Wind influence on the exterior ballistics of the bullet movement from the SVD

Abstract

In the paper the author investigate the dynamics of the movement of the bullet of the cartridge LPS in the air released from the sniper rifle Dragunov. The main influence on the bullet movement in the air has the force of the frontal air resistance, the bullet’s mass and the force caused by the action of the counter wind on the bullet. It is assumed that the force of the frontal air resistance depends on the factor described the aerodynamics properties of the bullet, the cross-section of the bullet, the density of the air and the sound velocity in the air , the velocity  of the accompanying or opposite wind and the bullet’s velocity. In addition, its functional relationship contain two dimensionless coefficients that have different values in supersonic and subsonic velocity of the bullet and are determined using the results of experimental studies. The action of the accompanying or opposite wind affects the value of the force of the frontal air resistance of the bullet’s movement and is taken into account through the corresponding force expression. There is a slight difference between the theoretical and experimental results of the kinematic parameters of the bullet. The value of the force caused by the action of the crosswind is proportional to the maximum area of the longitudinal section of the bullet, the air density, and the difference of the wind velocities and cross drift of the bullet, which is elevated to a certain degree. The values of the coefficient of proportionality and degree depend on the nature of the air movement  – laminar or turbulent. Analyzing the results of theoretical calculations, we can state that the velocity of the cross drift of the bullet is constantly increasing; the value of the cross drift of the bullet increases according to the nonlinear law. In addition, there are significant differences between the results of theoretical and experimental studies, if the coordinate of the point of zeroing of the trajectory is greater than 700 meters. During the theoretical verification of experimental values, it was established that the value of the average velocity of its cross drift on certain sections of the bullet movement contradicts the laws of mechanics. Consequently, certain values of experimental studies, given in the shooting tables, cause distrust.