Storm the Castle Project

For our second project, we were given the task of creating a catapult, ballista, tribuchet or other siege engine that had to be able to launch marshmallows 15-25 ft away. The machine had to be consistent and must be able to fit on a 8.5 x 11 sheet of paper.

The concepts we learned about for this project were mainly regarding energy and energy transfer from potential to kinetic like when the rubber band compresses and decompresses.

The learning goals for this project were to be able to build a machine that can accurately and consistently launch a marshmallow while being confined to a 8.5 x 11 in space for building.

For our design we started with a simple catapult with a 15 in lever situated between two pieces of wood on a dowel rod. Above the lever is another piece of wood where rubber bands connect to the arm. This allowed us to get a lot more power from the catapult. On the bottom a locking mechanism was added so it would not fire unless we meant it to.

Our catapult was able to shoot accurately up to 25 ft away. The catapult also held up very well through every test and was able to launch the marshmallow into a bucket every 1 out of 3 attempts.

We had to make extensive redesigns to our project to make it launch far. Originally it would only launch 8 feet. We had to change where the rubber bands were mounted to the base, and this gave us a lot of improvement. 

For this project we had no lack of resources. First, we have a lot of time to work on this project, over 2 weeks to build and perfect. We also had access to good tools including band saws, drill presses and jigsaws.

The biggest challenge was finding out how to increase our range as much as possible. We found out the maximum trajectory comes from launching the projectile at a 45 degree angle.

I learned that redesign is extremely important. For this catapult our redesign increased our final range by over 400%, going from 8 ft all the way to 25 ft.