Date: Sun, 29 Nov 92 05:03:23 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #469 To: Space Digest Readers Precedence: bulk Space Digest Sun, 29 Nov 92 Volume 15 : Issue 469 Today's Topics: Evil wicked flying bombs! Mars: "unusual" landforms, lat/long Pop in space Scuttle replacement (3 msgs) Shuttle replacement (11 msgs) Want info: sharp gun/launcher 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: Sat, 28 Nov 1992 23:39:43 GMT From: James Davis Nicoll Subject: Evil wicked flying bombs! Newsgroups: sci.space In article martinc@hatteras.cs.unc.edu (Charles R. Martin) writes: >In article <1992Nov28.092941.14207@ringer.cs.utsa.edu> sbooth@lonestar.utsa.edu (Simon E. Booth) writes: > > One thing that's being overlooked is that we've had fully-loaded bombers > flying over our heads with megatons of nuclear firepower on board for years, > and yet we worry more about the safety of the DC-series of spacecraft once > they're in use. > >Just a quibble, but it's real damned hard to get a n-weapon to go off in >a crash. This is a direct correlary of the fact that it's hard to get >one to go off at all. N-weapons, at least in NATO, are also carefully designed to not go off unless the proper procedures are followed. If you don't know the PAL codes, improper arming should leave the user with a mildly radioactive paperweight. Modern nukes have spiffy electronic 'locks' which are said to be next to impossible to crack. I think most of the older devices with mechanical security devices have been retired. If someone acquired a nuclear device illicitly, to use it would require access to the proper PAL code as well. James Nicoll ------------------------------ Date: 28 Nov 92 16:49:18 -0600 From: kebarnes@memstvx1.memst.edu Subject: Mars: "unusual" landforms, lat/long Newsgroups: sci.space Anybody out there have the latitude and longitude coordinates of the "unusual" Martian landforms which have been discussed in the popular press in recent years? Specifically, I'm looking for the lambda and phi (Martian latitude and longitude) coordinates of: The "Face" in Cydonia and The "Pyramids" in Elysium (I'm writing a novel that's partly set on Mars, and I'd really like to know where these minor "tourist attractions" are.) Thanks in advance, Ken Barnes -- *.x,*dna************************************************************** *(==) Ken Barnes, LifeSci Bldg. * * \' KEBARNES@memstvx1.memst.edu * *(-)**Memphis,TN********75320,711@compuserve.com********************** "When I was a boy I was told that anybody could become President; I'm beginning to believe it."--Clarence Darrow ------------------------------ Date: Sat, 28 Nov 1992 19:39:35 -0500 From: "Jonathan R. Ferro" Subject: Pop in space Newsgroups: sci.space torh@syma.sussex.ac.uk (Tor Houghton) writes: > 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? Yes, the bubbles would have no preferred direction to escape towards in freefall IF they were to form in the center of the "blob", but it is more likely that no bubbles would form at all or only on the blob's surface. The reason that bubbles form in a glass of soda on the Earth's surface is because the soda is in contact with the glass. The glass surface undoubtedly contains impurities, oils, microscopic scratches, etc., which are more favorable as "nucleation points" for the bubbles than just the middle of the bulk liquid. Bubbles of gas (CO2, in this case) form at these nucleation points and break off to head for the surface when they grow large enough so that buoyant forces dominate the surface tension forces. Chemists often use this property when they add small chips of porcelain, or "boiling stones" to liquids that they are going to boil to cause the vapor bubbles to be generated more evenly. So, it is more likely that a blob of soda in freefall would not bubble, but just gradually become flat as the CO2 diffuses from the liquid out into the air. It would be interesting, instead, to flick a boiling stone into the blob to watch the nucleating bubbles spread away from it. -- Jon Ferro Einsprachigkeit ist heilbar ------------------------------ Date: 28 Nov 92 18:33:20 GMT From: Gary Coffman Subject: Scuttle replacement Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >In article pgf@srl03.cacs.usl.edu ("Phil G. Fraering") writes: >>3. An abort mode for landing is a good prerequisite for safety for >>an aircraft that needs a mile of concrete to slow down and stop after >>touching down at 150 mph. > >As Max Hunter says: "if the Wright Brothers had had engines with the >thrust:weight ratio of modern rockets, the word `runway' would not >exist in the English language". That's right. Instead we have the farmer standing next to his burnt haystack saying, "I hope you're insured Mr. Wright." :-) 