Multi-objective optimization of rotary-wing aircrafts at the predesign stage
Résumé
Subsystems of rotary-wing aircrafts, such as helicopters for instance, are strongly interrelated due to their intrinsic specificities. Convergence to a feasible design is then not ensured and implies an iterative process. Moreover, rotorcrafts must cover a much wider range of missions than their fixed-wing counterparts. For those reasons a correctly sized rotorcraft is difficult to obtain and finding the best design for a defined set of missions needs numerous iterations. This article presents the application of a multi-objective optimization approach from the predesign stage. The standard predesign approach has been reformulated to highlight sizing constraints and three strategies are then proposed to solve those constraints: the first one is the basic transcription of the standard predesign approach; the second one leaves the problem solving to the genetic optimizer through penalization; the third one is a hybrid of both previous methods based on a constraint repairing approach. Those strategies also involved the adaptation of the helicopter modelling. Here, the focus is on two components of that new model: namely the main rotor polar and the weight assessment model.