In the fall of 2015 I worked on both the Mach 2 pumpkin launcher and a brand new one. The new launcher was modeled after an ancient roman catapult called an onager. It used thick twisted bundles of rope as a torsion spring to propel the throwing arm forward. In this case the torque generated exceeded 1000 ft-lbs. This also generates an enormous lateral crushing force. To compensate and disperse these forces ¾ inch aluminum plate and black steel pipe were used.