Maybe this will help clarify this matter of what kind of joint we are discussing. On a fully articulated rotor there are two axes. The driving axis and the driven axis. Under ideal conditions in a hover these two axes are coincident with each other. When the pilot places a cyclic input (in any direction) the driven axis will deviate from the driving axis as a result of flapping and the flapping results in leading and lagging. Does the Hookes’ joint effect or the universal joint effect or the Carden joint effect cause this? The answer is no.
The characteristic of a Hookes’ joint is that it has the capability to drive off of the primary drive axis and that the resultant is that the driven shaft is not rotating at exactly the same speed as the driving shaft. However, the speed differential will be the same around the shaft rotation. The speed differential is dependent on the angular difference between the driving and driven shafts and this will continue until the Hookes’ joint locks up. However on the articulated rotorhead the speed differential is not constant as it varies around the rotational plane.
The lead and lag is the resultant of conservation of angular momentum resulting from the variation in the mass of the blade shifting relative to the driving axis during the flapping up and down.
But then again I never studied Newtonian Physics.
