I need advice on what the ideal dimensions are for maximizing trebuchet throwing distance?

i already built this trebuchet. it has a 100 lbs of counterweight, and is about 3 feet tall w/o the arm. the weights side of the arm is 12.6 in, and the throwing side is 39 inches. i have been fooling around with different slings, and i want more distance. i can throw a golf ball 215 feet with a 39 inch sling. and the biggest projectiles i can fit are golf balls, baseball, and softballs. can someone please help me launch stuff really really far?I need advice on what the ideal dimensions are for maximizing trebuchet throwing distance?
You're throwing 66 times the long arm length now, which isn't bad. Your short arm (the weight side of the arm) is long in proportion to the counterweight and the long arm (sling side). Moving the counterweight mounting point closer to the axle would give more tip speed. 8 inches would be better than 12.6.





One thing that would work would be to convert to a King Arthur or Whipper. They will throw about 80% farther than a conventional design.





http://www.youtube.com/watch?v=JLDS21YdE鈥?/a>





And you don't need 100 lbs to throw a golf ball. 20 is a lot.