Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!accuvax.nwu.edu!delta.eecs.nwu.edu!phil From: phil@delta.eecs.nwu.edu (William LeFebvre) Newsgroups: sci.space.shuttle Subject: Re: shuttle escape systems Message-ID: <1307@accuvax.nwu.edu> Date: 17 Oct 89 15:46:46 GMT References: <538.252A3A3B@mamab.FIDONET.ORG> <34577@srcsip.UUCP> <126311@sun.Eng.Sun.COM> Sender: news@accuvax.nwu.edu Reply-To: phil@delta.eecs.nwu.edu (William LeFebvre) Organization: Northwestern U, Evanston IL, USA Lines: 30 In article <126311@sun.Eng.Sun.COM> admiral%m-5@Sun.COM (Michael Limprecht SUN Microsystems Mt. View Ca.) writes: >Most people don't realize the enormous forces and pressures the shuttle >is under during the boost phase (The time the soilds are running). > >First off, nothing known on this planet at this time could have saved the >Chalenger crew with the failure they had. How much time was there from >main tank ignition to total breakup? Millisecounds?... The flight dynamics people probably saw something wrong as much as 10 seconds before the explosion, because the trajectory was wrong and the engines were gimballing (sp?) a very large amount to try to compensate. Of course, they probably didn't associate that with impending disaster. But even if they had known there was a problem, there wasn't a thing they could do about it until after SRB separation. It is acknowledged that the first two minutes of ascent---the time when the SRBs are burning---is the most critical and the most sensitive to disaster. If something goes wrong during that time, there is nothing that can be done. You just have to hope that you can ride it out until the SRBs are separated. You can't turn off a solid rocket, and in this case it is providing a very large percentage of the total thrust (so you can't just "eject" them at will, either). Note that the rescue system put in place post-Challenger (the "rod") can't even be used during SRB burn. So even if that was in place for Challenger, it would not have helped. William LeFebvre Department of Electrical Engineering and Computer Science Northwestern University