cage@fmeed1.UUCP (Russ Cage) (11/10/90)
In article <2688@polari.UUCP> crad@polari.UUCP (Charles Radley) writes: >In <9011072124.AA13810@iti.org>, Allen Sherzer wrote: >+Actually, it makes micorgravity better. By putting the microgravity >+facility in a crew-tended free flyer it won't be subjected to the >+vibration which Freedom will subject it to. >- >True, but it won't benefit from continuous manned presence to fix >problems. Continuous manned presence *is* a problem for microgravity research. So is a shifting CG, which moves the experiments into regions of greater or lesser tidal force. This is not a benefit, it is a liability. Ask the micrograv researchers. A free-flyer can be tailored to the job, and does not suffer from vibration or CG shifts on the station proper. > For a free-flyer to fly "in-formation" with a nearby >manned base will require frequent disruptive thruster pulses, so it >is not totally quiet. Otherwise it would have to rely on nodal >regression to rendezvous with a station, with weeks or months of no >human access. On a free-flyer, thruster pulses can be scheduled to coincide with dead time, furnace re-loads, and so forth. It may mean a delay between the time something breaks and the time it can be fixed, but if something is broken you don't care about giving it a bit of gee, there is no processing to be disturbed. On a manned platform, you are going to have vibration any time the crew is moving around, which will be much of the time. There is work which cannot be done on a manned platform, and the Fred design doesn't allow for it at all. --------------------------------------------------------------- And now for the part I find confusing. This posting brings an apparent contradiction into sharp focus, because it holds both parts of it in more detail than ever before in this discussion: #1: >What commercial needs ? It puzzles me why people such as yourself >prefer a small station to a big one. Here you are apparently saying that the LLNL station would be smaller than Fred, but then you say... #2: >+Two Titans gives you more interior room than Freedom. >- >Interior volume is not particularly exciting, except for recreation. >Maybe useful if we ever get a space tourism industry up and running. >Right now more interested in maximum science for minimum weight and >cost. There you admit that LLNL would have more volume than Fred (and thus more room for equipment). Well, which is it? Or were you talking about Fred in #1, and not LLNL? If so, I'm sure there is an answer to your question. -- Russ Cage Ford Powertrain Engineering Development Department Work: itivax.iti.org!cfctech!fmeed1!cage (CHATTY MAIL NOT ANSWERED HERE) Home: russ@m-net.ann-arbor.mi.us (All non-business mail) Member: HASA, "S" division.
crad@polari.UUCP (Charles Radley) (11/13/90)
+Continuous manned presence *is* a problem for microgravity research. +So is a shifting CG, which moves the experiments into regions of +greater or lesser tidal force. +This is not a benefit, it is a liability. Ask the micrograv +researchers. A free-flyer can be tailored to the job, and +does not suffer from vibration or CG shifts on the station proper. - In an ideal sense this is true. In practice, experiments fail all the time, and benefit from human intervention to get them going again. +On a free-flyer, thruster pulses can be scheduled to coincide with +dead time, furnace re-loads, and so forth. - It is rather the reverse, the experiments will have to be scheduled around when the burns are required, which will be once or twice per orbit. +It may mean a delay between the time something breaks and the +time it can be fixed, but if something is broken you don't care +about giving it a bit of gee, there is no processing to be +disturbed. - What about the non-broken expts ? Or do you only plan on having one experiment on the free-flyer ? if you have multiple experiments, every failure is a complete loss until human operators return. The other experiments will continue. +On a manned platform, you are going to have vibration any time the +crew is moving around, which will be much of the time. There is work +which cannot be done on a manned platform, and the Fred design +doesn't allow for it at all. - Indeed. It is a trade off. NASA considers human presence to be of benefit, on balance. --------------------------------------------------------------- +And now for the part I find confusing. This posting brings an +apparent contradiction into sharp focus, because it holds both +parts of it in more detail than ever before in this discussion: - I am sorry you are confused, I will attempt to clarify. +>What commercial needs ? It puzzles me why people such as yourself +>prefer a small station to a big one. +Here you are apparently saying that the LLNL+ station would be +smaller than Fred, but then you say... - As a space engineer, by "big" I habitually mean "heavy". Volume is of little interest to practical space engineering. In fact, large volume lightweight structres have high drag, so are undesirable. Better to have a maximum weight to cross section ratio. LLNL is "small" in the sense it has less weight, because it comprises less hardware with less capability. +There you admit that LLNL would have more volume than Fred (and +thus more room for equipment). Well, which is it? Or were you +talking about Fred in #1, and not LLNL? If so, I'm sure there +is an answer to your question. -- If LLNL plans to have more equipment than Freedom, then it must plan to be heavier than Freedom, which means it needs more launch flights than freedom. And if it plans to have more equipment than Freedom, then it will be more expensive than Freedom too. I am rather bored by all this interest in the volume of a station, there are many problems with Freedom, but "NASA Scientists Admit Serious Volume Problem on Freedom" is not a headline I recall seeing anywhere. LLNL would seem to be spending a lot of effort solving the wrong problem.
aws@ITI.ORG ("Allen W. Sherzer") (11/14/90)
In article <2721@polari.UUCP>: >+This is not a benefit, it is a liability. Ask the micrograv >+researchers. A free-flyer can be tailored to the job, and >+does not suffer from vibration or CG shifts on the station proper. >In an ideal sense this is true. In practice, experiments fail all >the time, and benefit from human intervention to get them going >again. But then the things you do to fix the failed experiment may well break several others. This is why microgravity people would rather have a free-flyer. >It is rather the reverse, the experiments will have to be scheduled >around when the burns are required, which will be once or twice per >orbit. Not a serious problem. >+On a manned platform, you are going to have vibration any time the >+crew is moving around, which will be much of the time. There is work >+which cannot be done on a manned platform, and the Fred design >+doesn't allow for it at all. >Indeed. It is a trade off. NASA considers human presence to be >of benefit, on balance. This is true. The problem is that the benefit goes to NASA and not to the people doing microgravity work. Many material scientists, concerned over vibrations in the station that would be caused by nearby astronauts, continue to urge NASA to consider removing their projects to orbiting laboratories that would only be visited by astronauts. -- Avation Week Nov. 12, 1990 page 27 Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer| I had a guaranteed military sale with ED-209. Renovation | | aws@iti.org | programs, spare parts for 25 years. Who cares if it | | | works or not? - Dick Jones, VP OCP Security Concepts |