Key Takeaway: The variable load factor guidance algorithm effectively produces close-to-optimal trajectories for low-altitude jet fighter fly-to-point maneuvers, outperforming the constant n-guidance scheme.

Abstract

This paper describes the formulation andnumerical investigation of a variable load factor guidance algorithm(variable n-guidance) that allows an aircraft pilotto approximate minimum-time low-altitude quasi-level fly-to-pointmaneuvers of a jet fighter aircraft. The maneuvers studied consistof flight to a point at a radial distance of 50 kft from thestarting point, with the final position vector oriented at 45,90, 135, 180 deg from the initial course and with the requirementthat the initial and final altitudes be the same.First, the fly-to-point maneuver is optimized from the time viewpointwith respect to three controls (angle of attack, power setting,angle of bank) via the sequential gradient-restoration algorithm.Then, from the study of the optimal trajectories, a variablen-guidance algorithm is developed, connecting theload factor to the turn-to-go. This algorithm is implementedvia feedback control and tested. For comparison purposes, a constantn-guidance scheme is also tested. The main conclusionis that the variable n-guidance algorithm producestrajectories that approximate closely the optimal trajectories.On the other hand, the constant n-guidance schemedoes not approximate well the optimal trajectories.