Development of the Composite Bearingless Main Rotor System

The bearingless rotor concept. is certainly familiar to the helicopter industry, at least for tail rotor applications. The tail rotor development, which started at Kaman Aerospace in 1967 and recently culminated with bearingless configurations on both competitive UTTAS prototypes, is certainly worth noting, but is not discussed in this paper. Instead, the main rotor applications in terms of results from government sponsored contracts, and an outline of planned research and development efforts are reviewed. The primary prupose of the paper is to provide an overview of current R&D emphasis on main rotor applications and to indicate evoluation of configurations to date.