# The Naked Scientists Forum

### Author Topic: Could a maglev-based system be used to get things into space?  (Read 2654 times)

#### LetoII

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##### Could a maglev-based system be used to get things into space?
« on: 21/01/2012 13:26:00 »
current idea:
Using a maglev like system (imagine a maglev train propelling system) in a circular like shape to move away from the earth.

let me explain what i'm thinking:
if you use a maglev system to shoot a heavy metal like object towards the earth (inside the circle or outside doesnt matter much, i think the only thing that matters is the fact that the metal like object and the system exchange kinetic energy with eachother)  (downwards) it will force the system upwards into the air for a shot distance.
Ofcourse this isnt entirely true because it would mostly make the cirle like object counter rotate compared to the object it is propelling. This however can be countered by connecting it to a 2nd one moving in the exact opposite fashion, then it would translate into a upward movement like i started out with.
so the minimum number you'd have to use is 2.

All there is left now is the part where the object moves upwards instead of downwards.
When this happens the kinetic energy would be aimed downwards if you accelerate it, thus we decellerate it so it still becomes an upward motion. This is limited to the point where the heavy metal wouldnt reach the top and cross it but instead fall back, so there is only a limited amount of energy you can aim upwards during this phase.
In the phase where the heavy metal is moving down this is only limited by the force you can put into the heavy metal.
the only question remains, would it be enough?
this depends on: the total mass of the maglev like circle and whatever extra weight comes with supplying energy and whatever space humans might need inside VS the weight of the metal object and how fast you can make it go.
If i look at the incredible speeds that can be reached using these type of systems it would seem likely it's possible to make it, it's also energy efficient.

Let me know what you think

« Last Edit: 22/01/2012 09:53:37 by chris »

#### Soul Surfer

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##### Re: Maglev flight 2.0
« Reply #1 on: 21/01/2012 19:02:33 »
What you are trying to describe is not clear or unambiguous enough to give a sensible reply.
Please add a diagram or start very simply to describe exactly the sort of structure that you are talking about its orientation with respect to the surface of the earth and what you are trying to do.  I appreciate that your first language may not be English but it is only when we can clearly understand exactly what you are trying to describe we can give an answer with any degree of confidence.

#### CliffordK

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##### Re: Maglev flight 2.0
« Reply #2 on: 21/01/2012 19:25:48 »
I agree your post needs some clarification.

Are you discussing a space elevator?  Which is another topic currently being discussed here.
http://www.thenakedscientists.com/forum/index.php?topic=42683.0

In the case of a space elevator, the tensile strength necessary to make cables connecting upward and downward moving objects would be too high, so the upward and downward motion must be done independently with some type of autonomous climber.  If there is a system that creates excess energy, it could still be transferred with either a beam, or perhaps a direct electric connection.

As far as using magnetic propulsion for launching into space from the ground, air friction would limit the ability to use it on Earth, but it would be viable on the moon where there is little atmospheric resistance.

I believe the military has tested magnetic propulsion for cannons.

Issues with "equal and opposite force" as well as balance come into play, but it isn't always possible to shoot two projectiles in opposite directions, although, in a sense, that is what rocket and jet engines do.

#### wolfekeeper

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##### Re: Maglev flight 2.0
« Reply #3 on: 22/01/2012 05:56:06 »
He's talking about orbital rings.

http://en.wikipedia.org/wiki/Orbital_ring

#### LetoII

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##### Re: Maglev flight 2.0
« Reply #4 on: 22/01/2012 08:34:00 »
the orbital ring looks quite alike but it seems different, ill draw some schematics later today and upload them.

#### CliffordK

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##### Re: Maglev flight 2.0
« Reply #5 on: 22/01/2012 08:53:00 »
He's talking about orbital rings.
http://en.wikipedia.org/wiki/Orbital_ring
Thanks,

Interesting concept.
That would be a pretty harsh interface at the top of the ladder between the ladder, and the ring flying past at about 8,000 m/s.  I didn't see a discussion on how one was to accelerate the satellites to 8,000 m/s as required to maintain LEO.  Is one to just grab onto the ring?  Perhaps grab a car onto the ring at the same speed of the ladder, then slowly accelerate up to the desired speed...  then drop off and decelerate the car before encountering the second ladder.  A malfunction in the acceleration/deceleration, and one could get a pretty spectacular crash.  There certainly would be some energy transfers incurred with the acceleration/deceleration.  The car would then have to be flipped past the ladder in some fashion and re-attached to the ring for the next cargo acceleration.

Perhaps another use of the ring would be merely to add midway support to a much longer geosynchronous orbiting space elevator.

#### Soul Surfer

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##### Re: Maglev flight 2.0
« Reply #6 on: 22/01/2012 09:35:20 »
Thank you wolfekeeper for providing the critical fact that made the original question a bit more understandable.  The fundamental problem for most of these big engineering ways of getting from the earth's surface into an orbit that will enable reasonably low energy solar system space travel to be accomplished on a large scale is the amount of material needed in space to make the structures and the stability during building them.  The effort would probably not be justified for even reasonably active space exploration however if a last ditch effort was being made to achieve a significant exodus from a dying planet the effort and risks would probably be justified.

