[Vwdiesel] Rabbit droppings --OT ----( The Discovery take off ? )

Gavrik Peterson gavrik at cablespeed.com
Tue Aug 2 19:16:28 EDT 2005

>NASA ignored a guy saying the "O" rings are not tested for >the low temperature launch.
>    (STUPID)

I hear that there was more to the Challenger disaster then 
cold o-rings. I was my understanding, that before the 
launch of the Challenger, the engineers at Thiokol warned 
NASA that the propellant in the solid rocket boosters was 
too cold for a safe launch.

The story goes like this:

When Thiokol cast the fuel in each section of a SRB they 
control the dimensions so when the sections are joined the 
fuel grain is in compression where it butts up against the 
adjoining fuel grain. As long as this seam is in 
compression the fuel does not burn on these surfaces and 
the grain burns as though it was continuous. As the 
temperature goes down the fuel grain shrinks relative to 
the rocket body. If the temperature gets low enough the 
this compression goes to zero and the adjacent sections of 
fuel start to separate creating a crack. If these exposed 
surfaces start to burn, the rocket body joints are 
subjected to high temperatures that they would normally 
only experience in the last seconds of a burn.

Is this true? Does anyone know about this? I would think 
that Val Christian might have an opinion.

   --  Gavrik

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