An initiative in multidisciplinary optimization of rotorcraft

Abstract : An emerging trend in the analytical design of aircraft is the integration of all appropriate disciplines in the design process. This means not only including limitations on the behavior of the design from the various disciplines, but also defining and accounting for interactions so that the disciplines influence design decisions simultaneously rather than sequentially. The integrated approach has the potential to produce a better product as well as a better, more systematic design practice. In rotorcraft design (the rotor in particular), the appropriate disciplines include aerodynamics, dynamics, structures, and acoustics. This paper describes a plan for developing a helicopter rotor design optimization procedure which includes the above disciplines in an integrated manner. Rotorcraft design is an ideal application for integrated multidisciplinary optimization. There are strong interactions among the four disciplines cited previously; indeed, certain design parameters influence all four disciplines. For example, rotor blade tip speed influences dynamics through the inertial and air loadings, structures by the centrifugal loadings, acoustics by local Mach number and air loadings, and aerodynamics through dynamic pressure and Mach number. All of these considerations are accounted for in current design practice. However, the process is sequential, not simultaneous, and often involves correcting a design late in the design schedule.