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From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: The Ariane V36 failure (was Re: Ariane launches ON TIME! (again))
Message-ID: <1990Nov13.185458.5052@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <1990Nov6.192118.6012@cc.ic.ac.uk> <1990Nov9.145517.1891@cc.ic.ac.uk> <1990Nov10.151130.29117@eagle.lerc.nasa.gov>
Date: Tue, 13 Nov 90 18:54:58 GMT

In article <1990Nov10.151130.29117@eagle.lerc.nasa.gov> lvron@earth.lerc.nasa.gov writes:
>(1) the failure was due to a piece of cloth.  How could this have been 
>    isolated after the failure?

They pinned down possible causes based on the symptoms, and then went through
the recovered debris very carefully, and found the cloth.

>(2) what is the mechanism by which a piece of cloth was able to cause the
>    failure?  By that I mean 
>    - was the cloth of sufficient size/porosity to totally restrict water
>      flow?  or did it have to be?

I believe it was large enough and solid enough to completely block the line.
We're not talking about 30-cm pipes here.

>    - how is a piece of cloth able to be in the water line anyway?

Good question.  Nobody knows for sure.  The obvious possibility is some
minor blunder during manufacturing.  If that's the case, there is little
hope that the person responsible will ever admit it.

>    - what is the sequence of events leading to the failure, given the 
>      presence of the cloth?

Water flow to one engine chokes off, chamber pressure and thrust in that
engine drop, the other engines gimbal farther and farther to compensate,
eventually they hit their gimbal limits and the booster starts to turn,
and the attempt to fly sideways exceeds its structural limits and it
breaks up.

>(3) how can Arianespace ensure no repeat of this mechanism/sequence of 
>    events?

The usual:  more care during manufacturing, more thorough inspections,
and some managerial changes to clarify who's responsible for that water
line (one company had hold of each end and nobody was in charge of the
whole thing).
-- 
"I don't *want* to be normal!"         | Henry Spencer at U of Toronto Zoology
"Not to worry."                        |  henry@zoo.toronto.edu   utzoo!henry