There could be bennifits to putting the space ring on the outside, preventing water/ice from entering. And with just a ring the stator could be mounted differently, like directly to the axle instead of using mounting brackets. I have many different ways in mind to do this, including the way the stator is made.
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It has the bolts on the outside of the rotorplates, to mount them together.

It's basically an upscaled version of my tiny genny (10W/.8m turbine diameter). My system gives slightly bigger rotordiameters, but you get more room in the center where you need it most.

However, with my bike genny I was already running into scalability problems; the system works, but for anything larger I'd go to the standard Volvo-hub method (rotorplates connected in the center).

With my method, your rotordiameter increases because you need extra room (bigger diameter of the rotorplates than the statorplate. At larger sizes, these few extra cm's make for much extra weight and 'perceived' size, whereas at smaller diameters it's hardly noticeable.

I thought I said in the thread of the bike genny that for larger sizes the standard layout might work better. Just wanted to repeat the point here.

However, for the 'back' rotorplate (the one furthest from the prop), my method gives a big hole in the center, with the magnets mounted on a small 'rim'. This saves a bit of weight. Still, I think I'd go with the system of the Dans rather than mine.

You might try to 'skeletonize' your rotorplates, or drill holes to reduce weight & better cooling/ventilation to the stator? It would reduce strength only very little.

Looking forward to your updates,

Sorry Ed, I think it would weigh more like 350lbs maybe 400lbs, the second rotor would have no center becuse it's just an outer ring, but we have to add some for bolts and spacer also.

I figure the Lenz2 I build might turn it ok, 8' Dia 4'tall?
Just kidding.

Actually I have put alot of thought into some of these BIG ones. I found some OLD tractor wheels, spoked steel wheels, broken cast iron hubs. The outer rim was like a ring of channel iron probably around 6'dia.

I did not buy those then, no way to haul them, but it got me thinking on this really big stuff.

48" dia? Shucks they are almost half way there now at 22", what will be be seeing them build in June or July, 36" so this time next year (or sooner) they may hit that size.
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On the main subject I have also had similar thoughts on using one disc with a ring on the outside. The spacers could be steel but something lighter would be a good idea.

Even with 2 discs it would be a good idea to have support to take the load of the magnet pull. Could make the supports act as a fan as well. Not that I shall make anything that big.

Don't forget the bearings too. I bet the wheel and axle will handle more than the bearing will. Is that Mercedes a big car?

My rule of thumb is sort of figure weight of car, divide by 4, add a whole lot more :)

Old heavy cars 4,000+ pounds, is over 1,000 pounds per wheel :O
My 67 olds was 4,400lbs without people or cargo!
The wheels not only have to carry the weight, but at 70-95 MPH they have more spinning forces trying to rip them apart also. Then  take a sharp turn at 60MPH and if the tires don't skid there is all that weight and other forces trying to break them in half sideways. Add to that POT HOLES they smash into at highway speeds.

Is it really posible to over load the axle, wheel, bearings ec.. with a low rpm heavy genny yawing in hard winds??? Would your tower support 1/2 a car?

I really don't know that answer so play it safe!

 And not all cars are built the same, some barely will go 60MPH and don't weigh much either, smaller less solid wheels etc.. so what your working with will change in what it can handle.
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