Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Sun, 18 Mar 90 01:27:24 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 18 Mar 90 01:26:55 -0500 (EST) Subject: SPACE Digest V11 #161 SPACE Digest Volume 11 : Issue 161 Today's Topics: Re: Coilgun on a 747 - supplies to orbit at $20/lb? Re: Artificial Gravity rephrased Re: Challenger last words Re: Coilgun on a 747 - supplies to orbit at $20/lb? Re: What was Challenger really up to? Re: Reliability, Bureaucracy, and Spaceflight Costs (long) Gerard K. O'Neill lecture Re: USF ---------------------------------------------------------------------- Date: 16 Mar 90 23:12:07 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Coilgun on a 747 - supplies to orbit at $20/lb? In article <8444@pt.cs.cmu.edu> vac@sam.cs.cmu.edu (Vincent Cate) writes: >Sounds like a coilgun on a high flying 747 should be a cheap way to ... >What are the hard parts of this type of approach? My guesses would be recoil and muzzle aerodynamics. Some of the momentum of the aircraft gets transfered to the projectile. Your projectile mass is limitted by the need to keep flying. There is a minimum size payload that will be useful, and multi-shot groups will be spread out over a whole lot of orbit. Fuel, for instance, really wants to be launched in large batches for a decent payload/container mass ratio and handling costs. And a 747 really doesn't fly that high. Maybe you could reengine one for operation where the air is rare, but in any case you'd start running out of lift and have to derate your mass calculations. You could get above a lot of atmosphere but you'd still be shooting through a lot, and now you'd have it shearing past your muzzle at 450 kts or whatever. I do know that the energy storage problem has a solution. A group at Texas A&M (if memory serves) has a railgun power supply "the size of a garbage can", using some kind of magnetic/electromechanical principle. The primary generators in the engines or your APUs place one limit on the firing rate, but once you charge the secondary generator you can pull megawatts out of it for the duration of the shot. A 747 is what, 200 ft long? Calculate the accelleration required to reach orbital velocity from, say, 1200 kts (air speed plus rotation, fudged for inclination and wind) in 200 ft. It won't be as kind to your payload as a longer ground based gun would be, but you may make it up in reduced heating for some payloads. Interesting idea, but I think you need a high-altitude, hypersonic aircraft for your first stage. A 747 just isn't enough better than a ground station to justify the cramped quarters, increased operation risk, and weight limits. One advantage it does have over a ground station is the ease with which it can match launch to window. Just fly to where the window is and yank the cord. -- Steve Nuchia South Coast Computing Services (713) 964-2462 "You have no scars on your face, and you cannot handle pressure." - Billy Joel ------------------------------ Date: 16 Mar 90 23:36:55 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Artificial Gravity rephrased In article <1541@key.COM> perry@arkon.key.COM (Perry The Cynic) writes: >Sure. Let's look at the "natural gravity" counter-experiment: you stand on an >idealized, spherical earth, and horizontally throw a baseball at circular orbit >What's really happening of course, in both experiments, is that you make use >of the local geometry to impose pseudo-forces on your ball. Uhm, well, the situations are duals of one another. In the "natural gravity" case you are using circular motion to cancel gravitational acceleration. In the artificial gravity case you are cancelling motion to remove geometric accelleration. >And yes, atmospheric drag will get the ball, in either experiment. But that's >just a minor detail :-) In the natural case drag will win, because the earth is coupled to the atmosphere and all moving together. In the artificial case one could easily imagine that the squirrel cage was a mere circular catwalk inside a stationary room. In that situation the air might be coupled to the walls better than the floor. So if you do succeed in momentarily cancelling the ball's relative motion, the air conditioning system wins. Somebody mentioned proposed rotating sleep chambers as a counterexample to the assertion that tidal effects in a small diameter artificial gravity rig will make you puke. The answers there are 1) the rig is proposed, they don't know how well it will work in practice, and 2) If you laid down on the floor of a squirrel cage you probably wouldn't get sick. You also wouldn't get much work done. It's having your head at a different radius, and therefore acceleration, (ie, tides) plus corlais (sp?) effects (which happen when you move) that get you. -- Steve Nuchia South Coast Computing Services (713) 964-2462 "You have no scars on your face, and you cannot handle pressure." - Billy Joel ------------------------------ Date: 17 Mar 90 07:40:44 GMT From: elroy.jpl.nasa.gov!usc!