Active control device for aircraft tail buffet alleviation

Abstract

A rotatable slotted cylinder (RSC), partially embedded within the contours of a tail surface, such as an aircraft tail airfoil, serves as a force-producing element in a closed-loop active control system for buffet alleviation. A longitudinal axis of the RSC runs spanwise to the airfoil at or near the three-quarter chord location. In a so-called 'home' position, the RSC projects as two small spanwise humps out of opposite sides of the tail surface. By active feedback control using a buffet response signal measured by an accelerometer, the RSC rotates up to .+-.45.degree. maximum deflection from the home position, thus allowing free stream air to flow through the airfoil, thereby creating lift forces for the active alleviation of the buffet response on the tail surface. An alternate embodiment of the invention places the RSC and a drive motor assembly outside of and adjacent to the tail surface near the airfoil quarter chord station. In this closed-loop active control system, the RSC is driven to rotate relative to the home position. The system alters the pressures on the tail surface, thus developing lift forces necessary to counter the buffet response. The invention allows a low-cost, lightweight solution to alleviate severe buffet response on the tail surfaces of a fighter aircraft at high angles of attack. Thus, the invention overcomes the problem of extreme vibrations which have caused premature structural fatigue failures and the need for costly repairs.