Originally Posted by
Globocnik
Ok. Thanks you live and learn. ! Aren’t the mast heads on the chinook and sea knight etc slightly offset. ? We’re talking probably microns here.
Back to the OP. It is one of the joys of rotary wing flying ( there are many ) which no one gets unless you’ve tried it.
it’s the same principle as described for tail rotor aircraft. The heads are a foot or two displaced vertically when hovering and thus generate a couple. Because the aft head is doing more of the lifting (ie the c of g is closer to the aft head than the front) the difference in force means that lateral cyclic (and pedals) are needed to maintain the hover.