Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
hen918, Tue Oct 21 2014, 04:56PM

Looks like someone had supercharged a levitating globe. No new technology, not even a proper specification.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Artlav, Tue Oct 21 2014, 05:21PM

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.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Conundrum, Tue Oct 21 2014, 05:27PM

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.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Nucleophobe, Tue Oct 21 2014, 05:45PM


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" .

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Sigurthr, Tue Oct 21 2014, 06:25PM

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.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Nucleophobe, Tue Oct 21 2014, 10:12PM


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" ?

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Sigurthr, Tue Oct 21 2014, 11:35PM

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.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Wed Oct 22 2014, 12:26AM

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.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
2Spoons, Wed Oct 22 2014, 01:14AM

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.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Nucleophobe, Wed Oct 22 2014, 02:23AM

They only claim about a 10-minute ride per charge, so if they have about a 500-1000Wh battery that would make sense (extra watts for the added weight of the board and battery).

A lead-acid car battery has around 1kWh and Li-ion batteries have higher specific energy (100 - 200Wh/kg).

Not sure what room there is for improvement though.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Conundrum, Wed Oct 22 2014, 06:38AM

Using superconducting wire would reduce current usage substantially.
Most of the losses are resistive in the coils so 10% less loss = 10% cooler.
Also one improvement I came up with is to use switched coils so they never heat one small area too much, and spread out the field over about a square meter of copper surface to both increase lift capacity and increase system efficiency.

Shame there isn't a way to make any surface briefly conductive, maybe something that filters out argon from the air, sprays it onto the surface and applies a transverse RF field to form a glow discharge plasma which then acts as a pseudo-conductive surface?
Great Scott!
(scuttles off to Patent Office..)

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Wed Oct 22 2014, 07:06AM

No, No, stupid... what you really need is neutrino polarized di-lithum yttria film. Duh.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
dexter, Wed Oct 22 2014, 08:37AM


wouldn't that produce very high back EMF unnecessarily complicating the system?

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
carrotSnack, Wed Oct 22 2014, 09:27AM

My understanding is that it doesn't use coils but electric motors that spin halbach arrays.
That's what it means when it says it 'focuses' the magnetic field.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Uspring, Wed Oct 22 2014, 11:24AM

My understanding is that it doesn't use coils but electric motors that spin halbach arrays.

Any idea how the array is rotated? Along its long axis? Rotational axis being horizontal?

A simple magnetic dipole rotated perpendicular to its axis would cause a similar pulsating magnetic field.
I'd expect also some sideway forces from these kind of rotating magnets. By using several arrays rotating at different speeds, these boards could be made self propelled, which seems almost a necessity, since the eddy current braking effects might be significant.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Artlav, Wed Oct 22 2014, 06:15PM

That reminds me of a certain device i have, namely an axial flux outrunner motor, that can be used for an experiment.

The magnets on the rotor are flat, and are flipping polarity one after another.

Here is a video of how it behaves next to a slab of copper:


The magnets on the rotor's bottom are spinning in the same plane as the slab, and that produces significant repulsive force.
The motor struggles to spin, the eddy currents try to stop the rotation.
At low RPM it tends to oscillate, but at higher speeds it's floating quite stable.

The motor's body tries to spin out the other way, so i can't let it just float there, but it's hovering on it's own - the strings are only pulled counter to the momentum.
It's quite hard to make it touch the surface, even if dropped - it jumps back up, and maintains about 1cm of distance at full RPM.

There is almost no friction when moving sideways spinning, while there is some when it's not.
All the braking seems to happen to rotation, not to the sideways motion.

I can totally see two or four of these counter-spinning to make a stable hoverboard, but i'm not rich enough to get a sufficiently big slab of copper. :)
Perhaps aluminium...

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Wed Oct 22 2014, 07:01PM

Yes, it seems to be a souped up version of this:



Halbach arrays do work, but are a pain in the ass to make. Iron backing plates work almost as well, and more or less self assemble.

If anyone wants to make one, I can help you out with the design parameters; I warn you, you will need some serious neodymiums aka 'death magnets'.

The conductive sheet needs to be roughly half a centimetre or so thick aluminium.

Incidentally, propulsion is easy to arrange; I don't know why they aren't doing that.

n.b. that video's not mine, but I've been working on similar tech, and I've specifically had to work out how to do that

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Artlav, Wed Oct 22 2014, 07:13PM

Drats.
An i was just warming up to print the second motor to do just that...
Foiled again. :)

Seriously, nicely done - it does actually work that way.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Wed Oct 22 2014, 07:55PM

All of these methods revolve around a non ferrous conductive sheet below. so sliding through town is out, youd be limited to prepared areas.

