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Will this work? Fly on magnetic fields

J

joburnet

Senior member
This is for those of you who sat through Electromagnetic Fields and actually understood what is going on. The idea is to use a wire with a whole lot of current to create an upward force using the earth?s magnetic field. I did some quick calculations in my head and using a magnetic field of .00005 Tesla a wire, or coil of wires, with 1000000-ampere turns should produce about 50 pounds of upward force. For this to be practical to get anything off the ground a superconductor would be needed, so it's not going to happen any time soon, but I would like some confirmation if the idea will work.

The idea: You have a rectangle of wire in the earth?s magnetic field as shown on this page.

http://library.thinkquest.org/16600/advanced/magneticfields.shtml

If the B field is parallel to the ground then the force on one horizontal wire will be up and the force on the other will be down. Both forces will be equal so the net force will be zero but it will create a couple. Apply a torque to the rectangular wire that opposes the couple and it should create a net force on the entire rectangle. Now if the rectangle is allowed to spin past a plane perpendicular to the B field then the net force on the rectangle will reverse, but if you reverse the current when this happens then you will always have a net force in the same direction.

This net force in the same direction is basically a way to ride on a magnetic field. This could be used to fly on the earth?s magnetic field instead of flying on air, but some kind of superconductor would be required. It could also be used with satellites or space vehicles that have an infinite source of electricity via solar panels. It would be used with low current and low force but over enough time, possibly circling the sun which has a much larger magnetic field then the earth, it could build up enough speed to slingshot itself out into space.

If anyone has any ideas why this would not work, how it could work better, or just comments I'd like to hear them.
 
my advice to you if you want it is to look for a market and then work for a solution in technology. If you can make sth work with solar power eg a telco microwave baloon over a city, or some way of reducing freight train or car or plane costs then work on it! You can also speculate on emerging tech like conducting plastics, free power from heavy water or sth like that, also from zero point energy if anyone can manage to create a zero point energy machine.
 
After thinking about it a little more, I think that the rotation of the rectangle would have to be near the speed of the magnetic field, which I would guess is the speed of light, for this idea to work. So a much simpler idea is just to have a non moving rectangle and then use magnetic shielding over all of it but one side. This would be just like having a line of currnet with force F equal to IL x B where I is in amps, L is in meters, and B is in Teslas. Assuming that I and B are perpendicular to each other the equation equals F = ILB. For a 1 Newton force you would need I = F / LB = 1 / (1*.00005) = 20000amps. You would need to pass 20000 Amps through a 1 meter long wire weighing 100 grams in order to make it float. I wanna superconductor and some bad ass capacitors and I'll be set😉 Anyone have some other ideas that might actually make this feasable? I'll do some calculations on copper wire and how thick and hot that will get when I get more time.
 
I keep rereading your explanation of how to get a net force but I am really not seeing it.

If memory serves me correctly, a constant force is exerted on a wire carrying current by a B field(i.e. think of a stream of electrons in the wire, with the B field exerting a tiny force on each one of these electrons). But your example describes what one would do to generate an induced emf in that loop of wire. By spinning it, you are changing the orientation of the normal to the plane of the loop, thus changing the flux going through the loop. The loop "resists" this change in flux, and tries to "create" its own flux to keep the amount of flux at a constant level, it does this by creating an induced current(which flows in a direction dictated solely by the change of flux going through the loop). I don't see this constantly changing flux generating a net force on the loop, but I could be wrong. I'm only an undergrad ME major, so I'll be the first to admit that this isn't my area of expertise.

Now, let's say I'm completely off base here and you have proposed a way to generate a net force by spinning this loop of wire in the earth's B field. Wouldn't both the forces be in the same direction when the loop "flipped" past this vertical plane? As in, the B-Field does not necessarily see any geometry of said "clump of wires", so you can ignore that when doing the analysis. So does a straight wire have two different directions of force on it when a current is applied? Nope. If the force is upward, it is upward all over the wire. Same wth the loop. When it crosses that imaginary vertical plane, both the forces will "flip" to the same side of the loop(i.e. -k to +k). So this won't create a couple.

That's just how I see it. But of course, I'm by no means claiming to be an expert in this area. Heck, I've only had one semester of Emag, so this might be completely off base.


If things worked that way, that sure would be a nice idea though. 🙂


Defster
 
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