Research Projects

Helicopter and Tiltrotor Noise Modeling Procedures Document

Assigned to Juliet Page

The objective of this research effort is to develop written documentation on best available methods to model community noise generated from helicopter and tiltrotor operations. The document should address integrated and simulation modeling techniques, and methods for collecting and analyzing noise source data, and outline noise source development protocols. The language and format of the document shall be suitable for standards submission.

Background (Describe the current situation or problem in the industry, and how your idea would address it.)

Existing noise modeling standards [SAE-AIR-1845; ICAO, Doc-29] for prediction of fixed wing community noise have been promulgated internationally and serve as the technical justification and defensible rationale upon which numerous noise models such as the Aviation Environmental Design Tool (AEDT) and the Integrated Noise Model (INM) rely. At present no such standards address modeling of helicopter or tiltrotor noise.

The ACRP 02-44 Project provided seven key recommendations for improving AEDT (integrated) noise modeling which included metrical quantification, source acoustic emission fidelity, flight operations and flight mode capability and propagation/environmental modeling requirements. However, final recommendations could not be provided for maneuvering flight acoustic considerations, though research has certainly advanced significantly in recent years.

Technical progress towards commercial operation of a new class of civil tiltrotors continues with expected entry into service of the AW609 tiltrotor expected in 2020. Presently AEDT does not have the capability to model tiltrotor operations, though existing models having tiltrotor modeling capability (AAM and formerly RNM) have been employed by the US DoD for some time.

Recent cooperative helicopter flight tests conducted by NASA and FAA/Volpe have gathered significant data that is being used to seed various helicopter noise models such as AAM and AEDT, but maneuvering flight noise data was also gathered for validation of first principles and semi-empirical modeling tools such as CHARM-PSU-WopWop and FRAME. This supplemental information and the associated models have advanced and could provide critical insight for development of recommendations for modeling maneuvering flight acoustics.

Objective (What is the desired product or result that will help the airport industry?)

The objective of this research effort is to develop written documentation on best available methods to model community noise generated from helicopter and tiltrotor operations. The document should address integrated and simulation modeling techniques, and methods for collecting and analyzing noise source data, and outline noise source development protocols. The language and format of the document shall be suitable for standards submission.

Approach (Describe in general terms the steps you think are needed to achieve the objective.)

Draw on the existing modeling tools and knowledge base to develop documentation for prediction of helicopter and
tiltrotor community noise. This project should address both simulation and integrated noise modeling methods and
leverage the series of recommendations for improvements in integrated noise modeling provided in ACRP 02-
44.
Recommended tasks include:

Literature review of helicopter and tiltrotor noise modeling,

Evaluation of new research related to maneuvering flight modeling,

Develop modeling recommendations for maneuvering flight modeling, and

Prepare a document on helicopter and tiltrotor noise modeling procedures that could serve as a start to a
standards review process.

Cost Estimate and Backup (Provide a cost estimate and support for how you arrived at the estimate.)

$250k. Cost includes modeling analysis; examination of new research for maneuve
ring flight modeling; outreach for
peer review of new components not already documented in ACRP 02-
44; and Preparation of Tiltrotor and Helicopter
Noise Modeling Procedures technical documentation.

Related Research - List related ACRP and other industry research; describe gaps (see link to Research Roadmaps above), and describe how your idea would address these gaps. This is a critical element of a synthesis topic submission.

Airport Cooperative Research Project (A
CRP) No. 02-
44, Sept. Available from
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=3439.
Brentner, Kenneth S., et al., "Final Report, Rotorcraft Noise Abatement Operating Conditions Modeling," ASCENT
Project 6: https://s3.wp.wsu.edu/uploads/sites/192/2017/03/ASCENT
-Project
-6-Final
-Report
-v3.pdf
Brentner, Kenneth S., et al., "ASCENT Project 38, Rotorcraft Noise Abatement Procedures Development,"
https://ascent.aero/project/rotorcraft
-noise
-abatement
-procedures
-development/
European C
ivil Aviation Conference (ECAC), "Report on Standard Method of Computing Noise Contours around
Civil Airports," Doc 29 -
4th Edition, 7 December 2016
Greenwood, Eric, Benjamin May, Christopher Hobbs and Robert Rau, "A Maneuvering Flight Noise Model for
He
licopter Mission Planning", AHS Forum 2015.
Greenwood, Eric "Fundamental Rotorcraft Acoustic Modeling from Experiments (FRAME)", PhD Thesis, UMD,
2011.
Leonardo Press Release, Rome, 27 February 2018, "Era Group to mark entry of AW609 tiltrotor into the U
S
commercial market." http://www.leonardocompany.com/en/
-/hai
-heliexpo-
aw609-
era
Nelms, Douglas, "US Government Conducts Flight Testing to Prove Noise Prediction Models," Vertiflite, Jan/Feb
2018. https://vtol.org/files/dmfile/Noise
-Nelms_VF
-JF181.pdf
Page, Juliet A., Christopher M. Hobbs, Benjamin May, Eric Boeker, Harry Brouwer, Clint Morrow, 2015.
"Guidance for Helicopter Community Noise Prediction Final Report", National Academies of Science,
Transportation Research Board,
Saetti, Umberto., "Rotorcraft Simulations with Coupled Flight Dynamics, Free Wake, and Acoustics", 2016,
10.13140/RG.2.1.2259.3529.
Society of Automotive Engineers (SAE), 1986. "Procedure for the Calculation of Airplane Noise in the Vicinity of
Airports", SAE Standards AIR 1845, issued Mar.
Transportation Research Board (TRB) 2016. "Recommended Community Noise Model Enhancements to Improve
Prediction of Helicopter Activity Impacts", National Academies of Science, Transportation Research Board, Airport
Cooperative Research Pr
oject, Research Results Digest 24, January. Available from:
http://www.trb.org/main/blurbs/173719.aspx.
Watts, Michael, Eric Greenwood, "Maneuver Acoustic Flight Test of the Bell 430 Helicopter
- Data Report," NASA
TM 2014-
218266, 2014.

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