Date: Tue, 24 Nov 92 05:04:29 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #451 To: Space Digest Readers Precedence: bulk Space Digest Tue, 24 Nov 92 Volume 15 : Issue 451 Today's Topics: ...and another golden oldie... (2 msgs) Another in the continuing Golden Oldies series Dyson Spheres, again golden oldie: jep on "Shuttle's and laser launching system" golden oldie: launch idea golden oldie: more on spaceports golden oldie: nasa budget golden oldie: Shuttling off the mortal coil Golden Oldies... golden oldies: Advanced Rockets and SSTO's Looking form information about Martin Marietta Pumpless Liquid Rocket? (2 msgs) Shuttle Landing Schedule Shuttle Replacement (2 msgs) 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: Mon, 23 Nov 92 15:46:44 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: ...and another golden oldie... The NAA and its Sky Shuttle, obviously a reference to NASA and the Space Shuttle, is not a valid analogy. The reason is simple: it is very easy to build a scale model of a bridge out of balsa wood, but you must use a qualitatively different material when building the real thing. In case you didn't follow that, I'll rephrase it: scale is very important. There is a very real difference in scale between the fictic- tious Sky Shuttle, an airplane, and the Space Shuttle, a space ship. An airplane is such a simple device, in its most primitive form, that one can be built single-handedly with the resources available to a single person. Thus, the Wright brothers were able to pioneer in the field without any financial backing. The Space Shuttle, on the other hand, is one of the most complex machines ever built by man to date (even if it will look hopelessly primi- tive some day in the future). The moral of the Sky Shuttle scenario is that space travel would be better developed by tinkers working in their backyards, or, more realistically, by major corporations. However, the simple fact is that the Space Shuttle is too complex a machine to be /developed/ by any corporation existing today. NO company has the financial resources to plunge billions of dollars into something that will take decades to pay itself off. I am willing to concede, however, that once space travel has been FIRMLY ESTABLISHED, private enterprise will be running the space ships under the equivalent of the airlines' air traffic control system, and I do support NASA's plan to eventually sell its shuttles. Note from phil: god, didn't any of these people use .signatures? BTW, nice how "NASA's plan to eventually sell its shuttles" worked out, huh? -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 15:50:20 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: ...and another golden oldie... Begin article: The most recent number I have heard for the marginal cost of a shuttle flight is $50M, but I don't think this includes an adequate allowance for the ground support. To round up for inflation, and to be generally conservative, assume that the actual marginal cost to a private user would be about $80M. I have seen first cut designs for a passenger module for the shuttle that would pack about 60 people in like sardines. In addition to being technically doubtful, that kind of arrangement would significantly reduce the market for some kinds of travel (vacation in particular). If you allow a reasonable amount of room for support equipment, a bar, and the like, a passenger capacity of 20 is probably believable, which would yield a per person cost of #$2M. This, of course, doesn't take into account the purchase of the passenger module, much less it's development cost. I guess my vacation in space will just have to wait a few years. TCS End article. Comments: at last, someone with a .signature. And a solid number for space shuttle costs... NOT! Although to quote an old song, I wish I didn't know now what I didn't know then... pgf -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 15:43:46 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: Another in the continuing Golden Oldies series Here's another. Commentary to follow, article begins here:" The discussion about private business getting into the space business in a serious way DOES belong here, because it falls into the scope of SPACE digest (I feel), and there hasn't been much traffic on this list recently anyway (things need to be livened up around here). To wit: While opening space to non-governmental use has potential dangers, (one can see cost-cutting on safety hardware for a priviate shuttle, leading to a launch pad explosion or reentry burnup), leaving it exclusivly in the hands of the government (especially the military) makes it a political hostage. Let me advance another scenario that can happen if the bureaucratic hold on space is not broken: 1983 - Furthur budget cuts for NASA cause cancellation of fourth Shuttle orbiter. Funds for completion of Discovery (the third orbiter) are in doubt. The Air Force steps in and pays for the third and fourth orbiters. Congress readily approves this "national defense" expenditure. 