sentences:  The W.9 was to investigate James G. Weir's contention that a powered tilting hub-controlled rotor with automatic collective pitch control, and torque reaction control using jet efflux, was both safer and more efficient than the Sikorsky R-4 helicopter fitted with manually controlled main rotor cyclic and collective pitch and the anti-torque tail rotor system.The W.9 was completed late in 1944 and assigned serial "PX203".It was damaged during ground-running due to incorrect control phasing arising from a high order of pitch-flap coupling, and did not start test flying until 1945.