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Recommended TSTO technical papers?
What are the best technical papers to read that deal with TSTO launch
vehicle studies? I'd like to survey the best thinking that's been put into the topic. I'm also curious about simple hydrocarbon fuels like propane/methane and their relative merits. For one thing: does propane soot if used in a fuel-rich preburner? I've heard methane works fine in FRSC. Last I heard, there were people like Henry Spencer advocating LOX/Propane, for SSTO if I remember. Would LOX/Propane still be the way to go for TSTO, or would another propellant choice be better? Do the ground infrastructure issues outweigh the advantages of using two fuels for a TSTO, i.e. propane/hydrogen rather than propane/propane. |
#2
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Recommended TSTO technical papers?
WvB wrote:
What are the best technical papers to read that deal with TSTO launch vehicle studies? I'd like to survey the best thinking that's been put into the topic. I'm also curious about simple hydrocarbon fuels like propane/methane and their relative merits. For one thing: does propane soot if used in a fuel-rich preburner? I've heard methane works fine in FRSC. Last I heard, there were people like Henry Spencer advocating LOX/Propane, for SSTO if I remember. Would LOX/Propane still be the way to go for TSTO, or would another propellant choice be better? For TSTO, it's a bit easier than SSTO. The second stage can live with less dense fuels, as it has no need to fly through significant atmosphere, and overall strucutral fraction can be a tad higher. All the same arguments apply for fuels as do to SSTO, but less so, though there is the added issue of if you want to use common fuels or not. TSTO is just plain easier, and will probably work whether you chose all LOX/LH2, or go for something like H2O2/kerosene for stage 1 and LH2/LOX for stage 2. You may well end up looking at a very stubby stage 2, of similar diameter as stage 1, so there is almost no drag penalty, which is a significant driver for going to LOX/propane, or other 'dense' fuels for the bottom stage. -- http://inquisitor.i.am/ | | Ian Stirling. ---------------------------+-------------------------+-------------------------- Among a mans many good possessions, A good command of speech has no equal. |
#3
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Recommended TSTO technical papers?
Ian Stirling wrote
TSTO is just plain easier, and will probably work whether you chose all LOX/LH2, or go for something like H2O2/kerosene for stage 1 and LH2/LOX for stage 2. Kerosene is safer and easier to use than propane, but you'd get a slightly better isp with propane or even ethane, methane or lng. I don't know if that's enough to make them better overall than kerosene though. Where ground support is available and there are no special storage requirements, lox is probably the only sensible choice of oxidiser, especially if you are doing lots of launches. It's by far the cheapest, it gives good isp, it's non-toxic, and it's reasonably safe as long as you keep things clean. It's only disadvantage is that you are at the edge of the possible, especially for reusable engines. It's pretty harsh as far as long engine life and switch-on-and-off-ability goes. For reuseability, you might want to look at something slightly gentler. H2O2 is a no-no for reuseables. Forms unstable explosive peroxides which accumulate in nasty places. There isn't a real aircraft or spacecraft anywhere that doesn't have minor leaks. N2O4 is also a no-no, for environmental and cost reasons. IRFNA is similar, and IWFNA is still pretty bad. N2O is a bad greenhouse gas and gives lower isp. Me? I'd stick to lox, and work on the engineering. You may well end up looking at a very stubby stage 2, of similar diameter as stage 1, so there is almost no drag penalty, which is a significant driver for going to LOX/propane, or other 'dense' fuels for the bottom stage. The Skylab 1 Saturn V 2 was stubby like that. It used two stages, lox/kerosene and lox/LH2. It put 75 tons into LEO for a launch weight of around 2,500 tons - 5% payload, not bad for the '70s, and considering it wasn't designed for that. I really liked the Saturn V, "the rocket that never failed". -- Peter Fairbrother |
#4
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Recommended TSTO technical papers?
Peter Fairbrother wrote:
Kerosene is safer and easier to use than propane, Propane has the substantial advantage of being easier to purge from the system. This is important since a little bit of hydrocarbon left in the LOX plumbing can be catastrophic. Paul |
#5
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Recommended TSTO technical papers?
Peter Fairbrother wrote in message ...
H2O2 is a no-no for reuseables. Forms unstable explosive peroxides which accumulate in nasty places. There isn't a real aircraft or spacecraft anywhere that doesn't have minor leaks. What do you base this on? Peroxide has more extensive use in reusable engines than any other rocket propellant. All the rocket belts, rocket dragsters, rocket helicopters, as well as a commercial reusable RATO in England all were long service life peroxide engines. True, they were all monoprop, but that does exonerate the oxidizer. Leaked high concentration peroxide doesn't hang around very long. Practically anything it leaks onto will cause it to start decomposing, not forming explosive peroxides. Only if you made the incredibly bad system design choice to use high concentration peroxide and alcohol in a biprop system would this be a credible danger -- simultanious leaks from both tanks could indeed combine to form a detonable mixture. With kerosene and most other hydrocarbons, they aren't miscable. Lox can also form explosive mixtures with quite a few fuels, like propane. Peroxide leaks onto random surfaces may well be a fire hazard, but the same can be said for any oxidizer (except nitrous oxide). Higher cost and somewhat lower performance are valid reasons not to use peroxide, but "Forms unstable explosive peroxides" really isn't. Lots of people have negative things to say about peroxide that are mostly extrapolations from historic folklore, but most of these people (assuming they aren't strictly armchair engineers) have had much more direct experience with, say, frozen lox valves... John Carmack www.armadilloaerospace.com |
#6
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Recommended TSTO technical papers?
