Handling Qualities Analysis

10.1 INTRODUCTION

The human pilot would generally be very successful in flying an airplane if he or she blends maximum performance and adequate handling qualities (HQs) [1]. For an efficient flight operation satisfactory HQs are essential. Cooper and Harper [2] state that ‘‘handling qualities are those characteristics of an aircraft that govern the ease and precision with which a pilot is able to perform the tasks required in support of an aircraft role.’’ In the opinion of the pilot, the HQs (of an airplane) depend on aircraft dynamics, control system performance, cockpit environment, outside view, and instrument display [1]. In the early years of HQ research the pilots’ evaluations in various types of existing aircrafts, variable stability research aircraft/in-flight simulation (IFS), and ground-based simulators have helped in the development of HQs criteria. Certain government agencies would usually and often compulsorily demand compliance with certain HQs requirements for military as well as transport aircraft. The purpose of the military requirement is to ensure a certain level of mission performance and also safe operation of a new aircraft, whereas for the civil aircraft it is the safe operation (rather than the mission effectiveness) which is much more important. Modern aircraft development requires comprehensive evalu­ation of HQs for different controller modes, loadings, and operational missions at various points in the flight envelope. Flight testing would be nearly impossible or it will consume lot of time and effort to cover in all these conditions. Therefore, it becomes necessary to supplement the test results obtained by the pilots at several critical conditions with those obtained from analytical evaluation, using mathemat­ical models of the aircraft as well as the human pilot to describe the performance on computers. The main objective of a good aircraft design and control system is to provide an aircraft-control system with good HQ throughout the flight envelope.

10.2 PILOT OPINION RATING

Pilots are provided with rating scales. While flying various configurations, pilots give a rating number on this scale and comment on the workload experienced. This rating scale is known as Cooper-Harper rating scale [2] and is given in Figure 10.1. The Cooper-Harper pilot (opinion) rating scale is also called handling qualities rating scale. The evaluating pilot, after performing a maneuver, arrives at a numerical number on the scale (1 to 10) based on the series of decisions made by him or her for a given flight operation/testing of the aircraft, wherefore the judgments are made in the context of the defined mission. The rating scale is a guide to the quality of the

aircraft and its overall performance. Once trained, the pilot can easily use the scale; however, it is not necessarily linear.