Hey all,
I searched the board, like a good little boy, but didn't find this question arising.:-)
Why not composite rotors? It seems possible, given modern chemicals and materials, to cast a rotor with a magnetic property similar to iron, yet be much lighter and by far stronger. Could a honeycomb structure, like used in some other composite cast structures, but with mild induction silicone steel, like used in electric motors, provide the proper flux paths to work? Imagine a sandwich of very thin steel folded into tiny little ripples, a layer of carbon fiber with magnetic binder, a layer of thin folded steel, ect...
If not done with a honeycomb a solid casting of some sort, maybe with the magnets set before curing to lock the attractive particles into their natural positions? Steel "skins" could be used on the magnet side as a placement guide/lock and a backing skin to trap the cast and act as a final barrier to magnetic attraction.
Ceramics comes to mind but are they really strong enough to withstand the attractive forces of opposing rotor effects? The Japanese experimented with cast engine blocks that didn't need a cooling system. Clearly ceramics can be strong. If a method could be developed to maximize the return path effectiveness with more accurate, lighter and better balanced spinning parts the mechanical advantages become clear, on "paper".
Maybe a combination of methods. Cast a ceramic "core" with the magnet recesses formed and ready after baking. Lock the magnets into position with space shuttle tile glue onthat ring. :-) Build up several layers of die cut fiber on the magnets, and cap with a steel skin, also die cut, to terminate the magnet face lay-up. On the out-facing side of the ceramic ring a series of precut mats of fiber are laid up and the terminating steel skin is applied. In the binding epoxy a magnetic material is added to the mix and the entire lay-up is clamped into a jig for curing and final alignment. Post cure trim and finish with hyper protective paint.
Cost effective? I doubt it. I also doubt any of us could immediately see a pile of bucks show up in a UPS truck as result of this "idea". There are very few members here that could even attempt to tinker with such a notion. I ain't one of 'em! In the end auch thinking is often required to inspire others to think somewhere outside the box, but to so far as to need a crate to get where I was already headed.
It just seems to me that the lighter the rotational mass of the generator, without a reduction in strength, with possible gains from use of exotic metals in the casting chemistry, works out to all good results. The life of the shaft bearings and the responsiveness to the wind in actually generating electricity instead of accelerating mass also seems like a good trade off. In a mass production setting the rotors could be cast matched where very little "jacking" would be needed to allow the opposing rotors to remain true to each other.
Ideas?
