Showing papers on "Aircraft noise published in 1969"

Assessment of Aircraft Noise Disturbance

Abstract: The disturbance due to aircraft noise which is being experienced in residential areas around the world's major airports is generally recognised as a serious problem. Indeed, the problem has reached the stage where public reaction is already influencing the development of future aircraft. Such influence may be seen in current international intention to include noise limitations in the certification of aircraft. Limits imposed on the noise generated by aircraft engines should serve to prevent the problem from becoming catastrophic, but cannot be expected to provide a final solution. Aircraft manufacturers may seem confident that further improvements in performance could be achieved without corresponding increase in noise, but further increases in air traffic could cancel out these gains and still leave communities near airports excessively disturbed.

Noise Encountered in Rotary‐Wing Aircraft

Abstract: The acoustic environment encountered within rotary‐wing aircraft constitutes a mixture of several noise‐generating mechanisms. Primary and secondary noise‐producing mechanisms that are associated with the ground and airborne operation of rotary‐wing aircraft are identified, described, and illustrated. Some of the noise sources studied include main rotor(s), antitorque rotor, main and secondary transmission and gear‐shaft distribution systems, and auxiliary power units. In addition to reporting specific noise generators, composite noise envelopes are provided, which illustrate typical noise environs found within rotary‐wing vehicles with different configurations of rotor‐power plant matings. Alterations in internal noise that occur during conditions of hover and forward flight are described, and aeromedical factors such as speech interference and potential auditory risk are identified.

Helicopter rotor noise generation.

Abstract: Distributive loading rotational theory for helicopter rotor noise generation, considering steady and fluctuating force radiation and impulsive blade slap

Turbine Noise: Its Significance in the Civil Aircraft Noise Problem

Abstract: The authors show the presence of noise from the turbine of a turbojet or turbofan engine to be a significant contributor the overall engine noise. They review currently available information from both full-scale engines and model turbines and correlate it along lines following those previously developed for fans and compressors.Copyright © 1969 by ASME

Building vibrations due to aircraft noise and sonic-boom excitation

Abstract: Residential structures vibration response to aircraft flyover noise, discussing noise transmission, rattle phenomenon, spectra, etc

Noise exposure forecast contour interpretations of aircraft noise tradeoff studies

Abstract: : The effectiveness of changes in aircraft operating procedures and aircraft hardware regarding the reduction noise near airports were rated by determining the changes in land areas falling within the Noise Exposure Forecast contours. Sets of NEF contours were constructed for two different aircraft types operating from a single runway airport; the number of operations per day was varied from 200 to 1000. The changes included power cutbacks after takeoff, two segment approaches and retrofit of four-engine turbofan aircraft with acoustically-lined nacelles or with a 'quiet engine'.