1984 - Increased doubts about Shuttle availability and reliability (due to trimmed operational funds) lead potential customers to use expendable vechiles instead (Ariadane for example), cutting income from cargo loads. 1985 - The Congress wonders why the Shuttle is in such red ink and declares "The taxpayers of America cannot afford to subsidize this money-losing boondoggle". NASA gives some under-booked shuttle flights to the Air Force. 1987 - Shuttle use has fully replaced expendable rockets for the military. Since the military is continually launching new spy satellites, plus testing particle-beam weapons, Vandenberg AFB is keeping busy while Cape Canerveral is winding down. 1988 - The Shuttle is declared "too vital for national defense to be used for other things", since the military now leans heavily on it (and they have the bucks to do so), so NASA is reduced to buying cargo bay space from the Air Force to do science. I admit for this pessimistic scenario to take place, a lot of things have to go wrong in the next year or two. I neither expect nor desire these things to happen. However, if space remains, as it is now, exclusively in the hands of the government, this CAN happen, and there will be no failsafe against it. A solution is to open up space to private speculation (with proper licensing and [gasp] regulations). In the interim, the money for the R&D must continue to flow from the taxpayers to build the basic technology for space industrialization (the Shuttle). Alright, folks.... let's see those brickbats fly! ------- Phil here again: what do we know from here in the future? Basically, the shuttle has turned out to be an expensive waste of money that Proxmire couldn't even conceive of, and we can't even get rid of the danged thing if that's what it took to save the space program. I mean in terms of having a space program that does something, not just spend money... -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: 23 Nov 92 20:52:14 GMT From: Henry Spencer Subject: Dyson Spheres, again Newsgroups: sci.space In article <1992Nov23.020045.15067@dartvax.dartmouth.edu> Frederick.A.Ringwald@dartmouth.edu (Frederick A. Ringwald) writes: >> Well, Dyson himself did not actually propose a solid sphere... >> What he invisioned was a large number >> of habitats in orbit about a star which, together, would completely >> encircle the star in a ball-of-twine formation... > >Have you read Dyson's original article? I have it here in front of me... >This sounds like a solid sphere to me... >...the idea of a swarm of independent space habitats wasn't >Freeman Dyson's, it was Gerard O'Neil's, circa the late '60s... Sorry, not so. Dyson's *original* paper demonstrated the adequacy of the supply of materials by postulating a solid sphere, but he followed up on that with more detailed discussions which specified a swarm of smaller bodies. See his paper "The Search for Extraterrestrial Technology" in Perspectives in Modern Physics (R.E. Marshak, ed.), published in 1966. (I've seen references to the same material appearing in a talk given by Dyson somewhat earlier.) O'Neill's key contribution was not so much the idea of space colonies, but the observation that space is a *better* place to live than the surface of a planet -- that an industrial civilization would *prefer* operating in open space even if planets were available. -- 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: Mon, 23 Nov 92 16:11:22 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: golden oldie: jep on "Shuttle's and laser launching system" From Jerry Pournelle, on 15 Dec. 1981 (yah, I think I'll start doing the date on these: Art Kantrowitz is the new Chairman of the L-5 Society and will be writing on laser launch systems for the L-5 News. (Subscribe by sending $20 to L-5 1060 E Elm Tucson AZ 85719) (I don't get paid nothing nohow for L-5 News) NASA has a decision to make: operate stuff, or develop advanced technology? There's a conflict. Worth thinking about. --------------------------- -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 16:19:30 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: golden oldie: launch idea Here's yet another: - pgf : The orbiting linear accelerator article (I thought both the article and the idea were extremely good) was Roger D. Arnold and Donald Kingsbury, The Spaceport, Part 1: Analog v99 #11 November 1979 pp 48:67 and Part 2: Analog v99 #12 December 1979 pp 61:77 They propose an accelerator length of 600 km subjecting payloads to 5g, with an active stiffening system on the structure. Neither the mass nor the complexity is obviously lower than a cable performing the same task: Imagine a cable in low earth orbit that spins in the plane of the orbit so that the spin just cancels the orbital velocity at the points where the cable tips come closest to the ground. The cable is like two spokes of a giant wheel that is rolling on the earth's surface at orbital speed. A flying machine can now