cjp@vax135.UUCP (Charles Poirier) (02/07/86)
Richard Piner has written, concerning two points: > 1) The External Tank's insulation would prevent it from burning through? Not necessarily. A high R value does not ensure nonflammability. One could make passably good insulation (for some range of T) from nitrocellulose. > 2) The ET's liquid content would cause a large presure increase before > any possible burnthrough of the ET. This is a serious problem. Once the insulation burns through, aluminum conducts heat very well, as does the LH2 inside. Given that apparently many seconds of heating occurred before the blast, my speculation is that the blast was caused by pressure-induced rupture of the ET. That NASA would not monitor the internal pressure of the ET tanks would strike me as "strange". If they did but are not telling us, that would strike me as unnecessarily secretive, and strange. I have a different speculation (with I admit lots of holes in it) which *might* supply a mechanism for burnthrough of the SRB. *That* is still lacking a good explanation, considering that the SRB fuel burns inside-out. Suppose a relatively small hole occurred in the LH2 tank, as if from (say) a rifle shot. This might have happened much earlier than 1 minute into the mission. (Cue: accuse me of paranoia now. Thank you.) This results in a jet of LH2 directed against the SRB. The pressure drop might go undetected. The jet would ignite and burn relatively invisibly, albeit cooler than an LH2/LOX flame. This flame eventually either melts through the SRB or causes outside-in ignition of the SRB fuel, leading to the burnthrough. (This speculation could easily be tested, by noting the presence or absence of a bright spot on the (iron-clad, yes?) SRB considerably before it bursts into flame, in the right-side-view pictures. A pressure-induced burst of the SRB would, I think, be more sudden. I regret not having a copy so I can check for myself.) Charles Poirier