Trying to get a flinging motion to use for a catapult like feature

I’ve attempted to figure this out for the last two days on my own and have nothing to show for it, any help or direction would be appreciated. What im trying to do is attach an arm to the back of the vehicle in the advanced vehicle example. Then have it rotate up and forward to launch a ball while maintaining its connection to the car.
I’ve tried using a physics constraint and messed around with impulses and rotations with both the mesh and constraint, but was unable to get any results from either.

Thanks in advance. =D