Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!gatech!prism!ccsupos From: ccsupos@prism.gatech.EDU (SCHREIBER, O. A.) Newsgroups: sci.space.shuttle Subject: Re: Why 3 SSME's? Message-ID: <2152@hydra.gatech.EDU> Date: 28 Sep 89 22:04:15 GMT References: <24@loop.UUCP> <1979@hydra.gatech.EDU> <4337@wpi.wpi.edu> Reply-To: ccsupos@prism.gatech.EDU (SCHREIBER, O. A.) Organization: Georgia Institute of Technology Lines: 37 In article <4337@wpi.wpi.edu> tmurphy@wpi.wpi.edu (Tom [Chris] Murphy) writes: >>albeit in the form of escape towers. It seems to me that you don't >>just design a manned space vehicle by being satisfied with a >>percentage of catastrophic failure low enough, you ought to >>supply a backup escape system at least in the most traumatic >>sequence of flight (vertical ascent). > >It seems to me that manned aircraft are designed exactly like this, by >keeping a failure rate low. >Perhaps this is a bad approach, but if it's >good enough for commercial aircraft, >it should be valid for spacecraft as well I would like to know how low the percentage of catastrophic failure was for the shuttle when they sized its reliability. I think that they cannot make it as low as that of an airliner because of the vertical take off phase which involves by definition enormous thrust levels. This is why I say that they should have kept the concept of the escape system... or gone to a horizontal take off configuration. >Back when NASA was choosing contractors for the SSME, Pratt & Whitney >had a 2MN LH/LOX engine on the shelf; NASA went with Rocketdyne for >political reasons. For what market did P&W intend its product or why was it ready so much earlier than Rocketdyne's? Olivier Schreiber (404)894 6147, Office of Computing Services Georgia Institute of Technology, Atlanta Georgia, 30332 uucp: ...!{allegra,amd,hplabs,seismo,ut-ngp}!gatech!prism!ccsupos ARPA: ccsupos@prism.gatech.edu -- Olivier Schreiber (404)894 6147, Office of Computing Services Georgia Institute of Technology, Atlanta Georgia, 30332 uucp: ...!{allegra,amd,hplabs,seismo,ut-ngp}!gatech!prism!ccsupos ARPA: ccsupos@prism.gatech.edu