@Goos
I just found this thread on google and I'm not entirely up to date with you guys but maybe you could have the batteries strapped to your leg or chest like a suicide bomber.

Despite the somewhat disturbing description, that kinda takes away the essence of the idea, not to mention that batteries might generate some heat during stress.

Well I'm sure there's a way to protect your skin from the heat assuming it doesn't get too hot and it might not be exactly like ATs but it's still pretty close.

You guys really think something like AT's can be made in the near future?... looking how the Amercan population goes more into the FAT future... being able to drive those things with a big body mass will be kind of chalenging.

Looking at most of the motors u guys have found the only way i see to get them to transfer energy to the wheels is trough a chain or some kind of system alike those with belts... and that kind wastes too much energy.

Have anyone though about some kind of pancake motor where the rolling mass is the outside part ? Just like those in the Bah great! desing?.

I've been reading through this for a while now and it seems your on the right track with the batteries using Li-Po cells as their the only thing on the market that will give you the necessary power output. At this point the technology is still fairly new so you can't expect more than 5-10 minutes of running time for a few more years but it will definitely be possible to increase this in the near future.

As for the motor I might as well break it to you that you'll most likely have to build something. The silencer series of motors that have been mentioned a few times are a good idea but they can't be converted to be used as an in-wheel motor. Unlike a brushed motor the windings of a brushless motor are in the can with a magnetic rotor spinning in the middle. This makes it impossible to have the can spin while the rotor is stationary because the wires must be attached to the can and would get spun with the motor and eventually break. It could be possible to convert a brushed motor but the amount of work and precision needed to do it don't make it worth the time and effort.

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OK guys, the silencer series can still be used but you need to modify the wheel mounts to accommodate a larger wheel. As for pancake motors that is possible, I've mentioned before that if you simply reverse the power connections, the motor will spin the other way. But the pancake motors need a lot of power. Also, thats exactly what we had thought of previously for the acceleration, but for now there is no point in talking about it, at least until we have a working prototype (by witch i mean, skate with motors,batteries and a power switch, nothing else). Finally, the best option we have at this point to carry our power supply is a backpack, as long as you put slack on the wires, they won't effect your mobility, and to be honest most skaters carry backpacks anyway.

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I'll shoulder the burden and carry you all up to the sky

@goos
we could use le wheel motor's battery
now your saying that the problem is a space for the battery to fit in the frame........
I think the solution is sticking it at the back of the roller blades instead of putting it inside the frame......
btw its just my suggestion

You have been working with RC-cars, right? Do you know how much regenerative coasting could do for the batteries? I'm still new to the stuff, but since we'd spend almost more time coasting off the wheels without the motors spinning than we would with the motors spinning, wouldn't that possibly add a lot to the distance?

And Tokuin, why is it exactly that pancake motors require more power than other motors? And do you think it would be possible to mount two pancake motors per wheel? I.E. one each side. Wouldn't that possibly reduce the torque required per motor to get someone moving, making it possibly to opt for a higher-RPM motor?

EDIT: I've also tried to come into contact with some people here in Sweden to make a prototype or share some expertise, but the people in the local "innovator's forum" are all on vacation till early august. :<

I've been racing RC's for more than 5 years now. I'm not sure how much charge we could generate in the batteries form coasting but it is a good idea. The only problem is we would need to design some sort of generator within the wheel that could convert the inertia into usable power. This would be quite hard since there is very little space to begin with but I'll see what I can find since it could greatly increase the running time.

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Well goos, if you look on the website, the motors are actually meant for fans and things like that, so the motors are made to run from n outlet and not a battery. If I'm not mistaken, the lowest power consumption out of all the pancake motors on goldenmotor.com is 30v. Also, while i agree with the concept of using two paralleled pancake motors, the extra torque really isn't necessary. For one, we won't be relying on the motors to from 0-40km/h, we will be propelling ourselves with our feet than to reach a higher speed we would use the motors. If we did use the motors from the start, it would be a major drain on the battery, even if the motor had the necessary torque, it is really the batteries that limit us at this point. But there is one problem with the idea, in total it would be thicker than the silencer motor.