The halbach ideas are usable, but i ask, will they spend more on a gaggle of "hover" boards or the skate park. ALuminum and copper are not cheap, and you'd need a certain minimum thickness a presume?

This could all be done, not saying its impossible, and an entry fee to a park eases any such burden. Especially if these whacky young kiddos' take a cult liking of it. Rob Dyrdek should be in on this...

And once im an old grey man im sure they'll have it all figured out.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Thu Oct 23 2014, 12:28AM

Oh there's no problem.

I find you need about 3mm or more thickness to get decent lift; but pretty much the thicker the better (it's because inductance goes as the square of the thickness, surface resistivity goes inversely); but obviously there's no point in it being thicker than the skin depth at the frequency you excite it at; but you can always slow the spin down; you want one skin depth thickness.

2m x 1m x 3mm ally costs about £125 by the look of it. so it's moderately expensive, but not obscenely so, the board will probably be more expensive unless you're covering a large area.

However, if you make the poles very big, then the required thickness goes down, but you tend to end up with very, very big magnets if you're not careful, turns out thin, wide magnets don't work very well; they need to be about half as tall as they are wide for good lift. edit: you can probably get away with thinner metal if you spin faster to get the skin depth down, and use lots of magnets rather than big magnets

There are some stability issues, if you lean, one edge will sort of dig in and spin you around.

DOIT

Incidentally, you really, really need an iron backing plate in your disk, about a fifth the thickness of the magnets. Doing that will do something like double or quadruple the maximum lift. Make sure the iron is well saturated.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Shrad, Thu Oct 23 2014, 07:37AM

that would be a nice thing to try with HDD motors running iron plates and hard disk magnets...

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Uspring, Thu Oct 23 2014, 10:23AM

Compliments on how you guys figured this.

I'm now wondering about the efficiency, i.e. the lift to drag ratio. I'd expect the eddy currents to be proportional to rotational speed of the rotor and the lift and drag forces also. Power consumption would then be proportional to the square of speed, lift only linearly. That would give slower rotors an advantage as long as these can support the weight.

Another question is about the arrangements of magnets. Is that optimal or could they be placed so that their axes are parallel to the circumference of the rotor? Another idea would be AC driven coils with vertical axes. Might be somewhat more efficient since the eddy currents create a directly opposing fields, i.e. lift only and power consumption is only in the eddy currents (assuming the electronics to be 100% efficient).

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
dexter, Thu Oct 23 2014, 11:23AM


HDD motors are to week for this as they have very little torque capability

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Thu Oct 23 2014, 11:28AM

At a given gap size the lift curve looks like this (this is actually a linear motor curve, which has the same properties):




The blue curve is the drag curve, and needs to be multiplied by the rotation speed and radius and multiplied by a constant to get the power. The red lift curve is fairly flat once you get lift.

Notionally, the constant depends on the resistance of the plate seen by the rotor. The resistance depends inversely on 'how much' copper/aluminium is involved in carrying the current to achieve the lift; i.e. the volume of copper/aluminium under the magnet in which the currents are flowing.

The lift and losses are both proportional to I^2. Obviously you want the resistance to be as low as possible; as the I^2 R losses are the power you need to levitate.

Ideally you would want no resistance (superconducting plate) but that's impractical due to the low temperatures and large areas (but it's certainly possible for small areas).

Failing that, the biggest area of magnet possible because that gives the biggest volume of aluminium/copper.

Now you might think that a big very thin layer of magnet is just the ticket, but when I tested it, it doesn't perform-you get very low levitation forces. You need a layer of magnet that is about half the pole size thick (preferably with an iron backing plate), because that increases the field strength... the pole diameter also determines the lift height because the field of the magnet has a scale height that is the pole diameter.

Interestingly there's no theoretical low limit on how little power you need; levitation doesn't take any power (vertically, force times distance is zero). It's the horizontal drag that's the problem. In practice these kinds of systems usually make excellent room heaters. However large enough area of magnet/thick plates can give low loss because it brings down the I^2 R; you're sharing the force over a large area, and so the resistance is very low.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Uspring, Thu Oct 23 2014, 02:02PM

The lift and losses are both proportional to I^2

Why would lift be proportional to I^2 ? I'd expect the field caused by the eddy current I to be linearly dependent on I and consequently the lift and drag force also. What I can understand is that they seem to level off at higher f, probably due to the skin effect.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Shrad, Thu Oct 23 2014, 02:05PM


I mean at a lower scale, as when they are rewound they can be pretty nice and could provide great RPM... and you'd easily secure the aluminum body to a frame of some sort...