jump up and grab the cable end at its lowest and slowest point (for a few seconds the tip is actually stationary with respect to the ground, just like the portion of the rim of a rolling wheel in contact with the ground is momentarily stopped). The cable can actually enter the atmosphere (and with terminal guidance and high precision, it could even kiss the ground), so the job of docking with it is simpler than for the linear accelerator spaceport. The payload then hangs on to the end, and lets the cable flip it around to be flung off at high velocity later. At the top of the swing the cable tip is moving at twice the (orbital) velocity of the cable's center of mass, and if the payload lets go then, it is sent off with a factor of more that sqrt(2) beyond escape velocity. The cable loses some orbital momentum in the process, wich it can regain from incoming payloads, or high specific impulse engines at its middle, just like the orbiting linac. Such a non-anchored skyhook can be build low and spinning fast, or long and orbiting high and turning slow. If you build one to orbit at synchronous height, it has most of the properties of the synchronous beanstalk. It turns out that there is a lower orbit which is optimum in the sense that it minimizes the taper required by the cable. The length of such an optimum cable is one third the diameter of the earth (this is a general principle; cute, huh?). So we have the cable about 4000 km long, with its center orbiting 2000 km above the surface. With a material that can make a beanstalk with a taper of 100, we can make an optimum rolling cable like this with a taper of only 10, using 100 times less material for the same payload capacity. The rolling cable can hoist 1/50 of its own mass on each touchdown. Such touchdowns happen every 20 minutes, in succession at six equally spaced points around the orbit. The cable is very long relative to the depth of the atmosphere, and because of the scale and the cycloidal shape of the tip trajectory, the cable ends appear to descend from the sky vertically on each touchdown, with a continuous upward acceleration of 1.4 g. They stab downwards into the atmosphere at a tame 2 km/sec, slow to a dead stop for an instant at their lowest point, and accelerate gently upwards to leave in the same way. The tip stays in the atmosphere five minutes each touchdown. The material of the cable (if graphite) has a tensile strength of at least 3 million pounds per square inch, so one or two square inches at the cable ends is certainly sufficient for most tasks. The average cross section would then be about five square inches. This gives the whole rolling skyhook somewhat the scale and geometry of a typical transatlantic telephone cable, except that the graphite is five times less massive than the copper and steel of the phone cable. It seems at least possibly cheaper to me than the accelerator, but cost analyses would have to decide. The big advantage of the accelerator is that it can be engineered entirely with known materials and techniques, while the cable awaits the next increment in high strength materials. Re: collisions with aircraft, I agree that most of the time a taut 3 million psi, inch diameter, cable would be to a slow moving aluminum plane much like a cheese cutter is to a piece of cheese. Almost all of the cable is above the atmosphere, however, and a collision at orbital velocity would be another matter. The hit probability is no greater than for a big satellite. The rolling cable is 4000 km long and about 5 cm in diameter. This gives it the same "frontal" surface area as a 500 meter diameter sphere. A collision would not be much of a disaster on the ground, because the small cable diameter insures that the cables burns up on reentry (though the sheet of flame across the sky as several thousand kms burn simultaneously should be interesting). Still the cost to the owner (or insurance) and to the payload on the cable at the time certainly make this event undesirable. Some kind of Norad (or coast guard) traffic control or monitoring would seem worthwhile. Given a few hours or days warning a skyhook can dodge a few kilometers, but it will probably be the least maneuverable object in earth orbit. It will probably have to be given right of way most of the time, just as law of the sea gives oil tankers right of way. Here are a few more skyhook references: Arthur C. Clarke, The Fountains of Paradise, Harcourt, Brace and Jovanovich, 1978. Charles Sheffield, The Web Between the Worlds, Ace SF, 1979. Charles Sheffield, How to Build a Beanstalk, Destinies Vol 1 #4, Aug-Sep 79, pp 41:68, Ace books. Charles Sheffield, Skystalk, Destinies Vol 1 #4, Aug-Sep 79, pp 7:39 Charles Sheffield, Summertide, Destinies Vol 3 #2, Aug 81, pp 16:84 And yet another person doesn't sign his name! -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 16:22:35 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: golden oldie: more on spaceports >Date: 19 December 1981 03:10-EST >From: Robert Elton