Another often not mentioned problem is the likely need for human activity in the synchronous orbit area around the earth because that is in a very high radiation part of the earth's outer atmosphere and is dangerous for long term human activity. communications and broadcasting satellites use radiation hardened electronics.
« Last Edit: 22/01/2012 10:08:21 by Soul Surfer »

#### LetoII

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #7 on: 22/01/2012 11:32:40 »
i think i can clear some things up by making a different comparisson.
Imagine a maglev track in miniature form made into a circle, now we go and lay it down on a table.
inside the miniature circle there's a weight (imagine a train if u will) that's going to be traveling along the inside.
now as we turn it on there's 2 things that can happen:
1: the train moves along the inside and the track doesnt do anything at all as it is just lying stablized on the table.
2: the track will move in the opposite direction as the accelerating force of the weight (train) is greater than the natural forces keeping the circle where it was in the first place.

what we need for the idea to work is the 2nd posibility or we can't be going anywhere at all.

now here's what we do next. We double the minature cicle by connecting it to a 2nd one thats exactly the same but it will spin in the opposite direction.

When you turn it on now instead of just rotating, it will move out of place.
This is the principle we'll use to withstand gravity.

please hit me with your next questions this brings up and i'll work with you from there.

#### MikeS

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #8 on: 22/01/2012 12:10:28 »
I still don't understand how what you describe is going to get anything off the ground.

If you used a maglev 'gun' with a long enough barrel I don't see why that would not work.  If the barrel were long enough then the initial acceleration could be kept under control but it would require a very long barrel and present immense engineering problems but seems to be, in principle a possibility.

#### LetoII

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #9 on: 22/01/2012 16:17:58 »
my device is nothing like a gun. what you suggest is currently not possible BUT there are maglev systems that can be used to slingshot a rocket into the air as a means to safe fuel. It greatly reduces the fuel costs to get of earth (1/5).

#### CliffordK

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #10 on: 22/01/2012 20:55:30 »
As far as constructing a ring or space elevator in space.  Anything in orbit is reasonably stable, so that shouldn't be an issue with construction.  However, initially getting millions of tons of cables and equipment into space is a big issue.  Likely one would have to find a good source of the raw material already in space, for example on the moon (which still would require a lot of effort).
A large part of our rocket fuel is 2H2+O2, which can be formed by electrolysis, but still requires a lot of energy to generate.

LetoII,
I'm still not clear on your design.  Is it at the surface of the Earth?  Keep in mind that there is a speed limit of about Mach 4 in the atmosphere, and one needs to get to about Mach 10 to achieve orbit.  Any boost would help though.

Coordinating two nearby rings rotating at high speed in opposite directions would be problematic.  If they ever touched, they would cause significant damage to each other.  On Earth, air friction is always an issue, and would at least cause vibrations between the contra-rotating rings.  Actually, the air friction could cause a low pressure that would suck the rings together and tear them apart.

If an airplane was sitting on a runway moving in the opposite direction of flight, that would not give significant additional lift, except for a portion of ground-effect with the moving runway causing wind near the ground.  The effect would be of limited altitude, and the plane would still have to achieve adequate airspeed to actually fly.  I think there was  a Mythbusters episode that looked at the effects of a moving runway, but I don't remember the conclusion.  I don't think there was much of an overall effect.
« Last Edit: 22/01/2012 20:57:21 by CliffordK »

#### Soul Surfer

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #11 on: 22/01/2012 22:41:26 »
LetoII  as described your ideas will not work in the way that you think that they will because they are not doing anything that will as you seem to suggest lift hem into the air and defy gravity.

#### LetoII

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #12 on: 23/01/2012 03:33:39 »
ofcourse the two miniature rings system wont work, as in getting us of the planet, but it was to aim your thoughts in the right direction.
if you thought everything through correctly you should  have come to the conclusion that the 2nd design i suggested would only cause... let's say vibration. the rings would move out of place and back into place. as one would expect with a completely constant acceleration and a circle like shape.
the first half of the cicle you'd move 1 way and the 2nd half of the circle would move you in the opposite direction.

the acelleration, however, doesnt need to be constant. it can change, it can even be turned into deceleration.
so since we can vary in direction and speed, freedom of movement should be possible.

to take this back to the 2 rings (vibrating) on the table, if we were to let the rings acellerate the first half and decelerate the 2nd half then instead of just moving in and out of place. it would move in one direction.

about collisions: that's unlikely to happen. I can understand the concerns but it's not realist to say 2 trains traveling in opposite direction would collide. they wont because the engineer has thought of this.
e.g. im sure the people using maglev trains are confident they wont end up crashing into the train coming from the track next to it.
damn at those speeds that really would give a mess i'd say.

air pressure is an issue though, although im sure we can work around that too :)

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##### Re: Could a maglev-based system be used to get things into space?
« Reply #12 on: 23/01/2012 03:33:39 »