Circulation Coontrol Rotor Flight Demonstrator

The circulation control rotor (CCR) system being developed for flight demonstration on an H-2 is described. The CCR concept represents a significant departure from conventional rotor systems. The rotor is driven mechanically, but the blades operate in fixed pitch. Cyclic control is achieved by direct control of circulation about the blade airfoils. Air to the blades is supplied by a separate compressor system driven from the main transmission. The ejected airflow induces a circulation of free-stream air around the rotor blade and provides a degree of boundary layer control, substantially reducing blade section profile frag. Control is obtained by cyclically and collectively modulating the amount of ejected airflow. Because only airflow is being modulated, higher harmonic control can readily be obtained.