Every diagram I have seen puts the flapping hinge closest to the rotor hub, but there seems to be variation whether the feathering comes next followed by the drag/lead-lag, or vice versa.

For this CH-47D the feathering hinge (labeled 'pitch change') is closer to the flapping hinge, followed by the drag hinge (lead lag). The consequence of this is that the lead-lag isn't restricted to the plane of rotation, but changes depending upon how the blade is feathered.
enter image description here

For this hub on the other hand, the drag hinge appears closer to the flapping hinge, with the feathering occurring further away from the hub. This restricts lead-lag to the plane of rotation, but the consequence is that lead-lag could slightly offset the effect of the control rods.
enter image description here

Is there a reason that a particular helicopter uses one or the other arrangement? Is one considered "better" or more the standard option?



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