Neat progress on the motor, especially with the cooling.
I love the forced air cooling, which I probably would make into a CO2 on-demand system, with the custom aluminum wheel likely being fine for me most of the time.
There's still a lot of room for improvement in the wheel's capacity to dissipate heat.
First, surface finishes have a big impact on heat transfer efficiency. Polished metal has about the lowest emissivity of any surface, and what you actually want there is to take advantage of black body radiation on the surface of your heat exchanger. That's why radiators are usually flat black. Black anodizing a dull aluminum surface on the outer wheel would be good, but a thin coating of flat paint is actually better- and cheaper. Here's an interesting short paper about it from the computer business:http://www.vxibus.org/files/Transferrin ... 20Heat.pdf
There's also a lot of room for improvement in the shape of that wheel. Ideally, it would be like a turbine blade, with axial cooling fins pulling air through itself and around the motor. Probably prohibitively expensive to cast, but fewer, wider blades with enough spacing between them for the machine tools to work could be CNC milled from a thick blank, perhaps within reason on cost. if that isn't practical, blades could be made separately and fitted to spokes cut into the wheel. If nothing else, axial and/or radial fins like on the brake drums of old bikes and cars would also help remove the heat, but they would work even better with the fan blades- cast, machined or attached.
Lastly, even with the best possible fit, the motor should be mounted in the wheel with thermally conductive paste to maximize heat transfer.
Just some ideas for you. By the end of the year, I'll hopefully be needing a setup like this. Also very interested in the 2-4 turn switching.
Great job so far, Mark.