Discussion of design methods for silent and fuel efficient medium range civil transport

People are more and more concerned about the influence of industrial products on environment.Aircraft noise around airports is the complained environmental impact of civil aviation. The goal of silent aircraft initiative is to design a conceptual aircraft, which is inaudible outside the airport perimeter and also in fuel efficiency and emission control superior to present and future conventional aircraft. By introducing three generations of conceptual silent aircraft experiment (SAX), this paper discussed the design method and enabling technology, including a quasi-3D design method with fast turnaround time and adequate fidelity; aerodynamic design of the blended wing body by optimally shaping its centerbody; deployed drooped leading edge and trailing edge brushes of the outer wing; distributed multi-fan embedded turbofan with boundary layer ingestion; thrust vectoring nozzle with variable exit area; advanced acoustic linears; and faired undercarriage, etc. Finally, the resulting conceptual aircraft design, SAX-40, yields a calculated noise level of 61 dBA at the airport perimeter, which is close to the background noise in a well populated area and imperceptible to the human ear on takeoff and landing. SAX-40 also has the potential for a reduced fuel burn of 124 passenger-miles per gallon.