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How To Build A Trebuchet Part 5


Let's Fire off the Little Dragon Trebuchet!


Put the projectile in the pouch and lower the arm of the trebuchet Run the strings and pouch along the bottom of the runway they should stretch out nice and flat. When you release your finger the arm will swing around and the ball will be thrown forward.
. Here is a quicktime movie of the Trebuchet launching Trebuchet launch (MOV apple quicktime)

Some Tips on making your Little Dragon Trebuchet launch even further

  • Put a heavier counterweight
  • Move the pivot pin in the swing arm closer to the counterweight. Remember you drilled three holes in the swing arm? This change in location has a big impact on arm swing speed.
  • Change the length of the string pouch. The longer the string the faster the projectile will go
  • Important: Change the angle of the nail on the end of the swing arm. This angle determines when in the swing the pouch is released. The sharper the angle the later in the swing the pouch is released. So if your projectile is going too high toward the ceiling make the angle of the nail sharper. If your projectle is going toward the ground too soon lessen the angle of the nail
  • Make the trebuchet swing arm skinnier and lighter by shaving it or using a thinner piece of wood

Remember to Paint your Trebuchet! It makes a big difference!

Some More Tips on Making it better:

  • The optimal weight ratio for counterweight and projectile is 133 to 1 so try to make your counterweight 133 times heavier than your projectile I have more info about weighing your counterweight here
  • Optimum distance is reached if the projectile releases between 40 and 45 degrees
  • A lighter projectile will go faster but not as far
  • Adjusting the hook forward will release later and cause it to go faster but not as far
  • Adding wheels will add more power! The wheels add more power because as the counterweight falls the whole machine moves forward slightly to "meet" the fall thus giving you a more vertical drop leading to more energy being transferred to the throwing arm.


This is the finished and painted trebuchet. I hope you enjoyed this project! Bookmark This website and check back again I have more projects coming.

PhotobucketWant to make an improvement to the Trebuchet? A web visitor has made this treb and he added a nice little design change so he can lock it in the ready to fire position. Pulling the pin fires it off. See his trebuchet and the design improvement here



Want to make even more improvements? Another web visitor who is an engineering student did some research and made a treb that is even better. He has also given some great information about projectiles and weights. See his trebuchet and information here