Blade pitch decreases as it moves in the direction of flight. Pitch increases as the blade moves opposite the direction of flight. This evens out the lift of the blade as the helicopter moves forward. Google retreating rotor stall.
Wow, never realized that the blades rotate with every 360* turn of the rotor assembly. It makes perfect aerodynamic sense, but that must be an interesting arrangement. I will have to google that to see what arrangement is used to keep everything turning and how they adjust it.
My father flew for the county and was an IP in helicopters and airplanes. One day I was out flying with him in the helicopter when I went home on leave. We were flying around over the river when he said something didn't feel right ( I didn't feel a thing different ) and he put it down on a sandbar in the middle of the Banana River at Cocoa Beach.
As the rotor slowed down, he pointed and said " there it is ". It turned out to be a piece of plastic wrap wrapped across on of the blades and had thrown the balance off. When the blades slowed down enough it fell off, he started back up and off we went.
Eventually with enough trips home, I could fly the thing around all right once it was in the air, but never got enough time in to take off or land.
I didn't mind a bit; flying a helicopter is nothing but work.