Nasa has tested a new technology that enables aircraft to fold their wings to different angles while in-flight.

The flight series took place at Nasa’s Armstrong Flight Research Center in California, US, and is part of the Spanwise Adaptive Wing (SAW) project.

This project intends to use lightweight material that can fold the outer portions of aircraft wings and their control surfaces to optimal angles in-flight.

SAW is a joint effort between Armstrong, Nasa’s Glenn Research Center (GRC) in Cleveland, Langley Research Center in Virginia, Boeing Research and Technology in St. Louis and Seattle, and Area-I in Kennesaw, Georgia.

Although folding wings in-flight had been studied, the ability to fold wings in flight has always been dependent on heavy and bulky conventional motors and hydraulic systems.

“Folding wings has been done in the past, but we wanted to prove the feasibility of doing this using shape memory alloy technology.”

The SAW project aims to use a lightweight material called shape memory alloy. Built into an actuator on the aircraft, it has the ability to fold the outer portion of an aircraft’s wings in-flight without the strain of a heavy hydraulic system.

It has been found that systems with this new technology could weigh up to 80% less than conventional systems.

In the recent series of flight tests, the material’s application and use were demonstrated between zero and 70° up and down in flight.

SAW co-principal investigator Othmane Benafan said: “We wanted to see: can we move wings in flight, can we control them to any position we want to get aerodynamic benefits out of them, and could we do it with this new technology.

“Folding wings has been done in the past, but we wanted to prove the feasibility of doing this using shape memory alloy technology, which is compact, lightweight, and can be positioned in convenient places on the aircraft.”

Triggered by temperature, the alloy works by using thermal memory in a tube to move and function as an actuator. Once heated, the alloy would activate a twisting motion in the tubes, which then moves the wing’s outer portion up or down.

Alloy material developer Nasa Glenn worked closely with Boeing to use the alloy with an actuator in-flight.

For testing the technology, Nasa turned to Area-I to operate a remotely controlled flight testbed called Prototype Technology-Evaluation Research Aircraft (PTERA).

This aircraft was designed and built by Area-I, which was also involved in the design and integration of the shape memory alloy-actuated, wing-folding mechanism for the aircraft.