So, whats going on with the blades here...
"Sikorsky Aircraft has submitted better than projected performance test results of its latest testing on the 4th generation rotor blade to the US Marine Corps.
The 4th Generation™ blade follows in a long chain of innovations in the area of rotor systems. It builds on the work done for Sikorsky’s state-of-the-art Growth Rotor Blade (GRB™) currently used on the UH-60M and S/H-92™ helicopter..."
... to make them so much more efficient?