The Effect of Bullet Diameter and Free Stream Mach Number on Flight Noise

Abstract

The US Army Research Laboratory has a newly developed experimental setup consisting of a sensor array that allows for expedient and accurate measurement of projectile flight noise. This study examines the effects of projectile flight diameter on the peak sound pressure level (SPL) of the bullet in flight. Additionally an empirical model has been derived from the results of the experiments to aid in the prediction of flight noise given the diameter and Mach number of a projectile. The in-flight signature of projectiles is of particular importance when considering the impact of a weapons signature on the surrounding environment. Included in this research are 4 diameters of small caliber bullets of the same approximate non-dimensional shape. The projectile flight noise was characterized across multiple free stream Mach numbers between Mach 0.5 and Mach 3.0.