I can't let the flywheel run down like that. For my purposes, it can safely be assumed that the object the motor is attached to is free-floating. (The flywheel turns one way, and the object turns the other.) Letting it run down would be too time consuming.
In other words, if the motor slows the rotation of the flywheel, and the motor is fixed, the kinetic energy of the flywheel has to be absorbed by the motor. However, if the motor slows the rotation of the flywheel, and the motor is free, the kinetic energy of the flywheel should rotate the free-floating motor, and not have to be absorbed by the motor.
I took a look at the model car ESCs, and they seem to run in the $40-50 each. For my physics project, I will need a minimum of three. I would prefer to keep my costs low, which is why I was looking at model airplane ESCs ($10-30).
I need to work on doing more calculations to confirm that the kinetic energy would not be absorbed, but if I'm correct, would a model airplane ESC work?