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A circular track to get you up to orbital velocity? A novel idea, but you run into the problem of having to keep a multi-tonne ship traveling tens of thousands of kilometers an hour from touch the side of the track due to centrifugal force, which would prevent magnetic levitation. The force on the payload (like the crew...) would be extreme if the track is anything less than an insane size. It would be easier just to build the linear one.
I found a formula for centripetal force: F=(mv^2)/r where F=force, m=mass, v=velocity, and r=radius, and I did some calculations with it. You're right that it would be way too much force for orbital velocity at any sort of practical radius. For supersonic speeds needed for a ramjet or scramjet though it might work. I'm not entirely sure what speeds you need for these, but I calculated that for a 100kg passenger to survive (survivable force limit is 1.2x10^5N) going around a circle at the speed of sound (using 331m/s, the speed in air at 0C) the circle must have a radius of at least 91.3m. Obviously you want the guy to not only survive but be reasonably comfortable, you want to accomodate passengers heavier than 100kg, and you want, at least for a scramjet, to accelerate to faster than the speed of sound. I am not really sure what numbers to use here, but I would imagine that with a track radius of not more than a few kilometers it could be done.
Trip time up a space elevator cable is not the problem so long as you can have two elevator car rails operating simultainiously up and down. The weight of a maglev rail up its length would be very prohibitive, it has enough trouble just supporting its own weight of a 36,000km cable.
You're probably right about the weight, certainly for the first elevators; who knows what tech we'll develop in the future. I'm not sure if this is just another ill-thought-out idea, but I was thinking that you could have a loop cable with several cars along it that is simply moved by a pulley-type mechanism at the base and/or at the top. The cars don't move and don't need any fuel. Instead the whole cable is moved and power can be generated on the ground or by space-based solar arrays. Cons are that all parts of the cable would have to be strong enough to take the strain of the hardest parts and that the system could be wearing on the cable. However, all parts of the cable will at tiimes be conveniently down on Earth for inspection and repair.
Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun.
-The Hitchhiker's Guide to the Galaxy
by Douglas Adams
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A sled is a good idea. You can build it to be very strong without having to make it super-ultra-light weight like the space plane.
.... it would be more than fast enough for a ramjet engine.
Isn't that what those Germans want to do with their spaceplane?
(The it's-only-a-mockup one, thet did a low altitude glide test quite a while ago...)
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That is a steam rocket powered sled. The problem with that is it still has to be as big or even bigger as a normal first stage, even though it is reusable and doesn't have to fly. But they were not thinking about going to km/seconds with that one if memory serves.
Ps.: Just found an old newspaper article from 1998 with some numbers as an example. I calculated ISP to about 150s based on those numbers
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Sorry to be a pedant, but I couldn't get past your first premise, ie:
"First there is a large space station at one end of the tether. Its functions are to be
a ballast,
a control center for the rest of the tether,
be living quarters for astronauts,
be the maintenance workshop for the tether
and later on a construction facility for larger space vessels
(only thinking about final montage of Earth produced parts for the time being).
This is made possible by its position at the end of the rotating tether, that would ensure high quality artificial gravity for the whole station."
My query: If the large space station functions as a ballast, I can't see it ensuring artifical gravity too. What am I missing?
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Ok let's first assume you have a long symmetrical tether without anything on it rotating around with the center of the rotation in the middle of the tether.
The centripetal acceleration for a point at a distance of r from the
center is
a_centr=omega^2*r
with omega being the rate of rotation (tip_speed/tip_radius)
Now for a tether that is roughly 50 times the mass of the payload it holds at the tip and a few hudred kilometres long and made of high strength materials you can achieve tip speeds of 3 to 4 km/sec, which at that lenght means tip acceleration of 2g to 6g, depending on how long you make the tether.
Now imagine you go to the radius where the centripetal acceleration is let's say only 1/2 g and cut off the tether at this point and replace the pulling force of the part that you cut off by a single large mass.
That is the space station I was talking about. It has to be more massive than the cut off tether part, since the whole mass is only tugging at 1/2 g instead of 2 to 6g at the tip, so let's say 1 to 3g on average.
That way you can get space stations with 1000-s of tons at this low g for recieving multi ton payloads, or a less massive one further out with higher gravity (like 1g for starters).
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a_centr=omega^2*r
Maybe I'm mistaken, but I thought centripetal acceleration was omega^2/r. Or v^2/r as my book says where v is velocity of the object in question (just a different variable, same thing I think).
Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun.
-The Hitchhiker's Guide to the Galaxy
by Douglas Adams
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yup and v=omega * r
just replace v by omega*r and you get the equation.
omega is the turning rate independent of radius.
Multiply it by 1/(120*Pi) and you get RPM of the tether.
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That's what I thought, only:
"This is made possible by its position at the end of the rotating tether, that would ensure high quality artificial gravity for the whole station"
fails to state that "it's" refers not to the ballast space station, but to one at the other end. Trivial? Not if you're trying to sell us on the idea of captive tethered systems for routine cis-Lunar space travel. Fortunately, the scheme is very amenable to computer simulations (contrary to space sailing, which still needs to be proven in principle, unfortunately). Great stuff!
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i changed my idea.
i got new patent on new idea.
we are creating animation with 3dsmax with a friend, and we do some math on idea. after we finish animation of idea, i'll post to this forum details of idea.
we built a magnetic catapult with 90 degree angle inside a mountain. length of catapult will be 2km or 3km.
magnetic catapult will be in a vacuum tube so we can speed it up do 20km/s easily.
we also carry a vacum tube to 30-40km height with hundreds of ballons.(90 degree angle) ballons can carry high mass up to 42km, so we can use ballons to carry parts of vacum tube.
once all parts of tube is in air, with a mechanic system we clamp parts each other and we get 30-40km line of vacum tube. we clamp this tube to vacum tube of capatult which is inside a mountain, we vacuum air in tube and we
get air friction free launch tube !
there will be electric line on parts of vacum cubes. horizontal movement will be created with electric powered propollers. This is new idea and i patented this too.
with 3km catapult and 2500G launching speed, we can send nuclear & chemical waste to splease in bullets safely with 12,135 km/s speed. Bullet will pass catapult in 0,494s and pass vacum tunel (40km) in 3,049s.
if we cretae long catapult with on a side of mountain, we can send satellites and human witj low G too. i am trying to calculate necessary catapult designs for human & satellites.
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