Gust Alleviation of a Passively Pitching Wing Equipped with a Torsional Spring

Abstract: Rejecting perturbations is an essential ability of an aircraft while operating in a gusty environment, especially for urban uncrewed aerial vehicles (UAVs) in complex aerodynamics within a city environment. This paper presents a passively pitching wing tested as a mechanical means of mitigating the adverse effects of gust conditions during UAV flight. A wind tunnel model of a NACA0015 airfoil with a hinged, variable torsional stiffness pitch axis was designed, fabricated, and experimentally investigated. The gust alleviation characteristics were examined under continuous gust flow conditions of varying frequencies at different pitch angles. The gust responses of the pitching wing were compared with a non-pitching baseline wing. The spring-hinged pitching wing has a significant impact on the gust loading and possesses a unique dynamic behaviour with varying gust reduced frequency. The results indicate a correlation between the spring dynamics, gust reduced frequency, and gust load alleviation. This study contributes insights into the literature on developing small fixed-wing UAVs capable of operating in gusty dynamic environments. Keywords: Gust alleviation, Passive pitching, Unsteady aerodynamics, Wind tunnel testing