Date: Tue, 1 Dec 92 05:04:16 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #477 To: Space Digest Readers Precedence: bulk Space Digest Tue, 1 Dec 92 Volume 15 : Issue 477 Today's Topics: Breasts in zero-g FREE-ENERGY TECHNOLOGY For Spacecraft Hubbles's mirror (good spin) Magellan Update - 11/30/92 manned vs. unmanned spaceflight Patriot Missile Pop in space Scuttle replacement Shuttle replacement (10 msgs) Terminal Velocity of DCX? (was Re: Shuttle ...) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 30 Nov 92 19:51:25 GMT From: Legene Subject: Breasts in zero-g Newsgroups: sci.space magnus@thep.lu.se (Magnus Olsson) writes: >I recall reading somewhere (I think it was in the Omni Space Almanac) >that NASA was completely unisex: the only difference between the >clothing of male and female astronauts was that the women wear bras to >keep their breasts in place. I assume this does not include space suits. Does NASA even have space suits for females? Taking care of unexpected potty breaks for someone in a space suit is supposed to be much easier with a male's urinary output apparatus. disclaimer: S.D.S.U. made me say it! ------------------------------ Date: 30 Nov 92 09:15:19 GMT From: Patrick Chester Subject: FREE-ENERGY TECHNOLOGY For Spacecraft Newsgroups: sci.space In article <1992Nov18.145425.2798@twisto.eng.hou.compaq.com> mccreary@sword.eng.hou.compaq.com (Ed McCreary) writes: ] ]Aaarrrrrrggghh! This has got to be the tenth time I've seen ]this damn article! What gives, do you have a cron job running ]that posts the same five articles every week to random newsgroups? ] ]Give it a rest or at least post something new! ] Check sci.skeptic and think of that Chinese saying: "Be careful what you ask for, you may get it." -- Patrick Chester |---------------------------------------------------- wolfone@ccwf.cc.utexas.edu |"The earth is too fragile a basket in which to keep Politically Incorrect | all your eggs." Robert A. Heinlein Future Lunar Colonist |"The meek can *have* the Earth. The rest of us are #^%$!! Militarist | going to the stars." Robert A. Heinlein (Of the Sun Tzu mentality) |---------------------------------------------------- ------------------------------ Date: 30 Nov 92 19:24:06 GMT From: "G. Scott Smith" Subject: Hubbles's mirror (good spin) Newsgroups: sci.astro,sci.space In article <1992Nov29.080102.21166@highland.oz.au> gregw@highland.oz.au (Greg Wilkins) writes: > >What are the chances that hubble would have flown if the flaw in the mirror >was detected? There exists a second mirror made by another contractor. The mirror would have been replaced and the mission flown. > >If there was a chance that hubble would have been grounded, maybe it is >better that it went up half blind (but fixable). The science learned from >fixing it in orbit must also be worth something -> probably will save an >extra flight practising for Fred. If the problem had been found, it would have been fixed and the vehicle flown. You don't spend several billion dollars and not fly the thing. Making another mirror would be cheaper than canceling the program, even if there wasn't another mirror already made. -- Scott Smith |Ozman's First Law: If someone says he will do | something "without fail", | they won't. ------------------------------ Date: 1 Dec 92 05:55:42 GMT From: Ron Baalke Subject: Magellan Update - 11/30/92 Newsgroups: sci.space,sci.astro,alt.sci.planetary Forwarded from the Magellan Project MAGELLAN STATUS REPORT November 30, 1992 1. Magellan continues to operate normally, transmitting a carrier plus 40 bps X-band signal which is precisely tracked by the DSN (Deep Space Network) stations to provide gravity data. 2. The spacecraft continues to operate under the G2325 command sequence. All except two starcals (star calibrations) over the 4-day holiday were successful. On board counters indicate the occurance of another double TWTA (Traveling Wave Tube Amplifier) SSO (Spurious Shutoff). 3. Spacecraft temperatures remain in the expected range. Bay 7, which contains the CDS (Command Data Subsystem), is at 51 degrees C with a cycle depth of 6 degrees. Transmitter B is at 52.7 degrees C which is below the temperature where satisfactory performance at 1200 bps is found. 4. The spacecraft has completed 6211 orbits of Venus; 575 so far in Cycle 4, which will end on May 25, 1993. 5. Doug Griffith, Project Manager, left Saturday for Nagoya, Japan, where he will present at paper at the 1993 International Space Symposium. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Learn to recognize the /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | inconsequential, then |_____|/ |_|/ |_____|/ | ignore it. ------------------------------ Date: 30 Nov 92 18:54:00 GMT From: "Dave Batchelor, Space Phys. Data Facil. 