CORRELATION OF F A-18 BUFFETING FROM WIND-TUNNEL AND FLIGHT TESTS/

A method to predict full-scale buffet of the F/A-18 vertical tail usin g measurements taken on a rigid wind-tunnel model is presented, Tests were performed on a rigid 6% scale F/A-18 in the 1.5-m trisonic blowdo wn wind tunnel at the National Research Council in Ottawa, over a rang e of angle of attack and Mach number, The results from the prediction code were compared to night test results, which were obtained from nig hts undertaken at the Aerospace Engineering Test Establishment in Cold Lake, Alberta. In general, comparisons between flight and scaled wind -tunnel data were good, although the initial prediction code invariabl y underpredicted the full-scale response. Through the use of a variabl e pressure correlation technique (based on flight conditions) the accu racy of the prediction model was significantly increased. The night da ta was also reduced to the nondimensional buffet excitation parameter. It was found that buffeting in the fundamental torsional mode at appr oximately 45 Hz occurred at a lower angle of attack (with larger overa ll magnitudes) compared to the fundamental bending mode at 15 Hz.