Circulation Control for Quiet Commercial Aircraft

Abstract

Aircraft Noise Pollution in Communities living close to commercial passenger airports world-wide could have been avoided if, following the Second World War, Governments and Local Planners had built very large commercial airports according to strong directives and regulations preventing the building of residential houses in zones in the vicinity to the airport boundary. Today the challenge is to use the experience gained in recent years on ∞ow and noise control in respect of quiet aircraft noise reduction technology(QAT) and its applications, capable of reducing and even eventually eliminating the aircraft noise problem within communities close to airports. In this study the necessary parameters are set out for the design of such future aircraft having safe ∞ight trajectories at takeofi and approach to landing when over∞ying residential areas close to all airports. To achieve this future noise reduction goal it is necessary to extend the present QAT program, based on an interim solution requiring the refurbishment of existing conventional takeofi and landing (CTOL) aircraft to reduce by 10dB the noise in communities close to the airport. It will be shown that to achieve the extended goal the likelihood is that all commercial aircraft will need to ∞y higher and slower in over∞ying residential areas involving a revolution in the low speed operation of all air transport. Residents, however, would then flnally recognize by sight and sound that technology, supported by Governments and Local Authorities, has at last produced a solution to this long standing aggravation of aircraft noise nuisance and annoyance in residential communities. The difierent types of aircraft capable of meeting this challenge are reviewed in the current study. It is shown that one solution to this problem is to changeover from CTOL aircraft to short takeofi and landing(STOL) aircraft operating with Circulation Control. This would eliminate the need for the flnal approach to landing along the 3 ‐ ILS glide slope, involving over∞ying at low altitude communities living close to an airport. Such a revolution in ATC, ∞y-by-wire and pilot handling in replacing this tried and tested approach, by a slower speed STOL circulation control aircraft ∞ying a new safe steep approach path trajectory with the aircraft ∞ying at a low shallow nose up attitude relative to the ground will need pilot approval with FAA and International acceptance. The flnal approach would follow a continuous descent trajectory from cruise to an altitude near 1000m with a changeover to STOL operation for the flnal approach to landing. Such a STOL approach to landing is similar to that used by helicopters. There exists a vast amount of knowledge and experience on this type of STOL aircraft, which has been used successfully for military and small commercial aircraft on short-haul operations. This approach to landing will allow an increase in the slant distance from aircraft to people on the ground, and thereby reduce the noise in residential communities close to the airport. Current research is now focused on the optimization of this type of aircraft for small, medium and large commercial aircraft to ensure this type of aircraft can not only meet all its cruise and low speed performance and economic goals with safe ∞ight trajectories, but also those specially related to the large noise reduction predictions that will need conflrmation in the communities close to airports at take-ofi and on the approach to landing. Little research has been directed so far to the assessment of the noise, and methods for its reduction, for the circulation control aircraft ∞ying a steep approach trajectory. The aim of this study is to seek a revolution in the optimum design of the STOL circulation control aircraft ∞ying safe and acceptable low speed and ‘low’ noise trajectories for all commercial passenger aircraft, including both subsonic and supersonic aircraft. The aim is to ensure all aircraft over∞ying residential areas maintain a separation distance of at least 1000m.