Maas >Subject: Spaceports >To: Hans Moravec at CMU-10A >cc: SPACE at MIT-MC Even if the mass and complexity of the 600 km linear accellerator is the same as the rotating&dipping cable in orbit, the l.a. is much easier to build. Why? (1) It can be built and tested incrementaly. Each piece can be installed in sequence and suborbital test flights of cheap passive material (dirt, rock) can be made. When enough sections are installed to achieve orbital velocity, it becomes operational. The dipping cable, on the other hand, must be built and installed as one big piece somehow. (2) The cable must be put into space somehow whereas the linear accellerator can be installed by conventional means such as bulldozers cranes trucks etc. Thus the linear accellerator can be started now without needing the shuttle whereas the dipping cable will DETRACT from shuttle payload capacity by diverting capacity from normal use to cable use, and can't be started anyway until the shuttle is operational. Thus I don't think the cable should be done until after we are well out into space, whereas unemployed construction workers could be assigned to the accellerator in 1982. We could use the shuttle for delicate equipment and people, and the linear accellerator for bulk materials. (I'm not sure whether we should do the Earth-based accellerator now and use it for bootstrapping ourselves into space industry, or go instead with the moon-based accellerator which WILL need a few shuttle payloads to get it installed but possibly be more effective due to lower moon gravity and lack of atmospheric friction.) -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 16:39:26 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: golden oldie: nasa budget Here's something from Jerry Pournelle on 7 Feb 1982: There are other developments; and some private work on Big Dumb Boosters, and the like. But Single Stage to Orbit technology is indeed very important, and somewhat overlooked. It may, nowever, get funding directly from DOD. --------------------- -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 15:58:55 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: golden oldie: Shuttling off the mortal coil Administrative change: titles of the reposted articles now appear on the subject line. - Phil. Now here's the article: As concerns having 'blown' it by building the Shuttle, I remind the audience that the Shuttle, although full of innovations and new hardware, is based in mid-70's space technology, which IS reliable AND proven (unlike esoteric methods such as laser launching and mass drivers). It is obvious that chemical rockets are not going to be sufficent in the long run for getting places. HOWEVER, that is exactly what we are stuck with for the time being. Of course, the esoteric methods could probably be made to work if a gigabuck or two were poured into them, but there is always the problem of "What if it doesn't work on the scale we need it to?" With current technology, we KNOW it will work on the scale involved (up to the scale of the Saturn V). While undoubtedly politics were involved with the Shuttle winging its way back to earth, that is ALSO based on known, proven aerodynamic technology. Also, an aerodynamic return vechile has more flexibility on landing site selection than the falling-rock Mercury/Vostok/Gemini/Vokshod/Apollo/Soyuz genre. Face it, there are LOTS of things that COULD have been done. But if you were going to attack the problem of reusable (cheap) space transportation, with ~2 gigabucks of taxpayers money, (and all the political bullshit attached thereto) would you adopt untried technology for its base? No one wants their head on a pole because of a wrong decision, not scientist or engineer or Congressman. ------- Final comment from Phil: how much have we spent on the Scuttle since this article was written? According to the header, it was written by Clyde Hoover. I need to keep the attributtions straight.... pgf -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 15:36:45 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: Golden Oldies... As I stated before in a message to sci.space that I hope got through, I've been reading the old space-digest archives. I'm posting some of the better messages for the perusal of everyone... and also some of the suprising ones... Well, here's the first. I wish someone had taken this more seriously back in '81/'82. Article begins: [This item is an excerpt from the November 1981 issue of Reason, a conservative political journal. It is a sidebar to an article on goverment vs. private means of developing industry in space. Poli-Sci is getting a copy because the recent discussion has been on govermental vs. private means of doing all sorts of things. This item may be considered a fantasy. Then again...] ---------------------------------------------------------------------- Imagine... Dawn is breaking over the plains of Kansas, a glorious spring morning in 1982. The rising sun gilds a few clouds in an otherwise clear