Theres also evap stages for a precooler to a regular AC unit, which can greatly increase the efficiency of that. These dont need their own motors, though, becuse the one for the regular AC unit would pull the air thru. (or it could be replaced with a larger blower if more airflow is needed). I need to build one of those for the house roof unit we have now (because it needs *something* to cool the air from the roof that gets sucked into it to do the cooling of hte exchanger coils. That air is something well over 130F at best in summer, at least when it starts up.
At least some regular A/C units use brushless motors in their fan systems now. IIRC our roof unit does; it has is own built-in controller. A friends from at least a decade ago did, too; we tried to fix the controller (since that was all that was wrong with the motor) but it was potted in a way we couldnt get into to test and fix stuff without more work than it was worth.
Didnt occur to me till you said this, but I suppose it might also be possible to build a mount for the hubmotors axle that replaces the central spindle of the squirrel cage, and places the hubmotor at one side of the squirrel cage, centered in it with a mounting bracket or ring, so it drives the cage directly. Just arrange a nother bearing on the other end of the cage, if you have to remove the original, and then setup the voltage for the motor to be the right RPM for the fan.
What about an intermittent misting system for the roof?Id also like to add a shade over the whole roof, but I dont yet have a practical design I could build that would also survive storms with gusty high winds.
http://www.partsforscooters.com/120-58_motor_Currie This is the motor or one of them. Don't want to spend a lot of money on belts?