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From: piner@pur-phy.UUCP (Richard Piner)
Newsgroups: net.columbia
Subject: Speculation
Message-ID: <1953@pur-phy.UUCP>
Date: Thu, 30-Jan-86 12:55:16 EST
Article-I.D.: pur-phy.1953
Posted: Thu Jan 30 12:55:16 1986
Date-Received: Sat, 1-Feb-86 04:05:34 EST
Distribution: net
Organization: Purdue Univ. Physics Dept., IN
Lines: 44


  This is just my own idle speculation about Tuesday's sad events.
I too watched the slow motion pictures of the shuttle's destruction.
I must agree that it is unlikely that a burn through of the SRB
was the cause. I was watching the CBS special last night. I noted
a bright flash between the shuttle and the external tank. Dan Rather
said that the location of the flash was in the area of the umbilical
connecting the shuttle to the tank. If this is true, a failer there
could explain what happened. I will offer here my own scenario.
  Several hours before launch, the shuttle is exposed to a fair amount
of moisture. Then the temperature drops forming ice. We know that this
did happen. What if some of that moister was inside some part of
the connector where the umbilical joins the shuttle. If that moisture
froze, it could damage the connector. While that umbilical and
connector are designed to take very cold temperatures, I do not
know if they were designed to take a freeze / thaw cycle with water
all over them. Anyone who lives up north knows that water and cold
can do an amazing amount of damage. Let us assume that indeed the
connection or umbilical were damaged.
  Why didn't the shuttle blow up on the pad as soon as fuel started
flowing into the shuttle? Well, hydrogen will dissipate at an incredible
rate. If there were a modest leak in the umbilical system, it is unlikely that
enough hydrogen to cause an explosion would reach the engine flames
or hydrogen ignitors many feet below. Hydrogen would just go away
when vented in open air. But as the shuttle begins to gain speed,
the air stream would tend to draw the hydrogen towards the engines in
a smaller and smaller, denser and denser steam. When the order to go
full throttle was given, the flow from the tank almost doubled and the flow
though the faulty connector increased in proportion. Now the hydrogen
stream reaching the engines is dense enought to ignite. The flame shoots
up the stream like a lit fuse. Until it gets to the umbilical. Then BOOM!
This would explain the flame seen at the base of the tank first, followed
by the flash at the umbilical. By the way, burning hydrogen makes no
visible flame, so any flame we saw must be due to some other material
being burned, such as paint or insulation. This would explain why
it might not be possible to see the whole stream buring. In fact, it
might have been burning for some time, we just couldn't see it until
it got some of the paint on the SRBs to burn. To sum it up,
what we may have seen was the same effect as a flash back on a
hydrogen fueled bunsen burner. Anyway, I hope I'm wrong.

					Richard Piner
					Purdue Physics Dept.
					piner@pur-phy.UUCP