sky. In a backyard behind an old, weatherbeaten Midwestern farmhouse is an incongruous scene: a cluster of modern trailers, with cables running in all directions, and a large crowd of doers and onlookers, engineers, reporters, and cameramen. One of the network reporters is conducting an interview with an older man, clearly by dress and demeanor a Senior Official. Reporter Intro: Good morning, Americans. We are here in Owl's Eye, Kansas, to witness another chapter in the forward march of science and technology, the controversial and long-awaited "next step" in America's costly and exciting conquest of the air. Today, finally, if all goes well, we will see the National Air Administration's controversial Sky Shuttle aircraft perform its first applications mission as part of NAA's "Skydust" program, in which the mammoth aircraft will swoop down over the fields of farmer Ed Shultz and spray them with pesticides. With us today is NAA's deputy director, Buzz Wingnut, who will be answering some of the tough questions which have come up about NAA and the Sky Shuttle. Buzz, what are the chances of success of today's mission? Official: Well, Jules, all the indications are good. The weather is right, the aircraft, aside from a few minor problems, is in good condition, and the crew is in excellent spirits. It sure looks like we have a "go". Reporter: What about the rotor problems? Everybody knows that the rotors have been giving you trouble ever since the start of the Sky Shuttle program. Critics have charged that there is still a serious chance they'll fall off. Official: I can assure you that the rotors will not fall off this time. The rotor problem has definately been solved. Reporter: Some critics have questioned the whole idea of having a set of rotors on an airplane, saying that the idea of an aircraft that can take off vertically \and/ fly 10,000 miles at supersonic speeds is unnecessarily complicated. Could these missions be better performed by separate aircraft? Official: Jules, this kind of talk puts our entire technology development system in question. I might point out that each of those requirements you mentioned, as well as others -- such as the ability to land on both land and water, the ability to perform aerobatic maneuvers, and the ability to fly at treetop level -- were inputted to NAA by responsible sectors of the government. There is no doubt that each of these capabilities is needed by the nation's aviation-using sector. As for the idea of developing a separate aircraft for passenger, cargo, defense, and scientific purposes, such talk is the height of irresponsibility. What with the cost overruns and time delays which were unavoidably encountered by the Sky Shuttle program, there is no chance of getting Congress to appropriate funds for development of a new aircraft in this decade. Reporter: Buzz, Senator Buttermore has been highly critical of both the Sky Shuttle program in general and the Skydust experimental program in particular. He has said, and I quote, "The Skydust program has been an enormous boondoggle from the beginning. It is mearly an excuse by the NAA administrators to find new 'needs' for their services. Ask any farmer -- the idea of spraying chemicals on crops from the air as a part of day-to-day agriculture is inherently absurd. Both as a Senator and a taxpayer, I say, 'Not a penny for this nutty fantasy!'" How do you respond to that, Buzz? Official: Well, all I can say is that I am glad Queen Isabella didn't take this attitude toward Christopher Columbus. "Crop-dusting", as our boys like to call it, is an extremely promising technique, and one which today's demonstration will prove technologically feasible. The Sky Shuttle will reduce the cost of aerial application from $500,000 per acre to only $100,000 per acre. I can confidently predict that, given Congress's continued support of development funding, hundreds, maybe even thousands, of American farmers will enjoy the benefits of "crop-dusting" by the year 2000. Reporter: There have been some voices, so far a distinct minority, who have called for private operation of the aircraft program in this country, saying that private operators could do the job more efficiently. Could you say a few words on that, Buzz? Official: Well, Jules, it's hardly worth my time to answer that one, don't you think? The Sky Shuttle has cost nearly $100 billion dollars to develop. Where could a private firm raise that kind of capital? We at NAA have always valued the contributions of private industry -- we feel that the free-enterprise qualities of our contractors demonstrate exactly the kind of government-industry partnership it takes to maintain America's leadership in high technology. But romantic notions of competing "airlines" operating passenger and freight operations across the continent as if they were railroads -- that belongs in the 19th century. Aviation in America has been in sound hands ever since Congress suppressed dangerous cranks like the Wright brothers and created