An Approximate Analysis of Wing Unsteady Aerodynamics

摘要

A brief review of the unsteady aerodynamics in lifting surface theory is reported. For utility in design application, simplified but accurate analytical expressions were developed for generalized unsteady aerodynamics of wings of finite aspect ratio and sweep. This includes a means of calculating the unsteady lift load on the wing and tail surface of arbitrary shape and angle of attack variation. In addition, a formulation to include the indicial aerodynamics in the longitudinal equations of motion of the aircraft was performed. Sample numerical solutions to the longitudinal equations for a step input in elevator deflection are presented for the Navion aircraft. From these calculations, a noted difference in angle of attack and pitch rate response can be seen for the cases of unsteady and quasi-steady aerodynamics. The apparent increase in damping effects in the aircraft response due to the unsteady aerodynamics indicate that various design constraints might be relaxed somewhat if the unsteady aerodynamics is modeled properly. (Author)