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. Gary ------------------------------ Date: Sat, 28 Nov 92 17:27:37 -0600 From: pgf@srl03.cacs.usl.edu (Phil G. Fraering) Subject: Scuttle replacement >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. Last I heard (although I may be wrong) the failure was caused by a structural problem and not an engine control problem... >Gary -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ PGP key available if and when I ever get around to compiling PGP... ------------------------------ Date: 28 Nov 92 23:04:08 GMT From: Henry Spencer Subject: Scuttle replacement Newsgroups: sci.space 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. Gosh, do you think Mr. Korolev ever heard of this? His "A" booster, with *twenty* main engines firing at liftoff, has flown 1000+ times successfully, and has launched every Soviet manned mission (except possibly Soyuz 1, which some people think went up on a Proton). It is probably the most reliable space launcher on Earth, because it's the only one that's been thoroughly tested. Initial debugging of such things can be interesting, of course. Mind you, the only US launcher with an absolutely, unquestionably perfect record had 8 main engines (the Saturn I/IB), and the runner-up had 5 (the Saturn V, whose second test was less than a complete success). 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. -- MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology -Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 28 Nov 92 18:43:51 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov27.201717.5298@iti.org> aws@iti.org (Allen W. Sherzer) writes: >In article <1992Nov27.145218.24381@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: > >>Well the Shuttle doesn't weigh 750,000 lb, it's max rated landing >>weight is 240,000 lb. > >Don't quibble. Henry's point was that a Shuttle colliding with an apartment >building would kill lots of people. do you agree? When the Navy jet hit the apartment complex, the impact didn't kill anyone but the pilot. The *fire* did the bulk of the damage. Coming in on empty tanks does wonders to reduce fire risk. Sure, a Shuttle hitting an apartment complex might kill some people in it's path. It's big and it's moving fairly fast. But it won't burn the whole block to the ground like a vehicle with fuel in it's tanks and hot engines to ignite it. >>>Please don't compare light sporting aircraft that fly only in good weather >>>with operational commercial cargo/passenger aircraft that are two orders >>>of magnitude larger. > >>Fine, use the large cargo gliders from the Normandy invasion as your >>baseline. > >Sorry that doesn't meet Henry's criteria. Those gliders only flew during >very good weather. As it is, they only saw very limited use because they >where judged too dangerous. Actually they landed at night with no lights or runway. That's because Ack Ack makes very hostile weather. Most of the troops *still* survived the landings in shape to fight even though several of the gliders tangled with hedgerows. They saw limited use because we don't stage Normandy invasions every day. Gary ------------------------------ Date: 28 Nov 92 19:28:22 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov28.003044.13296@iti.org> aws@iti.org (Allen W. Sherzer) writes: >In article <70357@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) writes: > >>However, my argument was that the RL-10, which will power the DCX, has >>failed twice in flight in the past 18 months. > >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. 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. 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? Actually I suspect they'll static test the engines a bunch of times before trying to light them in flight. But let's consider a different scenario. DC-1 is supposed to receive airliner grade servicing. We know that airliners receiving that grade of service have engines *fall 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? Or assume it's at takeoff and they have a full fuel load. Airliner servicing isn't zero defects because that costs too much and stresses are fairly low and an engine falling off or a fuel line rupture is generally survivable due to the presence of wings and a fire bottle. Spacecraft stresses are much higher and DC-1 will glide like a flaming rock. This is high risk stuff, not airliner grade hazard at all. It costs a lot more to do zero defects, recall that standing army at the Cape? And things still sometimes go boom. DC-1 better stay away from populated areas until it's been crash tested a few times. Gary ------------------------------ Date: 28 Nov 92 21:45:25 GMT From: "Allen W. Sherzer" Subject: Shuttle replacement Newsgroups: sci.space In article <7#913pl@rpi.edu> strider@clotho.acm.rpi.edu (Greg Moore) writes: >>No problem. We launch it to Mir or Freedom. In a pinch we launch a Soyuz/Atlas >>to meet and fix it. > Ok, assuming we use Titan to launch your Soyuz (only because the number >is here, and a syou admit, an Atlas may not work), your launch cost for your >satellite is now a minimum of 6,000/lb. No, my launch cost is now a minimum of $3,000/lb. Most of the time I won't need the Soyuz so i won't launch it. >This does not include the cost of your Soyuz. So, your savings is less. Using your numbers I am saving about $4,000 for each and every pound I put up. I'll bet if you where spending YOUR money that's the way you would pick. >>If the first fails, I can launch a second and save money over Shuttle. If >>the second one fails, I can send a third and still be ahead of the game. > No, you can LAUNCH 3 satellites for the cost launching one from >the shuttle. You can't build them though. Sorry. I can build and launch a typical satellite for ~$200 million. $600M is a low cost for a Shuttle launch. (Others may claim the cost closer to $500M but those people are only considering operational costs and ignoring NASA overhead, orbiter depreciation, development amortization, and other costs which easilly add over $100M per flight). Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------147 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Sat, 28 Nov 1992 22:04:24 GMT From: "Allen W. Sherzer" Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov28.182639.737@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>>Do we really give a damn what the launch costs if the payload doesn't >>>work after we get it on orbit? >>If the first fails, I can launch a second and save money over Shuttle. If >>the second one fails, I can send a third and still be ahead of the game. >Of course you've lost you launch window for your probe for the next >umpty ump years while you build the next one and stack another launcher >because celestial mechanics waits for no man. Only a factor for interplanetary flights. To date they have done just fine on expendables. With the billions saved, we can launch more missions. In fact, with the money saved by not using Shuttle we can afford to build and launch two or more probes. The end result will be more science done. >For less time critical >payloads, you just grit your teeth and watch your insurance costs >spiral out of sight, Come on now, think. Insurance costs for a system which is 97+% reliable (like current expendables) are far less than systems which are only a little more reliable yet cost three times as much. >and your customer go to your competitors. Having >on site startup personnel is a major plus that's worth a considerable >sum of money for expensive space systems. The companies who went with Shuttle went out of buisness long ago. They paid too much for launch costs. BTW, with the money saved using expendables my customers are building a space station where they do an order of magnitude more science for less cost than using your Shuttle. One fo the things they plan to do is integrate their own spacecraft at the station. This greatly reduces their costs and allows for on site repair when needed. Needless to say, they are very glad they didn't waste the money they are building the station with on Shuttle. >Expendible throwaways are cost effective for many payloads. That's >why so many payloads are launched that way. But not all payloads >are best handled "cheaply". Example? Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------147 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 28 Nov 92 22:18:24 GMT From: "Allen W. Sherzer" Subject: Shuttle replacement Newsgroups: sci.space 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. But let's say it happened anyway. A landing DC should weigh about 100K pounds. All engines operating together produce 1.3 million pounds of thruse. So if half the engines fail, we will have 'only' 650,000 pounds of thrust or about six times more than what we need. 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. >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. >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. