[EricH]

Originally Posted by DarkRune

Yes, out initial plan was cutting the power to the motor right before we fire. Not quite sure yet what we will use as a clutch though.

Take a look at McMaster's ratchet and pawl setups, or maybe just some ratchet straps (take the ratcheting mechanism out of the strap, or leave the strap on and re-rig the mechanism to suit your design).

Now, the hard part is disengaging and reengaging exactly when you want to, but that's for your design crew to figure out. I got no ideas off the top of my head.