Accession Number : ADP007520

Title :   A Brief Review of the Source Noise Technology Applicable to Fixed-Wing Military Aircraft,

Corporate Author : DEFENCE RESEARCH AGENCY FARNBOROUGH (UNITED KINGDOM) AEROSPACE DIV

Personal Author(s) : Pinker, R. A.

Report Date : APR 1992

Pagination or Media Count : 14

Abstract : Historically, civil aircraft have been required to meet ever tightening international standards, namely ICAO Annexe 163 in Europe and FAR part 364 in the United States and as a result the noise levels for new civil aircraft entering service have dropped by almost 20 dB5 as shown in Fig 1. This was initially due to the change from turbojets (or low-bypass ratio engines) to the modern high-bypass ratio engines 6 such as the RB21 1,JT9 and CF6. The impetus behind their development was primarily for greater propulsive efficiency but the associated move towards lower specific thrusts, that is thrust provided by greater mass flows and lower exhaust velocities, reduced the dominance of the jet mixing noise and this trend is evident from Fig 2. Further advances in noise reduction technology, driven by tighter legislation, and coupled with the gradual retirement of the older and noisier jets has thus significantly improved the noise climate around civil airfields.

Descriptors :   *NOISE REDUCTION, *MILITARY AIRCRAFT, *AIRCRAFT ENGINE NOISE, *FIXED WING AIRCRAFT, AIRCRAFT, CLIMATE, EFFICIENCY, EUROPE, INTERNATIONAL, LANDING FIELDS, LEGISLATION, MASS, MIXING, NOISE, RATIOS, REDUCTION, RETIREMENT, STANDARDS, THRUST, UNITED STATES, VELOCITY, LOW ALTITUDE.

Subject Categories : Acoustics
      Military Aircraft Operations
      Noise Pollution and Control

Distribution Statement : APPROVED FOR PUBLIC RELEASE