Optimization for Fighter Aircraft Vertical-Plane Maneuvering Using Poststall Flight

Abstract

A time-optimal, vertical-plane, evasive-offensive maneuver using poststall e ight is found for a e ghter aircraft similar to an F-16. An evader aircraft initially followed by a pursuer aircraft transfers position using the verticalplane maneuver, becoming the pursuer. The aircraft that was initially the pursuer is assumed to continue e ight at constant velocity and constant altitude. A direct numerical method, collocation with nonlinear programming, proveswellsuitedforsolvingthisproblem.Theevaderaircraft’ soptimaltrajectoryisfoundtobeacobramaneuver, one of the vertical poststall maneuvers. Allowing the evader to use thrust vectoring yields a small improvement in e nal time. Nomenclature CD = drag coefe cient CL = lift coefe cient D = drag force e = unit vector directed along the longitudinal axis of an evader g = gravitational acceleration h = altitude J = cost function L = lift force m = mass Nz = normal acceleration r = position vector of a pursuer relative to an evader S = wing area T = thrust t = time v = velocity x = downrange position a = angle of attack c = e ight-path angle q = air density s = thrust vectoring angle s LMT = absolute value of limitation of thrust vectoring angle Subscripts e = value for initial evader f = value at e nal time