To: imabel and Crab
coriolis effect; the acceleration of the blade that flaps up and deceleration of the blade that flaps down. simple aerodynamics.
"lead and lag, (hunting); the tendency for a rotor blade to hunt for the centre of pressure of the blade, forward on the advancing blade, (lead), and rearward on the retreating blade, (lag). simple aerodynamics".
The blade that flaps up is the retreating blade and the blade that flaps down is the advancing blade. Please note that the two statements above (quoted from your post) are diametrically opposed to each other. In the first quote (Coriolis effect) you state that the blade that flaps up accelerates and the blade that flaps down decelerates and in the second (lead and lag) you state that the advancing blade leads and the retreating blade lags which is what I have stated in my posts. Lead and lag results from the aerodynamic effect that causes the flapping but the actual movement of the blade about the lead-lag hinge is a purely mechanical effect that has nothing to do with aerodynamics.
Regarding my ignorance I have attended 18 helicopter factory schools and I have taught POF and I never heard of Hooke’s joint effect until I worked on the A-310 and had many English colleagues on the program. In the USA what you call a Hooke’s joint is called a universal joint.
