Wing rock suppression in the F-15 aircraft

Abstract

This study was a limited investigation to determine a basic linear feedback control architecture to delay the onset angle-of-attack (AOA) of wing rock in the F-15B. An eight state F-15B model is analyzed using bifurcation theory and the solutions to the eigenvalue structure to determine the sensitivity of each of four different aerodynamic coefficients, Cy^, Cyp, Clp, Clp, have on the onset of wing rock. A previously developed parameter, the Trigger Parameter X^, is also analyzed for sensitivity to changes in each of the four basic aerodynamic coefficients. A procedure is developed to feedback parameters to a control surface that will strengthen the most sensitive parameters. The results show a significant delay of 3.7 degrees in the onset of wing rock with the use of sideslip feedback to the aileron and rudder simultaneously. The sideslip feedback is accomplished to strengthen the most sensitive parameter, Clp. Clp was the next most sensitive parameter but attempts to effectively increase Clp with roll rate feedback offered little to no significant change in delay of the onset point.