Constrained Spanload Optimization for Minimum Drag of Multi-Lifting-Surface Configurations (April 1989).

摘要

An interactive computer program system has been developed that can be used in aircraft drag minimization studies. It comprises algorithms for choosing the spanwise distributions of lift, pitching moment, chord and thickness-to-chord ratio of lifting elements. The choices are optimal in that they minimize induced plus viscous drag while satisfying constraints of aerodynamic, flight-mechanical and structural nature. The configurations that can be dealt with, may consist of a number of segments representing, for instance, wings or parts of wings, horizontal tails or canards, winglets, flaprail-fairings, etc. Also the interaction between propellers and lifting elements may be included in the procedure. The induced drag is computed using the Trefftz-plane integral (farfield analysis), while the viscous drag follows from form factor methods. Novel mathematical formulations of the constrained optimization problems are used, that are based on the calculus of variations.