Wing Sails

[Eweston]

Don't know if you've run acrossthis variation or not. I've seen some inflatables used with windsurfers also.
I'm still drawing and thinking on my latest version. I hope to complete it and if I can figure out how display it on this forum, do so.
In short a fully rotatable wing mast which would set directly on deck. The cloth, or other material of the aft sail, would be fully battened. This has been used, or used in attempts before.
I saw an earlyer thread discuss the uncertainties of what airfoil shape would work best. It would be a heavy and involved practical experiment to investigate this with a real soft wing sail. I envision something using lasers to detect wind movement over the sail.
I've figured that induceing an assementrical curve to the sail and adjusting its width would be flexible enough of an approach to investigate what does work.
This shaping would be based on four c section vertical struts. Two would locate the front of the cloth. Pulling one edge forward and allowing the other to slack off will produce the shape of an assemtrical airfoil. The two other struts would be located arround 1/4 to 1/3 aft. The struts will be attached to the battens. These struts will be pulled forward and inboard, or allowed slack to let the negative air pressure pull it outboard.
The four c section struts will use a luffrope (not real sure this is the proper term) to both allow attachment to the sails forward edge, sides and to be used to hoist the sail. Supporting these struts from above, while allowing sufficient movement and maintaining even tension on the halyards is fairly clear. But not finalized yet.

[Eweston]

Two interacting wings does have advantages. You could also add a slot/ small foil forward of the main wing. Its mechanism would take some thought though