301/286-2988" Subject: manned vs. unmanned spaceflight Newsgroups: sci.astro,sci.space In article <1f0isjINNkei@topper.ksu.ksu.edu>, jregehr@topper.ksu.ksu.edu (John David Regehr) writes... >Sorry if this is a dead subject, but I've only been reading this group for a >week or so. I'm writing a paper contrasting manned and unmanned spaceflight. >I'm in the middle of a couple of books, but I haven't been able to come up >with a good thesis statement yet. I would appreciate hearing from people who >have opinions on the subject, or who can suggest some good reference material. >I am trying to approach this from a practical and philosophical standpoint, >rather than detailing the historical controversy on whether the focus of space >exploration should be on manned or unmanned flights. Thanks. > >----------------------------------------------------------------------- >John Regehr jregehr@matt.ksu.ksu.edu >Kansas State University >----------------------------------------------------------------------- > A fine article on this subject appeared earlier this year in _American Scientist_. The title was approximately "An Argument for Manned Space Exploration." The basic concept was that critics of manned flight say automated/robotic missions are safer, cheaper means to achieve the same scientific returns that manned missions can; however, AI and robotics are acknowledged by professionals in those fields to be primitive and very modest in their accomplishments, outside the space probe context. The author of the article highlighted this logical inconsistency. Robots of today and the near future are DUMB and CLUMSY, compared to astronauts. Why should we risk getting inconclusive or skimpy results from missions limited to what robots can do or will be able to do in the next few decades? Examples: the Viking Mars lander could not answer the burning question of whether life exists on Mars (rather than strange soil chemistry that resembles life). Many activities of the astronauts during the lunar landings would have been far beyond the capabilities of robots then and in the near future, such as retrieving soil core samples (which happens to be a very delicate and demanding task). When the Skylab space station was disabled by loss of half the solar power arrays during launch, the astronauts were able to restore it to nearly full functioning, saving a multi-million dollar spacecraft and returning tremendous scientific advances in solar physics and other disciplines. Also, the Hubble Space Telescope almost had to be rescued by space walkers during its deployment from the Space Shuttle. The article gives such examples and really makes its point well: critics of manned missions actually propose reliance on some very limited technological substitutes for a human being with a tool kit or some instruments. And does anybody explore places like Antarctica with robots? Enjoy, ])ave ------------------------------------------------------------------------------ Dr. David Batchelor Space Science Data Operations Office Mail Code 632 NASA Goddard Space Flight Center Greenbelt MD 20771 USA batchelor@nssdca.gsfc.nasa.gov == &( personal_opinions && !NASA_policy ); ------------------------------ Date: 30 Nov 92 16:28:12 GMT From: Brian Weaver Subject: Patriot Missile Newsgroups: sci.space The Patriot missle was developed as a aintiaircraft missle over a long period by the US army , and I believe it was completed sometime in the late 70's or early 80's. What was completed previous to the Gulf War was a new antiballistic version that had a new guidance system capable of intercepting another missle in flight. Brian Weaver (Dude) @swvgs.vak12ed.edu ------------------------------ Date: 30 Nov 92 17:38:56 GMT From: David Toland Subject: Pop in space Newsgroups: sci.space torh@syma.sussex.ac.uk (Tor Houghton) wrote: > If a blob of, say Coke, was floating weightlessly in space (inside a > spaceship - normal air pressure), would the "fizz bubbles" go from the > centre to all directions? [and someone else, I lost the name, discussed nucleation] An interesting picture that comes to mind is if the drifting blob of beverage drifts up against a suitable piece of grit. The fizz is concentrated at that point on the surface, and the blob goes whizzing off in the opposite direction, especially if the grit is held by surface tension for a while. I don't claim this is anything but idle speculation... -- -------------------------------------------------------------------------- All opinions are MINE MINE MINE, and not necessarily anyone else's. det@phlan.sw.stratus.com | "Laddie, you'll be needin' something to wash | that doon with." ------------------------------ Date: 30 Nov 92 17:40:39 GMT From: Gary Coffman Subject: Scuttle replacement Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >In article <1992Nov28.183320.822@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>Does anyone remember the pictures of the balloon with four helicopters >>attached crashing and burning. Control is difficult when your lift >>comes from several active sources. [deleted] > >Control can be tricky when your lift comes from several *aerodynamic* >sources. It's a solved problem when the lift producers are rocket engines, >which are much easier to control. I don't think aerodynamics had anything to do with it. It was *throttle* response synchronization failure that caused the crash. Note the Soviet booster doesn't use throttlable engines, but DC does. Note that airliners can have throttle synchronization problems and keep flying because the engines aren't what's *directly* holding them up. DC doesn't have that luxury. It's not an impossible problem, but it's another disadvantage of DC versus horizontal landing systems using wings, or other aerodynamic devices like lifting bodies, or even VTOL via parachutes. SSTO doesn't *require* powered VTOL, it's just the way DC is supposed to do it. Gary ------------------------------ Date: 30 Nov 92 16:26:07 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article <70467@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) writes: >>>If the same failures happen to DCX then all they need do is shut down the >>>engines which did start, find and fix the problem, and fly again. This will >>>result in RL-10's with one less malfunction and a more reliable system. >> >>They're at 10,000 feet, closing fast with the ground, and half their >>engines don't start (that's what happened in the recent failures). So >>they just stop the others, get out and fix the problem, and proceed >>to land? I don't think so. I think they'll smear all over the landscape >>before they even have time to realize they have a problem. A failure >>on the pad is one thing. A failure coming down is something altogether >>different. > >>Gary > >Uh, Gary... the RL-10s in Atlas-Centaur don't ignite until Centaur does, >which is after Atlas seperation, about six minutes and several hundred >thousand feet above the ground. That's alot more than 10,000 ft. You misunderstand. I'm talking about a DC *landing*, not an Atlas- Centaur takeoff. The parenthetical expression was meant to convey that *half* the engines, on the Centaur stage failed to ignite in the recent failures. Gary ------------------------------ Date: 30 Nov 92 17:30:25 GMT From: Pat Subject: Shuttle replacement Newsgroups: sci.space In article steinly@topaz.ucsc.edu (Steinn Sigurdsson) writes: > >Ooh, I love analogies: so, Allen, would you argue that an Aircraft >carrier is best left anchored in mid-ocean and the planes flown in? >After all, it seems silly to sail the thing back and forth all the >time when what you really want is a launch platform for aircraft >(somewhere) in the ocean, no? > Actually that is how carriers operate. the air wings fly off as the carrier approaches home port so they can under go depot level service. also that way they are available for other ops while the carrier refits. the carrier then steams off shore and the wings are flown on. ------------------------------ Date: 30 Nov 92 19:11:30 GMT From: Dave Michelson Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov30.134803.12023@iti.org> aws@iti.org (Allen W. Sherzer) writes: > >>I recall at least one case (Apollo? Gemini?) where >>one of the astronauts was faced with data suggesting this decision might be >>required - it's not an easy one. > >I believe it was Guss Grissom. The engines on their Titan launcher ignighted >and then shut down after the control panel indicated liftoff had occured. If >the panel was correct and they didn't punch out, they would be dead 1/10 of >a second later. Grissom however felt that "it felt solid beneath" and >made the correct decision not to eject. This has come up *so* often during the past six months that everyone should it straight by now.... The flight was Gemini 6A. The command pilot was Wally Schirra. The date was December 1965. 