Of course I don't think a HDD motor would lift a man ;)

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Thu Oct 23 2014, 02:06PM

Oh wait, my bad. I was thinking of an induction motor; it's I^2 on the primary current there. It's (essentially) because the current creates a proportional current in the secondary, and the two currents, the primary and secondary currents repel each other.

With a permanent magnet system, the ampere current in the permanent magnets is constant, so the lift is proportional to the current (for constant field) in the secondary (i.e. the plate), but the losses go as I^2 R, so you want the lowest resistance you can, but still a high current to give you good lift.

So far as I can tell that changes the detail, but not the broad brush effects.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Sigurthr, Thu Oct 23 2014, 09:58PM

Btw, in the kickstarter video you can see they're using a RC hobby transmitter to indeed control propulsion on one of their R&D boards.

I wonder what the upper weight capacity on these boards will be. I did some back-of-the-napkin math the other day and came up with somewhere around 4kW to levitate my 100 kilo self. Not real promising. I figure a common hobby 50C 3S 6Ah lipo might get me a minute of "flight time" if the system was incredibly efficient. I am on a diet but the math doesn't look good, haha.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Thu Oct 23 2014, 11:20PM

Sounds about right. I looked at this before and reckoned a few horsepower. Basically, we're talking lawnmower engine type levels of power, or, with care, a 13 amp socket could potentially supply the necessary power.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Fri Oct 24 2014, 06:03AM

ive been seeing videos and stories on the national cable news channels. But as others have said, it all comes down to power stored, vs. power consumed.

this is the very problem many of us have with light aircraft, spacecraft and micro-drones. Even the best LiPo/LiFe batteries are just terrible for run time.


I use one of these batteries in my current drone for 8 minutes of flight time. so if a teenie-bopper has less mass, and you pile ten LiPo's on it, you might get a few minutes of useful time in a skate park.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Uspring, Fri Oct 24 2014, 08:54AM

this is the very problem many of us have with light aircraft, spacecraft and micro-drones. Even the best LiPo/LiFe batteries are just terrible for run time.

Nice analogy, especially if you consider, that the lift to power consumption ratio improves with rotor area or number for hover boards similar to helicopters.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Fri Oct 24 2014, 01:59PM

If I was doing it I would probably try to use an IC engine, like a model aircraft engine.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Fri Oct 24 2014, 03:20PM

I have a glow-drone battery replacer here on the forum some where. But the Planar-ferrite and drone-prop projects have my full attention right now, so i cant help anyone out on such a solution, though i really think IC is the way to go.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Conundrum, Sat Oct 25 2014, 08:47AM

Possible ideas: metamaterials (not quite superconducting but still viable) and materials more magnetic than sintered NdFeB yet to be discovered ?

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Sat Oct 25 2014, 01:23PM

It's the conductivity of the plate that's the problem. Silver, graphene or superconductors are better than copper.

At high frequencies, you need litz wire loops, and poles big enough to fill them.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
dexter, Sat Oct 25 2014, 03:34PM


if only those materials were cheap.....

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Mon Oct 27 2014, 04:34PM

I don't think by normal standards this is expensive.

Per metre the aluminium is about £200 for a 4m wide strip.

Compare this to a road for example, a road will cost about £1000-£3000 for roughly the same width; so topping them with aluminium adds very little cost; it would last ages, and it doesn't wear.

So you could quite conceivably put aluminium channels everywhere and use that instead of roads.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Nucleophobe, Mon Oct 27 2014, 05:35PM


I'm not sure I follow - you need to consider cost per length for aluminum channels vs. traditional asphault road. A road costs "about £1000-£3000" for what length?
*EDIT: Apparently I can't read. You said "Per metre...", but you didn't specify the thickness. Anyway, I verified your claim I guess!
********************************************
Some quick numbers I found say that it costs ~$6 million (USD, or ~£4 million) per lane per kilometer of asphault rode

If, in addition, two narrow aluminum channels, say 60cm wide x 0.5cm thick, were to added to the road surface, that's about 10m^3 of aluminum per km. Density of aluminum is ~2700 kg/m^3, so we are talking about 27000 kg of aluminum at about $2 / kg... so only ~$60000 / km / lane? (or £40000 /km /lane) Wow.

