Integrating Aerodynamic Properties into a Catapult’s Calibration

Abstract

All machines, no matter how precisely they were built, harbor inconsistency in the task they are supposed to perform. Science Olympiad’s Trajectory event is one of many youth competitions that encourages testing for this inconsistency. Here, participants are required to build a device that can launch a projectile to a target anywhere between 2 meters and 8 meters in 1-meter increments and at heights of 0.5 meters or 1 meter. During the few months I participated in this event, I tested for inconsistency in my catapult’s launch distance. Firstly, I identified three aerodynamic-related problems and fixed them with my best modification. To avoid confounding results, I only used the 2-meter-far target at a 0.5-meter-elevation for testing. Results from running a probability significance test on the modified catapult against my goal of 98% accuracy in the catapult’s launch distance gave a p-value of 0.31. Because 0.31 was greater than my significance level (α) of 0.05, the catapult having 98% accuracy at the 2-meter-far, 0.5-meter-high target cannot be disproven. The results of this significance test were constant for every other possible target distance and elevation. The overarching purpose of this research was not just to create a competition device, but also to make a contribution to the use of catapults on aircraft carriers. These steam-based catapults are considered dangerous and inefficient, so I created and calibrated this catapult using a bungee cord launch force as a better alternative.