the predecessors of the NAA to give American wings, and let us pray to God it remains that way, Jules. I'm going to have to cut this short. The count-down is entering the final stage. Reporter: Well, thank you, Buzz and Godspeed. It's a great day to be an American. ---------------------------------------------------------------------- [ Just as a trivia item: the current cost for crop-dusting is under $10/acre, plus cost of chemicals. ] Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ -- Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: Mon, 23 Nov 92 17:11:59 -0600 From: pgf@srl01.cacs.usl.edu (Phil G. Fraering) Subject: golden oldies: Advanced Rockets and SSTO's This message was posted by some dude named Paul Dietz. ;-) Anyway, you'll be getting the header for this one, since I've been forced to abandon the digest peruser for "more" to read these: they're not in standard digested format. (At least, not the ones I'm reading now. Here it is: Date: 28 Mar 1982 1614-PST From: Paul Dietz Subject: Advanced Rockets and SSTO's To: space at MIT-MC I went to an interesting presentation last night about a new rocket idea called the Dual Expander rocket engine. The idea is this: most of the mass of propellant in a rocket is burned during the first parts of the launch. As it turns out, if you want to build a single stage to orbit vehicle the fuel burned during the first part should NOT be chosen for high exhaust velocity, but rather for high propellant density. Specifically, we should use hydrocarbons (like propane, methane or kerosene) instead of hydrogen. The dual expander rocket engine burns both hydrocarbons (propane) and hydrogen. It is essentially an engine within an engine. The interior engine burns propane and LOX during the first part of the launch with a chamber pressure of 6000 psia. It is surrounded by an annular combustion chamber where hydrogen and LOX are burned. This outer chamber has a smaller aperature than the space shuttle main engine, so a smaller nozzle is needed. When the center engine is shut down it generates far less thrust than the SSME, but at that point you don't need much thrust. The eignine has a top thrust of 1/2 of the SSME, but weighs 1/3 as much. The speaker presented several designs using the engines. The first is an upgraded shuttle. The SRB's are removed, and the main tank is enlarged to include a propane tank and extra LH and LOX. On the bottom of the tank goes a cluster of (eight?) dual expander engines. Both the tank and the orbiter are placed in a stable orbit. The engines are removed from the tank and returned inside the shuttle. If you want a real heavy lift vehicle, put the SRB's back on. I forget the exact figures but this thing lifts well over 100,000 lbs. of payload. And you have a tank in orbit to play with. A one man Air Force shuttle was also described. It is much smaller than the space shuttle. Depending on the exact design, it can be launched from a C5A or from the ground. It uses two dual expander engines and strap on propane tanks that get left in orbit. Next, several commercial SSTO's. Three designs were given, the smallest smaller than the space shuttle, the largest weighing 10,000,000 lb. and having 29 (!) engines. The speaker also showed how you can take the proposed airforce shuttle, put it on an upgraded space shuttle tank and get a vehicle capable of getting to geosynchronous orbit and back again. Another proposed design used LEO refueling from an ordinary shuttle. The last and most practical design is a disposable SSTO unmanned booster. It has two dual expanders. On top goes a second stage that propels the payload to geosynchronous orbit. It could carry over 6000 lbs. of payload. The kicker is this: the first stage is ~14 feet in diameter by 50 some odd feet long. These numbers should ring a bell, because the shuttle cargo bay is 15'x60', making this a "fully reusable disposable". Final note on this thing: it can be air-launched from the back of a 747! This would avoid dynamic pressure problems. Launch procedure involves putting the 747 into a 45 degree climb at 30,000 feet, igniting the rocket and pulling negative g's to get away. Boeing is examining putting a SSME in the tail of a 747 (!) to get it higher. The launch altitude then becomes something like 50,000 or 60,000 feet. This last idea has been looked at by SAC already; in the 60's they considered putting a Titan engine in the tail of a B52 to get it away from the field quickly: said vehicle could be at 30,000 feet 30 miles from the runway in 1 minute! I hope they get to develope the engine. It uses no really new technology. The speaker claimed it could be developed in 4-5 years at a cost of $400M (1980). He works for Aerojet (the company responsible for this thing) so he isn't unbiased. ------------------------------ Phil here again: it now looks like these engines are the wave of the future: although you have to buy them from the Commonwealth of Independent States instead. What did we gain from not developing that engine: 1 (1) flight of the Space Scuttle... Phil Fraering "...drag them, kicking and screaming, into the Century of the Fruitbat." <<- Terry Pratchett, _Reaper Man_ ------------------------------ Date: 23 Nov 92 22:15:02 GMT From: Steven Back Subject: Looking form information about Martin Marietta Newsgroups: sci.space I'm looking for information about Martin Marietta, especially the type of computers they us for. 1: CAD and space craft design 2: "Normal" information processing (payroll systems, inventory systems) 3: Space Craft check-out stations. 