[Madison]

Originally Posted by Chris is me

All things considered, if you only need 14 pounds to release your mechanism you're in good shape. The 3/4" bore piston at 60 PSI pushes with 26.5 lbs of force. It pulls with somewhat less force since the piston rod takes away some surface area.

Are you having trouble shifting the piston under load? Does it take too long? An easy fix would be moving the gear to the end of the shifter so that you push to shift to neutral. If you still need more force, it is possible to get creative and mount a bigger piston to the mechanism, but be warned that the Vex shifter components (bearing and e-clips) cannot handle a ton more than 30 pounds of force.

One last thing: are you sure it's the gearbox that's slowing you down?

I understood this to mean that more of the energy stored in the surgical tubing is being used to unspool the rope and spin the drum than they're happy with.

If possible, a simple solution might be to counteract the force require to unspool the rope and spin the drum with a spring acting on the other side of your pivot. It'll take that much more energy to load the catapult, but if you were to counteract the torque of the spool and rope with a spring, you'll get a bit more energy into the ball.