Roll Damping Measurements on Basic Finner Model Using Both Forced and Free Methods

Abstract

Determination of aerodynamic damping coefficients has always been difficult due to the dynamic nature of measurements for both forced and free methods. Although aerodynamic damping identification is available since the 1960s, this testing capability is not available in most of the high-speed wind tunnels due to its complexity, although the aerodynamic damping coefficients are needed for every aerospace vehicle. Herein are presented the development of the rig for roll damping determination, which uses both free and forced methods in the working cycle; the calibration process using the basic Finner model with reference data; and the experimental results obtained. Also, considering the challenges for computational fluid dynamics to match the experimental results, numerical results are presented for the calibration points required for interpolation of the roll damping coefficient along a Mach number range. The calibration points cover all regimes from subsonic to supersonic at Mach numbers ranging between 0.4 and 3.5. Conclusions are presented, focusing on the comparison between forced and free methods, as well as the rotation direction, considering the flow deflection that is increasing the level of uncertainty.