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LOX/CH4
Am I correct in thinking that for a given amount of O2 that a fuel
tank for CH4 would be 1/4 the size of the size of a LH2 tank? Given the storability of CH4 vs LH2, I'd think a LOX/CH4 engine would be an extreme priority of NASA and am surprised it has not been developed. |
#2
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LOX/CH4
On Nov 25, 6:15 pm, wrote:
Am I correct in thinking that for a given amount of O2 that a fuel tank for CH4 would be 1/4 the size of the size of a LH2 tank? Given the storability of CH4 vs LH2, I'd think a LOX/CH4 engine would be an extreme priority of NASA and am surprised it has not been developed. For that matter, Diborane would be even better, considerably higher ISP and reasonable boiling point, not too very toxic, not hard to make. |
#4
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LOX/CH4
On Nov 25, 3:15 pm, wrote:
Am I correct in thinking that for a given amount of O2 that a fuel tank for CH4 would be 1/4 the size of the size of a LH2 tank? Given the storability of CH4 vs LH2, I'd think a LOX/CH4 engine would be an extreme priority of NASA and am surprised it has not been developed. My analysis, (very rusty chemistry skills probably flawed), starts by assuming that the structural mass required for the tank depends on both pressure at each liquid's and the mass ... however you are asking about the volume of the tank which that total mass structure will affect but probably not too significantly. So, calculate the mass of each feul consumed by the fixed amount of oxygen. And then look up of density of cryogenic hydrogen and cryogenic methane. The density ration should give us the different sizes required for tanks for the feuls. Well a first cut. I guess we might count the different in volume of insulation required if it is significant and I will not know if it is until I look up the heat equations and discover how thick the insulation required on each tank. http://en.wikipedia.org/wiki/Hydrogen_storage has interesting energy density and storage target tables but not the straight density (mass/ volume) at cryogenic equilibirum I am looking for. Article claims 21 degrees kelvin as temp and that should be good enough to get estimated ratio you asked for ... moving on. http://en.wikipedia.org/wiki/Rocket_...ellant_density gives ratio of about 7 times tank volume required for LH2 as for kerosene but do not give their analysis so we can check accuracy and assumptions for ourselves. If we figure this answer out I will put an abstract on the discussion page and link to Lunar Boom Town to help create traffic there. Interesting, Wade's Encyclopedia Astronautica has everything except methane by any designation I can recognize. Perhaps someone can check me. It seems unlikely he simply left out methane unless he is conspiring with the academic grading mafia and methane is the current training feul of choice in grading competitions. ? http://72.14.253.104/search?q=cache:...lnk&cd=2&gl=us provides specific gravity of .55491(Water=1) but no temperature assoicated. Boiling point is -161.48 deg Centrigrade whle the freezing point is -182.61 deg c. I do not remember the precise definations of specifc gravity and the version of density we have for hydrogen but a low level chemistry book or CRC should have that. I must leave this incomplete but I will check back. If want the answer immediately you might take this partial assistance and cust and paste it in (I give you permission to GPL it so you can put it on the Wikiversity Help Desk. or just link to this thread from the question desk http://en.wikiversity.org/wiki/Wikiversity:Help_desk hope this was helpful mirwin |
#5
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LOX/CH4
Interesting, Wade's Encyclopedia Astronautica has everything except
methane by any designation I can recognize. Perhaps someone can check me. It seems unlikely he simply left out methane unless he is conspiring with the academic grading mafia and methane is the current training feul of choice in grading competitions. ? http://www.astronautix.com/props/loxlch4.htm |
#6
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LOX/CH4
On Nov 26, 5:39 am, "Article 14, section 31" http://cerbermail.com/?
HEEdK0nIA6 wrote: Interesting, Wade's Encyclopedia Astronautica has everything except methane by any designation I can recognize. Perhaps someone can check me. It seems unlikely he simply left out methane unless he is conspiring with the academic grading mafia and methane is the current training feul of choice in grading competitions. ? http://www.astronautix.com/props/loxlch4.htm There was a thread on the methane engine being developed by Northrop at: http://groups.google.com/group/sci.s...1e8b464dcd6556 No one ever replied to that thread though. |
#7
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LOX/CH4
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#8
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LOX/LH2 LOX/CH4
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#9
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Hot Air(O O N2)/LH2 LOX/LH2 LOX/LCH...
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