Subject: Space-tech Digest #97 Contents: Japanese SPS plans (1 msg) AUSROC (1 msg) DC-X Main Engines (6 msgs) misc. comments on Bid Dumb Hybrid writeup (9 msgs) ------------------------------------------------------------ Date: Wed, 22 Jan 92 09:35 GMT From: Karl Dishaw <0004244402@mcimail.com> To: space-tech Subject: Japanese SPS plans This was downloaded from America On Line's news section: TOKYO (JAN. 21) KYODO - THE JAPAN EXTERNAL TRADE ORGANIZATION (JETRO) SAID TUESDAY IT HAS DISPATCHED A MISSION OF GOVERNMENT AND INDUSTRY EXPERTS TO THE UNITED STATES TO STUDY THE FEASIBILITY OF AN INTERNATIONAL PROJECT FOR SOLAR POWER GENERATION IN OUTER SPACE. OFFICIALS OF THE SEMIGOVERNMENTAL TRADE PROMOTION BODY SAID MISSION MEMBERS WILL MEET U.S. EXPERTS ON SOLAR POWER GENERATION AND SATELLITE TECHNOLOGIES TO DISCUSS COST, TECHNICAL, AND ORGANIZATIONAL PROBLEMS IN SUCH A PROJECT. THE MISSION COMPRISES A DOZEN OFFICIALS REPRESENTING THE GOVERNMENT'S ELECTROTECHNICAL LABORATORY AND NATIONAL SPACE DEVELOPMENT AGENCY OF JAPAN, TOSHIBA CORP., AND MITSUBISHI HEAVY INDUSTRIES LTD. (explanation of SPS deleted) POSSIBLE PROBLEMS IN THE PROJECT INCLUDE REDUCING THE COST OF LAUNCHING SOLAR CELLS, PREVENTING ENVIRONMENTAL DISRUPTION THAT COULD BE CAUSED BY MICROWAVE TRANSMISSIONS, AND SOLVING TECHNICAL DIFFICULTIES IN RECEIVING THE TRANSMISSIONS, THE OFFICIALS SAID. Hmm . . . aren't these the same folks who sent a probe to the moon a couple of years ago? Somebody better grab them and say "lunar resources" real fast. Karl ------------------------------ Date: Wed, 22 Jan 1992 17:30-EST From: Marc.Ringuette@DAISY.LEARNING.CS.CMU.EDU To: space-tech@cs.cmu.edu Subject: AUSROC Last month I came in contact with a guy from Australia involved in amateur rocket projects. I realized I forgot to forward his message here. I'd suggest sending him mail if you're interested in finding out more. M. > From: mnb@dstos3.dsto.oz.au > Date: Tue, 10 Dec 91 09:12:37 pdt > To: marc.ringuette%daisy.learning.cs.cmu.edu%munnari.cs.mu.oz@fang.oz.au > Subject: RE: Small rockets > > > Marc, > Thanks for the E-Mail. Yes I would be interested in contacting > some internet folks. We will be launching a 6m lox/kero rocket from > Woomera next year and we are planning a larger lox/kero vehicle which > will loft a 100 kg payload to 500 km on a suborbital trajectory. > Our ultimate goal is to place a microsat into polar orbit, but this > project will depend on the success of its predecessors. The project > is called AUSROC. > > You already have my email address, my home address is > > Mark Blair > Ausroc Projects > 42 Broadmeadows Rd. > Elizabeth Nth. > S.A. Australia 5113 > > Thanks, > > Mark Blair ------------------------------ Date: Mon, 27 Jan 92 17:17:40 PST From: David.Michelson@mtsg.ubc.ca To: space-tech@cs.cmu.edu Subject: DC-X Main Engines On several different occasions, I've seen references to the Delta Clipper using a cluster of RL-10 engines. (Sorry, I can't provide any specific citations). But this can't be right if the DC-X will use kerosene (and not LH2) as its fuel. What sort of engines *is* the DC-X going to use? An upgraded version of the H-1, perhaps? Or are McDD developing a new engine? The latter sounds rather expensive and I assume McDD would avoid doing so if they could. I checked out the recent article about DC-X in Ad Astra but technical details are sadly lacking (of course)... Pointers to better sources will be cheerfully accepted. Dave Michelson "davem@ee.ubc.ca" Applied Electromagnetics Group UBC Electrical Engineering ------------------------------ Date: Tue, 28 Jan 92 09:26 EDT From: BEAUFAIT%CEBAFVAX.BITNET@BITNET.CC.CMU.EDU Subject: dcx To: space-tech@cs.cmu.edu I have McDonnell Douglas's flier right in front of me. It says that P&W sea level RL-10s are to be used for the DC-X and interim propulsion with engin design to be done for the DC-Y. ------------------------------ From: henry@zoo.toronto.edu Date: Tue, 28 Jan 92 16:47:22 EST To: David.Michelson@mtsg.ubc.ca Cc: space-tech@cs.cmu.edu Subject: Re: DC-X Main Engines >On several different occasions, I've seen references to the Delta >Clipper using a cluster of RL-10 engines. (Sorry, I can't provide >any specific citations). But this can't be right if the DC-X >will use kerosene (and not LH2) as its fuel. DC-X is using slightly modified RL-10s and LH2, as far as I know. The manned DC-Y might have to do something different. I doubt that you could make orbit with one kerosene stage, although it's probably feasible with lighter hydrocarbons like propane or with two fuels. