A Preliminary Investigation of Individual Blade-Control Independent of a Swashplate

The gradual evolution of helicopter main rotor design to its current status has had little impact on the method by which blade feathering control is achieved on production helicopters. Conventional rotor blade feathering is controlled by means of a complex swashplate that provides the interface between rotating and nonrotating segments of the system. The potential for substantial improvements in reliability, maintainability, weight, and life-cycle costs could be realized if a simplified alternative could be developed. The Individual Blade-control Independent of a Swashplate (IBIS) system offers such an alternative by providing a complete two-fail-operate concept that integrates actuators, power supplies, and logic into the rotating system. This logic includes the sensing of rotor azimuthal position for control synchronization. Individual blade control is most effective in terms of reductions in both linkage and power required when mounted on the rotor hub. Transition of control signals through the rotating/nonrotating interface is required and transmission of these signals is made possible by the use of fly-by-light technology.