Transonic buffet characteristics of a 60-deg swept wing with design variations

Wind-tunnel tests of a typical swept wing fighter aircraft were conducted to determine the improvement in the buffet-onset lift coefficient CL^, resulting from wing camber and from leading and trailing edge deflection. The coefficient CLB was determined from trailing edge pressure, wing-root bending moment, fluorescent oil flow photographs, and force data. All four types of data are arranged in a composite graphical form to insure proper CLB selection and to identify the location on the wing where separation first occurs. Results at Mach 0.9 showed that 0.2 increase in camber (airfoil design lift coefficient) increased CLB approximately 0.08; a 5° leading edge droop 0.15; and a 5° inboard trailing edge flap 0.12. Analysis of design trends shown by previous experimental results are described for the effects of wing thickness ratio, sweep, aspect ratio, and camber on CLBSpecific buffet problems related to variable swept wings are discussed.