h a l f b a k e r yPoint of hors d'oevre
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Jim reckons maglev is expensive - and might be the reason people
used horse drawn boats running in water filled canals instead…
He also figures the physics have not changed.
Jim proposes a magnetic field strong enough to attract a thin layer of
saline to the surface of a train. The said vehicle
can then be drawn
along an empty ((edit) not dry) canal as if it was water filled.
Sneaky…
how to do it
http://en.m.wikiped...agnetohydrodynamics
belive it or not [madness, Oct 22 2011]
[link]
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Po check out the link (feel free to delete your comment) because
I am about to… |
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Max has a horrible feeling that the viscous drag on
the train will be far greater than the rolling friction
of wheels. He also thinks that this idea is
evolutionarily convergent with a slug. |
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He does, however, think it's ingenious. If he can
ever meet this Jim chap face to face, he would give
him a bun. |
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Too complicated; why use magnetohydrodynamics (yes, I
believe it, as does anyone else who has ever A) wondered
if Tom Clancy was full of $#!+ or B) seen or read about
that Japanese MHD-drive boat) when the train could just
as easily work by simple capillary action? |
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Is Jim is not capable of posting his own ideas? |
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Or is Jim being set up as a scapegoat? |
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Slow-moving boats are great, because water has no limiting friction, but drag increases with the square of velocity. And with a thin layer of liquid, and massive shearing forces, drag is going to be substantial. |
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The train won't float, as such; its weight is not counteracted by buoyancy due to displacement. Instead, the liquid is acting as a lubricant. So why not use a ferrofluid, or an oil ? |
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Maintaining ride height and stability will be ... challenging. |
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Jim needs to make sure he takes his meds regularly. |
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What [Master Quest] said. |
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As others have said, this would not work to float a vehicle, the best you could hope for is a hydrodynamic lubrication, but that only works by letting some of the fluid trail of the back. You could then use magnetohydrodynamics to pull thr fluid around to the front. |
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At that point, however, you will find it far more effecient to simply put wheels on the vehicle. |
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Saline solution was presented because it is a natually occuring organic compound. I agree that there is likely to be a better inorganic compound. |
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//This would mean carrying a large supply of saline in on-board tanks, and at that point you've lost all chance of gaining any efficiency. |
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Not really --- the fluid supporting the train can be gathered from the water way itself. Only a small amount of saline needs to be present, just sufficient to 'wet' the surface. |
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//the best you could hope for is a hydrodynamic lubrication, but that only works by letting some of the fluid trail of the back. |
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Again not really --- the amount of fluid trailing out the back will be small and constantly replenished. |
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//At that point, however, you will find it far more effecient to simply put wheels on the vehicle. |
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I think the analogue here is that of an ice skate. Which is to all intensive purposes frictionless. The pressure of the skate on the ice melts/creates a tiny bead of water which will trail behind the skater. |
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Here, energy is required to gather and maintain such a bead of water under the train. The amount of energy required is small compared to that required to levitate. Which is why ice skates and this idea work so well... |
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