Multiaxis unsteady aerodynamic characteristics of an aircraft

Abstract

The multiaxis unsteady aerodynamic characteristics of en F-18 aircraft are presented and analyzed in this paper. The wind-tunnel tests using the Dynamic Plunge Pitch-Roll model mount at Virginia Tech Stability Wind Tunnel are first described, and the data reduction techniques are briefly discussed. The typical experimental results for harmonic oscillatory maneuvers in roll are illustrated, and the resulting hysteresis loops analyzed. On the basis of data obtained, a state-space formulation is proposed to describe the unsteady aerodynamic characteristics of the aircraft in multiple axes. This formulation consists of a number of basic statespace models each of which is used to characterize the unsteady aerodynamics of a single lifting surface. The unsteady aerodynamic characteristics of the whole aircraft along and about each axis are then obtained by the contributions of these lifting surfaces about the corresponding axis. The performance of this aerodynamic formulation is also shown based on the current windtunnel data.