We're working on a project that's using a double fly-wheel system (like a pitching machine) to launch a 390g ball at a maximum speed of 9m/s. What sort of motor would be appropriate for this? The two main features we need are variable speed control that's as precise as possible and enough torque to reach maximum speed (around 500rpm) in less than a second and launch the ball.
After a lot of research I think a 1/4hp motor rigged to some sort of speed control apparatus would be way, way more horsepower than needed, but don't know for sure. I'm coming from a math/comp sci background and don't have much experience in situations like this.
Any advice would be really appreciated!