Ok, ok...I agree, Lu was right about the blade leading and lagging. But the question was about the blades being so unevenly spaced. The answer is in part lead lag, but I believe the photo that most drew vfrpilotpb was the black and white head on in which the culprit is much more camera shutter effect than lead lag (though lead lag is most certainly involved). And Lu's balance bit is sketchy. Lead and lag does not always keep the system perfectly in balance, and is the source of vibrations.
But none of this should detract from such a beautiful aircraft.
Could it take troops? Were there any interested parties looking to buy? The Shah eventually took Cobra (J or Ts werent they?)