Air Drag and External Ballistics

Patrick Butler


During the course of my studies in physics, I have come to apply much of what I have learned to some of the activities that I enjoy outside the classroom. During the course of this study, I will apply my knowledge of air drag to ballistics, in an attempt to do an in-depth study of the drag force. Many ballistic tests have been performed within much higher ranges of velocity, such as military applications, while many others have been performed at much lower speeds, such as an athlete throws a ball through the air. For this procedure, I will attempt focus on the intermediate range of velocities, trying to bridge the gap between both ranges of velocity.

I will perform this procedure with a custom built air cannon to launch the projectile. As with many projects that are built from scratch, the majority of this study will come to be about simply calibrating and understanding the apparatus. Before the air drag can be determined, several ways for measuring velocity and the motion of the projectile will need to be devised and put into practice. Unfortunately, due to constraints on the precision of the apparatus, this project will not be able to gain much depth into examining the drag of an object moving through the air, but I will develop a procedure for studying such drag. Data will be collected and the procedure will be proven effective, to a degree, but more time will be needed to gather a considerable amount of data and conclude the study. One value in particular which this study will focus on is the coefficient of drag, which is both unknown and unique for the projectile studied. Despite a large error on the final value of the coefficient of drag, a reasonable range which it may exist within will be identified. Even if the results of this study are limited, I believe the work done here will make a much more thorough and complete ballistics test possible, given that more time is committed to this project.