Accession Number : ADP006228

Title :   Predictions of F-111 Tact Aircraft Buffet Response,

Corporate Author : GENERAL DYNAMICS FORT WORTH TX FORT WORTH DIV

Personal Author(s) : Cunningham, Atlee M., Jr. ; Coe, Charles F.

Report Date : SEP 1990

Pagination or Media Count : 16

Abstract : This report presents a method for predicting buffet response from pressure-fluctuations on scale models in wind tunnels. The method embodies the following features: (1) The buffet forcing function is obtained by real time integration of pressure time histories with the natural modes. (2) Damping is obtained for pivot modes from model buffet response. (3) A hybrid method was developed and applied to extend the pivot-mode damping measurements to multiple modes by the use of theoretical damping data. (4) A technique was developed to form composite modes to obtain better one-to-one correspondence between model and aircraft modes to improve the scaling of damping. (5) Diagonalized equations of motion were derived and applied to simplify the multiple degree-of-freedom buffet response calculation. The results presented have shown correlations of predicting and measured buffet response of the F-111 TACT aircraft at M = 0.8 with 26 deg. and 35 deg. wing sweeps for a range of angles-of-attack that includes buffet onset to high intensity buffeting.

Descriptors :   *BUFFETING, JET FIGHTERS, FLIGHT MANEUVERS, MATHEMATICAL PREDICTION, PRESSURE DISTRIBUTION, FLOW SEPARATION, TRAILING EDGES, DAMPING, STRUCTURAL RESPONSE, WIND TUNNEL MODELS, SCALING FACTOR, EQUATIONS OF MOTION, COUPLING(INTERACTION), TRANSONIC CHARACTERISTICS.

Subject Categories : Aerodynamics
      Attack and Fighter Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE