pstinson@pbs.org (09/28/90)
In article <1990Sep26.174811.8026@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: > The Saturn had reached a launch rate that the > shuttle is struggling, so far mostly unsuccessfully, to beat. > -- There is not much I can say in rebutal today, but I truly believe you have underestimated the Shuttle's capabilities. The year 1992 has been proclaimed an International Space Year. Let's just wait in see what the Shuttle is doing by the end of 1992. I exdpect we will see at least 9 launches in 1991 and at least 12 more in 1992. No year after that will see less than 10. By the way. How long do you think the U.S. Congress would have let NASA go on building from scratch 5 Saturn V's a year simply to be discard them after one launch? The rate you mentioned from late 1968 through late 1969 was unsustainable.
henry@zoo.toronto.edu (Henry Spencer) (09/28/90)
In article <10230.27023455@pbs.org> pstinson@pbs.org writes: >... Let's just wait in see what the Shuttle is doing >by the end of 1992. I exdpect we will see at least 9 launches in 1991 and at >least 12 more in 1992. No year after that will see less than 10. I'm willing to wait. As I recall, NRC suggested that 12 was attainable only as a "surge" rate, and then only if everything went well. How long do you think it will be before the next orbiter loss? Higher flight rates will make that happen sooner. >By the way. How long do you think the U.S. Congress would have let NASA go on >building from scratch 5 Saturn V's a year simply to be discard them after one >launch? ... Probably no longer than necessary for a reusable first stage to be developed, which was being seriously thought about. (Indeed, the "flyback F-1" -- a Saturn V first stage with wings and engines -- was almost chosen as the shuttle's booster. Development would have cost 20% more than the SRBs.) -- Imagine life with OS/360 the standard | Henry Spencer at U of Toronto Zoology operating system. Now think about X. | henry@zoo.toronto.edu utzoo!henry
dil@mace.cc.purdue.edu (Perry G Ramsey) (09/28/90)
In article <10230.27023455@pbs.org>, pstinson@pbs.org writes: > In article <1990Sep26.174811.8026@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes: > > > The Saturn had reached a launch rate that the > > shuttle is struggling, so far mostly unsuccessfully, to beat. > > -- > [1992 is] International Space Year. > Let's just wait in see what the Shuttle is doing > by the end of 1992. 20 years after the Shuttle design was selected. >I expect we will see at least 9 launches in 1991 and at > least 12 more in 1992. No year after that will see less than 10. That's what they they said in 1985 about 1986. > By the way. How long do you think the U.S. Congress would have let NASA go on > building from scratch 5 Saturn V's a year simply to be discard them after one > launch? The rate from late 1968 through late 1969 was unsustainable. And that is the real irony of this whole situation. Expendibles are clearly inefficient. It's just that the Shuttle is worse. As I see it, the current NASA couldn't launch Saturns, either. The kind of operational paralysis which currently grounds the Shuttle (a vehicle which should be relatively easy to launch) would be even worse with a large, complex expendible. They can't currently get the two major liquid propulsion system with five engines to work right; the Apollo/LM/Saturn had six major systems with 14 engines. Shuttle Propulsion systems: Main: 3 Hydrogen OMS: 2 hypergolic Saturn SIC: 5 RP-1 SII: 5 hydrogen SIVB: 1 hydrogen LM Descent: 1 hypergolic LM Ascent: 1 hypergolic CSM: 1 hypergolic I don't include the solids, because solids are so simple that they can't fail, and don't warrant comparison in complexity to the main propulsion system (I'd put a smiley here if I could smile about it.) If you insist on throwing them in, that's one and a half more systems and two more engines. In any case, that's half the number of systems and engines. I don't want to get into the mode of mindless Shuttle bashing here, (I'm actually an ex-Shuttle engineer), but there is no doubt that we have a seriously flawed system here, and it needs to be fixed. Getting starry-eyed about "Space ... the final frontier" and ignoring the Shuttle's problems isn't going to help make it better. -- Perry G. Ramsey Department of Earth and Atmospheric Sciences perryr@vm.cc.purdue.edu Purdue University, W. Lafayette, IN USA dil@mace.cc.purdue.edu We've looked at clouds from ten sides now, And we REALLY don't know clouds, at all.
petej@phred.UUCP (Pete Jarvis) (10/02/90)
In article <1990Sep28.163456.25849@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: > >How long do you think it will be before the next orbiter loss? Higher >flight rates will make that happen sooner. > >Henry Spencer at U of Toronto Zoology You seem to assume there will be another Shuttle loss. Higher flight rates increase the *probability* of some kind of accident. Doesn't mean there is going to be one. Peter Jarvis.........
henry@zoo.toronto.edu (Henry Spencer) (10/04/90)
In article <3264@phred.UUCP> petej@phred.UUCP (Pete Jarvis) writes: >>How long do you think it will be before the next orbiter loss? Higher >>flight rates will make that happen sooner. >> >You seem to assume there will be another Shuttle loss. Higher flight rates >increase the *probability* of some kind of accident. Doesn't mean there is >going to be one. The observed shuttle reliability is one failure in 30-some flights (I forget the exact current count). Unless the actual reliability is *orders of magnitude* higher than that -- which nobody believes, although a factor of 2 or 3 is plausible -- then it is quite likely that we will lose another orbiter sometime in the next decade, with over 100 flights scheduled. See the OTA report "Round Trip To Orbit" for numbers and graphs. Of particular note is that if you assume that the observed reliability is the actual reliability (note that we have only something like 50% confidence that the actual reliability isn't *worse* than observed), the probability that another orbiter will be written off before space station assembly finishes is something like 70%. We can't say for sure that there is going to be another shuttle loss... but that's the way to bet. -- Imagine life with OS/360 the standard | Henry Spencer at U of Toronto Zoology operating system. Now think about X. | henry@zoo.toronto.edu utzoo!henry