Re: ATM magnetic altitude bearings

[Andy Saulietis <iss@pvtnetworks.net>]

Ian Sterling writes,

>Ernshaw (?) proved that you can't do static frictionless bearings, using
>only permenant magnets. (there are some caveats, supporting rapidly rotating
>things that can precess is sometimes possible), but a magnetic bearing
>out of permenant magnets isn't.

You can statically levitate a magnet, eg a N-S magnetic
bar in a superconducting lead tube or dish, since
the flux lines can't penetrate the superconductor.

We built an accelerometer at MIT using this
technique, the bar magnet was suspended in the
SC tube with external coils to keep it inside
& track its motion. The ends of the magnet
had mirrors & formed the moving part of an
interferometer. The sensitivity was amazing,
~10e-8 g's, it could measure the acceleration of
changing the temp of a block of aluminum it
was mounted on. This was in 1965...:) 

Now all we need is room temp superconductors to make
magbetic bearings..;)

Air bearings would probably be easiew and hydraulic
ones have beed around for a long time (eg 200" hale etc)





Andy Saulietis
ISS Enterprises
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Mayhill NM 88339
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e-mail: iss@pvtnetworks.net