h a l f b a k e r y"Bun is such a sad word, is it not?" -- Watt, "Waiting for Godot"
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Half the fuel the space shuttle uses is used just getting it moving off the ground. Why not mount the space shuttle on a giant springboard or better still a gas powered catapult like they use on aircraft carriers.
This would get it *moving* and clear of the ground. A 50m metre tall tower would
be ideal. Put the shuttle on some sort of runners, light the engines to full throttle and then give it a kickstart off the ground.
the launch tower would then retract vertically and rapidly into the ground, leaving the shuttle to continue it's journey skyward.
I would have thought this could at least negate the need for the 2 side booster rockets, saving fuel, money, time and environmental damage.
An added advantage is that without those 2 fuel filled boosters there would be less to go wrong.
Anyone good at physics want to comment on the maths of this?
gerald bull's super-gun...
http://world.std.com/~jlr/doom/bull.htm
...and the story behind it. [mihali, Jun 20 2001, last modified Oct 17 2004]
[link]
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> Half the fuel the space shuttle
> uses is used just getting it
> moving off the ground. |
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How can this be true? The solid rocket boosters continue to fire for several minutes after the shuttle gets "moving off the ground." Even only a minute into the flight, the craft is travelling at substantially more than 10 kph. |
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First off, NASA wants to dump the solid boosters due to the billion-dollars-a-launch price tag attached. Current funding is around 12 Billion a year with half dedicated to launching the shuttle only 5 times a year. Springboard? Do you realize the pressure that would be exerted on an object as large as the shuttle? It would crush it. Steam or gas powered catapult? The distance and pressure needed to lift the shuttle and obtain a decent velocity would be far too large for a piston system. Now something like a Mag-Lev launcher where the tracks run like the first hills of a rollercoaster (over a longer distance) with the shuttle mounted on a sled might be feasable. Anyway, the whole thing will hit the scrap pile shortly with the next wave of spacecraft. |
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> Anyway, the whole thing will hit
> the scrap pile shortly with the
> next wave of spacecraft. |
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You'll pardon me if I don't hold my breath. |
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[centauri] I agree, but we can always hope that the X project will pan out. |
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gerald bull already baked this one, and was assassinated for it. see link for more details. |
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There is a good idea I read on newscientist (I tried searching for the article but couldn't find it). The idea was to have a tube that goes from sea level down a long distance under the ocean. The water would be pumped out and a spacecraft placed at the bottom. The water would be let back in and the spacecraft would be launched upwards as the waterlevels equalised. It could save a whole load of fuel. |
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Has anyone every timed the amount of time the shuttle spends on the launch pad after the engines have ignited to when it clears the tower - it doesn't take an idiot to work out that just getting it clear of the tower would save a lot of fuel. Acceleration would not cause much more G than being in a fast car - you are only accelerating it from 0 to 10 in about 2 seconds - compare that to the bungie-accenders at fairs grounds and it's nothing. |
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I don't think any of this will ever happen anyway as it looks like Bush will scrap almost all of the space budget anyway. |
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(Remember, it's Congress that
holds the purse-strings, not the
President.) |
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If you think the first hundred
feet are *that* important, just
move the launch platform to some
place a hundred feet higher in
elevation. |
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[Casa Loco] The key item you need to look at is velocity. The shuttle must carry all that additional crap in order to achieve escape velocity approx: 11.2 km/s. Combine this with the speed needed to gain orbit: 0.71 × escape velocity and you can begin to get the picture. The first 15-30 seconds of burn are mostly to insure that everything is functioning properly. If you watch a launch closely you'll notice that once the engines are fully engaged the shuttle pops off the pad at a very high rate of speed. Within the first 45 seconds the shuttle is transonic. Sooo, if you just pop the shuttle in the air 100 feet you've probably saved nothing when you offset the savings in fuel to the cost of the device to propel it. |
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And where does the energy to get the shuttle up the
tower come from? You may save on shuttle fuel but you'll
use just as much (if not more) in crane fuel or catapult
fuel. |
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Mihali: Gerald Bull wasn't assassinated for his desire to to launch satellites with big guns...He was assassinated because he was building a gun that could shell Israel from Iraq. It's a shame, all he ever wanted was a cheap way to launch satellites, and saw the Iraqui supergun as a test platform...unfortunately, the Israelies saw it differently... |
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RobertKidney: If you do find that, post a link? I'd like to see it...It sounds interesting, and most definately half-baked. <grin> |
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Catapult? No way. Those boosters are necessary. |
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But we should dump the shuttle, no question about it. |
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For now, the best ways of reaching space would be reusable ssto spaceplanes, or massdriver (railgun). |
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Not that there was anything wrong with killing Gerhard Bull. He knew what that gun was going to be used for and chose not to care. |
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