The Trebuchet is one of the neatest medieval weapons I have found. In my opinion it beats the catapult hands down. Working on the idea of lever arms, it uses a weight box conected to an arm that is hooked to a sling that launches whatever you want!

Side view shows the points of rotation. Plans and more information on the trebuchet can be obtained at www.trebuchet.com Mine was designed with the help of several existing sets of plans, but I modified them to a size I liked. Mine stands 4 feet tall with a lever arm of 6 feet.

This is a close-up of the catch system that holds the treb in the cocked position. 3 screw eyes with a bolt passing through them holds it.

The weight bucket can be filled with anything heavy. I chose to use some heavy chain and rocks. The carpet was to cushion the box's rest on the main arm in the cocked position. Cement balls (3-5 pounds) were are primary projectile, and the treb could launch these about 75 feet up and 150 feet out. Amazing what they used to capture castles! Their trebs were a bit larger, able to launch boulders, dead cattle, or whatever else into the castle.