An Airframer’s Comments NASA’s 4th Environmental Compatibility Workshop August , 1999 Colorado Springs, CO Robert D. Cuthbertson Boeing Commercial Airplanes

Significant Events Since 3rd Workshop Production at peak rates in 1998 and New Generation 737 Family - New Customer Driven Derivatives Participated in NASA sponsored Environmental Technology development Advanced Subsonic Transport & High Speed Research Programs Formed Aviation Partners Boeing to provide opportunity for installation of winglets on large commercial airplanes - Can provide ~ 4% fuel burn reduction - Can reduce noise - Can impact the existing fleet Large reduction of NASA budget for aeronautics research

Turbofan Duct Propagation Model OBJECTIVES: ACCOMPLISHMENTS: Validate the parabolic duct acoustics code “cduct” Use cduct to imrpove fan duct acoustic lining designs Inch by inch optimum impedance target Substantial noise reduction vs. present designs Eliminate unnecessary cost and weight Validation test using active impedance control completed Full scale scarf inlet test completed Phased array on the inflow control device Two inlets and several lining configurations Preliminary fan duct impedance optimization Six zones in a production-type fan duct 5-10 dB improvement Improved treatment of flow Genetic algorithm for impedance optimization Fan duct zones for impedance optimization cduct HW (1,0) Z = (1,0) (1,0) horn data Validation test with active impedance control Fwd fan sleeve Mid fan sleeve Aft fan sleeve Aft FDIW Mid FDIW Fwd FDIW Fwd bifi Mid bifi Aft bifi

Jet Noise Installation Effects and Model Development NOISE ENGINEERING TECHNOLOGY Enabling Technology Task Status Summary OBJECTIVES: ACCOMPLISHMENTS: Determine Propulsion Airframe Integration (PAI) effects on jet noise by testing and develop improved empirical model for prediction of installation effects on jet noise. Develop an enhanced jet noise prediction model to cover high bypass ratio jet nozzle systems by analyzing NASA LeRC & LaRC data. Installed jet noise test successfully completed generating a valuable data base. Identified mechanisms and key parameters related to installtion effects on jet noise. Completed data analysis and developed a prediction model for installed jet noise. Analyzed NASA data and determined high bypass ratio nozzle systems effects on jet noise. Developed an enhanced prediction model to cover high bypass ratio jets.

Noise Map Airframe Noise Research Flap edge Gear Noise Reduction concepts examined under NASA AST Program: Flap-edge fences Micro-tabs along flap edge Low Noise Slat Design In Plan: Improved (Low Noise) Landing Gear Porous Flap Landing Gear Flap Interactions Flyover noise map with acoustic telescope

Fully Dressed ConfigurationClean Configuration 1000 Hz Ref. SPL = Hz Ref. SPL = Hz Ref. SPL = Hz Ref. SPL = Hz Ref. SPL = Hz Ref. SPL = Hz Ref. SPL = Hz Ref. SPL = 88.9 Airframe Noise Reduction Wind tunnel testing indicates 2-3 dB reduction in Landing Gear Noise possible dB from Ref.

Aviation Partners Boeing Winglet Program Winglet prototypes tested Summer 1998 on Flight test with winglets completed March 1999 on BBJ Can provide ~ 4% fuel burn reduction Can reduce noise Can impact the existing fleet

Boeing Faces a Future of Increasing Competition A world of global alliances among commercial airplane producers, suppliers and airlines is going to create unprecedented competition for manufacturers by placing tremendous pressure on airplane prices, said Commercial Airplanes President Alan Mulally. “The people who are going to win are the ones who lower their cost structure,” he said.

Impact of Reduced NASA Budget Substantially reduced funds for research contracting - Slower progress in the future - Technology transfer negatively impacted Future research: Cooperative, Collaborative, Cost Sharing - Misaligned goals - Company focus on cost reduction - NASA focus on 3-pillar long-term

Wrap-Up Environmental issues are complex mix of local and global concerns - Continued incremental improvements, appropriate long-term research, and balanced treatment of air transportation is one positive course Need advocates for NASA research