Some subsonic and transonic buffet characteristics of the twin-vertical-tails of a fighter airplane configuration

Vertical-tail buffet response data were obtained from tests in the Langley Transonic Dynamics Tunnel using a rigid, 1/6-size, full-span model of an F-18 airplane that was fitted with flexible vertical tails of two different levels of structural stiffness. Response data are presented at Mach numbers from 0.30 to 0.95 over a range of angles of attack from -10 to +40 degrees. These data indicate the following: (1) the buffet response occurs in the first bending mode; (2) the buffet response is a maximum in the angle of attack range from 30 to 40 degrees; (3) the buffet response increases with increasing dynamic pressure, but changes in response are not linearly proportional to the changes in dynamic pressure; (4) the buffet response is larger at M = 0.30 than it is at the higher Mach numbers; and (5) the maximum intensity of the buffeting is described as heavy to severe using an assessment criteria proposed by another investigator.