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Author Topic: what technology do we need to build a space fountain?  (Read 11634 times)

Offline wolfekeeper

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what technology do we need to build a space fountain?
« Reply #25 on: 06/04/2011 21:16:08 »
Yes, I believe it can be upgraded like that.
 

Offline briligg

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what technology do we need to build a space fountain?
« Reply #26 on: 07/04/2011 23:41:21 »
My question now is about the the different launch trajectories of each system. Launch loops are a horizontal launch, space fountains are a vertical launch. If a vehicle is accelerated up the height of the fountain and flung outward into space, how much energy does it take to then turn it into a stable earth orbit? Could you have rockets kick in at its apogee to give it the orbital speed it needs?

The thing is, space fountains appeal to me more because they are more efficient. The energy lost due to waste heat is huge in the case of launch loops.

btw, this thread now shows up in position 16 in google if you search for 'space fountains'. sheesh.
 

Offline wolfekeeper

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what technology do we need to build a space fountain?
« Reply #27 on: 08/04/2011 00:03:01 »
Going above about 80kms makes the structure susceptible to meteorites and space junk. You need a long structure anyway, because otherwise the accelerations need to become too high to be survivable; you end up with a spam launcher (people get spammed).

Note also that launch loops are not inherently more inefficient than space fountains; in fact it's pretty much the other way around, the higher the vertical aspect of the structure, the more the structure weighs; these types of structures hang down from the top, and the tensile members have to be tapered; as the height increases you need more and more taper, and for any given capacity, the weight of the tension members increases.

That means that you get more waste heat from the small fraction of stabilisation power to handle the magnetic instabilities associated with Earnshaw's theorem to carry these extra loads.

And in any case you need lots of sideways speed to reach stable orbit.
 

Offline briligg

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what technology do we need to build a space fountain?
« Reply #28 on: 08/04/2011 00:43:10 »
Note also that launch loops are not inherently more inefficient than space fountains; in fact it's pretty much the other way around, the higher the vertical aspect of the structure, the more the structure weighs; these types of structures hang down from the top, and the tensile members have to be tapered; as the height increases you need more and more taper, and for any given capacity, the weight of the tension members increases.

That means that you get more waste heat from the small fraction of stabilisation power to handle the magnetic instabilities associated with Earnshaw's theorem to carry these extra loads.
Huh, that's new information, and quite over my head, i'm afraid. I waded through the Wikipedia article on Earnshaw's theorem, but i don't have the math. One question though - are you considering that all the weight is supported at the top? Because a large portion is supported by the coil guns and drag devices on the sides.
 

Offline briligg

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what technology do we need to build a space fountain?
« Reply #29 on: 08/04/2011 00:46:20 »
Btw - here is a great site on launch loops, way better than anything i've found for space fountains.
http://launchloop.com/LaunchLoop
 

Offline briligg

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what technology do we need to build a space fountain?
« Reply #30 on: 10/04/2011 04:21:24 »
And now, Saudi Arabia is about to spend the $30 billion necessary for the really good launch loop - on one really huge skyscraper a mile high.
http://gizmodo.com/#!5790505/saudi-arabia-to-be-permanent-member-of-mile+high-club

sigh...
 

Offline wolfekeeper

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what technology do we need to build a space fountain?
« Reply #31 on: 13/04/2011 02:35:12 »
These types of dynamic structures are not very good at heavy lifting, but they could look down on those more traditional structures from above easily enough.
 

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what technology do we need to build a space fountain?
« Reply #31 on: 13/04/2011 02:35:12 »

 

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