Roll Rate and Reduced Frequency Effects on Blunt Body Dynamics in a Supersonic Wind Tunnel

Free-oscillation tests are performed for a faceted blunt body in a supersonic wind tunnel at M = 2. The model is free to rotate in pitch, yaw and roll by means of a spherical air bearing, and a non-invasive photogrammetry method is selected to track the angles in time. Roll generators are fitted at the tips of the model’s panels to produce different roll-moment magnitudes and assess their effects on the dynamics. The model's coning motion is shown to be sensitive to roll rate, with dynamic instabilities associated to the divergence of the rolling trim and precession modes. Additionally, two values of reduced frequency are tested by changing the bearing material. It is shown that the dynamics scale well with reduced frequency. The main difference occurs during sustained precessional motion, which appears to be more unstable at higher oscillation frequencies.