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Levitation using magnets seems simple - just put one magnet over another, same poles facing, and the top one will float. Voila, right? Sadly, as we all find out (usually as heartbroken little kids) this never works. Due to something called Earnshaw's Theorem, a stable static equilibrium between two magnets is impossible. There have been a number of ways around this, but none have proven feasible enough for everyday applications. Until now.
Lenz’s law explains how eddy currents are created when magnets are moved relative to a conductive material. These eddy currents in turn create an opposing magnetic field in the conductor. Our core technology, which we call Magnetic Field Architecture (MFA™), focuses this field more efficiently.
You can go ahead and google both of these scientific principles, but to sum it up in regards to levitation: Lenz = Easy, Earnshaw = Hard.
I had lots of fun playing with levitation in high school (Physics Prof. had a levitron toy and I think we did some superconducting levitation demos with liquid NO2). Neat to see something new.
So, what do you think? Definitely some hype here, but is this MFA technology some groundbreaking stuff, or just more spinning magnets packed up in a creative way? Thinking about getting a developer kit to see how this MFA "engine" actually works. I figure if I take some videos of my cat levitating around in a cape I can probably make back the $300 on youtube ad revenue eventually .
Registered Member #8120
Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94
Get a slab of copper and a big magnet, drop the latter onto the former. It will slow down before impact. Try to move it along the surface, and it would resist. Moving magnetic field tend to produce currents that oppose it in conductors (aka Lenz's law).
In the same way, you can put AC through a coil of wire, and it would repel from any good conductive surface.
I guess with some fast feedback controls you can make the repulsion stable. Say the same thing in marketeese, and you'd get "Magnetic Field Architecture".
It's a cool idea, but i don't expect metal-paved roads any time soon, so it's useless outside specially designed locations.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
Heh.. Actually might work indoors. Hoverboard rink anyone?
Unless someone figurs out how to make an axion supercharged EmDrive or something then this might be as close as we ever get to a real hoverboard.
Also one big annoyance would be the coils heating up and melting down, any ideas how this might be fixed? The limiting factor is skin effect, even at RF using Litz wire it will still heat up and thermodynamics wins every time.
Registered Member #108
Joined: Thu Feb 09 2006, 11:44PM
Location: Billings, MT
Posts: 61
Conundrum wrote ...
Also one big annoyance would be the coils heating up and melting down, any ideas how this might be fixed?
I was wondering about this too... They claim that their "engines" are much more efficient than the technology used in maglev trains, but then the Henderson fellow says it takes about 40 watts / kilogram to levitate compared to 160W/kg for a Blackhawk helicopter (see link, looking for a better source...). Not sure if I should be impressed by that or not.
Oh, and if you scroll down on the Kickstarter page, they are planning some sort of copper-surfaced "hoverpark", because "a hoverboard needs a hoverpark" .
I saw this earlier and immediately thought about the materials transport applications in fabrication shops. Previously it wouldn't be worth it due to the energy inefficiency at providing even minimal lift for common weights, but this kickstarter board seems quite capable of hovering with a person's weight and uses small battery packs. A scaled up version could see some solid applications outside of the fun toy realm.
Registered Member #108
Joined: Thu Feb 09 2006, 11:44PM
Location: Billings, MT
Posts: 61
Sigurthr wrote ...
I saw this earlier and immediately thought about the materials transport applications in fabrication shops. Previously it wouldn't be worth it due to the energy inefficiency at providing even minimal lift for common weights, but this kickstarter board seems quite capable of hovering with a person's weight and uses small battery packs. A scaled up version could see some solid applications outside of the fun toy realm.
Yeah, interestingly the founder's original vision was to levitate entire buildings to protect them from destruction during earthquakes. But, he figured pitching a hoverboard would be better for getting the word out, so he went with that.
So far it looks like it's working - lots of media attention and over $100,000 raised within around 12 hours of launching.
Anyone have more ideas on how this works? It's not solid state, though they say future versions could be. I'm wondering if each of the four cylinders that make up the "engine" just houses a rotating disks with large neodymium magnets attached with alternating orientation (N-S-N-S-...). The faster they spin, the larger the generated repulsion force as per Lenz law. Then it's just a matter of balancing the forces, at which point the thing is basically a quad copter that uses EM.
This might explain why they don't have to worry about coils overheating as mentioned by Conundrum earlier.
Edit: more details in their "Is it safe?" note:
Our hover engines have been measured at inducing over 2000A per cm2 in the substrate below. Amazingly, it is harmless. We’ve all put our phones on it, hands under it, tried everything to harm ourselves so you don’t - its safe...as long as you don’t get a finger between it and a ferromagnetic surface (i.e. anything a magnet sticks to) you’re fine. The technology focuses the magnetic field downwards, while the field on top of the board/box is negligible. We’ve measured it. And while we feel a person with a pacemaker could lie on our boards safely, we certainly recommend caution around our systems for those with implanted electrical devices.
Does the technology really "[focus] the magnetic field downwards", or is this just a fancy way of saying "the magnets are on the bottom of the board, not the top" ?
I'd imagine it would be cost effective just to put high permeability metal (permalloy, mu-metal, etc) on top of the magnets, just from a standpoint of cost of magnetics. That's basically how they put NdFeB magnets inside a hard drive, where space and stray magnetic fields are major concerns.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
I dont know for sure, but i would think at 2000 A per cm^2 it would generate some heat in the sheet if it didnt move to a new location.
And if their spinning the magnets, doesnt that force need to eat power to exist? And i mean a significant energy for lifting, even though its not as bad as a reaction mass system.
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
At 40W/kg, levitating an 80kg person on the board will take 3.2kW. Thats going to be one hell of a battery pack if you want more than a few minutes ride time. Hovering a little box - ok. Hovering a person on something the size of a skateboard? - i'm a little skeptical.
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"Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
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