Variable Noise Reduction Systems for a Notional Supersonic Business Jet
Jeffrey J. Berton
Abstract
A variable noise reduction system consists of equipment on board an airplane that is designed to reduce noise in the vicinity of airports. They are anticipated to be used on supersonic civil aircraft currently under development by industry. They are investigated in this paper for a notional 55,000 kg supersonic business jet. The airplane concept was developed by NASA for use in environmental impact studies conducted by the International Civil Aviation Organization. The variable noise reduction system investigated implements a programmed thrust lapse procedure and a programmed flap retraction procedure. The procedures are expected to reduce noise in aircraft certification as well as in operational practice. Behavior of the aircraft in a noise certification setting is considered. Variables of the procedures are optimized to reduce noise levels. The optimization results in a reduction of 5.2 decibels (in the cumulative effective perceived noise level, measured in EPNdB) relative to levels reported previously. Certification considerations unique to these systems are discussed for transport-category large airplanes and jet-powered airplanes. A novel method for evaluating lateral noise is used.