to be on the outside of the SRB, away from the tank.

Joel Swank
Tektronix, Redmond Oregon