Lu,
"I'm really confused by what you said ....."
That makes two of us.
Sorry. I typed in the wrong plane in the original posting. It has now been corrected. Your 'prominent aerodynamist' said it properly.
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With this tilting of the driven axis you will get leading of the advancing blade and lagging of the retreating blade and assuming a four-blade rotor system the blades over the nose and tail will be aligned with the longitudinal axis of the helicopter. If this is the case then why doesn’t the rotor system go out of balance if the blades are not evenly disposed. I don’t know the answer to that question .....
When viewed, as mentioned by you, with your eye aligned with the mast axis, the four blades will
appear to not be evenly disposed. But, the rotor's CG will remain ahead of the mast's centerline throughout the complete rotation of the rotor.
When viewed with your eye aligned with the tip path axis, the four blades will
appear to be evenly disposed and they
are evenly disposed. The rotor's CG will remain ahead of the mast's centerline throughout the complete rotation of the rotor.
The position of the original post in this thread is; that vibration, resulting solely from coning, may be very small, irrespective of whether the disk is tilted or note. This is because conning does not cause the rotor's CG to move about during the rotation of the rotor. This may well be factual for all types of rotor heads.
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Vibration due to flapping will be another story and as mentioned by Robbo Jock, rotational vibration (acceleration/deceleration) will exist because of the Hookes joint effect.