Traditionally, aircraft have been provided with rigid airfoils such as wings and tails that have a fixed cross section. Aircraft wings and tails typically have movable flight control surfaces. These flight control surfaces include flaps, elevators and rudders. They are connected by hinges to the respective wing or tail of the aircraft.
One problem with traditional aircraft wings and tails is that the airfoil thickness of aircraft designed for high speed flight must be determined by high speed flight considerations. The resulting thin wings and tails require complex high lift systems to enable the aircraft to fly at low speeds. An additional difficulty presented by traditional wing and tail designs is that control surfaces generate unwanted radar returns on vehicles having a low radar cross section. Radar returns primarily come from hinge lines, the edges of deflected control surfaces and the necessary gaps between the control surface and the fixed portion of the wing structure.
A further drawback with existing wing and tail airfoil designs is that mechanical flight control surfaces require mechanical or hydraulic servo actuators to deflect the control surfaces. Mechanical or hydraulic actuators add additional weight to the aircraft.
Consequently, a device to adjust the shape of an airfoil that does not generate unwanted radar returns and that reduces the weight of control surfaces of an aircraft is desired.