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 28 Jan 92 15:31:04 PST From: David.Michelson@mtsg.ubc.ca To: space-tech@cs.cmu.edu Subject: Re: DC-X Main Engines I guess that McDD changed their minds about using kerosene as the fuel for the DC-X sometime during the past six to eight months. In the October 1991 issue of Ad Astra, Max Hunter is quoted as explaining that "There are many psychological barriers to using kerosene - most engineers assume that hydrogen is the fuel of the future." But kerosene is cheaper and easier to handle. "Today propellant isn't important," Hunter noted, "because the costs of launching are so high. But once costs are brought down through low maintenance and quick turnaround, spacecraft will operate like airplanes -- and they operate at about three times the cost of the propellant. Eventually, kersone will be important." He also explained that `in the SSX, kersosene fuel can be used even more efficiently than liquid hydrogen, further lowering launch costs.' A.R. Dalby, ``The Delta Clipper,'' Ad Astra, vol. 3, no. 8, pp.22--26, Oct. 1992. As Henry (and others) have noted previously, LH2 is a nice fuel (compared to an RP-1 (kerosene) fueled engine of similar size, liquid hydrogen fuel can increase the specific impulse of an engine by as much as 40 percent) but this increase in performance comes at a price due to LH2's extremely low temperature and density... As I indicated earlier, pointers to more definitive information concern- ing the Delta Clipper would be most appreciated. For anyone that's interested and might not have seen it, NASA SP-4206 "Stages to Saturn" (NASA History Series, 1980) contains some interesting anecdotes concerning the development of the RL-10 and J-2 engines (pp. 129-154). For that matter, the discussion about the H-1 and F-1 engine development isn't bad, either (pp. 89-128). It includes some interesting comments about the problems that were encountered with combustion instability and their resolution. At the time (1962), Von Braun noted that combustion instabil- ity wasn't particularly well understood and suggested that "universities in particular could put PhD candidates to work on aspects of combustion and combustion instability for their dissertations." (p. 114) Dave Michelson "davem@ee.ubc.ca" UBC Electrical Engineering Applied Electromagnetics Group ------------------------------ Date: Tue, 28 Jan 92 14:50:58 pst From: gwh@lurnix.LURNIX.COM (George William Herbert) To: zoo.toronto.edu!henry@tcsi.tcs.com Subject: Re: DC-X Main Engines Cc: David.Michelson@mtsg.ubc.ca, space-tech@cs.cmu.edu As an aside, the latest issue of Aviation Week had details on a number of variations on the RL-10 that are being developed. A number of models with higher chamber pressure and different nozzles are in design. -george william herbert gwh@ocf.berkeley.edu gwh@lurnix.lurnix.com ------------------------------ From: henry@zoo.toronto.edu Date: Tue, 28 Jan 92 23:55:56 EST To: David.Michelson@mtsg.ubc.ca Cc: space-tech@cs.cmu.edu Subject: Re: DC-X Main Engines >I guess that McDD changed their minds about using kerosene as >the fuel for the DC-X sometime during the past six to eight months. >In the October 1991 issue of Ad Astra, Max Hunter is quoted ... McDD != Max Hunter, although the two are definitely related. :-) More to the point, I suspect that McDD may well want to use hydrocarbon fuels for an operational launcher -- Hunter makes a good case for it, although last I heard he was pushing propane rather than kerosene -- but was constrained by available engines for DC-X. >... At the time (1962), Von Braun noted that combustion instabil- >ity wasn't particularly well understood ... Amusing side note: for all their rocketry experience, von Braun and his team were completely unfamiliar with combustion instability when they first came to the US. For some reason, the V-2 *never* had the slightest problem with it -- they lucked out on that one. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ From: henry@zoo.toronto.edu Date: Mon, 27 Jan 92 18:32:43 EST To: George William Herbert Cc: space-tech@cs.cmu.edu Subject: misc. comments on Bid Dumb Hybrid writeup > The thrust vector paddles are nozzle extensions, manufactured of >the same steel as the rest of the vehicle. Actuators are baselined as >aircraft-type electrical actuators (flap, etc). Problem: aircraft electrical actuators are used for things like flaps which need only relatively slow response. Thrust vectoring for at least the first stage of a launch needs to be much quicker, to cope with problems like low-altitude turbulence and high-altitude windshear. Ordinary electrical actuation is fine for trim and other slow-response