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!srcsip!jhereg!quest!viper!dave@decwrl.dec.com (David Messer) Subject: Re: Challenger last words In article <900312.09172868.038053@RMC.CP6> JC@RMC.BITNET writes: >In article <3271@viper.Lynx.MN.Org> dave@viper.Lynx.MN.Org (David Messer) > writes: >>Yes, the last words recorded were: "No, I wanted a BUD Light!" :-) > >You are quite a jerk, aren't you ? Hmmm... Suppose I agreed with you, what would that make you? ;-) Seriously, I find that humor makes lifes tragedies easier to take. I also find those who can't see the humor in such situations horribly depressing. But, to each his own... -- Remember Tiananmen Square. | David Messer dave@Lynx.MN.Org -or- | Lynx Data Systems ...!bungia!viper!dave ------------------------------ Date: 17 Mar 90 03:57:15 GMT From: nuchat!moe@uunet.uu.net (Norman C. Kluksdahl) Subject: Re: Coilgun on a 747 - supplies to orbit at $20/lb? In article <8457@pt.cs.cmu.edu> vac@sam.cs.cmu.edu (Vincent Cate) writes: >>Ever hear of recoil? > > If the gun weighs 50,000 lbs the gun will go >backwards at 1/1000th the velocity of the 50 lb projectile. > At 1/3 g something moving at >15 MPH can stop in a couple seconds and about 20 feet. Sure. You want to fly a 747 that has 25 tons shift by 20 feet? Does the phrase "death wish" mean anything to you? No doubt such an arrangement would shatter every conceivable limit on the CG limits of the aircraft. Plus, you have to consider that the force necessary to stop about 25 metric tons has to come from the aircraft. You find someone willing to try, and I'll shake your hand when you're done and buy you a beer. Just so long as I don't have to be in the plane. ===================================================================== Norman Kluksdahl ...!nuchat!moe ------------------------------ Date: 17 Mar 90 10:07:12 GMT From: agate!brahms.berkeley.edu!gumbyltd@ucbvax.Berkeley.EDU (Dmitry Gokhman) Subject: Re: What was Challenger really up to? In article <2052@v7fs1.UUCP> mvp@v7fs1.UUCP (Mike Van Pelt) writes: > A laser wouldn't be illegal even if it were there. It would be > unlikely in the extreme to be powered up and able to discharge during > the ascent. (What would its power source be? Solar cells? Folded > and stowed in the dark cargo bay. Nuclear reactor? Couldn't be > running during the ascent, or it would irradiate the crew.) Have you heard of chemical lasers perchance? They are definitely a part of SDI. As far legality is concerned, I wouldn't let the latest political scandals lead one to believe that only illegal goings on merit concealment/cover-up. Mind you I still believe in the O-ring theory. Are the votes in on the G-spot theory? :-) --------------------------------------------------------------- - Mr. Gumby * \oo7 Dmitry Gokhman says: `/v/-* Brahms Gang/University of Cauliflower/ MY BRAIN HURTS J L Broccoli CA 94720 --------------------------------------------------------------- ------------------------------ Date: 17 Mar 90 05:51:52 GMT From: elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!Wales.Larrison@decwrl.dec.com (Wales Larrison) Subject: Re: Reliability, Bureaucracy, and Spaceflight Costs (long) Henry, just to offer a quick response to your message on reliability, bureaucracy, and spaceflight costs.... >Summary: the costs of spaceflight are driven largely by desired >mission reliability. Bureaucracies tend to desire reliability as >high as possible, without regard to cost. Corporations may >_or_may_not_ do "better," depending on their internal structures. >If you're willing to accept, say, 85% mission reliability, you can >build things a lot cheaper. Use good design tools, but don't over- >analyze everything. Don't test every incoming part to death. Assume >that your workers know what they're doing, and don't pay QC people to >hawk their every move. In short, wait for something to break before >you try to fix it. Hmm... I thought I agreed with this, but after some reflection, I really don't. Here's why... Current space launch system reliability is driven by a vicous circle of circumstances - highly expensive systems must be made highly reliable to avoid the consequences of their failure, which further increases the costs, and forces them to be more reliable, which .... There are other ways. A couple of years ago I managed systems engineering for a joint USAF/NASA launch vehicle contract which focused on designing a $300/lb launch vehicle. There were several different ways identified to meet the goal - one of our competitors focused on a very reliable (and very expensive) reusable system to reduce recurring costs. We found we could probably reduce the costs below the target $300/lb by focusing on simplicity (it can't fail if you don't have one) and on process control. I can't emphasize enough the importance of process control and reliability - you can spend