OK, one last question.
On an articulated head, the blade is allowed to hinge in both lead/lag and up/down. Lead/lag is all fine to me, but the up down thing I have some trouble understanding.
Isn't it correct to assume that as the helicopter gains lift and the blades cone upwards, the blade must reach its up hinge stop. If not, the blade would just continue to fold upwards producing no lift and leaving the heli on the ground.
Now if this is the case - then what possibility does the blade have to flap upwards in the hinge if it's already at the up stop? None, I would assume. And if that's the case, that means that the blade itself absorbs that up-flap. Which makes it a rigid rotor blade in flight, by all definitions. So what's the point of having that hinge if it has no effect in flight and isn't allowed to hinge?
This ancient rotor blade in flight footage which you've all seen, seems to describe the above. From the age of the film, I'm assuming this is articulated head (rigid rotors are after all a pretty new invention). But look at thhe blade closest to the hub - it doesn't move at all. The rest of the blade and the tip is doing all the bending.
YouTube - Slow motion video of a helicopter rotor blade
Don't get it. Please explain.