Thanks stevez. Thats what I had in mind, I did not say it was a cheap DC motor but I could have implied it by saying from a model. I'm talking about a purpose built sophisticated high precision outrunner* AC type with ESC capable of spinning the the flywheel at very high speeds, In a hermetically sealed case, very heavily constructed, (see first post) only the wires (sealed of course) exiting. using a very efficient vac. pump. The flywheel would have a mass of around 100+ times that of the motor. The bearings would be non touch rare earth magnet type. But bottom thrust (mass)carrier maybe some form off jewel. But I do need to convert the output to DC.
*Windings stationery magnets inside very strong steel outer case.
Thanks to all Rog.