I hadn't thought of the fact that you would only need two narrow channels rather than coating the entire surface.
***************************************** ***

Still, losses with wheels are not so bad. Even if you go through all the trouble to make aluminum-plated roadways for hovering vehicles, you will still have aerodynamic drag. I'm not sure what you really gain other than cool factor and (maybe) a smoother ride.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Mon Oct 27 2014, 06:11PM

Where are we to mine all this aluminum, which will be permanently out of circulation for other purposes?

During WW2 and the cold war, the US, UK and others were desperate for aluminum, copper, mercury and other metals.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
hen918, Mon Oct 27 2014, 06:29PM

The aluminium would have to be smooth and flat for the greatest efficiency, if the aluminium was used on roads that were also used for non-hovering vehicles, there would be no traction in the wet, the aluminium would wear very quickly and, in the nasty outside environment, it would also corrode in a very short time (non-hovering vehicles or not)

Not to dishearten you or anything :)

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Mon Oct 27 2014, 07:42PM

There may be better use of this tech, like moving dangerous materials where the travel is predictable. Yuca mountain and Hanford type sites come to mind.

Non-contact to avoid tracking contamination, and sealed no-moving parts are two advantages.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Mon Oct 27 2014, 09:04PM

There's never going to be a shortage of aluminium. Aluminium is one of the most common elements on earth.

Aluminium is very stable except near the ocean. Even then you can paint it.

That is the issue with these kinds of systems; they're not sufficiently better to make them worth building. Aluminium would probably last better than roads though, maintenance costs for maglev are usually very low, but upfront costs are usually higher.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Patrick, Mon Oct 27 2014, 10:01PM

ok fair point, but it still requires enormous electricity to obtain Al.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Shrad, Tue Oct 28 2014, 11:05AM

isn't there a compound of aluminum which could be grind off in such a fashion as to provide enhanced conductivity as well as deliver mechanical properties which are compatible with modern road construction processes?

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Tue Oct 28 2014, 12:46PM

Well alumina is quite hard, but non conductive.

Road surfaces are surprisingly complex. Getting a flexible, hard wearing, water shedding surface that can survive winters is not at all straightforward.

It might well be possible to stick a cm layer of grippy alumina or other material on top of a sheet of aluminium; and run the levitation through it, to the aluminium below.

Although it's possible, whether it would be a practical system in the round, I doubt.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
hen918, Tue Oct 28 2014, 04:25PM

And then there is the safety issue. Top speeds couldn't be very high. As the hoverboard appears on the kickstarter page, stopping sharply would throw you off. (If you could stop sharply, that is)

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Shrad, Wed Oct 29 2014, 10:32AM

that's already the case with a car... if you stand up at the roof like you would do with a skateboard, no doubt you'd be thrown off...

I know how complex the process of making road surfaces is, I saw a test lab with different types of surfaces and this is a science in itself...

what I wonder about the adaptability is if we could conceive a conductive mix which would behave like modern road surface mixes while still achieving the (surface) conductivity required for levitating such devices

the aluminum relative cheapness combined with the fact that it would be possible, due to the absence of tire contact and degradation, to have a durable coating which would require little to no maintenance would make for a very interesting displacement medium even for personal transportation...

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
BigBad, Wed Oct 29 2014, 02:46PM

I don't think the combined road thing is a good idea, but you could conceivably make a luge style course out of aluminium as a halfpipe or something.

I haven't quite worked it out, but potentially you could steer these types of things; if you look at the graph I gave above- by varying the spin speed, if you have forward speed, some parts of the rotor will be moving at close to the track speed. That will then give you a significant lateral force based on the relative speed they see there.

Re: "Magnetic Field Architecture" and the HENDO Hoverboard - *ALMOST* a real hoverboard
Conundrum, Thu Oct 30 2014, 10:10AM


EDIT: Flooring materials.
SrTiO3 and a UV light to "charge" up the floor and make it conductive while the board is over it.
Adds to the challenge as fly height would depend on who has been over that spot before much like ice skating.

Also worth considering, put an induction charger pad under the floor as this would now be feasible due to the transient nature of the conductivity.
Any "hot spots" would rapidly transition back to an insulator.

Re. steering, a simple pair of coils that applies braking force on one side would allow sharp turns.