Lu,
A quick explanation of the Lynx rotor head. At the centre you will note the star shaped rotor hub, this is where the flapping occurs. The long cylindrical structure (commonly referred to in the UK as the “dog bone”) is where lead/lag loads are handled, it does not absorb flapping loads. The dampers you refer to are fitted to all Lynx, except French Navy ones. Their role is simply to reduce stress on the head during rotor engagement./disengagement cycles, it has no role in flight and can be ignored for the purposes of this discussion.
The graph scale is arbitary. The dotted blue line labelled “blade displacement” indicates exactly that. The DESIRED INPUT is the force required to achieve the blade displacement, you will note it is exactly 90 deg in advance of the blade displacement (this fits both my flapping to equality argument and your precession argument). The restorative force causes a problem, as it will modify the forces resulting from cyclic input, therefore the cyclic forces must be applied such that when combined with the restorative force they will equal the DESIRED INPUT. The key point, therefore, is that the REQUIRED INPUT in combination with the RESTORATIVE FORCE must equal the DESIRED INPUT, and thus they must be applied less than 90 degrees in advance of the desired blade response.
GA
[This message has been edited by Grey Area (edited 11 March 2001).]