A new approach for the estimation of longitudinal damping derivatives: CFD validation on NACA 0012

Aerodynamic longitudinal damping derivatives are of great importance for aircraft stability and control and for aircraft aeroelasticity problems. The classical methods adopted to calculate damping derivatives, using USAF Datcom or wind tunnel tests, are not accurate enough for unconventional shaped aircrafts in particular. Moreover, experimental methods refer to body pitch and plunge motion: it follows that the derivatives are affected to a great extent by the frequency. Some authors have proposed quasi-steady methods, which fail at the transonic regime. To overcome all of these shortcomings, a new approach, based on looping and heaving motion, is presented. The results of the proposed methods are validated, using CFD simulation with the NACA 0012 airfoil, against the exact Theodorsen theory, indicial functions and numerical results from other authors.