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This document describes a method to calculate noise level adjustments at locations behind an airplane (described by an angular offset or directivity) at the start of takeoff roll (SOTR). This method is derived from empirical data from jet aircraft (circa 2004), most of which are configured with wing-mounted engines with high by-pass ratios (Lau, et al., 2012). Methods are also described which apply to modern turboprop aricraft. Calculations of other propagation-related adjustments required for aircraft noise prediction models are described in AIR1845A, ARP5534, ARP866A, and AIR5662.

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.

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.

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. Due to lack of available data, application of the method has not been evaluated for application to tiltrotor, or other VTOL configurations, when operating in the helicopter mode. Since there are substantial differences between helicopter rotors included in the data base, and tiltrotor rotors, application to VTOL configurations other than helicopters is not advised. Application is limited to helicopters powered by turboshaft 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, and Sound Exposure Levels precluding the necessity for spectral details.

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.

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. Due to lack of available data, application of the method has not been evaluated for application to tiltrotor, or other VTOL configurations, when operating in the helicopter mode. Since there are substantial differences between helicopter rotors included in the data base, and tiltrotor rotors, application to VTOL configurations other than helicopters is not advised. Application is limited to helicopters powered by turboshaft 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, and Sound Exposure Levels precluding the necessity for spectral details.

This SAE Aerospace Information Report (AIR) summarizes prior empirical findings (AIAA 2018-3991; Chati, 2018) to recommend a modified baseline fuel flow rate model for jet-powered commercial aircraft during taxi operations on the airport surface that better reflects operational values. Existing standard modeling approaches are found to significantly overestimate the taxi fuel flow rate; therefore, a modified multiplicative factor is recommended to be applied to these existing approaches to make them more accurate. Results from the analysis of operational flight data are reported, which form the basis for the modeling enhancements being recommended.