Wind Tunnel Magnus Tests of Cylindrical and Boattail Army-Navy Spinner Projectiles with Smooth Surface and 20mm Equivalent Engraving (Rifling Grooves).

摘要

Supersonic wind tunnel and range tests on Army-Navy Spinner models with and without 20mm equivalent engraving (rifling grooves) indicate that a previously noted offset effect of deep grooves on Magnus data is also quite persistent for more practical depth engraving. However,the existence of any corresponding nonlinearities with spin mismatch is much less certain. A mechanism whereby the grooves affect the Magnus data by rotating the boundary layer is illustrated by oil flow results. The implications for bullet stability may be either adverse or beneficial,depending on the other physical and aerodynamic parameters involved,but are probably significant only for large underspin. Related smooth body results suggest that mixed boundary layer conditions and skewed transition may be more important contributors to erratic stability behavior for a wider range of spin. (Author)