Preliminary Evaluation of Noise Reduction Approaches for a Functionally Silent Aircraft

Abstract

Aircraft noise is a major inhibitor of the growth of civil air transportation. Airports in key locations are operating at full capacity and the noise in the vicinity of airports is so intrusive that local communities object to any further expansion. Thus, quiet aircraft would constitute a crucial step forward on an economic, societal and urban planning level. A functionally-silent aircraft is aimed at achieving a step change in airframe and propulsion system noise reduction to noise levels below the current NASA goals. “Silent” in this context means sufficiently quiet that the aircraft noise is less than that of the background noise in a typical well populated environment. Such aircraft would enable an expansion in air transportation by creating opportunity for new airports and allowing increases in operating hours at existing sites. This Engineering Note reports on a preliminary evaluation of noise reduction technologies for a quiet aircraft. The work was conducted under a NASA Langley research contract in 2001–2003 (Manneville et al.1).