Dynamic Blade Shape for Improved Helicopter Rotor Performance

Rotor morphing concepts that can significantly improve helicopter performance at the nominal speed and for the maximum speed and load capability are investigated. The physical mechanism for improving the helicopter performance are addressed. Based on the understanding of the physical mechanism, various potential blade morphing concepts are investigated. Among them, the variable rotor speed demonstrates a significant benefit for rotor performance improvement in cruise. Further improvements of the rotor performance can be achieved by using the variable rotor speed combined with 1/rev dynamic chord approach. 1/rev dynamic chord also shows to be a very effective approach for improving the aircraft maximum forward speed while, at the same time, keeping the required power at a low level.