Methodology for Flying Qualities Prediction and Assessment in Preliminary Aircraft Design

Abstract

Due to challenging environmental constraints there is rising interest in unconventional con gurations within preliminary commercial aircraft design. Fundamental changes in aircraft geometrical arrangement, however, can have signi cant in uence on ying qualities that can not easily be detected by common preliminary design methods. In view of the herein implied need for corresponding design capabilities, a methodology for the prediction and assessment of ying qualities has been developed and implemented into a design tool that is fully integrated into the Preliminary Aircraft Design Suite at the Institute of Aeronautics and Astronautics (ILR). For given aircraft con gurations, the program calculates stability and control characteristics and uses them to simulate various ight maneuvers that are strongly oriented towards civil and military certi cation standards. The response of the aircraft within the maneuvers is analyzed to derive associated ying qualities parameters. This allows for quantitative comparison of di erent aircraft con gurations with respect to its stability and control behavior. Further, in case of reduced ying qualities, guidelines can be derived to redesign special aircraft parameters (such as control surface geometries) or to estimate required feedback-control characteristics. The applicability of the program in preliminary design is demonstrated for an existing conventional single-aisle aircraft conguration. The determined ying qualities parameters are evaluated and veri ed against civil certi cation requirements or against the acceptability levels of United States military standard.