An Airframer’s Comments

NASA’s 4th Environmental Compatibility Workshop

August 12 - 13, 1999Colorado Springs, CO

Robert D. CuthbertsonBoeing Commercial Airplanes

Significant Events Since 3rd Workshop

• Production at peak rates in 1998 and 1999- New Generation 737 Family- New 717- Customer Driven Derivatives

• Participated in NASA sponsored Environmental Technology developmentAdvanced 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

HW

HW

HW(1,0)(1,0)

Z = (1,0)(1,0)

horn

data

Validation test with active impedance control

Fwdfansleeve

Midfansleeve

Aftfansleeve

AftFDIW

MidFDIW

FwdFDIW

Fwd bifi

Midbifi

Aft bifi

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 Configuration Clean Configuration

1000 HzRef. SPL = 94.8

2000 HzRef. SPL = 96.0

2500 HzRef. SPL = 83.0

1500 HzRef. SPL = 88.9

1000 HzRef. SPL =

94.8

2000 HzRef. SPL = 96.0

2500 HzRef. SPL = 83.0

1500 HzRef. SPL = 88.9

Airframe Noise Reduction

Wind tunnel testing indicates 2-3 dB reduction in Landing Gear Noise possible.

0

-3

-6

-9

-12

dB from Ref.

Aviation Partners Boeing Winglet Program

• Winglet prototypes tested Summer 1998 on 737-800

• 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