Tail Flare vs Fins in the Design of a Subcaliber Projectile

Abstract

A typical aerodynamic configuration of a subcaliber projectile is composed of a slender body with a small cross-sectional area and fins at the rear part of the projectile. Projectile fins require high-precision manufacturing because their shape and size are designed to achieve high normal-force coefficients and a satisfactory static-stability margin. The influence of aerodynamic asymmetry to the projectile flight is minimized by the projectile rotation. An alternative aerodynamic configuration can be obtained by replacing fins with a tail flare. In this paper, the criteria for designing a tail flare replacing the fins were the maximum effective range and the maximum height of the trajectory. Computational fluid dynamics was used for calculating the aerodynamic coefficients of both a finned projectile and a projectile with a tail flare, with and without holes. The computation accuracy was verified by comparing the calculated aerodynamic coefficients with wind-tunnel measurements. The justification of the replacement of fins with a tail flare was verified through an analysis of trajectories for two characteristic firing elevation angles: the elevation angle required for the maximum effective range and the elevation angle defined for accidental firing.