forever trying to inspect a lemon into a winner, and never succeed. A system designed to make lemons will make lemons, whereas a well- designed system will reliably produce quality. And if a failure occurs, you'd better know what caused it really quickly. However, this will cost up-front money. Regardless of whether you call it TQM, simultaneous engineering, QFD, systems engineering, Deeming, or Taguchi methods, you spend bucks early in the design program to test, verify, and validate your process. We didn't try to inspect for .99999 reliability, but aimed at designing a system for an achievable .98 (and I think we could have beat that!) Politically, this approach is suicide. You can't get increased up- front development money (What's the matter? You don't know how to build this thing?) Much of the problems on the shuttle program, in my opinion, are based upon the lack of early development money to explore and exploit alternative development paths in the early 1970's. The full-up testing and development approach (as was done on Saturn) turned out to be a mistake, as it limited the ability to examine, test, and refine the system parameters before the final design had to be frozen. Congress and OMB are the real culprits behind this - there were not dollars to do this, and the continual dollar flucuations and rephasings of the program did their share of adding an unncessary level of turmoil. U.S. Corporations have the same problem - and they almost always have a harder time getting money than the government. In the end, we lost the USAF/NASA Phase II contract. We were too simple - not enough dollars spent on neat technology development like new rocket engines, and too much money spent on uninteresting things like welding technology and improved instrumentation. ---------------------------------------------------------------------- Wales Larrison Space Technology Investor "Ad Astra Ab Perspera" ("To the Stars Through Our Sweat") -- Wales Larrison ...!{dhw68k,zardoz,lawnet,conexch}!ofa123!Wales.Larrison Wales.Larrison@ofa123.FIDONET.ORG 714 544-0934 2400/1200/300 [PCP: CASAN] [disclaimer.std] ------------------------------ Date: 17 Mar 90 12:35:11 GMT From: phoenix!mcconley@princeton.edu (Marc Wayne Mcconley) Subject: Gerard K. O'Neill lecture Opening "The High Frontier" The Princeton Planetary Society will present a talk by Dr. Gerard K. O'Neill, founder and president of the Space Studies Institute, on Tuesday, March 27, at 7:30 pm. Dr. O'Neill is the author of four books, including "The High Frontier," in which he discusses humanity's expansion into space. He is also Professor Emeritus of Physics at Princeton University. The evening's presentation will feature a slide presentation, a short lecture, and an audience question and answer session. The event will take place in McCormick 101, the auditorium for the McCormick Art and Archaeology Building, adjacent to the Art Museum at Princeton University. For directions to McCormick auditorium or the Princeton University campus ONLY, call (609) 258-3000. For additional information about this event, please call Audrey Robinson at (609) 734-0452. -- Marc W. McConley Vice President, Princeton Planetary Society Reply-To: mcconley@phoenix.Princeton.EDU || (609) 734-7986 ------------------------------ Date: Sat, 17 Mar 90 21:07:50 EST From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: USF Daniel Pezely remarks that there have been few comments on the proposed United Space Federation (USF). Here is a reply: Yes, the USF does sound like a very interesting idea, and something which could contribute a lot to space exploration, PROVIDED it does not get too heavily immersed in politics. Many of the topics listed sound like legitimate areas for fruitful research. Also from the text, it appears that there is a distinct possibility that the USF could eventually come to view itself as having a responsibility to push policies and legislation, perhaps going so far as to negotiate new Moon Treaties. This might not come about under the current leadership, but if the by-laws are sufficiently loose, politically-oriented people will tend to drift to the top. If this should happen, the organization could become ineffective, or even have a net harmful effect. It's difficult to tell from the information available which way the USF will go. There is therefore a tendency to reserve judgement. The problem with politics is that it's much easier than doing anything "real", so organizations usually start with politics. Many never get much further. (Before anyone objects, I also consider terrorism and harassment to be political.) I would urge people running organizations of this type to push politics only to the extent that it is necessary to remove legal and policy barriers that would prevent real accomplishments. (My own opinions, as usual.) John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ End of SPACE Digest V11 #161 *******************