STUDY OF GEOMETRIC ASPECTS OF BULLET FLIGHT IN SOLVING EXTERNAL BALLISTICS PROBLEMS

Abstract

The results of the study on the impact of geometric aspects of bullet flight along a ballistic trajectory on the calculation of the ballistic coefficient through changes in its characteristic cross-sectional area are presented. The aim of the research is to identify an analytical model for the variation in the characteristic area of the bullet’s normal projections along the ballistic trajectory based on the angle of deviation, which could be used to refine the changes in the aerodynamic drag coefficient when determining the ballistic coefficient (BC).

Given that the ultimate goal of external ballistics is to determine the ballistic coefficient, which helps shooters predict bullet behavior at different distances and adjust their sights for improved accuracy, the use of ballistic calculators simplifies this process, allowing for quick and precise sight adjustments under specific shooting conditions.

The subject of the research is the change in the characteristic cross-sectional area of the bullet in flight, which affects the bullet's form factor parameter when determining the ballistic coefficient.

The present study examined the trajectory diagram of a projectile with a range of 1400m for the 0.338 Lapua Mag. SWISS P Target caliber, weighing 19.4 g / 300 gr. During the research, the deviation of the aerodynamic drag angle of the bullet in flight was identified, providing the boundary values of the bullet’s angle of rotation relative to the vector of its movement along the ballistic trajectory.

Additionally, the characteristic areas of the bullet were calculated at different angles of attack of the aerodynamic drag force vector, and the dynamics of changes in the bullet's characteristic area along the entire flight trajectory were determined. The study revealed an intense increase in the bullet's characteristic area during the ascent phase following a polynomial law of change from the angle of attack of the drag force vector. In the study, a cubic mathematical model was established for the characteristic area as a function of the angle of attack for the test bullet, which can be used to refine the bullet's aerodynamic drag coefficient in the mathematical framework of a ballistic calculator, as well as a control function for the optimization task of finding the effective aerodynamic shape of the bullet using computational fluid dynamics (CFD) methods.

Keywords: ballistic coefficient, form factor, ballistic projectile, characteristic area, drag force, angle of attack, normal plane.