Applying Radar Cross-Section Estimations to Minimize Radar Echo in Unmanned Combat Air Vehicle Design

Abstract

Radar profoundly altered the development of vehicle technology for combat especially in the realm of aircraft design. The technique of purpose-shaping an aircraft to minimize the vehicle’s radar cross-section and avoid detection on radar systems became a crucial step in the development of conceptual air vehicles, however much of this work is classified by the U.S. government. The purpose of this research is to develop the best methodology for predicting the radar cross-section of an aircraft throughout the design process by using open source radar equations. In order to estimate a radar cross-section value, simple shapes and their known radar cross-section expressions were used to represent all features of the conceptual aircraft design. An unmanned combat air vehicle designated the QF-36 Thunder was designed specifically for a radar-cross section analysis. Each of the QF-36’s main components, including wings, tails, and fuselage shape, were analyzed and their radar-cross section contribution calculated to ascertain the overall aircraft radar cross-section. Adjustments to specific aspects of the QF-36 could then be made to minimize the overall radar cross-section value while maintaining performance specifications set by the Request for Proposal which defined the vehicle’s mission. Following the development of this radar-cross section estimation tool, the results showed that large volume components including the fuselage and wing contributed the most to the total radar-cross section especially in the side- and front-view respectively. This trend aligns well with the initial idea of which aspects would contribute most to the radar-cross section. However, the main design advantage found throughout this process was that the tails contribute much less to the overall radar-cross section than initially hypothesized. This allows for large tails and better maneuverability with little increase in the overall radar echo. With this observation, design strategies may focus on minimizing wing size and maximizing tail size for the best compromise between radar-cross section minimization and enhanced performance. This research reflects one of few studies that documents the methodology for estimating radar cross-section of an aircraft in its entirety.