Bullet Turning at Trajectory Apex.

A numerical study is carried out to investigate a 7.62-mm bullet turning at the trajectory apex, particularly when fired vertically. The bullet model includes an aerodynamic model, which basically covers angles of attack up to 180°. Computational fluid dynamics are used to estimate the aerodynamic properties at the high angles of attack. The role of aerodynamic moment, and particularly Magnus phenomena, in turning at the apex is studied. A positive Magnus moment tilts the total aerodynamic moment vector clockwise and generally drives the bullet turning nose down. The bullet turning was detected through a flat spin-type maneuver. The Magnus-moment oscillatory behavior and/or the Magnus-moment-caused bullet instability may occur during the turning at the trajectory apex. These were found to have a negligible effect on the bullet-turning launch angle, but they may contribute considerably to the bullet falling-phase behavior. Possibilities to affect the bullet descending part of the flight are also shortly considered. [ABSTRACT FROM AUTHOR]