I built 2 trebuchets.
THe first one sucked... Hard. Then it broke. It was about 5 ft tall.
My second one was an awesome calculus project. It had dual 150lb. garage door springs mounted to an 8ft arm. It produced an estimated 600ft.lbs at the axle, which was 6ft tall. The sling was 6 ft long. We tried throwing water baloons out of it, but it destroyed every single one due to the g-forces. Then, we threw fist sized rocks about 2.5 football lengths. We decided it was too dangerous to keep using at school so we stopped.
It took two people to cock the thing, another to set the hook.... it was not safe at all
