Subject: Space-tech Digest #132 Contents: P2-E Booster (16 msgs) ------------------------------------------------------------ From: pgf@srl03.cacs.usl.edu (Phil G. Fraering) Subject: Re: P2-E Booster To: Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) Date: Tue, 10 Nov 1992 08:58:37 -0600 (CST) Cc: space-tech@cs.cmu.edu Is this your idea? For a while I thought I was looking at George Herbert's latest revision... also, for a similar design}i, look at the designs of... you know, that guy whatshisname... Memory fault Cortex dumped Well, I guess I don't remember his name right off. I guess I should have this thing checked... ------------------------------ Date: Tue, 10 Nov 92 10:05:07 -0500 From: dietz@cs.rochester.edu To: Bruce_Dunn@mindlink.bc.ca Subject: Re: P2-E Booster (2/2) Cc: space-tech@cs.cmu.edu I was wondering if it would be possible to pressurize the peroxide tank with a hot gas if one could cover the peroxide with a lower density layer of some immiscible liquid, to reduce peroxide evaporation. Is there such a liquid that would not react with or catalyze the decomposition of the peroxide? Perhaps gas-filled glass or plastic beads could be used, floating on the propellant. Alternately, the peroxide could initially be kept cold, near its freezing point, to reduce vapor pressure. The tank would initially be pressurized with cold gas, before launch. Perhaps some means would be necessary to prevent the incoming pressurized gas from mixing too violently -- say, some sort of baffle system at the top of the tank to allow the gas flow to smooth out. The idea would be to get hot gas at the top, with only cold gas in contact with the propellant. The temperature gradient would be stable against convection. A nice hot gas would be steam, or steam + oxygen, formed from decomposition of peroxide or a water/peroxide mixture, or by combustion. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Tue, 10 Nov 92 17:35:26 -0800 From: George William Herbert To: space-tech@cs.cmu.edu Subject: Re: P2-E Cc: gwh@soda.berkeley.edu Phil, the P2-E is clearly a derivation of the origional P2 concept, not a knockoff of my work. Cross polination, however, seems present and is not indeed a bad idea (recall that I switched from LOX to Peroxide...). Speaking of which, I'm working on a tangent again in the Big Dumb Hybrid design, which I hope to run a test of as soon as I can finish up a (much delayed) report on small manned capsules. I think that using frozen peroxide may have some significant advantages (put it in the same pressure vessel as solid fuel... no pressurization system etc.) so it's mroe of a binary solid than a hybrid. What I can find on H2O2 says it's safe when frozen, though I'm planning on doing some very remote testing of both peroxide ice and its combustion performance before I bet a lot of time or effort. -george william herbert President Retro Aerospace - "A Force in a Different Direction" gwh@lurnix.com gwh@retro.com coming soon ------------------------------ From: pgf@srl05.cacs.usl.edu (Phil G. Fraering) Subject: Re: P2-E To: gwh@soda.berkeley.edu (George William Herbert) Date: Wed, 11 Nov 1992 10:43:09 -0600 (CST) Cc: space-tech@cs.cmu.edu > > Phil, the P2-E is clearly a derivation of the origional P2 concept, not > a knockoff of my work. Cross polination, however, seems present and is > not indeed a bad idea (recall that I switched from LOX to Peroxide...). > I wasn't accusing them of being a knockoff of anyone. I was just noting a similarity, in design philosophy more than anything else, to the work of that guy whose name I _still_ can't remember (he was the one working on water-launched boosters). ------------------------------ From: henry@zoo.toronto.edu Date: Wed, 11 Nov 92 13:45:06 EST Subject: Re: P2-E Booster (2/2) To: space-tech@cs.cmu.edu >I was wondering if it would be possible to pressurize the peroxide >tank with a hot gas if one could cover the peroxide with a lower >density layer of some immiscible liquid... Hmm. You'd need something pretty inert. A fluorocarbon, maybe? It has to be both nonreactive and noncatalytic, which is tricky. One potential problem is that there can be considerable surface turbulence. This is a problem for schemes that pressurize (e.g.) a LOX tank with warm oxygen: it can be cooled somewhat by mixing at the surface. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Wed, 11 Nov 92 13:49:30 -0500 From: dietz@cs.rochester.edu To: space-tech@cs.cmu.edu Subject: Re: P2-E Bruce's latest effort has the helium being heated by a propane/peroxide gas generator. By his figures, the exhaust of this gas generator contributes relatively little to the pressurization (there are 16 helium atoms for each combustion product molecule), and most of the combustion products are water anyway. One problem I have with the scheme is that he is using stoichiometric mixture in the gas generator. This means combustion probably won't be complete, especially if the flame is quickly quenched. I would worry about combustible compounds accumulating in the peroxide tank. Perhaps it would be better to run the gas generator oxidizer-rich, or just use peroxide as a monopropellant. Another possibility would be to heat the helium by passing it through a pebble bed. That is, have a volume containing refractory oxide or graphite pebbles that are heated before flight to high temperature. Some of the helium is pumped through the pebble bed, then mixed with additional helium to achieve the desired temperature. A problem here would be keeping the sides of the pebble bed cool before launch. A small gas generator, run off the main propellant tanks, could power the LHe pump. Did you ever determine the solubility of hydrogen in propane? Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Wed, 11 Nov 92 14:49:03 -0500 From: dietz@cs.rochester.edu To: space-tech@cs.cmu.edu Subject: Re: P2-E Here are some figures for the thermal capacity of a graphite pebble bed. Graphite begins to sublimate around 4000 K. Let's assume we can get a delta-T of about 2000 K (say, heat the graphite to 3200 K and end at 1200 K). The specific heat of graphite increases with temperature, but is around 2.2 J/g K. Heating .5 m^3 of liquid helium -- about 60 kilograms -- to 300 K requires about 90 MJ of heat. This would require about 20 kilograms of graphite. So the mass required is a bit worse than the reactant mass for the gas generator -- 1/3 vs. 1/5 the mass -- but not a whole lot worse. The complexity of the large gas generator is avoided, but a system must be included for preheating the pebble bed (electrical? by combustion?) Paul F. Dietz dietz@cs.rochester.edu ------------------------------ To: uunet!cs.rochester.edu!dietz@uunet.UU.NET Cc: space-tech@cs.cmu.edu, gwh@lurnix.COM Subject: Re: P2-E Date: Wed, 11 Nov 92 16:28:25 -0800 From: gwh@lurnix.COM >You might consider investigating fiber-reinforced >frozen peroxide. Fiber-reinforced ice is very strong... I was planning on reinforcing with aluminum wire. Organic fibers tend to be brittle when cold (though < 0C isn't that cold 8-). I'll take a look at them, though. The plan was to reinforce with enough aluminum wire that the peroxide ice and reinforcement will be combustable but with an oxygen surplus; in this way, the combination of peroxide ice and reinforcement is essentially a solid propellant by itself, though the exhaust is oxygen rich. Below the peroxide ice in the engine chamber is a chunk of fuel (HDPB?) as in a normal hybrid; the oxygen-rich peroxide/aluminum exhaust burns with the fuel proper to produce the primary combustion energy. Manufacturing this can be done "on the pad"; wall off the part of the chamber that peroxide ice will be in, put refrigerator coils in the bottom and the reinforcing wire, and seal around all the edges. Once the rocket's erected, pour (careful!) in the peroxide and freeze it. I was just going to use thin sheet steel for the walls; standard star pattern "grain" in frozen peroxide, with the sheet steel to hold the liquid in being burn-through on ignition (some external source from above would start the process). Advantages? Less moving parts and manufacturing than anything but a real solid. No pressurization problems. One tank. Tank can be steel since coldest temp. is a little under freezing, not LOX temperatures. Disadvantages: frozen peroxide combustion characteristics and stability untested (by me; research by others as yet unlocated), Isp lower than desirable (but comperable to other peroxide hybrid combinations). -george william herbert ------------------------------ Date: Thu, 12 Nov 92 07:40 PST To: space-tech@cs.cmu.edu Subject: P2-E Pressurization From: Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) Before the rest of this post, I would like to make a correction to a previous post in which I listed the steering method of George Herbert's booster as being via steerable nozzle. I think that he has now switched to differential throttling of the multiple engines. However, I don't see how throttling will work if the frozen peroxide idea is used. The helium pressurization scheme that I came up with (pumped helium, and a gas generator powered by peroxide and propane) was designed to be something that could clearly be built with a minimum of technical unknowns. Thus room temperature helium is used. This system gives a very low mass of pressurization gas - about 9 tons for a 900 ton booster. Anything using a higher molecular weight gas suffers from the problem of reduced performance due to the higher burnout mass. Using nitrogen rather than helium (the next lightest inert gas) results in using about 56 tons of gas. Heating the high molecular weight gas only helps somewhat - if nitrogen were heated to near 300 C, it would still take 23 tons of gas, plus the extra propellant for the heating. The propane could be pressurized by a hydrogen rich gas or possibly methane, but this would not give commmonality with the peroxide pressurizing system. Decomposing peroxide would be far to hot to use directly for pressurizing the peroxide tank. The decomposition products could be mixed with helium or nitrogen to form a suitable pressurizing gas. However, the amount of peroxide needed would be considerably higher than the amount of stoichiometric peroxide/propane needed to do the same job. This would still leave the problem of pressurizing the propane tank. This could be done by decomposing hydrazine and mixing the output with helium or nitrogen, but this introduces hydrazine into the vehicle. Furthermore, the single gas generator has now been replaced by two gas generators - I don't see the payoff. I like the idea of trying to insulate the peroxide with a layer on top to keep it from hot helium. I think what might work is to pressurize the tank ullage space with room temperature nitrogen or argon before starting the gas generator. The hot helium would come in at the top of the tank, and the nitrogen would stay in a layer approximately 0.5 meter thick over the peroxide. I never thought of anything like