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------147 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 28 Nov 92 20:27:34 GMT From: Gary Coffman Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov27.194900.3982@iti.org> aws@iti.org (Allen W. Sherzer) writes: >In article <1992Nov26.161842.19428@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: > >>Nor is the proposed DC-1 anything like a >>helicopter which can autorotate if there is a power failure. > >Helicopters have a single point failure: the tail roter. DC does not have >a single point failure. How about a main fuel line rupture? >>Nor do either of these systems require high performance rocket fuel. On a > >Perhaps you could answer a question: if this 'high performance rocket fuel' >is so dangerous why is it that about a million pounds of the stuff >couldn't blow up a Shuttle orbiter only inches away from it? Actually it seemed to do a pretty good job of making that flight unsurvivable. Note that tanks full of JP4 can't blow up in flight either. Burn a little maybe, but not explode. Shuttle main tank didn't explode because the fuel and oxidizer weren't mixed well. It did burn in a hell of a hurry. A major fire in flight is unsurvivable anyway. That's the glider's advantage, it can't burn in flight. >>related note, you said the proposed DC-1 would land on nearly empty >>tanks. Does that mean it can't abort an approach and try again? > >Aricraft need to abort, VTOLs don't. That's funny. We've had to abort helicopter landings many times. Some idiot walks out on the pad, some yo-yo parks in our space, a gust of wind blows us off course, etc. We often have to hover or go back up a ways, look for another spot, try the approach again, even fly around for a while until we find one or the pad is cleared. Wind gusts are the worst. You almost always have to go back up a ways, get straight, and try again. That all takes fuel margin. Gary ------------------------------ Date: 28 Nov 92 23:53:49 GMT From: Henry Spencer Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov28.192822.1246@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) 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? You're posing a different problem, since the recent failures were RL10s that would not ignite at all, and complete ignition failures on a DC get found at launch. *That's* when you stop the others and then fix the problem for the next flight. However, it's still nothing very serious. If half their engines don't start, they land normally -- half is plenty -- and then proceed as above. >... 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. 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? It is certainly feasible; single-engine failures in multiply-redundant stages have happened without dire consequences, e.g. the second Saturn V flight. The DCs also have an extra dimension of controllability to use in such situations, since their engines are throttlable. You can always postulate a failure too severe to be handled. Asymmetric lift is bad too; how many aircraft have landed safely with one wing gone? (I do know of one example.) >... airliners receiving that grade of service have engines *fall >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? ... Or suppose that #3 engine on a 747 somehow fails messily, and wipes out #4 while it's at it, and this happens with a heavy fuel load over Amsterdam. What's their abort mode? Answer: they die and so do a lot of others. The question is not "can unsurvivable failures occur?" but "how likely is such a failure?". Something meant to be certified as an airliner, e.g. DC-1, will have to be built to keep the probability of such failures low. That means, as with airliners, careful analysis of fatigue lives of parts and inspection/replacement schedules set up to avoid problems. (It also means, as with airliners, that there will probably be an occasional crash due to unanticipated problems.) >Spacecraft stresses are much higher... Spacecraft stresses are *zero* for most of the flight. The high stresses last a few minutes per flight. Hardware with a fatigue life of (say) 1000 hours wouldn't even be legal on a 747, but should last a DC-1 its entire operating life. -- MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology -Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sun, 29 Nov 1992 00:23:54 GMT From: Donald Lindsay Subject: Shuttle replacement Newsgroups: sci.space gary@ke4zv.UUCP (Gary Coffman) writes: >DC-1 is supposed to receive airliner grade servicing. We >know that airliners receiving that grade of service have engines *fall >off* in flight. I'm getting tired of your attacks on the DC. It's untried, sure. (It isn't even built yet - sure.) But you seem to be on some sort of crusade to prove that VL SSTO is inherently dangerous. There are a million airplane takeoffs a day (or was it a week - no difference). So, it's not surprising that we *regularly* hear about one-in-a-million events! If SSTO technology, or *any* *other* technology, were doing a million orbital insertions a week, we'd similarly hear about a lot of splatted spacefarers. Sure. But initially, the DC series will be static tested. Then, unmanned hovering. Then up to the stratosphere and back, unmanned. And that same progression is planned for *each* *craft* that's built, and the per-craft tests will be done at some sort