Self-Induced Roll–Yaw Oscillations of an Aircraft Model in a Wind Tunnel

Abstract

Wind tunnel oscillatory testing is a technique conventionally used for the measurement of dynamic aerodynamic loads on subscale aircraft models. Oscillatory testing is commonly used for identification of dynamic stability derivatives for flight mechanics models. Model oscillation is normally driven by a rig drive mechanism, or with the use of its control surfaces. This paper presents a new test technique in which self-induced coupled roll and yaw oscillations are driven purely by the aircraft’s natural modes of motion when constrained in translation and in pitch rotation. This method does not require external mechanisms to drive the motion, nor the use of aircraft control surface inputs to sustain the oscillation. Without these sources of error, it is potentially advantageous for identification of dynamic stability derivatives using parameter estimation techniques. The mechanics of and requirements for this self-induced oscillation are discussed. Computational simulation and dynamic wind tunnel tests of a subscale BAe Hawk model are used to demonstrate the self-induced roll–yaw oscillations and their results are compared. Effects of varying parameters such as wind tunnel speed and the addition of spring stiffness onto the aircraft rotation axes on the frequency and stability of the oscillation are investigated.