MAGNUS EFFECT OF YAWING-SPINNING TARGET PRACTICE PROJECTILES: GYROSCOPIC AND DYNAMIC INSTABILITIES IN SUPERSONIC FLIGHT

Abstract

Despite extensive studies, mechanisms governing the aeroballistics of yawing and spinning projectiles are still difficult to understand. This is especially true for target practice projectiles settled with additional roll damping devices. The first part of the paper is devoted to the aerodynamic comparison of classical and target practice projectiles. For classical projectiles it is known that, at small angles of attack, the spin induces a weak asymmetry of the boundary layer profiles. For target practice projectiles, the roll damping devices, settled as longitudinal grooves, could generate important modifications of the flow. Grooves act on the boundary layer asymmetry, strongly increasing the Magnus moment. The second part of the paper, based on 6 degrees of freedom computations, is devoted to the prediction of flight dynamic behavior. According to the grooves design, dynamic and gyroscopic instabilities could appear. The influence of grooves depth on the inflight behavior is highlighted.