I don't know a whole lot about aerodynamics, but it seems to me like relatively flat airplane wings with hinging flat surfaces on the trailing edge, such as elevators, flaps, and ailerones, probably aren't the most efficient kind of wings. If a wing had a variable curvature over its entire surface, I imagine this would work much better. This could be done in at least two ways. One, a series of small hinged surfaces would at least approximate a true curve better than a single hinge between two fairly large surfaces. Two, if the wing were made of a flexible substance it could actually be coaxed into changing its curvature over a truly curved surface. Assume that this flexible surface tends to spring back to a flat shape. Then, in order to create a curvature, simply bend it some by pulling it together at the ends with a cord or cable. Pulling the cable in would increase the curvature, and releasing the cable (allowing the surface to spring back toward a flat shape) would decrease the curvature. Seems simple enough to me.