Rick, "As I stated anyone who thinks a rigid wing will weathercock nicely above a rolling, pitching and yawing boat is delusional."
It depends on the amount of wind in relationship to the boats motion. If there is very little wind yes, the wing (mostly the stabilizer) will spin around and back and forth. That motion will dissipate some of the forces at the base. . . and there are no drag or lift forces to worry about (because they are always counter to the ships motion they actually help reduce the forces).
In conditions windy enough for the stabilizer to control the wing then yes the wing will stay properly angled to the wind. The "rake?" angle will be constantly changing, but the AOA will stay consistent. All the wing is going to feel is the angle to the wind.
Rick, "At some windspeed it will flutter wildly back and forth. Similar to a sail flapping violently but with a wing it will be in perfect harmony generating massive oscillating forces."
Yes flutter is potentially a huge deal. I know a guy who lost a wing in a Glass Goose to flutter and lived to tell the story. The wing and flight controls have to be balanced either statically or dynamically to prevent flutter (or both). Because of the boats motion I don't believe it is possible to statically balance the wing. . . and it is a bad idea to even try (specifically by adding weight forward). I understand why Greenbird did it for the land record, but not on boats.
The solution is to dynamically balance the wing, first by putting the rotation point at the aerodynamic center of the wing (it will still flutter at the right harmonics) and then by putting the stabilizer out of sync with those harmonics, (the proper distance from the wingspan). Luckily Curtiss Wright figured those numbers out.
The big thing to remember is that the drag on a feathered wing is almost non existent. It is seriously close to the same drag as a single shroud line. Windspeed's in the 30 knot range on a wing don't even hardly move the strain gauges.
I know, I know, the idea of having sails up in a hurricane terrifies me too, To a wing though (properly feathered) 150 knot winds are normal. . . Most pilots would consider that cruising speed.
Talador
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Posted by: taladorwood@yahoo.com.au
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