for the group-
The difficulty I have with Lu is mine, and I will wrestle with it. His posts are so misleading, and he is so unwilling to either think or understand that I am completely exasperated!
Imagine the ship is tossing like those movies Lu evokes, with vast pitch and roll motions like a bucking bronko. OK now forget that, it is wrong. Any pilot who lands on that deck without haul-down is nuts, and will be unemployed shortly.
The typical deck landing in commercial service never involves deck angles beyond about 8 degrees (commercial guys, please post the operating limits for deck landings from your ops manuals.) The typical period of motion for a large rig boat is several seconds, usually about 10 seconds or so. For a rig, it is often 20 seconds or so. This makes the deck motion actually very slow in roll or pitch rate, and the contribution of the dynamic motions very small.
The rotor will not wave around or depart from its commanded path due to these motions, no matter what Lu thinks. Even if underslung, the rotor is not free to wave around independant of the aircraft without a swashplate input, unless the angular motions are very fast.
Having investigated the roll-over of several aircraft, I can assure you the results are disappointingly static in nature, a combination of wind velocity (which will move the rotor) deck slope and where the pilot left the stick. For a broad sided helicopter in a cross wind of 35 knots with gusts that are higher, and with a deck roll that compounds the aircraft lean, all it takes is an unattentive pilot to allow a roll-over. The problem with Lu's assertion is that he believes the rotor does its own thing, and that wanders around. He has it backwards! As the aircraft rolls, the rotor follows the aircraft. With a cross wind, the rotor produces strong roll moments that add to the roll tendency that the deck is producing. A pilot would try to put roll cyclic in to keep the rotor disk parallel to the horizon, at the peril of those on the deck under the disk. The pilot is stuck - try to keep the aircraft glued to the deck, but hurt someone around the machine, or risk a roll-over. That is why most operators don't allow large deck angles.
A cure is to ask the ship to turn into the wind, so the roll angle is not aligned with the crosswind, but pilots are reluctant to impose on the ship operations (unless they are in the Navy, where the air boss helps the ship captain decide).
OK, that above is the kind of answer I expect from LU, something based on a blend of experience and common sense, not mumbo-jumbo. Should any pilots with experience want to disagree with what I said, I would (and have) listened, and I always admit when I am mistaken. I want to learn from this forum, too, and I always do. That is what I expect from the posters that I respect - good honest intellectual discussion.
