Stall Margin
I may have mistated my question and maybe its more complex than I thought. What I should have asked is: what is the average blade angle of attack in a hover with respect to the air?
Do helicopters operate normally with the rotor close to stall angle of attack?
Johnson's Helicopter Theory mentions the term stall margin several times but gives no hint as to what is a good stall margin.
Most airfoils stall in the range of 12 to 16 degrees angle of attack. I am wondering if the R22 flies with blades closer to stall than other designs. That would explain why the R22 rotor slows rapidly after engine stoppage.