'Nuff said. -- Dave Michelson davem@ee.ubc.ca ------------------------------ Date: 30 Nov 92 17:58:39 GMT From: Pat Subject: Shuttle replacement Newsgroups: sci.space >>> >>remember it is a piloted >>powered vehicle. if the ILS screws, the crew is still able to visualy >>guide as well as get instructions from ground control. > > At Mach 24, it doesn't take long for things to get out of hand. > Remember that Scott Carpenter missed his landing zone by so much > that Walter Cronkite was about to pronounce him gone. There are > many incidences of off-target returns in the Russian space > program too. What would that do to Delta Clipper? ("Ah! Set her > down in Golden Gate Park! Everybody remember where we parked!") > Please dont confuse the re-entry phase from the landing hover phase. certainly a phine guidance error at re-entry results in hundreds of miles in terminal descent. but shuttle has that same problem and you dont seem to scream about that. the key point that DC-1 will have over STS is that when they punch out of the blackout zone they can get a guidance update from GPS,LORAN, Ground radar or visual and if they are significantly off course they cna look for a convenient emergency descent location and make a powered landing. Your screwball scenarios require a guidance failure early in and major loss of control surfaces or better then 3/4 loss of power. remember airliners have landed despite total loss of electronics, or with on board fires or with loss of major controls or with all engines gone. a sufficiently redundant system induces survivabilty. certainly wings are a nice way to go but i think multiple lifting engines is an acceptable mode of landing. >>Besides, a DC flies on LOX/LH. coming in it should be low fuel and >>LOX/LH does not really explode effficiently. > > Actually, I'd rather it have enough fuel to buzz around in search > of a clearing. We don't want a repeat of Apollo 11's 20-seconds-of- > fuel-left when they're are populations down here! > I would hope that all aircraft try to land with more then 20 seconds fuel on board. usually 747s dont land on dry tanks. > Besides, most of that explosion we saw on 28 January 1986 was > the result of uncontrolled burning of LH2/LOX. I watched that from > my back yard, and I wouldn't want one of those on top of Orlando. > > -Brian You see. there you go. proving my point. what you saw of challenger was uncontrolled burning. it didn't detonate it deflagrated. very impressive but not the damage of TNT. Nobody likes a fire, but firemen dont like explosions. and if you dont want one of those on top of orlando, i suggest you picket the airport. ------------------------------ Date: 30 Nov 92 17:05:05 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: > >Please shut up about gliders, Gary, they aren't relevant. They *are* relevant since that's the Shuttle's landing style. Sure, I'd rather make a powered landing with the ability to glide as a backup, but Shuttle can't do that and neither can DC. That doesn't mean that a powered horizontal landing spacecraft can't be built. The ability to glide is a major safety backup that DC lacks. The ability to land under power is a major safety defect of the Shuttle. Neither is an ideal system. >>... Wind gusts are the worst. > >For vehicles relying on aerodynamic lift (wings or rotors), that is. Even for a bullet. I don't see any magic that makes DC immune to gusts. >>... That all takes fuel margin. > >Certainly, which is why VTOLs need (and have) fuel margins. As we've >been telling you. Of course you said that the DC lands on nearly empty tanks. Knowing how fuel hungry rockets are, I was questioning this margin. How many minutes of hover, or retreat to higher altitude, are available in those nearly empty tanks? Five minutes? Ten? Airliners declare low fuel emergencies when they're down to those kinds of margins. If you're going to treat DC like an airliner, it has to play by airliner rules. If you want to say this is a hot and risky system like all other space launchers, then I'll shut up because that's what I've been trying to say. DC is not like an airliner and can't be treated like one. Gary ------------------------------ Date: 30 Nov 92 17:17:05 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article <17930@mindlink.bc.ca> Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) writes: > >For a more accurate comparison with a DC-1 landing, consider that you will be >landing on a huge flat area which has been cleared of all personnel and >obstructions. Furthermore consider that it doesn't matter where on the area >you land - if there is a gust of wind which pushes the vehicle sideways, you >will have to do some thrust vectoring to kill the sideways velocity, but >there is no need to maneuver to regain your original touchdown point. Well, of course, Bruce, I know this. It's Allen/Henry claims of helicopter style touchdowns at ordinary airports I'm trying to debunk. Landing at White Sands or Edwards is a totally different issue with a much larger margin for error and much less serious consequences in case of disaster. As long as the DC series sticks to this, I have no complaints. Putting it down routinely on a small concrete pad in the middle of a metropolitan area