Discount just about everything stated by Fr O'Blivien in the above referenced post.
As previously stated if you push the "rudder" pedals the helicopter will spin about the center of the fuselage. This is differential pitch input in the fact that one rotor has a cyclic input to the left and the other rotor system has a cyclic input to the right. Pressing the opposite pedal will result in the helicopter spinning in the opposite direction. Cyclic input will not cause the blades to hit each other as they are locked in a fixed position relative to each other this is called phasing.
If the pilot moves the cyclic to the left or the right the helicopter will move in the direction of cyclic movement and once again cyclic input will not cause the blades to strike each other due to the fixed phasing. A coordinated pilot can input cyclic movement and at the same time press the pedals and the helicopter can be made to pivot either about the forward mast or the rear mast depending on the coordinated pitch input. A really coordinated pilot can perform a maneuver called walking the dog in which he alternates the pivoting from the front mast to the rear mast and back again.
Fr O’Blivien made a statement about the tilting of the transmissions when the pilot inputs forward cyclic. This is not the case. Movement of the cyclic either forward or rearward will cause one rotor system to increase collective pitch and the other to decrease collective pitch which causes the helicopter to move in the direction of the decreased collective pitch.
The pilot does not have any input relative to forward or aft cyclic stick movement other than to effect the collective pitch levels of the respective rotor system. When the helicopter reaches a forward speed of around sixty knots forward cyclic pitch is automatically applied to both rotor systems and at this time the pilot can lower his collective stick. When the speed drops below sixty knots the forward cyclic input is removed and most likely the pilot will have to increase collective pitch to a level it takes to fly with decreased weight.
