Mart,
You mention
"Higher Harmonic Control" Perhaps, I should have said, 'Independent Blade Control', not 'Higher Cyclic Control'.
As for Higher Harmonic Control, one report states
"The results show that properly phased 2/rev inputs can reduce the rotor required power by up to 3.8%. The improvements are very small." For Independent Blade Control, any appropriate types of sensors and actuators might be employed.
Reverse Velocity Utilization should be extremely compatible with ABC. A report by Sikorsky in 1980 summarizes the features and future improvements to the ABC rotor. It discusses reverse velocity utilization. It even shows the profiles of proposed airfoils.
In fact, virtually, all of the X2's currently known features were mentioned in the above, and other, 25 to 40 year old reports.
Also consider that; ~
If your mention of
"tip servo" is in reference to a trailing edge servo flap, I would be concerned. The sequence of events that must take place for the above flap to change the lift of the blade may be too slow for a high speed craft.
Slowrotor,
It is the circular rotation of the wing that concentrates the lift near the tip that gives the poor lift L/D. Also, the high tip speed.
You are absolutely correct. This is where utilizing a [Slowed Rotor Speed] during cruise is an advantage. The [Advancing Blade Concept] places most of the lift on the advancing blades. By slowing the rotational speed of the rotor, the airspeed differential between the advancing tip and the advancing root is reduced. A stopped rotor, if it was possible to do, would totally reduce this airspeed differential.
In addition, the slowed rotor speed allows the advancing tip to retain the same Mach number, but replace the reduced rotational speed with an increased aircraft speed.
Dave