SirGuillaume.com - To Ride the Trebuchet

When I was 12 years old my history teacher in junior high school asked me to do a project for the upcoming history fair. She recommended building a model of the famous Civil War ships the Monitor and the Merrimac or perhaps a reconstruction of what Stonehenge looked like around 3,000 years ago. Dissatisfied with these suggestions, I went off the the library to find something more dynamic to bring to the history fair. As I was flipping through an encyclopedia, it fell open to a page with a picture of a catapult on it. I read the article and instantly I knew what my project would be: a miniature working model of an onager-type catapult. With the help of my father I built that catapult. It could hurl small rocks, tennis shoes, paperback books and other items across the classroom and made me the hit of the fair.

While I was doing research for that project, I had come across a story about a king whose castle was under attack. The king needed food for his people and offered one of his sons as a hostage to facilitate a cease fire and open negotiations. When the negotiations fell apart the attackers put the king’s son in a catapult and hurled him against the castle wall. A sad page in history, but it got me thinking about what it might be like to ride a catapult. Fourteen years later I was thinking about that story again, and as a mechanical engineering student with a short summer break on my hands, I now had the skill and the time to do something about it. Being inspired by Walt Disney (he loved trains, and built the first rideable miniature trains) I set out to build a catapult scaled to throw me 40 or so feet through the air to land safely in a river. I set out to build and ride a replica of an ancient throwing machine.

I settled on a design called a trebuchet. I made some calculations, drew up a design, and built a small model, but the model didn’t work like I expected. The test loads fell short of the intended mark, so I took my drawings to a physics professor and tried to get things figured out. After some calculations, he showed me a number about 20 digits long and said “This is the centrepital acceleration that you’ll be experiencing. That’s enough force to rip your head clean off!”

I sensed that he did not approve of my plan to hurl myself through the air and into a river. So after modifying my story and consulting with a mechanical engineering professor (who also told me it wouldn’t work), I went on to build it anyway.

The next day I gathered up some of my (willing) friends to participate in the event (picutred in the image above, right). We loaded the big machine onto a trailer and moved it to the edge of the Blanco River. After a few hours of setting up the contraption and gathering some large rocks for another test launch, a small crowd of picknickers had gathered. They were interested in seeing just what the hell we were going to do with this big machine.

After the successful test launch, there was much applause and cheering from the crowd. They were very impressed to see that big pile of rocks fly into the air and kawhump, splash into the river. We recocked the machine, and I climbed into the launch bucket. there was an audible gasp from the crowd. Women told their children not to look and men advised me not to do it.

I turned to my friend at the trigger and said, “On the count of five, pull it.” I started counting backwards from five. “Five — ”

I never got to four. My literal friend pulled the trigger right then. Suddenly I was flying. I looked down and for an instant I was hovering, 30 feet over the river below. When I hit the water, I was elated! My dream of riding an ancient throwing machine had come true! I came up laughing.

My friends and I spent the rest of the afternoon riding the trebuchet, until the machine self-destructed in mid throw. I was the passenger, and luckily I was thrown clear just as it snapped. The increased counterweight was too much. I fixed the design, but my money and my time had run out. I couldn’t afford to rebuild again.

Now the broken pieces sit on an empty south Texas ranch, the cows look at it curiously from time to time. I became busy with other concerns: school, life, career, etc. I frequently think about building another one, one that will throw someone a little farther, a little higher. All I need is the time...