Abstract: A fuel level control system and method for an aircraft to passively manage fuel center of gravity during consumption includes an upper tank, a lower tank disposed below the upper tank, a fuel transfer line connecting the tanks, an upper fuel transfer line outlet in the lower tank and a lower fuel transfer line outlet in the lower tank. The outlet outlets are in fluid communication with the upper tank via the fuel transfer line. An upper line outlet valve is associated with the upper fuel transfer line outlet for opening and closing the upper fuel transfer line outlet. A lower line outlet valve is associated with the lower fuel transfer line outlet for opening and closing the lower fuel transfer line outlet. A control shutoff valve is disposed on the fuel transfer line for selectively limiting flow through the fuel transfer line.

Abstract: A fuel level control system and method for an aircraft to passively control the movement of fuel center of gravity during the fuel consumption sequence includes an upper tank for storing fuel, a lower tank for storing fuel, wherein the lower tank is disposed below the upper tank, and a fuel transfer line connecting the upper tank to the lower tank. The control system further includes an upper fuel transfer line outlet in the lower tank and a lower fuel transfer line outlet in the lower tank. The upper fuel transfer line outlet and the lower fuel transfer line outlet are in fluid communication with the upper tank via the fuel transfer line. An upper line outlet valve is associated with the upper fuel transfer line outlet for opening and closing the upper fuel transfer line outlet. A lower line outlet valve is associated with the lower fuel transfer line outlet for opening and closing the lower fuel transfer line outlet.

Abstract: A flexible airfoil section for a wing or a blade comprising a streamlined shape and an elastic structure whose stiffness distribution along its chord and span is tailored to provide a desirable cambered shape with proportional increases in camber with increases in lift, mounted to a supporting structure such that the airfoil sections are free to pivot about axes near their leading and trailing edges. In operation, the foil derives much of its lift from elastic bending deformation of its flexible shape, thereby achieving a higher lift than a symmetric foil at the same angle of attack while postponing the onset of flow separation and stall and, for operation in water, of ventilation and cavitation.