is a totally different thing. Gary ------------------------------ Date: 30 Nov 92 16:46:51 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov28.221824.20558@iti.org> aws@iti.org (Allen W. Sherzer) writes: >In article <1992Nov28.192822.1246@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: > >>They're at 10,000 feet, closing fast with the ground, and half their >>engines don't start (that's what happened in the recent failures). > >Not quite. The engines in question failed on the first attempt to fire them. >On return the engines would have already fired which greatly increases the >odds of successful firing. Or the extra stress they endured during the launch firing put them over the edge and ensured their failure. Cuts both ways. There isn't enough flight experience with restarted RL10s to prove the issue one way or the other. >I would say this will result in a normal landing. > >>different. Yeah I know they're lighter coming down, but asymetric >>thrust still sounds bad when you're close to the ground and have to >>make a perfect 4 point touchdown. > >You don't need a perfect touchdown. Perhaps not, but how much list can the DC tolerate and not topple over? Just where is the CG in relation to the thrust line? >>Can you gimbel the remaining engines >>enough to still stay perfectly upright as you descend? Can you do >>it quickly enough if the failure is close to touchdown? > >I would say this is a trivial problem. Easy for you to say. Demonstrating it's a trivial problem is something else again. >>off* in flight. Suppose a fuel feed line fatigues from multiple flights. >>It wasn't X-rayed before flight because this is airliner grade servicing. >>So the thing lets go as they pass through 10,000 feet on their way to >>a landing at O'Hare. A couple of tons of rocket fuel starts streaming >>down among the firing engines as they pass over the Loop. What's their >>abort mode? > >The engine control system will notice the loss of thruse in the affected >engine. That engine is shut down. But the fuel is still streaming out of the break into the hot exhaust of the other engines. It really doesn't matter if the engine is shut down by command or not, without it's fuel feed, it's going to quit anyway. This is an unsurviveable incident *despite* (perhaps *because*) of all the redundancy in the system. More fuel lines to more engines multiplies the odds that one will rupture. An old rule of engineering is that things with less parts have less things to break. Or as we say in control systems, "two wires make a light." Gary ------------------------------ Date: 30 Nov 92 10:39:08 From: Steinn Sigurdsson Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov30.011822.7870@iti.org> aws@iti.org (Allen W. Sherzer) writes: Re: DC1 Total turnaround is expected to cost around $10 million. I have seen figures for ground crew size and from memory is was on the order of 10 people. Not going to be a Union shop, I see! Now I'm intrigued. I presume the wheels will be slid under the landing legs and the spacecraft jacked up. That takes you in for payload and resupply of cunsumables etc., but how do they do the refueling? Do they fuel it on wheels and truck it over (in which case you need a 500 ton crawler - those don't come off the shelf do they? - I presume the wheels should be removed before launch ;-) - I presume you don't want launch too close to the tank farm ;-) or, do they take it unfuelled to the pad and truck the fuel? It takes what 300 tons LOX and 100 tons LH2? Can you do that with 10 people??? Does your count of 10 include tank farm personnel??? Note that this will be better understood after the DCX flights. Yup, the sooner the better... | Steinn Sigurdsson |I saw two shooting stars last night | | Lick Observatory |I wished on them but they were only satellites | | steinly@lick.ucsc.edu |Is it wrong to wish on space hardware? | | "standard disclaimer" |I wish, I wish, I wish you'd care - B.B. 1983 | ------------------------------ Date: 30 Nov 92 20:43:22 GMT From: "Allen W. Sherzer" Subject: Shuttle replacement Newsgroups: sci.space In article steinly@topaz.ucsc.edu (Steinn Sigurdsson) writes: >Now I'm intrigued. I presume the wheels will be slid under the landing >legs and the spacecraft jacked up. That takes you in for payload and >resupply of cunsumables etc., but how do they do the refueling? It goes something like this: 1. DC lands on its own internal gear 2. Ground crew jacks up gear and inserts weels 3. DC is towed to hanger (if maintenance is needed) or to launch platform 4. DC is placed on launch platform which can support fully loaded and fueled DC. 5. Internal landing gear is retracted 6. Payload is integrated 7. DC is fueled 8. Liftoff I hope this is less ambiguous. