The smaller wing surfaces, in turn, reduce drag and weight on all points of flight.

If air has to follow the wing surface, that raises one last question.

Levavasseur began working on an aircraft with variable wing surface in late 1918.

She drew the pod to a stop, and allowed it to descend, slowly, toward the wing surface.

The rear wing surfaces were also metal, though more conventionally built.

Roll control was via a system that pivoted the entire lower wing surfaces.

The number and size of the eye spots is variable, they may be missing on the upper wing surface.

Larger aircraft have rigid wing surfaces which provide additional strength.

When meeting the fence, the air is directed back over the wing surface.

Schempp-Hirth-type air brakes extend on the upper wing surface only.