NASA aircraft noise reduction research and technology program overview

A brief outline of the chief areas where NASA is making efforts in aircraft noise research is given. This includes studies of the physical basis of aircraft noise and methods for accurately predicting it, the development of practical technologies for noise reduction, and the subjective response of people when exposed to aircraft noise. The JT8D Refan Program was to explore whether the noise reduction design concepts used effectively in modern high-bypass engines could also be applied practically and effectively as retrofittable modifications to existing older, low-bypass JT8D engines. A program has been completed on developing and demonstrating safe and acceptable flight procedures together with necessary airborne electronics to permit two-segment approaches under either VFR or IFR conditions.