The continuing growth in air traffic and increasing public awareness have made environmental considerations one of the most critical aspects of commercial aviation today. In the current practice of commercial aircraft design, the focus is primarily on producing airplanes that meet performance goals at minimum operating costs. Environmental performance has been considered mostly at a post-design analysis phase, during which adjustments are made to satisfy the noise and emissions requirement of individual airlines or airports. This sequential design approach does not guarantee that the final aircraft is of overall optimal design with respect to operating costs and environmental considerations, but it served its purpose as long as only localized, minor adjustments were necessary to bring aircraft into environmental compliance. However, following the gradual tightening of environmental requirements, the cost and complexity of achieving compliance in the post-design phase has increased significantly. Therefore, there is a need for integrating environmental considerations at an early stage of the aircraft design process and for more systematic investigation and quantification of the tradeoffs involved in meeting specific noise and emissions constraints.

Under a research grant from NASA Glenn Research Center, research was carried out at the Massachusetts Institute of Technology (MIT) and Stanford University to explore the feasibility of including environmental performance as an optimization objective at the aircraft conceptual design stage, allowing a quantitative analysis of the tradeoffs between environmental performance and operating cost. During 2006, a preliminary design framework that uses a multiobjective genetic algorithm to determine optimal aircraft configuration and to estimate the sensitivities between the conflicting objectives of low noise, low emissions, and operating costs was developed. The framework incorporates ANOPP, a detailed noise prediction code developed at NASA Langley, NASA Glenn Research Center's Engine Performance Program (NEPP) engine simulator, and aircraft operation procedures, analysis, and optimization modules developed at MIT and Stanford University. It allows tradeoffs between aircraft design, operations, and environmental impact to be explored and quantitatively articulated, resulting in assessments of the relative benefits of different opportunities for improving air transportation. The design framework and its components are shown in this figure.

Glenn Authors and Contacts:
Michael T. Tong, 216.433.6739, Michael.T.Tong@nasa.gov

Programs/Projects:
Ultra Efficient Engine Technology Project

Reference:
Willcox, Karen E., et al: An Environmental Design Space to Assess Aircraft Technology and Operational Trades. Final Report, NASA Grant NAG3-2897, June 2006.