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------145 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 30 Nov 92 22:29:03 GMT From: "Michael V. Kent" Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov30.160558.11135@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: > >My question is whether any space launch system >can accumulate enough flight hours to make any of this analysis meaningful. >It seems to me that the launch requirement for something of the DC class >is small enough that there will only be a few built, and those flown >fairly infrequently. At least they will fly at nowhere near the schedule >rates of airliners. What I'm questioning here is whether airliner grade >ground servicing can work with such a system. Two points should be made here. 1) FAA certification does not necessarily mean certified to enter airliner service. Different certification criteria are used for aircraft with differ- ent functions operated by different organizations. A Velocity does not have to meet the same requirements as a 747, yet both can operate out of most large airports. The purpose of certifying the DC will be to prove a level of safety consistant with operating the craft without destruct charges and a few other current range safety limitations. This does not necessarily mean it will carry fare- paying passengers out of O'Hare. 2) DC is not being developed in a vacuum. The same types of composite struc- tures, for example, that MCAIR puts in its fighters, DAC puts in its trans- ports, and Burt Rutan puts into his creations will be used on DC. That exper- ience can be applied to Delta Clipper and should ease the technical risk and, to some extent, the certification requirements. Again, we don't need to match the maintenance of a 747, just be an order of magnitude better than the Shuttle, Delta, and Titan. >Somebody asked, "What's my solution?" to this problem. I mentioned it >earlier, a much bigger SSTO. Because of cube/square relations, a really >large SSTO could be built with ordinary structural steels and ordinary >shipwright techniques. Taking off and landing from the ocean, it poses >minimal risk to populated areas. Instant heavy lift, and low cost per >pound to orbit. Interesting idea -- this might make a good follow-on vehicle after Delta Clipper puts in a decade of service, and spaceflight becomes routine. But for now it is too much too soon. No SSTO has even made orbit yet. We will need DC to shake out the requirements for such a vehicle before we start scheduling routine flights to DisneyWorld -- Orbit. >I think DC is an attempt to build an exotic race car when a tramp >steamer is more in the realm of the possible. DC-3 was necessarily built before the 747. Delta Clipper, as currently en- visioned, will be more of the former, not the latter. The DC-747 will come later. If it's built too soon it becomes a Spruce Goose. Mike -- Michael Kent kentm@rpi.edu Rensselaer Polytechnic Institute "Interviewing during a recession is a lot like faking an orgasm. You have to pretend you're interested all the while getting badly screwed." - Anonymous Tute-Screwed Aero, Class of '92 Apple II Forever! ------------------------------ Date: 30 Nov 92 18:47:25 GMT From: Thomas Clarke Subject: Terminal Velocity of DCX? (was Re: Shuttle ...) Newsgroups: sci.space In article <1992Nov30.135505.12264@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes: > In article <70420@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) > writes: > > However, if DCX *loses* power on it's way in, then it becomes a falling > > rock, with *no* control. The pilot or computer would be unable to veer > > away from said apartment complex. Look out below. > > > Does anyone know what the terminal velocity of the empty DCX is > supposed to be? I heard a figure of 80,000 pounds empty. If it > were 20 meters in diameter its weight/area would be about that of > a human with a terminal velocity circa 100 mph. An additional thought. If the DCX's terminal fall velocity is only 50 meters/second and it weighs 80,000 pounds at landing, then only about 2000 pounds of fuel are needed to stop its fall; give it 3 or 4 thousand to be safe. It would be no fun to be near if it exploded, but it wouldn't be anything like the average chemical plant fire. By the way. Why not use a parachute to get rid of the final 50 meters per second or so. Would a chute be lighter than the extra fuel? -- Thomas Clarke Institute for Simulation and Training, University of Central FL 12424 Research Parkway, Suite 300, Orlando, FL 32826 (407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu ------------------------------ End of Space Digest Volume 15 : Issue 477 ------------------------------