The Catapult Project
Prototypes & Concept Renderings
For our prototype, we used simple classroom materials and our preliminary sketches to create a (almost) functioning trebuchet. As you can see we have a rectangular base, two support beams on either side of the base, a pivot point and, of course, the main beam. We have designed our trebuchet so that the end of the beam which holds the load consists of 1/3 of the beam, and on the other side of the pivot (the end of the beam which is to hold the counterweight) is 2/3 of the beam.
The Process
After building our prototype and doing concept renderings, we began to look for reusable supplies to build our catapult with. We found some two by fours and screws and bolts to use and got started building. The first thing we did was build the base of the catapult. Then, we installed the two vertical beams and drilled large holes in them at the top (where the PVC would go). Once that was done, we put the PVC through the holes and bolted it on both sides so it couldn't slide out. Then we bolted a two by four onto the PVC to be the main beam which was to carry the load and the counterweight. We also applied a beam a few inches below the PVC to stop the main beam from spinning all the way around and we wound up having to add more blocks of wood because the catapult was launching at too low of an angle. We decided that our catapult was a little wobbly so we put brackets attached to the base and vertical beams of the catapult. The last thing we did was put the "basket" on which was actually a plastic pickle jar that we sawed in half. We did have some trial and error to figure out how to add a trigger, but we decided not to use one and to just pull the beam back with our hands.
Reflection
For this project we had to build a real life working catapult to launch a baseball. We used math concepts such as quadratics and design concepts like scaling and perspective to create concept renderings, scaled drawings and prototypes of our catapults before and during the building process. To be honest, our whole group wasn't really invested in the whole prototype building process, but we did wind up with one. It was made of cardboard, duct tape, and bendy straws which somewhat resembled our final product, but it wasn't perfect. One thing that my group struggled with was the "trigger" for our catapult. We were originally using a bungee cord that was attached to the beam and the base of the catapult by being hooked on in holes, but that was problematic so we had to find an alternative. We went through a few more ideas that didn't work out before we agreed to just use our hands to draw back the beam and release it. When we were making our calculations on launch day there were some factors that might have affected our launch that we didn't account for. We didn't account for things like wind, error, etc... Some successes we experienced during this project was actually creating a catapult that launched. It didn't launch very far, but it launched and I was proud of it. I'd say the biggest challenge we had was the trigger.