Tom is correct, adding a flap adds a lot of lift, 3 to 4 times the lift but at the same time it multiplies the drag by 20 to 40 times.

See NACA 0018 (naca0018-il)

The CL is apx 1 and the CD is apx .03  lets say 100 lbs lift and 3 lbs drag.  If you add flaps and deflection your lift goes up to 300 lbs while your drag goes up to 40 lbs, not bad actually. but you have essentially doubled the area also so for a fair comparison make the single wing bigger.  Then it is 200 lbs of lift and 6 pounds of drag.  Now the numbers are closer 190 vs 260 ~ but the flap is clearly superior in generating lift.

That benefit comes with a cost in complexity, weight, increased drag at anchor, and much greater demands in controlling the wing while sailing.

However if you aren't constrained by artificial rules it is advantageous to increase the size of the simple symmetrical wing to produce the desired lift.  The thicker the wing the stronger and stiffer it is with less wall thickness.

Are you ready for this?  A thicker wing (more camber) will be lighter, stronger and cheaper than a wing of comparable surface area that is thinner. It is trivial to control it with an elevator, easier to build and can be easily faired into the wind at anchor.  And I think it wouldn't be too tough to put a hinge in it to fold it.

Apart from stowing the wing, I think the best thing about the hinge is that it means that the wing can be taken on and off manually, without the use of a crane.

Talador

 

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