This is a real working scale model of a medieval trebuchet (pronounced treb yoo SHET). The word trebuchet is from the Old French word trebucher, from Latin trans-"over" plus buc-"trunk or body." It was a machine designed to hurl objects into or over castle walls. These machines were so successful at knocking down castle walls that builders had to increase the thickness of the castle walls to strengthen them. The trebuchet has a weight which is suspended from one end of a long arm. The other end of the arm is connected to a sling. When the weight is released it is pulled down by gravity causing the arm to pull the sling down a chute and up into the sky. To get the maximum distance, the sling must release at the proper point of the throwing arc. This model is designed to use four one-liter water or soda bottles filled with wet sand for the weight. It will launch a tennis ball up to 200 feet forward. Make it from 3/4" pine boards and "2x2" lumber. The frame measures approximately 30" x 40" x 30" high (not counting the 46" long arm).