another terrible ATPL PoF question

[NickLappos]

Arm,
It is unfortunate that we cant just get to a chalk board, it would be so much easier.

Your picture is quite selective, you see the translating component of the rotor thrust, but you don't see the lift portion, which precisely cancels your argument.

One must resolve the forces to the CG to understand their effect of the motions of the body. For the main rotor thrust, for some convenience I show the vector summed at the head. In fact, the main rotor thrust is a single force vector that passes through the aircraft and directly through the CG. Otherwise, the rotor would be rotating the helo (which it does when we maneuver.)

The idea that the height of the rotor is a driver in this roll angle discussion is simply not correct. The rotorhead height DOES help the cyclic control the helo, because the higher the rotorhead, the more lever arm the thrust has when the pilot purposely tilts the lift away from the CG. For teetering rotors, high rotorheads are needed to make the cyclic more powerful. That is why Hueys and Robbies have high masts and Boelkows and Sikorskys have heads tucked down close to the fuselage.

With your dual TR helo (nice idea and a great "thought experiment, Arm!) there would be no translating tendency, because the two would cancel out the lateral force imbalance. Therefore there would be no need for the pilot to tilt the lift to stop the slide, and the helo would hover level. It would hover level no matter how high or low those pesky tail rotors were, as long as they were on the same height. It would hover level no matter how high or low those tail rotors were relative to the main rotor head, as well.