Quote:
Originally Posted by WVOtoGO
Kerry covered that one dead on.
Now that the question has been answered. How about a highjack to some trivia that came to mind along this same issue.
Did you know that in forward flight (fast). There is a length of a helicopters rotor blades, where the air is actually flowing backwards across the blade surface?
Things that make ya go: Hmmmmm. 
Or maybe they just make ya go: Who gives a ...?  |
Helicopters stall at high speed. The blader moving towards the rear stalls while the other one has lift, so the whole thing rolls to the left (if blade go counterclockwise). Much more apparent on 2 rotor systems than 4 rotors.
The other way to lose lift is settling with power (aka vortex ring state), where the rotors cause the air to rotate around the ircraft in vortices so there is reduced relative motion between the rotors and the air, so lift goes away. This occurs during rapid descent with low forward motion and near the ground. Pilots try to gun it which makes the vortices bigger making the descent faster.....