osmigo1@ut-ngp.UUCP (Ron Morgan) (02/28/86)
I'm not a technical expert where shuttle construction is concerned, but I have some doubts that O-ring burnthrough was the primary cause of the blowup. I'm recalling the "puff of black smoke" we saw on the launch pad at the time of ignition. There wasn't time for any kind of burnthrough then; the nature of the "puff" indicated that something BLEW OUT, like a cap or plug of some sort. This might support the idea of a crack in the propellant, eh? ...Ron Morgan ...osmigo1@ut-ngp ~r sig *** REPLACE THIS LINE WITH YOUR MESSAGE ***
jlg@lanl.ARPA (Jim Giles) (03/01/86)
In article <3011@ut-ngp.UUCP> osmigo1@ut-ngp.UUCP (Ron Morgan) writes: >I'm not a technical expert where shuttle construction is concerned, but >I have some doubts that O-ring burnthrough was the primary cause of the blowup. >I'm recalling the "puff of black smoke" we saw on the launch pad at the >time of ignition. There wasn't time for any kind of burnthrough then; the >nature of the "puff" indicated that something BLEW OUT, like a cap or plug >of some sort. This might support the idea of a crack in the propellant, eh? What you are describing is the mechanism of O-ring burnthru. The present theory is that the cold caused the O-rings to be less flexible than they shoud be. When the O-rings lose flexibility, they don't 'seat' properly at the time of launch. Lack of proper 'seating' allows the paste-like insulation putty that protects the O-rings to leak past the O-rings (this is probably the black 'smoke' that is seen in the pictures). Once this insulation putty has leaked out, the O-rings are exposed directly to the heat of the engine gasses. The O-rings soon burn through under this exposure - allowing engine exhaust through the gap between adjacent segments. This 'torch' of exhaust will then begin to cut the gap wider and to damage any external structures it hits (like the ET or the SRB mounting struts and control cables). All this eventually leads to the accident seen by millions. J. Giles Los Alamos