Development Program for the F-15 Inlet

Abstract

This paper describes the F-15 variable capture area inlet and the associated control system. Factors that influenced integration of the inlet/inlet control system with the total airframe are discussed. The methodology of using instantaneous total pressure patterns at the engine face to evaluate the effect of inlet distortion on engine operation is briefly described. Several inlet design variables that were tested are discussed. In addition to its effects on inlet behavior, the variable capture area reduces cruise drag, favorably influences aircraft longitudinal stability at low speeds, and reduces loads on the inlet backup structure at certain supersonic conditions. The boundary-layer bleed system optimization demonstrated that a slot in the throat was the single most effective location for bleed removal. Comparative results are presented for the final configuration between model and full-scale wind-tunnel testing, and subsequent flight testing. Results show that full-scale instantaneous distortion typically is equal to or less than that measured on a l/6th scale model.