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#51 2007-11-29 09:44:50
Re: Space Elevator or Scramjet?
A 10g (centrifugal) launch ring would be able to launch bulk goods as fast as desired. A bulk delivery could be accelerated tangentially at 1,000,000 g if we felt like it, that's not a problem. Big accelerations can be achieved however we like. It's the small accelerations (for humans and non-bulk goods) that have high requirements.
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#52 2007-11-29 09:51:24
- Antius
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- From: Cumbria, UK
- Registered: 2007-05-22
- Posts: 1,003
Re: Space Elevator or Scramjet?
There's no realistic way to get the gs down to merely tens with a mass driver. Even hundreds of gs is pushing it.
Maybe as a nationwide megastructure, barely.
For the record, here are the numbers:
For a 10 g force pressing you against the launch ring's outer wall, you will need a launch ring 1230km in radius (2470km in diameter).
100g, 123km radius.
1000g, 12.3km radius.
10000g, 1.23km radius.
I could see a 10000g mass driver being built, but beyond that is going to get real expensive, real fast.
And there's no reason to build multiple mass drivers. If you built a 10g one, you could also use it for the medium and bulk goods.
Some numbers for added clarity:
For a mass driver 100metres long and an exit speed of 10km/s, a mass driver with acceleration 50,000g is needed.
Total acceleration time = 0.02seconds.
Total energy required = 50MJ/Kg (probably closer to 60 including losses)
Total power required during acceleration = 2.5GW/Kg.
That's a lot of power pouring into a very small projectile. The odds are that it would melt within the barrel. Transmitting that much power to the balloon using beamed propulsion would appear highly dubious to me.
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#53 2007-11-29 09:54:55
- Terraformer
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- From: The Fortunate Isles
- Registered: 2007-08-27
- Posts: 3,969
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Re: Space Elevator or Scramjet?
I thought it would be in a vacuum so all the energy was kinetic?
Use what is abundant and build to last
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#54 2007-11-29 10:03:37
Re: Space Elevator or Scramjet?
Total power required during acceleration = 2.5GW/Kg.
That's a lot of power pouring into a very small projectile. The odds are that it would melt within the barrel.
Of course, you could just take it easier and use a mere 8MW of power, which would still fire off the projectile in 7.6 seconds.
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#55 2007-11-29 10:13:22
- Terraformer
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- From: The Fortunate Isles
- Registered: 2007-08-27
- Posts: 3,969
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Re: Space Elevator or Scramjet?
There is a thread called Mass Drivers.
Use what is abundant and build to last
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