These are the three pictures that we consulted to design our trebuchet. We took the scale of the third one and estimated it at around 4 feet tall, then scaled up the blueprint to fit the full size that we wanted. The second picture is almost the exact plan for our counterweight bucket, except we used metal.

The first three pictures are a progressive view of our trebuchet shooting. They demonstrate how the small amount of movement by the counterweight translates into a very fast moving sling as it is almost 10 times as far away from the fulcrum as the counterweight. This transfer is the PE in the counterweight moving through the arm and the string into the projectile and becoming KE. This transfer of energy in our trebuchet was extremely inefficient, achieving only an 11%. To increase the efficiency we could use a smaller arm, be more precise when drilling the holes for the support bar, and finding a way to ensure that the release angle is as close to optimal as possibly, consistently.