BTW, some1 has already mentioned an in-wheel generator that could be used to recycle power. Which means our rear wheel would have a motor and our front wheel would have a generator.

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I'll shoulder the burden and carry you all up to the sky

That in wheel generator is an awesome idea

@McBlaise

Well, in the anime the batteries for the ATs are stored in a compartment in the back of the skates. It is opened via a hinge-type door.

Since i'm really not that good with anything mechanic, that is really all i have to offer. So, if there is a battery that could be fit in the skates, it could be put there.

@oXMadHatterXo
what I meant is putting it vertically at the back of the skate...
in air gear they put it at the back of the skate horizotally to the frame...
my idea is for giving more space in the frame for the electronics to be stored

@ Tokuin; The reason I was proposing two pancake motors is because with the size we have available (probably ⌀60mm x 10mm per side of the wheel) the motor would probably produce insufficient torque/speed alone (even with us moving at our own force), and possibly require another motor. Now I don't know if they are available at small dimensions such as these, as I said I haven't done much "research" about it.

But in a scenario where one pancake small enough to fit in would produce enough torque/speed, couldn't we fit in an equally sized generator on the other side? That way we could still have a motor for each wheel to provide a "symmetrical acceleration". Or if we actually would need two pancake motors, wouldn't it still be possible to mount a generator inside the wheel?

And about the voltage, I think I proposed it elsewhere, but if we could get any decent juice out of the regenerative coasting, we could probably use some kind of ultracapacitor in conjunction with a [slightly smaller] battery. The ultracapacitor would then provide the power required for the motors and regain the charge from the regenerative coasting and from the standard battery constantly pulsing to the capacitor. Much like how new hybrid cars work.

And @ McBlaise, wouldn't it possibly be very hazardous to mount a battery on the back? It could work for the prototypes and early models, but once people get the hang of it and start jumping over small obstacles, they could easily get bumped from these various obstacles and stop working. Li-Po batteries are apparently really dangerous when handled without care


By the way, I've also been thinking of the matter of absorbing shocks. And first off, as we all know, similar magnetic poles repel each other. And before I explain the general idea, I made a "3D sketch" of sorts. (a halbach array is a way of setting up magnets to increase the magnitude of their force, google it to get an idea)

So the spring-part carries the riders' initial weight, keeping the magnets at floating distance (as in the maximum distance which they repel your bodyweight) and once force is applied, the spring will compress to its' minimal height, and just then will the magnets be pushed together, and since magnetic force is reversely proportional to the distance, the closer they get, the stronger the repelling force will be.
So the spring will take care of the small bumps without you feeling anything, while the magnet will effectively decelerate the large bumps such as jumping down from ledges etc..

Of course this inventor image is just an idea of the general layout, but I was thinking, to save space, this whole thing would obviously have to be minimized in several ways, but it would also be possible to mount this whole thing inside the molded frame, and then having the battery and other electrical components inside the space between the magnets. The upper transparent part would then be the sole which the boot remains upon. The whole thing would of course also have to be molded snuggly together to keep parts from going in other directions than up and down.

I would start working on a complete air-trek in 3D but until recently my CAD/inventor skills only stretched to making lifelike renders of certain famous owls and similar things, leaving the process relatively slow and chunky

Last edited by lambchopsil at 8:48 am, Jul 9 2009

@Goos: Exactly that's why I thought it would be good to have a single page for that. I don't know how many scribbles and really good ideas are going lost in this now 75 page thread but we all throw ideas in here that get lost over the time. It looks like you're using blender for design, maybe I can help you on that one, currently working on a material library and manager for blender. I can model a rough framework for this.

To everyone: What do we need on the page? Like I said there is going to be an IRC Chat, blueprint gallery a board and a google map. What more?