21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-1.7.4

HIGH ANGLES OF ATTACK FLIGHT DYNAMICS OF CONTEMPORARY AND PROSPECTIVE FIGHTERS AS A FUNCTION OF THEIR CONFIGURATION AND AERODYNAMICS

Goraj Z.
Warsaw University of Technology, Poland

Keywords: high angles of attack , flight dynamics, fighters, configuration, aerodynamics

This paper reviews the performance of modern agile aircraft at very high incidence, near and beyond stall. Includes discussions of the research and development efforts devoted to the investigations of the numerous flight dynamic and aerodynamic phenomena that are accentuated as the angle of attack of the modern complex configurations increases beyond stall. Necessary conditions to sustain appreciable lift force at post stall conditions for special maneuvers even far beyond stall angle as demonstrated in the "Cobra Maneuver", are reviewed. A dynamic entrance into the post-stall region of angles of attack has been numerically simulated. Static aerodynamic characteristics and some dynamic stability derivatives with respect to pitch and normal acceleration, used in this paper for numerical simulation of motion in the extended range of angle of attach (from 0 to 90 degrees), have been elaborated coming from results of wind tunnel experiments, numerical engineering methods (including panel methods) and results published by other authors. Aerodynamic hysteresis, associated lag and dependence of stability derivatives on frequency of oscillation were not included into analysis. Transient responses of an aircraft were numerically computed for different centres of mass position, tailplane control function, canard deflection etc. Trim parameters were found for steady flight at the below and post-stall regions. These parameters were computed either from the full nonlinear equations of the state of equilibrium or from simplified, two different sets of linear equations. All numerical results were obtained for a conceptual design project of an aircraft, considered as a candidate for subsonic, ground attack fighter.

view full paper