The Effects of Stick Force Gradient on Pilot Mental Demand

Abstract

During the flying task, the control feel of an airplane with a reversible mechanical flight control system enables the pilot to perceived small changes in airspeed with pitch control force changes. Current certification specifications for light airplanes are subjective, requiring only that there be perceptible stick force change with airspeed (or stick force gradient) and the final judgement is left to the test pilot. No minimum stick force gradient for desirable control feel is specified. Previous flight testing of selected airframes in the course of this program of research, showed that stick force gradients vary between aircraft makes/models and phase of flight. Flying tasks performed by twenty general aviation pilots using a simulated light airplane with configurable stick force gradient showed that as the stick force gradient is reduced to zero, simulating an airplane with neutral static stability, pilot mental demand increased significantly (p< 0.05). The results have implications for current airplane operations and future airplane design. 1 Senior Lecturer in Aerospace, Department of Aviation, Aerospace, Electrical & Electronic Engineering, Faculty of Engineering & Computing, Coventry University, Gulson Street, Coventry, CV1 2JH, United Kingdom. 2 Visiting Research Fellow, College of Engineering, Design & Physical Sciences, Brunel University London, Uxbridge, Middlesex, UB8 3PH, United Kingdom. 3 Visiting Research Fellow, College of Engineering, Design & Physical Sciences, Brunel University London, Uxbridge, Middlesex, UB8 3PH, United Kingdom.