Masters Theses

Date of Award

8-1992

Degree Type

Thesis

Degree Name

Master of Science

Major

Aerospace Engineering

Major Professor

Carroll E. Peters

Abstract

In this research, an attempt was made to develop a statistical description of the flight yaw of small-arms projectiles. An accurate description would be very useful, especially in the area of wound- ballistics. The lognormal and truncated lognormal distributions were examined and shown to be unsuitable for modeling the flight yaw, contrary to common belief. The computer model PRODAS, a commercial exterior-ballistic code, was examined and found to be inaccurate in predicting the projectile flight yaw. After the failure of PRODAS was determined, an attempt was made to examine a linearized system of equations of the flight motion of a generalized projectile. Although the linearized equations did not yield a complete solution for the flight yaw, they did allow some general conclusions to be drawn regarding the statistical properties. Finally, multiple linear regression analysis was performed on the available data. This analysis yielded results which are of some limited use in predicting the flight yaw of a given small-arms projectile. Several conclusions were drawn concerning the limited available flight data. It was demonstrated that, with the limited sample sizes typical of most ballistic tests, it is nearly impossible to demonstrate that the data follows a given probability density function. In this effort, it was learned that the the ratio of median/mean of the flight yaw data provides the simplest, most stable and accurate indication of the skewness of the data. It is recommended that more flight data, with larger sample sizes, are required to describe this problem, along with more research to determine the aerodynamic coefficients of the projectile in flight.

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