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Post by Count Zero on Feb 28, 2008 20:59:47 GMT -4
Over on the BBoard for From the Earth to the Moon at IMDB someone posted this question: I know the answer (having played around with the rocket equation), but I'm a bit busy ths week and can't give it the time it deserves. If someone could have a go at it, it would be a good learning opportunity. Thanks. |
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Post by jagster on Feb 28, 2008 21:13:39 GMT -4
It's not necessarily a factor "in space" but as big and powerful as the Saturn V was, it could only lift so much. They had to cut corners when they could.
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Post by Ginnie on Feb 28, 2008 21:18:49 GMT -4
My amateur explanation: In space, you can get by with small fuel tanks and solar power cells - but getting into space is a different matter. Escape velocity from Earth is 40,000 kph. So first you need a booster or spacecraft that can go that speed. But it also has to be able to go for a few minutes, so it has to have a lot of fuel. But the fuel weighs a lot too, so you need to make it bigger and carry even more fuel. But that adds weight too, so you need to make it bigger still, and add more fuel. By using stages, you can make your ship lighter as you approach velocity, because you can get rid of the stage as the fuel in it burns out. Oh, and on top of the rocket you have a payload - a satellite, or a manned capsule etc. So you need more fuel again to lift those objects into space. And if you want to carry more stuff, like a LM you need to add more fuel, and have bigger fuel tanks (stages). So at the end of it all, it takes enormous amounts of fuel and huge rockets to get everything into space. That's about as technical as I can get! On BobB's site, I'm sure he can explain it more accurately! www.braeunig.us/space+++++++++++++++++++++++++++++++++++++++++++++++++++ THIS IS A TEST. I REPEAT, THIS IS A TEST. I'M JUST SEEING IF I CAN EVEN ATTEMPT TO ANSWER A SPACE QUESTION ====================================================  |
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Post by Ginnie on Feb 28, 2008 21:25:01 GMT -4
I know the answer (having played around with the rocket equation), but I'm a bit busy ths week and can't give it the time it deserves. If someone could have a go at it, it would be a good learning opportunity. Thanks. |
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Post by Tanalia on Feb 28, 2008 22:36:37 GMT -4
My amateur explanation: ... +++++++++++++++++++++++++++++++++++++++++++++++++++ THIS IS A TEST. I REPEAT, THIS IS A TEST. I'M JUST SEEING IF I CAN EVEN ATTEMPT TO ANSWER A SPACE QUESTION ==================================================== Basically the right idea, though you've repeated one error that's common to people in the early stages -- escape velocity really has nothing to do with it. You could could think of it as an upper limit, but anything designed toward reaching that limit would be far larger and costlier than you need. |
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Post by Count Zero on Feb 29, 2008 21:34:11 GMT -4
I know the answer (having played around with the rocket equation), but I'm a bit busy ths week and can't give it the time it deserves. If someone could have a go at it, it would be a good learning opportunity. Thanks. Thanks, ginnie. I'm hoping to get a full night's sleep before the next Moon landing... |
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Post by Nowhere Man on Mar 2, 2008 9:57:47 GMT -4
Weight isn't a factor in space, mass is. Weight is merely the effect produced by a stationary mass in a gravitational field.
The more mass you need to more around, the more fuel you need. Adding fuel adds more mass, so you need more fuel to move that fuel around. Ad nauseam.
Pretty much what Ginnie said, but with mass, not weight.
Fred
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