Golf Ball Trebuchet

 This project is one of my favorites. I completed this at the end of my senior year of high school for a physics project. The project was very broad, we were required to pick anything that showcased any laws of physics we went over throughout the school year and describe what laws were at play and how the thing we picked worked. I instantly new that I wanted to build a trebuchet which is a great example of energy transfer. I decided on this design after watching Leonard Vance's YouTube videos on MURLIN (Multi-Radius Linear Nodes) trebuchets. These kinds of trebuchets use gradually decreasing lever arm lengths to achieve more torque at the beginning then higher speed at the end of rotation just like how a car has a transmission to get it up to speed. I thought that it was such a clever design and could not wait to start building it. 

Final MURLIN Trebuchet

I used plans found on Leonard Vance's website which helped a lot since I only had about a month to work on this. My trebuchet was constructed out of maple which is overkill considering pine would have worked just fine. I did this, however, because the maple was on sale for about the same price as the pine and I figured the maple would not flex as much as pine which is something I noticed in one of Leonard's slo-mo shots of a MURLIN trebuchet launching. I figured less flexing meant more energy being transferred into the golf ball, resulting in a further launch.

Frame assembled

MURLIN arm almost fully assembled, missing rope guides and sling

I am unfortunately missing some of the documentation on this project such as the hand sewn golf ball pouch, fully assembled MURLIN arm on its own, and the weight holder. The golf ball pouch was made from a heavy duty fabric strap and some elastic band used for sewing. The fabric strap was used for the part of the pouch that ran inline with the launch motion and the elastic band was used to go around the circumference of the golf ball to keep it straight. The elastic band was important because it allowed for the pouch to open up on launch.

Here is a SloMo shot of the trebuchet launching. My favorite part is
seeing how the arm stops rotating when the golf ball is just leaving
the trebuchet, indicating energy transfer.

Here is a regular speed video of the trebuchet launching

This picture was taken next to the trebuchet and I am that red spec
in the distance which is where the golf ball landed

Overall I am very happy with how this project turned out. I went back at later date and launched this with a friend that measured the launch distance with a range finder used for hunting and it turned out to be a little over 450 feet. Not only did it demonstrate energy transfer but it also showed how using variable lever arm lengths can be used to make a more efficient and effective trebuchet.