Experimental and Simulation Testing of Flight Spin Stability for Small Caliber Cannon Projectile

Momčilo Milinović,Damir Jerković,Mitar Kovač,Olivera Jeremić

doi:10.5545/sv-jme.2011.277

Abstract

The basic aim of this paper is to consider correlations of stability flight criteria, derived as the relations of aerodynamic coefficients and derivatives, on the model of small caliber cannon spin stabilized projectile. Model of stability criteria calculations are performed by experimentally testing of aerodynamic data in the wind tunnel, and composed with the semi-empirical data, both applied on the flight trajectory stability simulation test. Authors’ wind tunnel tests and calculated values of aerodynamic coefficients, as function of Mach numbers of projectile model are presented in the simulation flight trajectories stability criteria. The comparative analysis of experimental and calculated aerodynamic coefficients of projectile model is done, refers to the stability flight criteria. Calculation of projectile aerodynamic Magnus moment derivatives, with other aerodynamic representatives, is used as the critical stability factors testing data vs. flight Mach numbers. Influences of this derivative absence and presence on the model sequence of the flight trajectory are presented for the estimation of angles of attack damping and stability factors. Simulation tests are presented for the supersonic and subsonic integral flight velocities and spin damping data. Research is realized due to the considerations of further projectiles correction possibilities on trajectory, and other new applications, vs. existing of unreliable lateral moments.

Highlights

In the last twenty years the modern ammunition design, extended precision technology applications of guidance and control on the lower calibers of tactical ammunition
The characteristic functions of aerodynamic coefficients in relation to the flight Mach numbers and angles of attack α, measured in the author’s testing, [13] in the wind tunnel is presented in Figs. 2 to 5, and Fig. 6 represents additional data supposed from [14]
The influenced aerodynamic coefficients tested on the projectile model are aerodynamic coefficient of drag force, Fig. 2, derivative of lift force coefficient presented in Fig. 3, derivative of pitching moment coefficient given in Fig. 4, and all vs. flight Mach number

Summary

Introduction

In the last twenty years the modern ammunition design, extended precision technology applications of guidance and control on the lower calibers of tactical ammunition. Stable free ballistic flight of projectiles and stability criteria, determines attitudes of projectile axes towards the trajectory, [6] to [8] It depends on aerodynamic shape, sensitivities on the drag and lift forces, aerodynamic moments their derivatives and spin rate stabilization efficiency vs flight Mach vector, is question of stabilization [6] and [7]. As a result these lateral oscillations decrease perturbed amplitudes of total angle of attack if spin stabilization is successful, or increase if the projectile has not realized enough initial rpm by spin to form gyromoment for damping. Complex variable of the total angle of attack ξ, and its lateral angular motion due to the projectile body can be described by linearized differential equation derived by dimensionless distance instead of time as the main argument [6] in the form:

Objectives

Results

Conclusion