[LINK] Finally up to date on the Shuttle

Ann Moffatt annm@exocat.com.au
Mon, 3 Feb 2003 14:38:27 +1000


robin wrote
"Likewise, I really enjoy "Surely You're Joking, Mr Feynman".   The erudite
physicist whose lectures are highly renowned - and which I want to read and
listen to soon - who plays bongos, looks at an atom bomb without covering
his eyes, gets to the bottom of the mechanical and organisational failures
which caused the Challenger destruction . . . a great man!"


and read james gleick's "genius". it gives a real insight to feynman

peace & love

annm
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Ann Moffatt
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----- Original Message -----
From: "Robin Whittle" <rw@firstpr.com.au>
To: <link@www.anu.edu.au>
Sent: Monday, February 03, 2003 12:26 PM
Subject: Re: [LINK] Finally up to date on the Shuttle


> I recall from Richard Feynman's account that the whole of NASA was under
> pressure to pretend that the risk of failure was 1/1000 or less, because
> they had all been convinced that if they admitted it was any riskier,
> that Congress would cancel the entire project.   So I guess they figured
> a lie was better than no Space Shuttle at all.
>
> But this caused denial of real problems.
>
> The engineers at Morton Thiokol, who made the solid fuel boosters,
> looked at the various partial O-ring failures and found them to be
> strongly correlated with low temperatures at launch.  The planned launch
> was in much colder conditions, with ice on the launch pad.  I recall
> that they tried to get word upwards in their own company and in NASA, in
> the day or so before the launch, but were not successful in halting it.
> There was intense political pressure on the launch - an election due, a
> popular woman teacher flying into space etc.
>
> The O-ring is a 37 food circumference rubber ring, as thick as your
> little finger and is one of two which seals the re-usable steel sections
> of the solid fuel booster.  When the booster is ignited, the gap expands
> and the O-ring must expand instantly and maintain pressure in the larger
> gap, otherwise putty flows past it, and the flame follows the displaced
> putty and burns through the gap between the cylinders, burning a hole in
> the side of the rocket, which is what happened in the Challenger launch.
>
> But rubber's ability to rebound instantly when the gap is increased is
> severely curtailed by cold temperatures, as Richard Feynman demonstrated
> with some samples of an O-ring, some iced water and some C (we call then
> G) clamps in the Inquiry's Committee room.
>
> Richard Feynman also notes how the Mercury, Gemini and Apollo projects
> were built from the ground up by engineers - each component optimised
> and robustly engineered and then used as the basis for the next biggest
> part of the design.
>
> But the Space Shuttle was specified by committee, with assumptions in
> many key areas that in the process of designing it, that engineers would
> be able to exceed current engineering limits by 10, 20% or so.
> Consequently, they built things which were too highly stressed, such as
> turbo pump for the rocket fuel, which was smaller than anyone would
> normally have designed it.  But it fractured after a few runs, so they
> had to build a bigger one.  But then, that meant they had to redesign
> everything else, because the rest of the design assumed the too-small
> size of the committee-generated turbo-pump specification.
>
> There's a lot to learn from all this.  It is in Richard Feynman's "What
> Do YOU Care What Other People Think? - Further Adventures of a Curious
> Character".  Along with many other fascinating things, there is his
> account of the Challenger enquiry, with detailed photos and diagrams of
> the O-ring and all the stresses on the solid fuel booster.   Likewise, I
> really enjoy "Surely You're Joking, Mr Feynman".   The erudite physicist
> whose lectures are highly renowned - and which I want to read and listen
> to soon - who plays bongos, looks at an atom bomb without covering his
> eyes, gets to the bottom of the mechanical and organisational failures
> which caused the Challenger destruction . . . a great man!
>
>  - Robin
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