Introduction

Progress reported on principle NASA programs for the reduction of aircraft engine noise emphasizes the Quiet Engine Program. Considered are fan noise and performance, fan noise suppression, and jet noise reduction for a broad spectrum of airplanes including new subsonic airplanes, the older subsonic airplanes in service today, STOL airplanes of the future, and future supersonic transports. Noise reductions achieved in the framework of the Quiet Engine Program are demonstrated and future possible applications of low noise technology to airplanes are discussed.