jobs, but high-speed high-force electrical actuators are high-tech leading-edge products. I fear you're going to need hydraulics if you use a vectoring approach that relies on mechanical deflection of a high-speed flow. >... insulation in the LOX tank... Is this for something specific? LOX tanks typically aren't insulated. It's only liquid hydrogen, with its extremely low temperature and low heat capacity, that needs insulation in most cases. The layer of frost you get forming naturally on LOX tanks and plumbing is actually reasonably good insulation; this doesn't work for hydrogen because it condenses liquid air. >... Welding and inspection >performed anywhere but California can reasonably be estimated at... Point of curiosity: why is California a special case? Have you thought about a range-safety (aka thrust termination, aka destruct) system? How are you going to do your staging? The orthodox method is ullage rockets on the upper half and retrorockets on the lower half, but these are high-tech hardware that will run the cost up. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Mon, 27 Jan 92 16:27:46 pst From: gwh@lurnix.LURNIX.COM (George William Herbert) To: zoo.toronto.edu!henry@tcsi.tcs.com Subject: Re: misc. comments on Bid Dumb Hybrid writeup Cc: space-tech@cs.cmu.edu In order, replying to Henry's comments... I hadn't thought that the thrust vectoring response time was going to be a problem at low altitude. I don't like the basic idea of going to hydraulics, but am willing to accept it if needed. Other ideas, anyone? The LOX tank is insulated inside (between the LOX and the tank) to keep the steel warm. High Strength Steels tend to be picky about their low- temperature mechanical properties, so I'm being cautious. California is a special case because everything costs 1.3 to 1.5 times more here 8-) It's where I've been doing most of my cost research, to cut down on my long distance phone costs. I generally get one out-of state quote and several in state ones, and extrapolate. Range Safety is a few holes in the LOX tank to vent pressure. A good HEAP warhead (4-8 kg 8-) will do just fine for a hole. I was thinking of four per tank. And staging... I've been wavering back and forth in general configuration of the vehicle, and am now leaning back towards my very origional (pre-posting) idea of a cluster of seven units as stages one and two (outer six in hexagon are first stage, inner one is second, third is above those). For the 1-2 staging, just fire stage two and wait until it's thrusting more than stage 1 units, then explosive bolts. For 2-3 staging, I was winging it. BTW: anyone interested in contributing solutions to this project is more than welcome... 8-) I honestly don't see unsolvable problems with the design, and think that at the very least it's worth a technical paper sometime. Anyone who thinks they have a better idea or solution, let me know. Just keep in mind that the vehicle's intent is to provide $500/lb service, that it pays to be big and stingy, and that it's already sort of wierd, so creative solutions are fine. -george william herbert gwh@ocf.berkeley.edu gwh@lurnix.lurnix.com [btw: Henry and I had a long conversation at Usenix on several random aerospace topics, and up came an idea of his to build a model-airplane (ok, more like 10kg he said after I asked for clarification) sized solar said [ sail?? --MNR] demonstrator and launch it like the amateur radio satellites are launched, as ballast on comsats etc. I haven't seen it on the mailing list, so I thought I'd poke Henry into writing it up 8-) It would be an extremely interesting project, and not that demanding due to small size. ] ------------------------------ Date: Tue, 28 Jan 92 09:26 EDT From: BEAUFAIT%CEBAFVAX.BITNET@BITNET.CC.CMU.EDU Subject: bdb To: space-tech@cs.cmu.edu I'm no expert but my experience with models suggests that the lower at. stableization could be done with simple fins. These would stablelize the rocket through wind shear and soforth with the slower trim type thrust vectoring used to keep it pointed in the right general direction. The fins could be very light and if properly shapped would add very little drag (maybe even small lift?). Stage seperation is easy. High powered modelist have a selection of solid propel ent motors to choose from. Thrust varies from a few newton*sec to many thousand G motors are rated at around 120 ns thrust doubles with every letter designator say 5 J motors should do the job nicely. Cost would be under 1K. ------------------------------ From: henry@zoo.toronto.edu Date: Tue, 28 Jan 92 17:15:46 EST To: George William Herbert