spring loaded launcher

[sciguy125]

Has anyone given any serious thought to a spring loaded cannon? I've been toying with the idea on and off for the last few days, but I actually sat down and worked it out today.

I've had everything revolve around a cauking mechanism that uses a cam. Think of a flat egg shape with a bite taken out of the side. Put it on a motor with the shaft centered toward the larger side. Now, have a spring loaded plunger that is in direct contact with the cam. As as the cam rotates, it gets longer and pushes out. If you rotate far enough, you get to the "bite" and the tension on the spring is suddenly relieved. If you keep rotating, it will retention and you can start over again. (Crude drawing attached)

The ball needs 13J, so with 4" displacement on the spring, it'd need roughly 60lb of tension. I don't know how to do the exact math because of the oddly shaped cam, but it'll take between 0.3 and 1.3s (most likely close to the middle of those) using the FP motor.

I think that the advantage of this is that it is easier to mount on a turret than the much liked roller throwers. I also think that it might be more consistent (barring wear on the spring).

I think I'm going to build a prototype tomorrow.