Evaluation and prediction of aircraft handling qualities

Abstract

There is given briefly the analysis of some problems in evaluation and prediction of handling qualities (HQ) for highly augmented aircraft (HAA). There are considered the technique for definition of CooperHarper scale's metrics desired and adequate task performances (TP) and the technique for elimination of input signal influence on evaluation of handling qualities. Two criteria for prediction of HQ in pitch tracking and refueling tasks were developed. It is shown that criteria for prediction of flying qualities in pitch tracking task can be used and for evaluation of pilot-induced-oscillation tendency too. The criteria for prediction of HQ in pitch tracking and refueling tasks were obtained by investigation and standardization of pilot-vehicle system characteristics in experiments on simulators with 64 and 21 dynamics configurations correspondingly. There are also modified the pilot behavior optimal control model (OCM). The developed recommendations for the choice of cost function weighted coefficients and OCM parameters are general for single-loop longitudinal tracking tasks. These recommendations allow to use modified OCM model for the reliable prediction of HQ by means of mathematical modeling. INTRODUCTION The modern stage in development of aircraft is associated with wide usage of highly augmented flight control system transformed the classical aircraft dynamics considerably and allowed to increase the efficiency of airplanes sufficiently too. Because of this tendency the usage of the standards oriented on requirements to the HQ of aircraft with traditional dynamics causes: the bad agreement between HQ, predicted and evaluated in experiments; impossibility to get the real optimal dynamics in each piloting task (PT). These negative effects are associated with the different problems. * Professor, Ph.D.,Sc.D., The Head of Pilot Vehicle lab. T Senior Research Scientist, Ph.D. + Research Scientist. Copyright © 1998 by American Institute of Aeronautics and Astronautics, Inc. All rights reserved. One of them is imperfection of the basic principles used in standards. The modern standards supposes the division of requirements on classes of airplanes, flight phases and pilot rating levels. The division of requirements on classes supposes the dynamic similarity for aircraft of the same category of weight and maneuverability. The appearance of new types of responses doesn't allow to use the requirements developed for traditional dynamics. The division of requirements on flight phases means the unification of all precise tracking tasks in one phase. It was shown that the fulfillment of different piloting tasks is accompanied by the different pilot-vehicle system (PVS) parameters and pilot ratings (PR) too. This peculiarity requires to develop the requirements to HQ for each precise tracking task and to create the new principles for development of flying qualities standards, for example, the mission oriented approach. The division of requirements on levels supposes the usage of Cooper-Harper rating (CHR) scale. The absence of recommendations for the choice of CHR scale's metrics: task performances (TP) and pilot compensation (PC) causes the question of their definition prior to the experimental investigations. This task is tightly connected with the next one the incompleteness of technique for evaluation of HO in different PT. The main context of this problem is variability in PR due to: uncertainty in TP and PC parameters for the different PT. influence of conditions of experiments on flying qualities evaluation. The influence of TP and input signal parameters is discussed in a number of research' but nevertheless there is not developed a technique for their definition up to now. It causes the considerable variability in experiments fulfilled in different research. The discrepancy between the requirements to HO of HAA obtained by use of well-known criteria and in experiments was demonstrated in many research'' and is a context of the next problem. The attempt to decide it is the development of criteria based on standardization of pilot-vehicle system (PVS) characteristics. One of them is Neal-Smith criteria. The analysis demonstrated low potentialities of this criteria for prediction of HQ because of: