I cadged this from an old dirt bike to use one rotor on the rear of an existing generator to help with wind gust overspeeding. But a bench test convinced me I was adding more potential problems than I was fixing, so I solved that mess with a rebraced tail boom and quicker furling. With this thing still in hand, I decided to use up all the old HD magnets I have taking up space, in line with the thought that no magnet should go to waste.
With my metal lathe, I can clean up the hub interior, and adjust the spacing. The rotors are 9.5" across, and .25" thick. With the open rotor design, cooling should not be a problem. I am thinking 20 sets of magnets with 15 coils, wired three phase.