paul@axiom.UUCP (Paul O`Shaughnessy) (02/18/86)
A friend who has followed the shuttles from way back recalls that there was an alternate bid for a non-segmented SRB by Aerojet-General. NASA turned it down apparently because lugging the SRBs around in one piece would have been too expensive. I also hear that the Air Force has or is developing a non- reusable, non-segmented SRB with a wound filament composite casing (the same sort of material used in fighter aircraft), and that they intend to launch their shuttle flights with these boosters. Does anyone know the state of either of these alternatives? Certainly an untested boooster has unknown risks, but the lack of segmentation would reduce the chance of any burnthrough. I also have heard that someone once added up the MTBFs (mean time before failure) of each major part of the shuttle, tank, and boosters, and calculated that NASA would lose a shuttle in this manner every thirty flights. Apparently the physical complexity of the SRB's was a major part of that calculation. Again, can anyone confirm this? If such a calculation was accurate, the result would have been one shuttle per year and the loss of all the shuttles presently in use. Finally, it seems that there was no lack of apprehension about the SRBs and this launch in particular on the part of NASA's engineering staff, but that many decisions were made by managers and administrators contrary to this advice. In particular, launching in such low temperatures. Some of these administrators are now getting some heat in the press. Does anyone share this perception? I have certainly witnessed many engineering organizations becoming dominated by administative politicos who don't know their butt from their elbow. Has this happened to parts of NASA? I am posting this particularly to get some of the net back into a discussion of things that cannot be found in the morning paper. The stuff about what the group should be called, what celestial bodies should be named after who, why the Russians only want female names on Venus, and diatribes about Canadian television has really played itself out, and the density of worthwhile discourse has been dropping. Can we gently move on and see more of the hard facts, informed speculation, and philosophising? ------------ Paul O'Shaughnessy Axiom Technology Corperation Newton, Massachusetts
miorelli@pwa-b.UUCP (Bob Miorelli) (02/20/86)
According to the latest (2/17) Aviation Week the new style SRBs have
essentially the same type of joints found in the Challenger SRBs. The
new SRBs are filament wound to reduce weight, but have steel joints
between the segments. This causes two concerns: 1) the joints are
similar to the ones that presumably failed, and 2) there is a new
factor -- the filament wound casing to steel joint interface -- another
point for potential failure.
--
-->BoB Miorelli, Pratt & Whitney Aircraft
also, H & R Block tax perparer and Instructor
pwa-b!miorellitim@ism780c.UUCP (Tim Smith) (02/22/86)
A recent LA Times story ( I don't know the exact date ) talked about this. There were three companies that wanted to do the SRBs. They were Morton Thiokol(sp), someone I don't remember at all, and I think United Technologies. Thiokol was considered to have the best management, but was behind the others in technology. The company with the best technology was behind the others in management, and the other was in between on both. The two companies that were not chosen wanted to do non-segmented SRBs. There were some quotes in the story from engineers from these companies saying that it was clearly a *bad* *thing* to use segmented SRBs, but this sounds a lot like sour grapes to me. -- Tim Smith sdcrdcf!ism780c!tim || ima!ism780!tim || ihnp4!cithep!tim
henry@utzoo.UUCP (Henry Spencer) (02/23/86)
> ... I also hear that the Air Force has or is developing a non- > reusable, non-segmented SRB with a wound filament composite casing (the same > sort of material used in fighter aircraft), and that they intend to launch > their shuttle flights with these boosters... The Air Force is indeed developing a lightweight SRB using filament-wound casings, but those casings are segmented just like the current ones, I believe. The motive is reduced weight and increased payload. There is a rumor, by the way, that the filament-wound casings are most unlikely to be reusable, official claims notwithstanding. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
jlg@lanl.ARPA (Jim Giles) (02/25/86)
There is another solution to the SRB problem, and it is one that was going to be used at Vandenberg all along. That is to use the present design, but to heat the SRB's before launch. At Vandenberg, they had already planned to use modified jet engines to blow warm air on the SRB casings during any cold weather. NASA officials didn't think the cold would be a problem at the Cape, so the heater engines were never installed there. (Source: Wall Street Journal) I suspect that the SRB's will now be redesigned even if it turns out that the design was satisfactory as long as they were kept warm. I think people will feel skittish about flying with boosters which caused an earlier catastrophe. Even with a redesign though, I bet future Shuttle flights will start with a carefully maintained SRB temperature. J. Giles Los Alamos
mrgofor@mmm.UUCP (MKR) (02/27/86)
In article <1448@lanl.ARPA> jlg@a.UUCP (Jim Giles) writes: > >There is another solution to the SRB problem, and it is one that was going >to be used at Vandenberg all along. That is to use the present design, but >to heat the SRB's before launch. At Vandenberg, they had already planned >to use modified jet engines to blow warm air on the SRB casings during any >cold weather. NASA officials didn't think the cold would be a problem at >the Cape, so the heater engines were never installed there. (Source: >Wall Street Journal) > >I suspect that the SRB's will now be redesigned even if it turns out >that the design was satisfactory as long as they were kept warm. I think >people will feel skittish about flying with boosters which caused an >earlier catastrophe. Even with a redesign though, I bet future Shuttle >flights will start with a carefully maintained SRB temperature. > >J. Giles >Los Alamos I also suspect they will be redesigned. The word I've heard is that NASA ignored its usual fail-safe backup requirements regarding the O-rings, and I suspect that they will be required to do something about that problem. -- --MKR There is none so blind as he who cannot see.