the graphic pebble bed. The mass looks attractive - however I expect that available engineering experience will make a combustion style gas generator easy to build. As Paul points out, the products of combustion are overshadowed by the helium. Any incomplete combustion products are even more rare, and I don't think that the pressurizing gas will have enough oxygen or hydrogen in it to react with anything. There are definite limits below which say hydrogen in helium won't burn no matter what you do. -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ Date: Thu, 12 Nov 92 11:33:03 -0600 From: pgf@srl05.cacs.usl.edu (Phil G. Fraering) To: Bruce_Dunn@mindlink.bc.ca, space-tech@cs.cmu.edu Subject: Re: P2-E Pressurization Hmmph. They're already discussing frozen hydrogen peroxide. I wonder when they'll get around to discussing frozen ozone. Phil ------------------------------ Date: 12 Nov 1992 13:33:06 -0500 (EST) From: "GORDON D. PUSCH" Subject: Frozen Ozone (was: RE: P2-E Pressurization) To: space-tech@cs.cmu.edu >Hmmph. They're already discussing frozen hydrogen peroxide. I wonder >when they'll get around to discussing frozen ozone. Actually, I posted something about that about 3--4 yrs ago... Response: nary a ripple :-/ The original is archived on tape somewhere... The gist of it was that the *freezing* point of O3 is below the *boiling* point of LN2, and frozen O3 is *stable* (sort of... :-T); therefore, O3-slush in LN2 might make an, uh, *interesting* oxidizer... (better than florine, actually, if the O3/N2 ratio is high enough...). Main problem: liquid O3 is prone to *shock detonation*, especially if contaminated with organics. I can't seem to find any refences one way or the other RE: whether *frozen* O3 detonates... Any comments, this go-round? Gordon D. Pusch ! BITnet: TASCC A&D, Stn. 49a ! AECL, Chalk River Laboratories ! Phone: (613) 584-3311, X-4107 (off.) Chalk River, Ont. CANADA ! (613) 584-2368 (hm.) K0J 1J0 ! ------------------------------ Subject: Re: P2-E Pressurization Date: Thu, 12 Nov 92 13:03:36 -0800 From: gwh@lurnix.COM Aww, but Phil, frozen Ozone is Cryogenic and requires either expensive aluminum casings or even more expensive esoteric steels 8-) Frozen peroxide can be stored safely in any steel that I can think of (T-1 for example...). Remember the Big Dumb motto: Keep it Simple, Keep it Cheap, Bigger is Better, Launch every Week 8-) -george ------------------------------ Date: Fri, 13 Nov 92 09:06:07 +0000 From: Dominic Herity Subject: Re: Frozen Ozone (was: P2-E Pressurization) To: space-tech@cs.cmu.edu > Any comments, this go-round? I didn't see it first time round. What kind of specific impulse are we talking about, when used with hydrogen ? Are there any other show stoppers, apart from detonation ? Best Regards Dominic Herity ------------------------------ Date: Thu, 12 Nov 92 18:14:19 -0500 From: dietz@cs.rochester.edu To: space-tech@cs.cmu.edu Subject: Pressurization Some more thoughts on pressurization... There might be something to be said for pressurizing a peroxide tank with oxygen instead of helium. Granted, the oxygen is 8 times heavier than helium, but at the end of the burn it can be consumed as propellant. The oxygen could be vaporized by a peroxide gas generator. Again, the oxygen released by the gas generator gets used as propellant. As Bruce said, you'd need a separate system to pressurize the propane tank. (This is perhaps an argument for a hybrid rocket?) A rather low-tech way to vaporize a cryogenic pressurant is with stored steam. Steam at the critical point (say) has a density of 317 kg/m^3, a pressure of 22.09 MPa, and an internal energy of 2 MJ/kg. This is not competitive with the other schemes using helium, but would be small compared to the mass of oxygen if that gas were used for pressurization. And, unlike with graphite, the steam would end up being expelled through the rocket, adding a bit to the thrust. I was thinking it might be nice to heat the propane tank above room temperature, to decrease the volume of pressurant required. However, propane rapidly becomes less dense as it is heated. Would it be advantageous to use instead for fuel a high boiling point hydrocarbon, preheated to > 300 K? You might pressurize it with methane. Paul ------------------------------ Date: Thu, 12 Nov 1992 19:14:19 EST From: John F Carr To: dietz@cs.rochester.edu Cc: space-tech@cs.cmu.edu Subject: Re: Pressurization > There might be something to be said for pressurizing a peroxide tank > with oxygen instead of helium. Granted, the oxygen is 8 times heavier > than helium, but at the end of the burn it can be consumed as > propellant. The oxygen could be vaporized by a peroxide gas > generator. Again, the oxygen released by the gas generator gets used > as propellant. What ratio of pressurizer mass to fuel mass are we talking about? Even at 100 atmospheres pressure the pressurizer mass will only be a few percent of the propellant mass (to a first approximation, room temperature oxygen at 1 atm. pressure is about .1% the density of liquid fuel; hot gas will be less dense). I don't think this will help much. How much will it cost to make the engine accept oxygen gas as well as peroxide (we don't care about destroying the engine in the process, but we need to be able to count on the added burn time). How much heat transfer will there be between a hot pressurizing gas and liquid propellant? Do we need to consider this? ------------------------------ End of Space-tech Digest #132 *******************