Eric Gunnerson has recently blog about a Trebuchet (that he offered to his wife?). This remembered me of the one I built, with my friends, a few years ago.

The photo below shows the "implementation" of the Trebuchet and some facts about it:

• the rotating pole was 7m long and composed of two wooden poles of 15cm of diameter
• the rotation axis was made of a steel stick of 26mm of diameter. It was at 3.5 m of the ground. Note because the construction was not perfectly symmetric, it got twisted.
• the "counter"-weight was about 100kg altough not measured,
• the structure was composed of 10 wooden poles buried 50cm into ground.
• the projectile was a piece of wood, 50cm long, 15cm diameter, it got throwed at around 60 meter althought the trajectory was far from behing optimal (too vertical).