Anyway, I started by joining up a bunch of primitives w/ constraints till I got something that sort of worked. I used the method of keying the projectile release. By altering the weights of my items the release timing became flawed and I had to re-time it after every change. that ended up feeling really clunky to me, soooo.
Knowing that the release point of trebuchets is usually altered by changing the angle of the pin that holds the sling, I wanted something like that so I could tune my launch.
I created a distance measureing tool and parented one locator to my projectile and one locator to my arm rotation point. Then I created a simple if statement on the pin holding the projectile that one it reaches a certain length, to release the pin. Now I can change the masses of the objects and the release is always at the correct angle.
here are some screen shots, yeah, ignore that I have no respect for actual measurements or sizes, I was just throwing stuff together, but I thought someone may find the release method useful so I'm posting here:
here we are waiting to launch:
and here is launching - the measuring tool has the handy side-effect of tracking the launch distance as well:
That's it for now... this is fun tho