NASA Looks at Folding Wings to Increase Efficiency

The original idea, dropped in the 1960s, could be making a comeback.

NASA SAW
NASA's rendering of an aircraft with the Spanwise Adaptive Wing.NASA

Articulating airfoils, or folding wings, are nothing new to aviation. They’ve been used for decades as an efficiency tool to help store multiple airplanes in a small space. But NASA thinks a new airfoil known as the Spanwise Adaptive Wing (SAW) could fold an aircraft’s wings in flight, creating huge efficiencies but without the use of traditional heavy mechanical actuators.

On a supersonic airplane, for example, the wing typically creates large amounts of lift, but often lacks much yaw control. NASA said folding the ends of the aircraft's wings up or down could add stability by adding to the overall surface area available near the tail of the aircraft.

XB 70 Valkyrie
The XB-70 Valkyrie, created in the mid-60s, used flexible wingtips.NASA

The flexible wingtips on NASA’s SAW airfoil would create a mixture of lift and yaw controls. But SAW airfoils wouldn’t be short of lift because the wingtips could later be straightened out to increase overall wing area. NASA plans to test the SAW concept on a scale model this spring to validate the vehicle’s laws.

Flexible wingtips aren’t actually brand new; the XB-70 Valkyrie, created in the mid-1960s, used them to reduce drag at supersonic speeds. That research ended, however, when the XB-70 project was canceled by the Kennedy administration after deciding manned bombers had no future.