The Application of the Root Locus Method for the Design of Pitch Controller of an F-104A Aircraft

Abstract

This paper presents an application of the root locus technique for the design of a feedback control system of an F-104A aircraft. The analysis of the longitudinal aircraft stability was performed for the jingle Input Single Output (SISO) open-loop system, using linearised equations of aircraft motion and aerodynamic derivatives of an F-104A aircraft taken from the NASA report [1]. The dynamical behavior of the open-loop system was unsatisfactory and led to the introduction of the feedback control system. The closed-loop system was designed using the root locus technique, developed by Evans in 1948. The transfer function parameters of each element of the feedback control system are determined according to previously set design requirements. Although, the analysis of the closed-loop step response showed that all of the design requirements were realised, the controller designed within the proposed control system structure is not the only one, and there are different controller designs that lead to a satisfactory solution.