wales@ucla-cs.UUCP (02/13/86)
I'm confused. In the first several days after the Challenger disaster, speculation focussed on the possibility that a crack in the solid fuel might have opened up a path to the inside surface of the SRB. Such a crack was thought to have resulted either from the low pre-launch temperatures, or else from imperfect mating of propellant surfaces between adjacent sections of the booster. Supposedly, it was critical that combustion not find its way to the SRB's inside surface -- and the mass of propel- lant was supposed to prevent this from happening. Now, though, people are talking about problems with the O-rings and putty used to seal the joints between the booster sections. Reportedly, the "primary" O-rings routinely showed signs of fire damage. This would seem to suggest that combustion heat was expected to make its way to the joints of the SRB -- but would be kept from burning clear through by the O-rings and putty. Some are speculating that the low temperatures might have affected the O-rings adversely. These two accounts would seem to contradict each other. If the import- ant point is that the propellant should insulate the body of the booster from the heat of combustion, then why the concern over the O-rings as a line of defense? And if the O-rings are liable to burn through before the SRB walls themselves, then why the great concern over cracks in the propellant? Can anyone clear this point up? I would, of course, vastly prefer to hear from someone with authoritative knowledge from some source other than the same mass media I've been trying to follow. -- Rich Wales // UCLA Computer Science Department // +1 213-825-5683 3531 Boelter Hall // Los Angeles, California 90024 // USA ARPA: wales@LOCUS.UCLA.EDU -or- wales@UCLA-LOCUS.ARPA UUCP: ...!(ucbvax,ihnp4)!ucla-cs!wales
wales@ucla-cs.UUCP (02/20/86)
[I posted the following article a week ago -- but since I have seen absolutely no feedback on it, I am assuming it was somehow lost and am therefore posting it again. -- RBW] I'm confused. In the first several days after the Challenger disaster, speculation focussed on the possibility that a crack in the solid fuel might have opened up a path to the inside surface of the SRB. Such a crack was thought to have resulted either from the low pre-launch temperatures, or else from imperfect mating of propellant surfaces between adjacent sections of the booster. Supposedly, it was critical that combustion not find its way to the SRB's inside surface -- and the mass of propel- lant was supposed to prevent this from happening. Now, though, people are talking about problems with the O-rings and putty used to seal the joints between the booster sections. Reportedly, the "primary" O-rings routinely showed signs of fire damage. This would seem to suggest that combustion heat was expected to make its way to the joints of the SRB -- but would be kept from burning clear through by the O-rings and putty. Some are speculating that the low temperatures might have affected the O-rings adversely. These two accounts would seem to contradict each other. If the import- ant point is that the propellant should insulate the body of the booster from the heat of combustion, then why the concern over the O-rings as a line of defense? And if the O-rings are liable to burn through before the SRB walls themselves, then why the great concern over cracks in the propellant? Can anyone clear this point up? I would, of course, vastly prefer to hear from someone with authoritative knowledge from some source other than the same mass media I've been trying to follow. -- Rich Wales // UCLA Computer Science Department // +1 213-825-5683 3531 Boelter Hall // Los Angeles, California 90024 // USA ARPA: wales@LOCUS.UCLA.EDU -or- wales@UCLA-LOCUS.ARPA UUCP: ...!(ucbvax,ihnp4)!ucla-cs!wales
rjnoe@riccb.UUCP (Roger J. Noe) (02/25/86)
> If the important > point is that the propellant should insulate the body of the booster > from the heat of combustion, then why the concern over the O-rings as a > line of defense? And if the O-rings are liable to burn through before > the SRB walls themselves, then why the great concern over cracks in the > propellant? > -- > Rich Wales // UCLA Computer Science Department // +1 213-825-5683 The O-rings are to form a pressure seal so that the putty could not be pushed back so far that fire could reach the O-rings. If the heat of combustion does reach the second O-ring, it is almost certain that it will "burn through" (really leak out) the SRB casing. Actual burn-through of the steel casing is far less likely than a leak out of the joint. If there were no joints (segments) then there would be no need for putty and therefore no need for O-rings. But the cold is speculated to have (1) allowed the reactant to have contracted away from the container wall and created a gap, and/or (2) decreased the resiliency of the O-rings so that they did not form a good pressure seal. These (and other factors, all of which are just speculation so far - of course) could all have contributed to not a burn-through of the SRB casing, but a leak-through at one of the segment joints. -- Roger Noe ihnp4!riccb!rjnoe
brent@poseidon.UUCP (Brent P. Callaghan) (02/25/86)
I guess at some stage the investigators will be looking
the effect of cold temperatures on the components of a SRB.
The easiest way to do this might be to truck one up to
Minnesota. :-)
--
Made in New Zealand --> Brent Callaghan
AT&T Information Systems, Lincroft, NJ
{ihnp4|mtuxo|pegasus}!poseidon!brent
(201) 576-3475msc@saber.UUCP (Mark Callow) (02/27/86)
> Roger Noe ihnp4!riccb!rjnoe > -- > The O-rings are to form a pressure seal so that the putty could not be > pushed back so far that fire could reach the O-rings. If the heat of This is a circular argument. The rest of the article does not therefore make much sense. -- From the TARDIS of Mark Callow msc@saber.uucp, sun!saber!msc@decwrl.dec.com ...{ihnp4,sun}!saber!msc "Boards are long and hard and made of wood"