of test range. Having been through that, yes, some pump may be stressed and just ready to burst. But the computed odds are a *lot* nicer than any non-SSTO human-capable technology offers. (With the exception, of course, of the technologies such as skyhooks, which rely on unobtainium.) So, lighten up. Perhaps instead you could concentrate on how to build an even better SSTO. -- Don D.C.Lindsay Carnegie Mellon Computer Science ------------------------------ Date: 29 Nov 92 00:29:35 GMT From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >If the Shuttle loses flight control power on the way in, it'll plow >straight through that apartment complex. Look out below, and about a >mile in front. ^^^ ^^^^^ ^ ^^^^ ^^ ^^^^^ Are you saying that a Shuttle crash would spread debris over an area a mile long? That hardly seems likely. >> the Shuttle pilot could point his ship into the Indian River or the >> marshes out west. >Unless, of course, they lose power... >Jonathan H. Hmm... good point. By the way, does anyone know if the Shuttle has destruct charges on the orbiter itself? I know the SRBs and ET do, what about the orbiter? If a Shuttle lost power and ground-zero was Orlando, could NASA blow up the Shuttle out over the Gulf? What about DCX in same situtation? (I know, I know... 'same situation can't happen with DCX'. Accidents happen, though. Concorde upper rudders fall off, DC-9 tailcones fall off, a DC-10 *engine* fell off, *two* 747 engines fell off, Challenger went kablooey, etc. etc. ad infinitum.) -Brian ------------------------------ Date: 29 Nov 92 00:30:10 GMT From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >Of course you've lost you launch window for your probe for the next >umpty ump years while you build the next one and stack another launcher >because celestial mechanics waits for no man. For less time critical >payloads, you just grit your teeth and watch your insurance costs >spiral out of sight, and your customer go to your competitors. Having >on site startup personnel is a major plus that's worth a considerable >sum of money for expensive space systems. >Gary Tread very carefully here, Gary. I'm as big a supporter of the Space Shuttle as anyone, but I do remember a Space Shuttle 'malfunction' a few years back which screwed the heck out of three deep space mission launch windows. One mission was delayed for three years (Galileo), one for four years (Ulysses), and a third had to fly a longer trajectory to get there after leaving ahead of schedule (Magellan). Let's not throw stones at expendables when Martin just launched Mars Observer within it's original window, while the Shuttle missed all of it's deep space windows. -Brian ------------------------------ Date: 29 Nov 92 00:30:45 GMT From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >>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. -Brian ------------------------------ Date: 28 Nov 92 23:30:13 GMT From: Henry Spencer Subject: Want info: sharp gun/launcher Newsgroups: sci.space In article <1992Nov28.081011.9481@vlsi.polymtl.ca> d40937@aiken (Jean Yves Desbiens) writes: >What I know now : two tubes joined at a right angle, one is >sticking out of the ground; a piston compresses the hydrogen >that serves to propel a payload deadly or not in the tube that >sticks out of the ground. If the design works on a grand scale >it could but a payload in orbit for 50 times less than the current >price. That could surely upset in a very big way the future of >space trade . Why is this the first time a hear about such a >possibly incredible developpement effort... Perhaps because you haven't been paying attention? :-) Various gun-launch systems, this being one of them, have been in small-scale development for quite a while. This one I particularly remember, because it got a feature article in Aviation Week & Space Technology not too long ago, the 15 Sept issue I think. I'd actually back Hertzberg's ram accelerator or one of the various electromagnetic catapults over a straight light-gas gun, and a laser launcher beats any of them by a mile, but that's personal preference rather than doubt that the light-gas gun will work. There are *lots* of ways of drastically cutting launch costs that look good and have been demonstrated on a small scale, everything from better chemical rockets to laser launchers. The problem is not basic feasibility, but development funding. Incidentally, "deadly or not" is rather silly; light-gas guns are too unwieldy to make very useful weapons. A launch truck with a Scud on it is a better weapon. -- MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology -Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry ------------------------------ End of Space Digest Volume 15 : Issue 469 ------------------------------