Peter Fairbrother wrote in message ...
I really liked the Saturn V, "the rocket that never failed". Except that it did fail once. SA-502 failed to perform its assigned mission when its S-IVB J-2 engine failed to restart, leaving the rocket's Apollo 6 payload far short of its intended orbit (360 km apogee vs. planned 528,024 km apogee, or a velocity shortfall of nearly 26% (about 2,728 meters per second). Today's media would howl "failure" after such a performance. - Ed Kyle |
#7
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Recommended TSTO technical papers?
Ian Stirling wrote:
And the minor (?) advantage of possibly being able to share a common bulkhead with LOX, without lots of insulation. Whether you'd actually want to do this is another question. What happens if during chill-down you get a crack through the bulkhead? |
#8
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Recommended TSTO technical papers?
AIAA 86-1413, "Two-Stage Earth-to-Orbit Vehicles with Series and
Parallel Burn", Martin, James A., 22nd AIAA/SAE/ASME/ASEE Joint Propulsion Conference, Huntsville, AL, June 16-18, 1986. Jim Davis There were a few more at the last JPC in July... I'll dig up the paper numbers when I get home. |
#9
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Recommended TSTO technical papers?
John Carmack wrote
Peter Fairbrother wrote in message ... H2O2 is a no-no for reuseables. Forms unstable explosive peroxides which accumulate in nasty places. There isn't a real aircraft or spacecraft anywhere that doesn't have minor leaks. What do you base this on? Science, accident reports and experience. A bit of chemistry (I'm still an amateur, but not armchair, rocket-ist but I was a professional chemist before I became a mathematian/cryptographer). Caveat: this is not professional opinion, it should be considered as just general chatter. Peroxides are not my speciality. Don't rely on it for safety. 1) Inorganic peroxides. I'm sure you use high purity aluminium for your peroxide tanks, but Al/Mg alloys are better from a weight point of view for the rest of the structure, and Al/Mg will form both straight magnesium peroxides and mixed magnesium/aluminium peroxides. I've even heard of Al peroxides. I theorise that the oxide layer on the Al is what protects it, and it will form a peroxide under some circumstances, like perhaps leaks. Cu, Zn, Ni, brass and bronze will all form peroxides, and there are many other mixed inorganic peroxides, including some Fe ones. Yes those metals decompose the H2O2, but they _also_ form peroxides. These can be highly reactive or explosive by themselves, and likely will be explosive if they come into contact with organic materials. 2) Many salts will form addition compounds with H2O2, a bit like the hydrates. I don't know offhand which ones do, but it's probably broadly similar to the hydrates. Washing soda is an example, off the top of my head. They can decompose violently, perhaps explosively, just by themselves, and are likely to react explosively if in contact with organics. 3) Organic peroxides. It is well known that ethers, acetals and alcohols will form organic peroxides with hydrogen peroxide, but so will almost any organic with an oxygen atom in it, and even aliphatic hydrocarbons will do so eventually in leak conditions with air and metals present to act as catalysts. Many organic peroxides are sensitive explosives. BTW, alcohol is pretty bad here. It can oxidise in air (or slowly with H2O2) to acetaldehyde or acetic acid, when it will form really nasty peroxides with H2O2. Are you the guy who uses 50% aqueous H2O2 with small amounts of added alcohol? Beware. That's a bad combination to leave around. Nobody knows that much about any of these, they tend to be too dangerous to experiment on. There are probably unknown dangers involving mixed peroxides too. Chemists don't like working with them. There are many reports of not-quite-fully-explained accidents and explosions relating to the previous storage and use of H2O2. Things like shelves exploding when disassembled. Even a water-filled drainage pond (!). Peroxide has more extensive use in reusable engines than any other rocket propellant. All the rocket belts, rocket dragsters, rocket helicopters, as well as a commercial reusable RATO in England all were long service life peroxide engines. True, they were all monoprop, but that does exonerate the oxidizer. "Were" is probably the operative word here. The Royal Navy won't use it in it's torpedoes. The US navy has stopped using it. Even the Russians have withdrawn their peroxide torpedoes after the Kursk explosion. Whether that's because of peroxides building up from leaks or the "normal" dnagers of H2O2 I don't know. But I'd have to have a powerful reason, and do lots of research, before I used it in a reuseable (torpedoes are frequently test fired and reused). Leaked high concentration peroxide doesn't hang around very long. Practically anything it leaks onto will cause it to start decomposing, not forming explosive peroxides. There may well be peroxides forming while it's decomposing. Slow leaks are bad for that. The peroxides build up until.. -- Peter Fairbrother |
#10
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Recommended TSTO technical papers?
Ian Woollard wrote:
Ian Stirling wrote: And the minor (?) advantage of possibly being able to share a common bulkhead with LOX, without lots of insulation. Whether you'd actually want to do this is another question. What happens if during chill-down you get a crack through the bulkhead? IIRC, you can't actually mix propane and LOX, and get a explosive mix. Still a very bad thing to happen. -- http://inquisitor.i.am/ | | Ian Stirling. ---------------------------+-------------------------+-------------------------- "Give a man a fire, and he's warm for a day. Set him on fire, and he's warm for the rest of his life" -- Terry Pratchett-Jingo |
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