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Maglev trains are fun, but who wants to be stuck on a track? Dr. Acme had the brilliant1 idea of ditching the track and simply using the Earth's magnetic field as the base that would repel his vehicle, allowing free-flight across the earth! As his head assistant, he has naturally left it to me do the easy part and work out the details, now that he did the hard part and came up with the idea.
Of course the Earth's magnetic field is tiny, so the magnets in our vehicle need to be dialed up to 12. Presumably a superconducting electromagnet will be required to reach the necessary magnetic field strengths. The initial plan involved one large, spin stabilized, superconducting electro-magnet in the center of a saucer-like vehicle. The lack of redundancy of such an arrangement made me wary, but further research has suggested that spin stabilization would not be an option at arbitrary points on the Earth's surface anyway, so I'm working on a new design.
The only other option I can think of is using servomechanics, aka active balancing via sensors and automatic computer adjustment. Dr. Acme assured me that servomechanics will do the job. As a result I'm just left figuring out if the necessary field strengths are even physically plausible. Presumably this will require lots of power. I obviously can't carry around nuclear reactors, but we have some handy AcmeTM Power Plants that can be miniaturized and provide ridiculous amounts of energy as needed.
Of course, this is all pointless if the required magnetic field strength is so high as to be impossible to generate with modern technology, or would even require such unbelievably high strengths as to be effectively impossible to generate for other reasons (requires a magnet so strong it rips its own atoms apart?). To help give some specific numbers, I'm looking to build a typical "car"-sized vehicle: let's say I need to lift 4 tons total, and I'm assuming the weight of the magnets/power plant will be at most half of that.
Since the Earth's magnetic field is a dipole, I presume it grows weaker with distance from Earth faster than gravity, which means arbitrary altitudes may not be possible. Being able to operate up to thousands of feet above sea-level is a requirement, since there are plenty of places in the world where the ground is higher than that. Being able to operate up to or past LEO would be better (ignoring issues related to the need for maintaining a survivable atmosphere). To recap:
Ignoring energy needs, would it be possible to use powerful electromagnets to self-levitate a 4 ton vehicle using the Earth's magnetic field as a base?
Breaking that question down a bit farther:
- Are the required magnetic field strengths even remotely possible with today's technology?
- If not, are the magnetic field strengths even physically possible?
- If such magnets could be built, would it be feasible to use servomechanics/active adjustment to stabilize the system?