Multi-objective Optimisation and Preliminary Airframe Design

In this paper we explore established methods for optimising multi-objective functions whilst addressing the problem of preliminary design. Methods from the literature are investigated and new ones introduced. All methods are evaluated within a collaborative project with British Aerospace for whole system airframe design and the basic problems and difficulties of preliminary design methodology are discussed. Our Genetic Algorithm is expanded to integrate different methods for optimising multi–objective functions. First, methods based on scalarisation and the utilisation of weights are addressed. Methods based on Pareto order are then analysed and two different sorting techniques (dominated/non–dominated and Pareto rank) investigated. Finally, several variants of sub–population based algorithms are presented. All presented methods are also analysed in the context of whole system design, discussing their advantages and disadvantages.