4: Ground Systems 5: Technical wordprocessing. 6: Do they have internet access or are they on a private net. What would be especially usefull would be some contact names of system administrators at their various sites. Thanks Stevn Back back@paul.rutgers.edu sback@ew0400.astro.ge.com ------------------------------ Date: 23 Nov 92 20:15:38 GMT From: Frank Crary Subject: Pumpless Liquid Rocket? Newsgroups: sci.space In article <1992Nov23.160859.9657@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes: >I was thinking about the problem >of pumping in a liquid fuel rocket >and wondered if there might be an >alternative to fragile turbo pumps >or heavy pressurized tanks. >[Description of a gravity-fed rocket deleted.] >That is connect the tankage to the rocket engine >with a long pipe. When accelerating (or at >rest in a gravity field) hydrostatic pressure >at bottom of pipe can be fairly high... This system has two disagvantages: As acceleration changes, the pressure (and therefore the fuel flow rate and a few other characteristics of the combustion) will also change; also the system will not function in zero-gravity. An alternative is a pressure-fed system: A compressed, inert gas (He and N are popular) is used to keep the fuel tank at some constant pressure, and thereby force a flow into the lower pressure combustion chamber. Frank Crary CU Boulder ------------------------------ Date: 23 Nov 92 21:05:46 GMT From: Henry Spencer Subject: Pumpless Liquid Rocket? Newsgroups: sci.space In article <1992Nov23.160859.9657@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes: >That is connect the tankage to the rocket engine >with a long pipe. When accelerating (or at >rest in a gravity field) hydrostatic pressure >at bottom of pipe can be fairly high... The hydrostatic head in the plumbing, while useful -- it figures into the design calculations for both pump-fed and pressure-fed rockets -- is not enough to run a pressure-fed engine particularly well. Even low-performance pressure-fed engines need 5-10 atmospheres of pressure. (One atmosphere is a 10m column of water, and most fuels and oxidizers are substantially less dense than water.) I'd also expect stability problems, given the increase in feed pressure as thrust increases. -- 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: 23 Nov 92 04:56:37 GMT From: "Mr. Nitro Plastique" Subject: Shuttle Landing Schedule Newsgroups: sci.space Could someone please send me a Shuttle Landing Schedule? I'd like to plan a trip to Edwards for a big group, and need dates for scheduled Edwards landings. Thanks in Advance, * * *** ******* ********* ******* ******** ********************* * * * * * * * * * * * * * * * * * * * ******** * FIGHT * * * * * * * * * * * * ON * * *** ******* * ******* * * * TROJANS! * * * ******* ******** * * * * * ***** ****** * * * * * * * * * * * * * ******** * * * * * ***** * * * * * * * * * * * * ******* * * ******* * ***** ***** ****** -- |Victor R. Orly | "Try to imagine all life as you know it, | |aka "Mr. Nitro Plastique" | stopping instantaneously, and every molecule | |Univ. of Southern California | in your body exploding at the speed of light"| |Internet: orly@aludra.usc.edu| -Egon Spengler, from "Ghostbusters" | ------------------------------ Date: 23 Nov 92 19:57:54 GMT From: Henry Spencer Subject: Shuttle replacement Newsgroups: sci.space.shuttle,sci.space In article <1992Nov23.185809.4267@iti.org> aws@iti.org (Allen W. Sherzer) writes: >>It's not an accident that the more farsighted schemes for encouraging >>commercial launchers focus on guaranteeing a market, not on providing >>direct support. > >The problem with a 'Kelly act for space' is that the Government can >no longer be trusted to maintain the program long enough... Unfortunately true. One can think of ways around this, but they're not things the government is likely to be willing to do... -- 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: 23 Nov 92 20:56:25 GMT From: Henry Spencer Subject: Shuttle Replacement Newsgroups: sci.space In article 0004244402@mcimail.com (Karl Dishaw) writes: >Has the shuttle ever lifted more than 20 tons (vs. the rated capacity >of 30 tons)? ... That "rated capacity" is obsolete; the shuttle has never been capable of lifting that much without violating one operating rule or another. (Yes, this means that the original specs were never met.) -- 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 451 ------------------------------