What is a "nice range of voltage"? 90-270V ?
A potentiometer, by itself, cannot control the speed of a motor, unless it's a very, very, small motor. Typically, you will use a motor controller, that will typically use PWM to make/break power connections to the motor, to regulate how much power it generates.
A pound of force makes no sense for specifying a motor. Motors generate torque. You must decide how far from the center you want that amount of force. For example, if you want 60 pounds of force one foot away from the center of the output shaft, that means you want 60 foot-pounds of torque in the motor.
Note that gearing will affect torque, as well as inversely affect the shaft speed. A typically way to get lots of torque from a small motor is to use high step-down gearing -- 300:1 is possible with a multi-step gearbox.
So, you will need to know, at a minimum:
- AC motor. What frequency of AC? What voltage range, specifically?
- What gear box you are willing to add/use.
- What RPM you want.
- How much torque you want at that RPM.
Then, you may be able to choose a motor that matches those parameters.
Once you have that, look at parameters like current and temperature, and start figuring out how to drive the motor.
- Motor controller for the kind of motor you have (AC, DC, brushless, ...)
- Input mechanism for motor controller.
- Mounts and adjustments for motor, shaft, gearbox, linkage to flywheel, etc.
- Electrical connections of the right kind for your installation.
Now, you can start worrying about what you're going to do with your flywheel. Do you need a clutch, for example?
