Why Shouldn’t we Build a Trebuchet?

The first step in building a siege weapon is justifying why you need one. Or, like the SPS chapter at Colorado State University, you could skip that part. There didn’t seem to be any reason not to build one and trebuchets are objectively awesome, so we felt like we had hit the criteria of good science. We set out as 10 SPS members to explore the medieval device.

Planning was quickly underway to identify a budget, aim, and timeline for our new project. Then we informed our advisor that we were building a small siege weapon. There were some initial concerns about the wisdom of the endeavor, but our passion for science prevailed, albeit with some safety parameters.

Our project manager came up with sketches, spreadsheets, and goals for the build. Logistical planning is crucial for large projects, because translating passion to reality requires forethought. These types of skills aren’t really taught in our program, but they are crucial to physics research. At times we found the project overwhelming, but we kept making progress.

SPS members learned how to use shop tools, assemble pieces, and communicate schematic plans. As we practiced these skills, our confidence and momentum grew. We decided to bring our trebuchet to the SPS Zone 14 Meeting in April of 2024, meaning we had a deadline driving our project.

At that point, we had to send a crucial email to the meeting’s host chapter: “Hey, can we bring a siege weapon to the zone meeting?” The technique for sending such an email is to bury the crucial information in cushions of safety—and add terms like “small projectiles” and “science inquiry.” Luckily, the reply was enthusiastic. We were cleared for our first trebuchet event!

The day of the meeting grew closer, and pressure mounted. The trebuchet launched, but only straight up. Maybe the sling needs to be shorter? Maybe the projectiles need to be heavier? We modified every piece of the weapon. It required more physics than we had originally thought.

Less than a week before the event, it finally worked—we could launch socks full of beans a decent distance of a few feet. Rocks were a more effective projectile, but unfortunately, they were deemed unsafe. A CSU police officer even learned about our project, eventually deciding the siege weapon did not present an imminent threat.

On the day of the meeting, Colorado showed its true colors—it snowed. We packed up our project and drove to Denver, but the trebuchet didn’t even see the light of day. It was too wet and cold for an outdoor activity.

Despite the disappointing weather, we had still built a trebuchet! We now have a unique tool for physics outreach and engagement that we can bring to any number of events and pass down to future SPS members. Next time you see CSU at a meeting, ask us about our trebuchet! You better believe we’ll have it at the 2025 Zone 14 Meeting!

So, should your chapter build a small siege weapon? It matters less what specific project your chapter undertakes and more that you actually undertake something. The power of discovery is often found within the inquiry itself. Our chapter learned that there is inherent value in deciding, planning, and executing. Being able to transform theory into practice is fundamental in science, and we look forward to doing that more often