Time varying effects on the buffet response of a scaled F/A-18 vertical tail

Abstract

A wind tunnel experiment using a 15% scaled F/A-18E model was performed for the purpose of quantifying the effects of pitch rate on buffet loads and response. Tests were performed at dynamic pressures of 1.5 to 10.0 psf and simulated a symmetric pull-up maneuver by pitching-up the model at rates of seven deg/sec. Results indicate that the nature of the buffeting changes during a pull-up maneuver. In general, buffeting is a function of dynamic pressure and angle-of-attack. However, pitching the model decreases buffeting loads over measured static conditions. In addition, the center frequency of the buffet excitation increases with pitch rate. This effect on the buffet pressures changes the response of the tail by shifting the peak buffet response to higher angles of attack.