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Ever wish you could have a hoverboard like in Back to the Future II? Now you can... kind of.
The story I ran across this morning was short on technical details, but the hoverboard will only work above a conductive surface and its battery only lasts seven minutes, apparently using magnetism.
"Our engineering team has been amazing, rapidly iterating on design after design. In fact, this our 18th prototype, and we continue to make advances week after week," says the company’s Kickstarter campaign.
"The magic behind the hoverboard lies in its four disc-shaped hover engines. These create a special magnetic field which literally pushes against itself, generating the lift which levitates our board off the ground."
A pledge of $10,000 will get you one of the first production boards. Expected delivery is October 2015.
(Score: 2) by c0lo on Wednesday October 22 2014, @09:05AM
TFA mentions...
... you guess it: copper - which is diamagnetic [wikipedia.org] (tends to repel the magnetic lines - the most extreme case being the superconductor ones).
Lenz law and eddy currents [youtube.com] or not, I'd like to see them try their hoverboard over a steel sheet.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 2) by choose another one on Wednesday October 22 2014, @09:56AM
Their website (and other articles on it) specifically say it has to be "non-ferromagnetic conductor". Do you have a non-ferromagnetic steel sheet ?
Coating a skatepark with copper is the more amusing bit - just thinking about how long it'll last... (accessible copper doesn't tend to stay around for long even with 10s of kV running through it)
(Score: 2) by c0lo on Wednesday October 22 2014, @10:41AM
But the T(elegraph) F A(uthor) chose to drop the "non-ferromagnetic" requirement: scientific reporting at its finest.
Aluminium may be just fine.
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 2) by VLM on Wednesday October 22 2014, @12:17PM
"Do you have a non-ferromagnetic steel sheet ?"
Yeah austenitic stainless steel alloys aka most of them. Three digit number beginning with 2 or 3 or some others pretty much, from memory. "the vast majority" of stainless sold is like this. There are magnetic stainless steels, just not much.
Stainless steel is sorta marketing speak for just another boring steel alloy with more than 5% chromium or so. Its not like its made out of "stainless steel atoms" instead of normal iron atoms in steel. Chromium is nice and expensive compared to iron so whatever you buy will have the minimum regulatory limit of chromium for that specific alloy. But its just another kind of steel, fundamentally.
Don't believe me? If you have real cutlery in your kitchen (assuming you're not a member of the "hot pockets" and takeout tribe) try to stick a fridge magnet. It won't work. Also iron/steel over reddish heat is austenitic and you can do a really shitty job of hardening steel by heating it until a magnet won't stick to the hot steel but will stick to cold steel (aka you didn't just exceed the magnets curie temp) and then dunk it in oil or water or just let it sit and air harden depending on the alloy.
The good news is it doesn't corrode nearly as fast as copper and its tougher than hell. The bad news is you won't like the price and its a PITA to machine and its really heavy.
Another strategy is if you could hover 6 inches over the copper, you could bury copper wires in 4 inches of concrete. In fact concrete with steel rebar might be good enough if the rebar is "smooth" enough.
(Score: 0) by Anonymous Coward on Wednesday October 22 2014, @01:38PM
Welding stainless steel sucks too but not nearly as much so as aluminum!
(Score: 2) by jcross on Wednesday October 22 2014, @01:54PM
> accessible copper doesn't tend to stay around for long
I can't see any reason they couldn't (electrically) insulate the copper with a layer of vinyl or something. Seems like then it should have similar durability to something like romex wiring. The whole thing might be pretty expensive though, given copper prices these days.
(Score: 0) by Anonymous Coward on Wednesday October 22 2014, @04:33PM
GP isn't referring to losses due to environmental factors; it's more of human factors (ie, stealing) - and high copper prices will only make it worse.
(Score: 3, Interesting) by metamonkey on Wednesday October 22 2014, @02:46PM
Also, copper is expensive as shit.
I wonder how hot this thing gets. It's just Lenz's law, but they're not using superconductors so they've got ohmic loses and this must consume a significant amount of power.
It's a cute demonstration toy, but that's all.
Okay 3, 2, 1, let's jam.