Functional agility metrics and optimal trajectory analysis

Abstract

This paper examines several functional fighter agility metrics using optimal and nonoptimal maneuvers for a generic F-18-type aircraft to investigate the sensitivity of these metrics to the control strategy used to test them. The maneuvers tested are 180 deg heading changes. The metrics tested are the combat cycle time, the dynamic speed turn agility plots, and the relative energy state metric. Significant improvements in the measured agility metrics are possible if an optimal control strategy is used to test them. For example, reductions in combat cycle time of 60% with subsequent reductions in speed bleed rate of 80% are possible if an optimal maneuver is flown instead of a typical flight test maneuver. The specific agility improvements are vehicle airframe and control system dependent. However, the techniques used in this study are applicable to any aircraft and could provide insight into flight control system design and design tactics for maximizing performance during air combat engagements. Nomenclature M = Mach number Rt = turn radius Vc = corner speed a = angle of attack