Thanks rotortorque for the info. At 3 degrees night and 5 day, little rollover potential is there.
Now heedm, please compare 5 degrees to the picture Lu made of rolling tossing ships in a storm, and understand one reason why I dismiss his argument.
Regarding the reason why the underslung rotor doesn't move appreciably relative to the fuselage, please do not think I say it because I am a test pilot! The rotor cannot move appreciably differently from the swashplate because that is how it is connected mechanically. Please picture the pitch change links as you oppose the fuselage and rotate the disk through a new tilt angle - do they impose a pitch change on the blades? Of course they do, and that pitch change is going to force the rotor to follow the fuselage. Only a very fast fuselage rotation that matches the rotor's natural frequency will cause other motions. And the size and speed of typical ship motions do not cause the "dreaded rotor behaves with a mind of its own Lu Zuckerman syndrome".
The real culpret in this roll-over scenario is exactly BACKWARDS from Lu's assertion. The rotor is stuck with the fuselage, so in a rolling motion with a strong wind, the rotor is forced into an angle relative to the wind that creates strong roll-over forces. This can be considered as if the roll of the ship in a 35 knot cross wind causes the rotor to make a lateral quickstop maneuver because the rotor MUST follow the fuselage. The rotor's strong stability relative to the rolling motion is the problem, and Lu is yet again exactly ass-backward!
It does not matter if the rotor is underslung or not, nor does it matter if I am a test pilot or not, these are facts, not opinions. The problem we all have is the democratic principle, where if enough idiots vote that there is a green cheese moon, it must be true. The fact that Lu can email, and that he can spout theories, does not make him correct, nor does it make his discussion worthy. What is most difficult for me to face is that I could post 100 accurate descriptions of the physics and aerodynamics of the situation, and he will squirm out into another corner, squirt some ink of incredible colors, and be off and running!
In short, to avoid roll-over on a tossing deck, stay off wildly tossing ones, keep the rotor level with the horizon (at the peril of the people around the aircraft) and try to avoid situations where the cross wind and the roll are in the same direction.
Also, try not to believe that mysterious rotor dynamic misbehavior is the culpret, because you will be a worse pilot - an ignorant one - and more likely to have an accident. Also, believe nothing someone tells you just because they are a test pilot, or a consultant engineer!
