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#31
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CEV to be made commercially available
Alan Anderson wrote: Surprising, no? Do the math. Kinetic energy of 1 kg at orbital velocity is only about 75 megajoules. Burning a gallon of kerosene yields nearly twice that. We've got to add the cost of the LOX into the equation. Since LOX is far less dense than kerosene, we're going to need more of it than kerosene by volume to get this to work; so we take our $1.75 per gallon for the kerosene, divide that by two to end up with around $.85 for the kerosene, add around a gallon of LOX at $.67 to end up with around $1.50 for propellents. Pat |
#32
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CEV to be made commercially available
Pat Flannery wrote:
Alan Anderson wrote: Surprising, no? Do the math. Kinetic energy of 1 kg at orbital velocity is only about 75 megajoules. Burning a gallon of kerosene yields nearly twice that. We've got to add the cost of the LOX into the equation. Since LOX is far less dense than kerosene, Huh? LOX specific gravity (NBP, 1 atm) is a bit over 1.1, kerosene is a bit under 0.8. we're going to need more of it than kerosene by volume to get this to work; so we take our $1.75 per gallon for the kerosene, divide that by two to end up with around $.85 for the kerosene, add around a gallon of LOX at $.67 to end up with around $1.50 for propellents. Most commercial transportation seems to come out somewhere in the neighborhood of 7 times fuel costs. Or at least airlines and trucking companies do. So perhaps $10 per pound is not unreasonable, or maybe $100 per pound if you can get payload up to 10% of dry mass. -jake |
#33
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CEV to be made commercially available
There's a South Park episode lurking in there somewhere.
(Cut to image of Kenny impaled on a solar array.) :-D Pat There is an episode were the children are standing at the bus stop before school and MIR falls on Kenny. "Oh, my God, MIR killed Kenny! You *******s!" |
#34
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CEV to be made commercially available
"JHNichols" wrote in message ... There's a South Park episode lurking in there somewhere. (Cut to image of Kenny impaled on a solar array.) :-D Pat There is an episode were the children are standing at the bus stop before school and MIR falls on Kenny. "Oh, my God, MIR killed Kenny! You *******s!" In Dead Like Me's first episode the main character gets killed by a toilet seat falling from Mir. Then she got herself a new career. |
#35
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CEV to be made commercially available
In article .com,
wrote: The stick is only planned to be partially resuable. Planned, yes. However, the simple fact is that the first solid stage is reusable... Only in the loosest sense of the word, given the amount of refurbishing work that has to be done after every flight. The only reason anybody takes that seriously as "reusability" is the juxtaposition with the enormous efforts that go into refurbishing the orbiter. while the second stage goes to orbit, leaving large propellant tanks and the SSME available. The tanks would make a fine basis for a space station or an upper stage (or... That's not reusability; that's salvage. Reusability means it can do the same job repeatedly. ...the SSME can be cut off and returned. I don't believe that CEV, by current notions, is big enough to return it. This is a theoretical future possibility, not something that can reasonably be cited as a virtue of the current system. It's only a lack of even moderate imagination that makes the 2nd stage expendable. No, it's the lack of a reentry system that could return it for reuse. I agree that the hardware itself isn't inherently limited to a single use -- as best one can tell, given how little detail exists -- but as currently conceived, that stage is 100% expendable. There were proposals to make Saturn stages reusable too. That doesn't mean the Saturns weren't expendables, because those proposals were never acted on. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#36
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CEV to be made commercially available
In article ,
Pat Flannery wrote: The fundamental cost of putting mass into orbit with LOX/kerosene is under $1.50/kg. Wait a minute; leaving the LOX out of the equation... Which is reasonable, since the LOX (which is 3/4 of the propellant mass) costs almost nothing in large quantities. I can accelerate 1 kg of mass to 18,000 mph and 100 miles altitude with the energy in around 2/3rds of a gallon of Kerosene? Mutter, grumble, archaic units... It takes about 4kg of kerosene (and 10kg of LOX), and figuring RP-1 at a density of 0.8, that's 5 liters, or about 1.3 US gallons. I'm using price numbers a year or two old, because the recent upward lurch in petroleum-fuel prices is an artifact of politics and current events, and I'm skeptical on whether it will last. (Yes, we will run out of oil eventually, but it has *not* happened yet -- the current problems are a shortage of refining capacity and political limits on oil production, not wells running dry.) Price of LOX in 2001 was about $.67 per gallon. If I've done the conversion to sensible units correctly, that must be a small-quantity price. It's much less in bulk. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#37
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CEV to be made commercially available
That's not reusability; that's salvage. Reusability means it can do the same job repeatedly.
Or that it can be reused for something else. Ahem: re·use ( P ) Pronunciation Key (r-yz) tr.v. re·used, re·us·ing, re·us·es To use again, especially after salvaging or special treatment or processing. reuse v : use again after processing; "We must recycle the cardboard boxes" [syn: recycle, reprocess] OK. Where's my damned T-shirt? It's only a lack of even moderate imagination that makes the 2nd stage expendable. No, it's the lack of a reentry system that could return it for reuse. Such a system is fairly easily developed. The Russians have done it a few times, though they keep losing the friggen' things. |
#38
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CEV to be made commercially available
wrote in message oups.com... Stick is fully reusable. The stick is only planned to be partially resuable. Planned, yes. However, the simple fact is that the first solid stage is reusable, while the second stage goes to orbit, leaving large propellant tanks and the SSME available. The tanks would make a fine basis for a space station or an upper stage (or a propellant storage facility, hab modules for the lunar surface, raw materials for SPS, you name it); the SSME can be cut off and returned. Returned how? The CEV isn't big enough to return an SSME. Also, look how many ET's have been dumped into the ocean, despite the fact that when they are released, they very nearly have orbital velocity. Once the ET is dropped, the OMS system only has to perform a modest burn (compared to the burn of the SSME's) to get the shuttle into orbit. None of these ET's has been used for anything useful. It's only a lack of even moderate imagination that makes the 2nd stage expendable. NASA clearly lacks that imagination, as their lunar mission architecture requires only a single docking in LEO before departing for the moon. They lack the desire to do any orbital assembly (beyond a single docking). The second stages of the stick will do nothing more than create a light show as they reenter earth's atmosphere and burn up. Your wishful thinking will not change this, just as the same wishful thinking never resulted in a single ET being taken to LEO. Jeff -- Remove icky phrase from email address to get a valid address. |
#39
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CEV to be made commercially available
wrote in message oups.com... Really. As the man said: Don't think inside the box. The box is not your friend. Tell that to NASA. Their "new" lunar mission architecture is so similar to Apollo that it's pathetic. The only thing they've done is take the people off the heavy lifter and launch them on a smaller launch vehicle. The remainder of the architecture really is Apollo Part II. Jeff -- Remove icky phrase from email address to get a valid address. |
#40
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CEV to be made commercially available
Jake McGuire wrote: Pat Flannery wrote: Alan Anderson wrote: Surprising, no? Do the math. Kinetic energy of 1 kg at orbital velocity is only about 75 megajoules. Burning a gallon of kerosene yields nearly twice that. We've got to add the cost of the LOX into the equation. Since LOX is far less dense than kerosene, Huh? LOX specific gravity (NBP, 1 atm) is a bit over 1.1, kerosene is a bit under 0.8. I slipped up- the optimum mixture ratio of LOX or to kerosene is 2.56 to 1: http://www.astronautix.com/props/loxosene.htm And I confused that with LOX's specific gravity. we're going to need more of it than kerosene by volume to get this to work; so we take our $1.75 per gallon for the kerosene, divide that by two to end up with around $.85 for the kerosene, add around a gallon of LOX at $.67 to end up with around $1.50 for propellents. Most commercial transportation seems to come out somewhere in the neighborhood of 7 times fuel costs. Or at least airlines and trucking companies do. So perhaps $10 per pound is not unreasonable, or maybe $100 per pound if you can get payload up to 10% of dry mass. And providing your vehicle is 100% reusable, and needs very little maintenance between flights- similar to an airliner. Ideally it would be SSTO and take of and land horizontally like an airliner does to avoid the costs of elevating it on a pad for launch. I don't think we know how to do that yet. If you tried it you might end up with something the size of the Star-Raker to get a Shuttle-sized payload into orbit: http://www.abo.fi/~mlindroo/SpaceLVs/Slides/sld047.htm If you could be sure that the technology would work, that would probably be the way to go. They were shooting for a 100 ton payload, but this looks very iffy based on the X-33 debacle. Then there are the R&D costs for it that have to be ameliorated during the vehicle's operational life, which means that you had better hope that a lot of payloads show up once you can get the price down. At the moment, it probably isn't all that expensive to fly things to Antarctica- but there is no great demand to fly things to Antarctica despite that fact. Pat |
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