Subject: Space-tech Digest #102 Contents: SSME thrust question (1 msg) Project ClusterShuttle (1 msg) dumb really dumb big booster idea (6 msgs) Art Dula (1 msg) ------------------------------------------------------------ Date: Fri, 28 Feb 92 14:18:13 PST From: gwh@lurnix.lurnix.com (George W Herbert) To: tcsi!cs.cmu.edu!space-tech@uunet.UU.NET Subject: quick question Anyone know off the top of their head what the vaccum thrust of the SSME is? I have it at home, but I need it for a quick estimate of something. (It's around what, 370,000 lbs?) -george william herbert gwh@ocf.berkeley.edu gwh@lurnix.lurnix.com ------------------------------ Date: Fri, 28 Feb 92 14:24:43 PST From: gwh@lurnix.lurnix.com (George W Herbert) To: tcsi!cs.cmu.edu!space-tech@uunet.UU.NET Subject: Project ClusterShuttle Cc: gwh@lurnix.lurnix.com Here's an idea I'd like to run up the flagpole. Take a random shuttle orbiter. Remove the SSME's and replace them with 25 RL-10's. Also, put a 37-unit RL-10 pod at the back of the External Tank, with some sort of floatation and ablative heatshield and parachute assembly. The total thrust comes out about right. It would use structural mods to the ET that Martin Marietta is doing anyway (supporting the NLS idea). The orbiter is another story, but I can't believe it's not practical. [those numbers are the most that fit space-wise in a close packed array]. The RL-10 is more reliable and much more reusable than the SSME. If the recovery of the ones off the ET went fine, then it might just chop the SSME refurbish costs off the shuttle turnaround... -george william herbert gwh@ocf.berkeley.edu gwh@lurnix.lurnix.com ------------------------------ Date: Sun, 01 Mar 92 16:07:37 CST From: "Walker on Earth" To: space-tech@cs.cmu.edu Subject: dumb really dumb big booster idea I found an interesting fact while looking through the space-tech archives: apparently only 0.6% of the shuttle launch costs are allocated for fuel. It would seem logical then, to trade off pro- pellant costs against other costs(maintenance, etc.). So-don't laugh- how about designing an Orion-type vehicle using chemical instead of nuclear explosives? It would simplify the design im- mensly, and make it more rugged to boot; no more fussing with SSME pumps and tankage, for example. Of course, such a booster would tend to be rather massive :-), but then, LOX and liquid H are comparitevly cheap. Anyone willing to discuss this thread or point me towards suitable references feel free to respond privately or publicly; I admit it seems a silly idea, but. . . Thanks in Advance, Dwight Thieme ------------------------------ To: Walker on Earth Cc: space-tech@cs.cmu.edu Subject: Re: dumb really dumb big booster idea Date: Sun, 01 Mar 92 17:25:19 EST From: John Carr Propellant costs are low, but there are structure costs proportional to propellant mass and volume and structure is not cheap. However, fuel tanks cost less than engines and it takes probably takes less tank mass to support explosives than liquid fuel. I think chemical explosives have less energy than H+O. ------------------------------ From: henry@zoo.toronto.edu Date: Sun, 1 Mar 92 18:21:01 EST To: space-tech@cs.cmu.edu Subject: Re: dumb really dumb big booster idea >...apparently only 0.6% of the shuttle launch costs are >allocated for fuel... This is the fundamental observation behind a lot of the big-dumb-booster proposals: fuel costs are trivial by comparison to construction and operation costs, so a booster that is easier to build and run but larger can be a lot cheaper. >.... how about designing an Orion-type vehicle using chemical >instead of nuclear explosives? ... I don't think it would work. Despite the impressive things you can do with them, chemical explosives produce *much less* energy per kilogram than typical rocket fuels. Their detonation products also typically have a fairly high average molecular weight. All of which means that their exhaust velocity will be dismally bad, and you would have a lot of trouble designing anything that could get into orbit with them. >... no more fussing with >SSME pumps and tankage, for example... Bear in mind that thin tanks and rocket-grade turbopumps are actually a very simple and efficient way to handle very large masses of propellant. Any system which stores and handles solid charges will need quite a bit of machinery to do it. Don't judge rocket engines as a whole by the SSME. Most other liquid-fuel engines are robust and reliable. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sun, 1 Mar 92 18:34:44 EST From: dietz@cs.rochester.edu To: UC369801@UMCVMB.missouri.edu, jfc@ATHENA.MIT.EDU Subject: Re: dumb really dumb big booster idea Cc: space-tech@cs.cmu.edu Propellant costs are low, but there are structure costs proportional to propellant mass and volume and structure is not cheap. However, fuel tanks cost less than engines and it takes probably takes less tank mass to support explosives than liquid fuel. I think chemical explosives have less energy than H+O. TNT is about 4.2 MJ/kg. H2 + O2 (stoichiometric) is 13.4 MJ/kg. Even LOX + hydrocarbon is much better than high explosives. An Orion-style rocket with chemical explosives sounds quite impractical. The mass overhead for the shock absorbers would be large, and the launcher for the explosive packages would have to be much larger than for the nuclear version. This does raise an interesting possibility, however: how about a rocket engine using liquid fuels that operates in an unsteady mode? That is, fuel and oxidizer are injected into a rugged thrust chamber and exploded in pulses. The advantage would be that the pressure during fuel/oxidizer injection could be quite low, which would mean the fuel pumps could be small (or, tank pressure could be low, if the engine is pressure fed). The disadvantage would be the amount of vibration produced. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Sun, 1 Mar 92 16:10 PST From: trost@reed.edu (Bill Trost) To: Walker on Earth Subject: dumb really dumb big booster idea cc: space-tech@cs.cmu.edu So-don't laugh- how about designing an Orion-type vehicle using chemical instead of nuclear explosives? The technical term for these sorts of launch systems is "big guns".:-) I remember a fairly lengthy discussion in the space-tech archives (I think) about various ways of doing orbital artillery -- a summary of different artillery shapes, sizes, propellants, etc, etc, with numbers (or hints of numbers) to back them up. ------------------------------ Date: Mon, 2 Mar 92 08:43:51 EST From: davidsen@crdos1.crd.ge.com To: space-tech@cs.cmu.edu Subject: Re: dumb really dumb big booster idea Sender: mnr@DAISY.LEARNING.CS.CMU.EDU I don't think that use of chemical explosives is remotely useful, since the Orion idea makes inefficient use of the energy compared to a rocket. However, while thinking about this, it occurs to me how well nuclear would work for moving icy asteroids. Of course shoveling ice into a small nuclear heated rocket would be more efficient there, too. ------------------------------ Date: Tue, 3 Mar 92 15:14 GMT From: CSG0669@vax2.queens-belfast.ac.uk (Dale Amon) To: space-tech@cs.cmu.edu Subject: Art Dula Sender: mnr@DAISY.LEARNING.CS.CMU.EDU Art is a lawyer in Houston who has been heavily involved in space related things for many years. He was involved with L5 Society at an early date, served on it's board off an on, chaired the 2nd SDC in Houston, wrote papers on space law, etc. He was an important figure in the set up of the Space Foundation, which is the central administrative organization of the Space Business Round tables around the country. Sometime around 1987 or 88, he found Space Commerce Corporation. I believe he had contacts with Glavkosmos maybe as far back as 1984, since I seem to remember him making comments about dealing with the soviets when he gave a talk at the National Academy of Sciences during the 1st Lunar Bases in the 21st Century Symposium in fall of that year. SCC was certainly formed by 1988. I don't know if he is a libertarian per se, but he certainly leans that way, as did a large number of the early L5 people (myself included). He is dealing with the soviets because they have capabilities that he feels can A) speed up the opening of the space frontier B) make him lots and lots of money SCC has arranged tours of soviet space facilities; it has the marketing rights for Energia and other boosters in the US; it has helped market and has actively persued the possibility of sales of other soviet capabilities. Dale Amon ------------------------------ End of Space-tech Digest #102 *******************