Subject: Re: misc. comments on Bid Dumb Hybrid writeup Cc: space-tech@cs.cmu.edu >I hadn't thought that the thrust vectoring response time was going to >be a problem at low altitude... I don't have numbers on hand, but I know we're talking about relatively fast response. Most large rockets are aerodynamically unstable in most flight regimes; it's not just a matter of occasional tweaks, but of catching any deviation before it builds up unacceptably. Fins help once you have significant airspeed, but you need something non-aerodynamic before that. Model rockets and sounding rockets typically use launch rails and fairly high accelerations (to reach stable speeds before leaving the rail). If you read something like Michael Collins's description of riding a Saturn up, you'll see mention of the swaying, wobbling motion as corrections for turbulence and such (don't forget propellant sloshing, by the way) were made fast and furiously in the first few seconds. >Range Safety is a few holes in the LOX tank to vent pressure. A good HEAP >warhead (4-8 kg 8-) will do just fine for a hole. I was thinking of four >per tank. Note that it's not enough to just take the engines off nominal operating conditions; you must assure that no further significant thrust is possible. Hydrostatic head at the bottom of the plumbing is quite substantial, especially late in the burn when accelerations are high. I like the idea of just opening the tank -- you could do this mechanically, I would think, avoiding the need for pyrotechnics and their safety problems -- but am not sure it is enough, unless it is guaranteed to cause massive structural failure. >...For the 1-2 staging, just fire stage two and wait until >it's thrusting more than stage 1 units, then explosive bolts. Not enough; you need some way to positively separate the stage 1 units, unless you're very lucky. Explosive bolts fire. Now you have stage 2 flying in loose formation with the stage 1 units. What happens? Eventually the stage 1 units will drop behind, but what happens before that? Say stage 1 has fins to add stability. (Stages 2-3 are probably doing most of their burn at altitudes where fins will not be useful.) We want separation, so we push its nose away (how?). But the fins make it weathercock back. Unless you have very good damping somehow, it swings past the neutral point, nose towards you now. Of course, it's moved away a bit before this... but at a non-zero angle of attack it will have non-zero lift, which will push it in exactly the wrong direction. Crunch. (Exactly this has happened with finned drop tanks on aircraft.) Clean separation is not something you can take for granted, especially in the presence of enough air to make aerodynamics a factor. If your first-stage units form a ring around the second stage, we may have a low-tech solution: the first stage stays in one piece and the second stage slides forward on rails mounted on the first stage. There's still an iffy moment just as the second stage clears the first, but that's a lesser problem. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Tue, 28 Jan 92 15:45:14 PST From: David.Michelson@mtsg.ubc.ca To: Space-tech@cmu.edu, space-tech@cs.cmu.edu Subject: Re: misc. comments on Big Dumb Hybrid writeup Henry Spencer writes: > If your first-stage units form a ring around the second stage, we may > have a low-tech solution: the first stage stays in one piece and the > second stage slides forward on rails mounted on the first stage. > There's still an iffy moment just as the second stage clears the first, > but that's a lesser problem. That sounds like the old "Ortag" launcher concept of, I guess, about fifteen years ago. (I believe that's the correct name...) I never heard what happened to it though. Were a few test flights ever flown? It was supposed to accomplish much the same goal as the BDB being discussed here - substitute inexpensive parts and novel, innovative design for the "high tech" approach used in military derived launchers in an attempt to slash launch costs. It was a German initiative, I believe. Dave Michelson "davem@ee.ubc.ca" UBC - Electrical Engineering Applied Electromagnetics Group ------------------------------ To: henry@zoo.toronto.edu Cc: George William Herbert , space-tech@cs.cmu.edu Subject: Re: misc. comments on Bid Dumb Hybrid writeup Date: Tue, 28 Jan 92 19:06:47 EST From: John Carr >> Most large rockets are aerodynamically unstable in most >> flight regimes; it's not just a matter of occasional tweaks, but of >> catching any deviation before it builds up unacceptably. Fins help once >> you have significant airspeed, but you