Task Order 33 had four primary objectives as follows: (1) Identify and prioritize the airframe noise reduction technologies needed to accomplish the NASA Pillar goals for business and regional aircraft. (2) Develop a model to estimate the effect of jet shear layer refraction and attenuation of internally generated source noise of a turbofan engine on the aircraft system noise. (3) Determine the effect on community noise of source noise changes of a generic turbofan engine operating from sea level to 15,000 feet. (4) Support lateral attenuation experiments conducted by NASA Langley at Wallops Island, VA, by coordinating opportunities for Contractor Aircraft to participate as a noise source during the noise measurements. Noise data and noise prediction tools, including airframe noise codes, from the NASA Advanced Subsonic Technology (AST) program were applied to assess the current status of noise reduction technologies relative to the NASA pillar goals for regional and small business jet aircraft. In addition, the noise prediction tools were applied to evaluate the effectiveness of airframe-related noise reduction concepts developed in the AST program on reducing the aircraft system noise. The AST noise data and acoustic prediction tools used in this study were furnished by NASA. Lieber, Lys S. and Elkins, Daniel and Golub, Robert A. (Technical Monitor) Glenn Research Center; Langley Research Center NAS3-27483; RTOP 781-20-12-01

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

This manual provides direction for the preparation of noise and vibration sections of environmental documents for mass transportation projects. The manual has been developed in the interest of promoting quality and uniformity in assessments. It is expected to be used by people associated with or affected by the urban transit industry, including Federal Transit Administration (FTA) staff, grant applicants, consultants and the general public. Each of these groups has an interest in noise/vibration assessment, but not all have the need for all the details of the process. Consequently, this manual has been prepared to serve readers with varying levels of technical background and interests. It sets forth the basic concepts, methods and procedures for documenting the extent and severity of noise impacts from transit projects.

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