Paper Presented at the 1st Industry/University 1 Symposium on High Speed Civil Transport Vehicles, Greensboro, NC, December 1994 A MULTILEVEL DECOMPOSITION PROCEDURE FOR THE PRELIMINARY WING DESIGN OF A HIGH-SPEED CIVIL TRANSPORT AIRCRAFT Peter J. Röhl Graduate Research Assistant Dimitri N. Mavris Manager, Aerospace Systems Design Laboratory Daniel P. Schrage Director, Aerospace Systems Design Laboratory School of Aerospace Engineering, Georgia Institute of Technology Atlanta, GA 30332-0150 ABSTRACT A multilevel decomposition approach for the preliminary design of a High Speed Civil Transport Aircraft wing structure is described. The wing design is decomposed into three levels. The top level uses the FLOPS aircraft synthesis program to generate preliminary weights, mission, and performance information. The optimization criterion is productivity expressed by a productivity index for the specified mission. The second level of the system performs a finite-element based structural optimization of the wing box with the help of the ASTROS structural optimization tool. The wing structure is sized subject to strength, buckling, and aeroelastic constraints. The buckling constraint information is supplied by the third level where a detailed buckling optimization of individual skin cover panels is performed. KEYWORDS: Multidisciplinary Optimization, Multilevel Decomposition, High-Speed Civil Transport, Wing Structural Design INTRODUCTION As modern aircraft designs tend to become more and more complex in order to outperform previous models, new techniques in system design synthesis and optimization become increasingly important. This is especially true for the design of a second - generation supersonic transport aircraft as an example of a highly coupled system. At the same time, the methodology of multidisciplinary design and optimization is evolving into a new engineering discipline that seems most suitable to address this type of design problem where the traditional sequential approach will most likely lead to suboptimal results [1]. One obstacle for the fast evaluation of a relatively large number of candidate configurations in the development of a High-Speed Civil Transport Aircraft (HSCT) has been the long time, up to 24 months, for the completion of one full design cycle [2]. At the same time, studies performed in the 70s indicate that a sequential addressing of the strength and flutter problem in the structural design of a supersonic transport wing leads to severe mass penalties [3].