Noise Reduction Research Bill Willshire Home & Home Langley Research Center November 16, 1999

1. Noise Reduction Research Bill Willshire Home & Home Langley Research Center November 16, 1999 AT H&Hnr-vk

2. Environmental Concern • Quality of Life • Public Good Increased Capacity Improved Competitiveness • Balance of Trade • Public Good • Enables Growth • Public Good Noise Reduction Program Drivers

3. Noise Reduction Progress in Noise Reduction 120 Sideline 110 Noise Level, EPNdB (1500’ Sideline) 100 A321 A330 777-200 MD90-30 90 1950 1995 1960 1970 1980 1990 Year of Initial Service • Without new noise reduction technology, increasing demand coupled with increasing population will result in increased community noise impact.

4. Noise Reduction Current Program Objective and Scope • Objective: • 10 dB Community Noise Impact Reduction Relative to 1992 Production Technology • Scope: • A broad, $200M joint program with the FAA • Initiated in FY1994, ends in FY2001 • Technical program is result of an extensive NASA inter-center, FAA, and industry partnership. • Note: With the termination of the Advanced Subsonic Technology Program in FY00, the Noise Reduction Element was transferred to the Aerospace Vehicle Systems Technology Program

5. Noise Reduction Current Program Management Structure Aerospace Vehicle Systems Technology Program NASA Langley Research Center Darrel Tenney, Director Industry/Government Steering Committee FAA Noise Reduction Program NASA Langley Research Center Bill Willshire, Manager Loretta Shaw, GRC; Brian Smith, ARC Industry/Government Technical Working Group • Ames Research Center • • Engine Noise Reduction • • Nacelle Aeroacoustics • Airframe Noise Reduction • Clif Horne Langley Research Center • Engine Noise Reduction • Nacelle Aeroacoustics Joe Posey • Airframe Noise Reduction • Interior Noise Reduction Rich Silcox • Community Noise Impact Kevin Shepherd Glenn Research Center • Engine Noise Reduction Dennis Huff • Nacelle Aeroacoustics Primary Support

6. Noise Reduction Engine Noise Reduction • NASA/Allison Low-Noise Fan in Glenn Research Center 9’x15’ Wind Tunnel • Demonstrated 3 EPNdB Fan Noise Reduction Baseline Swept Stators Swept/Leaned Stators

7. SPL, dB Frequency, Hz Noise Reduction Flap-edge Airframe Noise Reduction • Airframe noise: • Today major source on approach • Tomorrow major source on takeoff • Components: flap, slat, and gear CFD/CAA Model in LTPT* • Flap-edge Airframe Noise Reduction • Physics-based mechanism identification • Source localization • Non-intrusive reduction concepts discovered and optimized • 4 dB flap-edge noise reduction Reduction Mic Array *Langley Research Center Low Turbulence Pressure Tunnel

8. Noise Reduction Propulsion Airframe Interaction Experiment Low Speed Aeroacoustic Facility Microphone Array Results Boeing 20 kHz Jet with Wing Isolated Jet • Presence of wing/fuselage dramatically impacts apparent noise source • Jet with wing up to 8 dB nosier • Interactions not understood and therefore not exploited

9. 120 100 Predicted, dB 80 60 60 80 100 120 Measured, dB Noise Reduction Validation of Noise Prediction Model in Community Noise Impact Models • 5001 Departures from DIA • 6 Aircraft Types • ≥ 60 Degrees Above Horizon Contour Plot Perfect Agreement Predicted, dB 10 dB Measured, dB

10. AT Vision • Reduce the perceived noise levels of future aircraft by one half (10 dB) from today’s subsonic aircraft within 10 years, and by threequarters (20 dB) within 25 years • 10-year Goal: 65 LDN at airport boundary • 25-year Goal: 55 LDN at airport boundary • Air transport system is constrained by noise • Current planned program will achieve 50% of 10-year goal • Broad-based customer support • Technology for 2020 and beyond needed soon • FAA relies on NASA for long-term noise solutions • No national noise program after 2001 • Objectionable aircraft noise contained within airport boundary. Enterprise Noise Goal Benefit Justification National Need for Noise Reduction

11. Key 5 10 5 5 20 10 20 20 10 55 dB 65 dB Airport 0 10 Miles Benefit O’Hare Yearly Average Day Night Level (DNL) Noise Contours 1997 Baseline • Not acceptable Current Program* 5 dB Reduction • Improvement - significant reduction • Does not meet public expectations • Constrained growth 10-Year Enterprise Goal 10 dB Reduction Scale • 65 dB contour contained within airport • Enable projected air travel growth • Reduce community noise impact *TRL 6 relative to 1997

12. Noise Reduction Concluding Remarks • Aircraft noise is a critical international environmental issue • Very visible public concern in the US • Noise will continue to constrain air travel growth until objectionable noise contained within airport boundary • Current noise reduction program will achieve half of 10-year goal (-5 dB) • Slow fleet turnover dictates near-term solution of far-term problems • No national noise reduction program exists or is planned for the future • Noise reduction research is about public good and enhances quality of life • Technical solutions should lead /guide national policy • NASA alone of the federal labs has the expertise/capability/track record to make the required contributions