Accession Number : AD0260759

Title :   GROUND AND IN-FLIGHT ACOUSTIC AND PERFORMANCE CHARACTERISTICS OF JET-AIRCRAFT EXHAUST NOISE SUPPRESSORS

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON D C

Personal Author(s) : COLES,WILLARD D. ; MIHALOEW,JOHN A. ; SWANN,WILLIAM H.

Report Date : AUG 1961

Pagination or Media Count : 1

Abstract : Characteristics were determined for a twin-engine jet aircraft with the following configurations: (1) eight-lobe exhaust noise suppressors, (2) eight-lobe nozzles and ejectors, and (3) the unmodified aircraft. In-flight sound pressure levels measured on the ground under the flight path were reduced 5 to 6 decibels by the suppressors. Similar reductions in perceived noise level occurred. Increases in total drag coefficient of 3 and 7 percent and decreases in specific range of 5 to 14 percent were found to result from the suppressor configurations. (Author)

Descriptors :   *JET ENGINE NOISE, COUNTERMEASURES, EXHAUST NOZZLES, FLIGHT TESTING, TURBOJET EXHAUST NOZZLES

Distribution Statement : APPROVED FOR PUBLIC RELEASE