need something non-aerodynamic >> before that. The aerodynamic instability and the benefit from fins should both scale as the square of speed, though the stability is probably different while subsonic and supersonic. I would expect wind shear, turbulence, and asymmetric thrust to dominate aerodynamic instability at low speed. >don't forget propellant sloshing, by the way Are propellant tanks normally full of liquid at liftoff? ------------------------------ Date: Tue, 28 Jan 92 16:24:24 pst From: gwh@lurnix.LURNIX.COM (George William Herbert) To: uunet!zoo.toronto.edu!henry@uunet.UU.NET Subject: Re: misc. comments on Bid Dumb Hybrid writeup Cc: space-tech@cs.cmu.edu I was actually thinking of staging by letting the forward mounts for the first stage seperate (pyro?), but letting it rotate about the rear mounts. presuming that we've timed everything so that the second stage is developing more thrust, then we just wait for the engines to rotate out until they're pointed away far enough from the second stage that it's safe, then release the lower mounts. The only complication is that the lower mount has to be able to rotate, and it doesn't have to do that really well, when it comes down to it. 8-) My presumtion in pyrotechnically terminating thrust is that I can do as good a job with that as you can with a Solid engine, if not better after a slight bit. Since solids are commonly used, they have to be somewhat safe (cough). -george william herbert gwh@ocf.berkeley.edu gwh@lurnix.lurnix.com ------------------------------ From: henry@zoo.toronto.edu Date: Tue, 28 Jan 92 23:51:05 EST To: David.Michelson@mtsg.ubc.ca Cc: space-tech@cs.cmu.edu Subject: Re: misc. comments on Big Dumb Hybrid writeup >That sounds like the old "Ortag" launcher concept ... Otrag. >I never heard what happened to it though. Were a few test flights >ever flown? They flew one or two small clusters, but ran into political trouble on a large scale and eventually folded. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ From: henry@zoo.toronto.edu Date: Wed, 29 Jan 92 13:55:21 EST To: George William Herbert Subject: Re: misc. comments on Bid Dumb Hybrid writeup Cc: space-tech@cs.cmu.edu >I was actually thinking of staging by letting the forward mounts for the >first stage seperate (pyro?), but letting it rotate about the rear mounts. >... we just wait for the engines to rotate out until they're >pointed away far enough from the second stage that it's safe, then >release the lower mounts. The only complication is that the lower mount >has to be able to rotate, and it doesn't have to do that really well... This amounts to a solution to the first question I posed (how do you get the first stages tipped outward?). It doesn't answer the question of what they do then, unless "far enough... that it's safe" means 90 degrees or so. I also wonder what happens if all six first stages don't tip evenly. My understanding of the common wisdom is that issues like this cannot safely be left to chance. A couple of other minor considerations come to mind. One, if you're relying on thrust decay in the first stages, you're going to have to coordinate them so they start running out of steam very nearly simultaneously. (This is not to be taken for granted; liquid-fuel rockets normally have a utilization-control system to make sure they empty both tanks at the same time, for example.) In a linked vehicle, some asymmetry probably doesn't matter that much during first-stage powered flight, but if you're relying on thrust decay in a staging scheme that has each stage separating independently, they'd better all be ready to do it simultaneously. Two, better reinforce the neighborhood of those lower mounts -- if the first stage wants to go and the lower mount sticks, something is going to give, and it won't necessarily be the mount. The mount doesn't have to rotate all that well, but it has to rotate well enough, for some value of "enough", and do so consistently and reliably. >My presumtion in pyrotechnically terminating thrust is that I can do as good >a job with that as you can with a Solid engine, if not better... I concur, but just putting holes in the tanks may not be enough. You might have to do what the solids do, and have a linear charge that splits the casing open along its length. (Some solids get away with less, typically because their propellant can't sustain rapid combustion at low pressures so it suffices to just blow the nozzle off or blow some vents in the chamber, but they need to be pretty sure of that.) Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ End of Space-tech Digest #97 *******************