On the subject of hovering

[speaker-to-trolls]

Very basically, is it possible to create some kind of magnetic levitation drive that can lift and move a vehicle without an already existing magnet for the drive to 'push' against?

[Braedley]

If I understand you correctly, then yes.
Without going into the physics too much right now, all you need is your linear induction motor to push against a conductive material.

If you are unsure what a linear motor is, it is basically the stator of an AC motor that is cut and laid flat. By applying a time varrying current (typically your standard sinusoid AC) to the stator, you can create magnetic flux around the stator. If you have a conductive material present in the magnetic field created by the stator, then curent is induced within that conductor such that the magnetic field the conductor produces opposes the magnetic field produced by the stator (IIRC this is Lenz's Law). 2 or more magnetic fields in the vicinity of each other cause forces to be exerted on the objects creating the fields. F=ma, and off goes your conductive material.

If you need more clarification, just say so.

[drachefly]

Suppose you're trying to use that to hover above the ground, though... you're not going to get a significant counter-current.
You could do it above a metallic floor... but you'd also need to have a pretty hefty electromagnet and be able to switch it very quickly. That's a lot of work.

[Braedley]

Well it has to be a conductive surface at the very least. The bare ground simply wouldn't be good enough. As for the stationary hover, I'm gonna have to think about that. I imagine that a high frequency, high voltage supply could do it, but as I have more pressing subjects to fill my mind with at the current time (like the subject matter for 3 midterms tomorrow), I'll have to get back to you later.

[Elheru Aran]

We already have this, to a degree-- maglev trains. I don't think levitation above bare ground a la repulsorlifts is a practical concept, definitely not for the next few centuries or so, but above a prepared roadway of some sort is quite possible IMO.

[Junghalli]

If you're aiming for a realistic "flying car" then I'd more recommend some kind of small low-power jet engine or something like that. I think we already have vehicles a little like that, but they're only used for travel over water.

[Just Another Dumb Guy]

Regarding the jet engine thing someone was mentioning earlier, most air cushion skirt vehicles use a powerful fan to trap a layer of air below the vehicle, allowing it to literally hover (however, the air cushion still touches the ground).

In any event, there is a problem with free-range maglev hovering that is the same as that of air cushion vehicles - applying motive force to and directing the vehicle when it have no contact with the ground. Maglev trains are tied to their tracks, so it isn't a problem, but free-range vehicles may need a giant fan to push ithem around, which works, but there should be a more elegant solution.

[Braedley]

In any event, there is a problem with free-range maglev hovering that is the same as that of air cushion vehicles - applying motive force to and directing the vehicle when it have no contact with the ground. Maglev trains are tied to their tracks, so it isn't a problem, but free-range vehicles may need a giant fan to push ithem around, which works, but there should be a more elegant solution.

Not really. A vehicle travelling over a highly conductive surface (some other physical properties come into play, but they are less important) using say 4 (rather large) electomagnets which are allowed to freely rotate could provide a means of free range propulsion. However, the problem arises in that anywheres that you miught want to go has to be covered in steal, copper or aluminum. Without it, this vehicle goes nowheres.

[Just Another Dumb Guy]

Not really. A vehicle travelling over a highly conductive surface (some other physical properties come into play, but they are less important) using say 4 (rather large) electomagnets which are allowed to freely rotate could provide a means of free range propulsion. However, the problem arises in that anywheres that you miught want to go has to be covered in steal, copper or aluminum. Without it, this vehicle goes nowheres.

That's an interesting idea. Would it be possible to construct future cities with embedded magnets in the streets so maglev cars like this would work?

[Braedley]

All you need is a conductive surface. No permanent magnets required. Permanent magnets are used in maglev trains only to reduce power requirements and increase overall efficency.