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Noise Gases Catalysts A-21 Aircraft Noise Measurement Aviation Emission Modeling

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Standard

COMPARISON OF GROUND-RUNUP AND FLYOVER NOISE LEVELS
2002-12-16
CURRENT
AIR1216
Because of the special circumstances under which these tests were conducted, it is necessary to carefully define the limitations on the validity of the results. The measurements and the comparisons reported here apply only to the specific locations of the noise sources and microphones and only for the specific weather and ground-surface conditions existing at the time of the tests. It cannot be assumed that these conditions are representative of most field measurements of aircraft exterior noise.
Standard

MEASUREMENT OF FAR FIELD NOISE FROM GAS TURBINE ENGINES DURING STATIC OPERATION
1995-09-19
HISTORICAL
ARP1846
Recommendations presented in this document are intended primarily for the acquisition of far-field acoustical data. The test engine is to be appropriately configured and operated so that the acoustical signals generated are consistent with the specific objectives of the test. The principal output of the data reduction system is one-third octave band sound pressure levels. However, broader or narrower bandwidth analysis of the recorded data may also be accomplished when appropriate. Although not specifically intended to apply to special purpose engine noise testing (for example, tests involving unique instrumentation or procedures to identify specific noise sources), some of the practices described herein may be appropriate for such testing. Specification of reference conditions is outside the scope of this document although procedures to adjust data to a reference condition are described in 7.2.4.
Standard

MEASUREMENT OF ROTORCRAFT INTERIOR SOUND PRESSURE LEVELS
1993-05-01
HISTORICAL
ARP1964
Satisfactory measurements of noise in personnel-occupied rotorcraft cabins may require test techniques different from those prescribed for other types of aircraft (ARP1323) because rotorcraft operate under significantly different flight conditions. Recommendations of this ARP apply to the recording of acoustical data on magnetic tape and the subsequent processing and analysis of the recorded data.
Standard

QUANTITIES FOR DESCRIPTION OF THE ACOUSTICAL ENVIRONMENT OF THE INTERIOR OF AIRCRAFT
1991-03-15
HISTORICAL
ARP4245
This Aerospace Recommended Practice (ARP) defines quantities that may be used to describe various attributes of the sound field in the interior of aircraft. For a particular aircraft, or for a specific situation in a particular aircraft, it may not be necessary to utilize all the quantities included here to provide an adequate description of an aircraft's interior acoustical environment.
Standard

TYPE MEASUREMENTS OF AIRPLANE INTERIOR SOUND PRESSURE LEVELS DURING CRUISE
1990-08-01
HISTORICAL
ARP1323A
The primary measurement procedure recommended in this ARP includes the recording of sound pressure signals in the interior of an airplane during steady state cruise conditions with analysis after the flight into octave band (or one-third octave band) sound pressure levels.
Standard

HELICOPTER EXTERNAL NOISE ESTIMATION
1989-05-01
HISTORICAL
AIR1989
This method estimates noise for both single and tandem main rotor helicopters except for approach where it applies to single rotor designs only. It does not apply to coaxial rotor designs. Application is limited to helicopters powered by turbo-shaft engines and does not apply to helicopters powered by reciprocating engine, tip jets or other types of power plants. It provides noise information using basic operating and geometric information available in the open literature. To keep the method simple, it generates A-weighted sound levels, precluding the necessity for spectral details. The method prescribes estimates for typical helicopter operations; certain maneuvers may produce noise levels different from those estimated. Estimates are given for the maximum sound levels at 4 ft (1.2 m) height above the ground. For aircraft in forward flight, the estimate is given for an aircraft at an altitude of 500 ft (152 m) on a path directly over the observer.
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