Clean-Sheet Design and Initial Optimization in Non- Traditional Multidisciplinary Design Problems

This paper presents some considerations for successfully applying automated design optimization techniques to the growing variety of aerospace design problems. Attention in the aerospace community is focusing increasingly on non-traditional classes of vehicles, including micro uninhabited air vehicles, vehicles for the exploration of other planets, and reduced-sonic-boom supersonic vehicles, to name a few. Whenever the optimization of a non-traditional class of vehicle is attempted, care is required (1) to insure that the initial starting-point design is appropriate and sufficiently mature for the proposed numerical optimization, and (2) to insure that the proposed optimization process is appropriate in view of the non-traditional aspects of the problem. Neither of these considerations should be taken for granted, and in fact each should be recognized as a task in itself in the planning and execution of any non-traditional optimization effort. A design study of a low-sonicboom supersonic business aircraft is presented as an example. The study started with a blank sheet, and concluded with a preliminary design that is an appropriate starting point for a computational fluid dynamics (CFD)-based numerical optimization process. The study developed and utilized a unique process in order to meet the challenges of design integration with a sonic boom constraint. The process included not only sonic boom analysis, but also the treatment of internal layout, volume allocation, and balance, at each design iteration, which would not be usual in a traditional design exercise. The need for these additional steps was identified by analysis of the design implications of the sonic boom constraint. The insight gained in the development of the starting-point design can be applied to the formulation of the subsequent optimization process.