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Comment by geon | Hacker News Reader

Superconductive magnetic locking is nothing new. Even the "hover board" has been done before.

The whole concept is so stupid it hurts. The superconductors in the board needs to be extremely cold, and the ground needs to be covered in magnets. Or vice versa. The liquid nitrogen needed for this is cumbersome and will evaporate quickly.

As seen the last time someone tried making a hover board it is impossible to stand on it. It will slide with equal non- friction in every direction making it impossible to keep the balance. The only alternative is to keep it locked to a track, like a toy train.

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It is perfectly possible to stand on it if it is powered. The same you can stand on a Segway: As long as it moves itself under your center of gravity when tilting. That would then also be the steering.

The problem is, there's no friction (as the article states) for the board. What would the board push against to adjust itself? In the Segway, the wheels touch the ground and provide something for the motors to act against. This is more like an astronaut in space (if I'm understanding the situation correctly).

I like the idea (my kids would love it). It certainly has marketing value and calls up dreams of an amazing future, but there do seem to be some real practical problems (as the parent alludes to). Stopping seems particularly exciting.

Now, I have close to no knowledge in super conductivity and how those puck manage to somehow stick to the rails centimeters away from the surface, but could we create some sort of directional friction? Sort of like a snowboard would work, so you could at least rely on one axis to balance yourself properly?

From what I gather, the board would apply a single linear resistance (vertical) aswell as resistance from every rotation axis. So theoretically, we enough skill, you could balance yourself on the board purely by using rotational resistance, even without the directional friction I just mentioned. You couldn't jerk your legs forward and backward, but you could push on the ball of your feet to shift backward, and push on your right foot to shift to your left.

Am I making sense?

Dynamic instability? E.g., give the board some extra electromagnets near the edge, which "balance" the same way humans to, by constantly pulsing back and forth. When you want to move, you exaggerate one half of the pulse cycle.

I think you're on to something. There's enough magnetic field there to levitate a couple hundred pounds. It you can shape that field electronically, or even by interposing the right kind of material, it might be possible to create some lateral force.

> The problem is, there's no friction (as the article states) for the board.

Where'd you read that? All I read was that they are working on a friction-free car.

It uses super-conductivity to facilitate levitation. Flux pinning creates an 'on-rails' movement between the two components (the superconductor and the magnetics on the ground).

Defects in the magnets and gaps would create areas of resistance, much like they do in toy-scale versions of this same concept, but you'll still be pinned to the magnetics as long as that superconductor stays cold.

There will be no 'astronaut-in-space' movement, because the board will only be able to achieve quantum levitation over a bed of magnetics, which will be many pieces and not defect-free.

http://quantumlevitation.com/the-physics/

http://www.ted.com/talks/boaz_almog_levitates_a_superconduct...

The board is pushing against the ground (and the load!). If you adjust that force depending on the tilt of the board, you can move it (up to a certain point) to stay under the load.

As others have pointed out, it depends a bit on how much lateral force you can achieve through tilting and reaction forces, but if you can balance a quadcopter, you can balance a hoverboard. It gets a lot easier if your load is attached to the platform.

The Hendo hoverboard uses similar technology to MagLev. People can not only stand on it hovering over a flat surface, but can ride it over a half pipe: http://www.engadget.com/2014/10/21/we-rode-a-hoverboard/

Edit: I realize now that superconductive magnetic locking might be different than this, but since you mentioned the need for magnets I guess I got confused. Sorry for the downvote.

"Ride it over a half pipe" is misleading as it makes people think of skateboards. The thing weighs a ton. "Slide" would be a more accurate description. Good luck trying to jump with this battle truck of a "board".

> and the ground needs to be covered in magnets... I guess there goes their claim that they'll be no need for roads. In the words of a modern day skater: "bummer"

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