NASA Used A Shape Memory Alloy Actuator To Fold An F/A-18 Wing

A shape memory alloy remembers its shape: stretch a spring made from it, crush it into a ball, heat it, and it returns to the original form. NASA used that behaviour to fold an aircraft wing.

The Test

NASA engineers used a new shape memory alloy actuator to fold the 300-pound (136 kg) wing of an F/A-18 Hornet. The test was conducted at the NASA Armstrong Flight Research Center in Edwards, California, using a newly developed high-temperature SMA torque tube actuator made of nitinol.

The Programme

The work sits under the Spanwise Adaptive Wing project, developed by NASA Armstrong Flight Research Center, Glenn Research Center, Langley Research Center, Boeing Research and Technology, and Area-I. By simplifying aircraft design, complex mechanical, hydraulic and electric actuators can be replaced with components made from memory alloys, reducing actuator weight by around 80%.

How The Actuator Works

An SMA actuator changes shape when heated or otherwise stimulated, without a motor, pulley or hydraulic circuit. That removes an entire subsystem from the aircraft rather than making it lighter.

What It Enables

NASA's focus is on foldable wings that could be lighter and simpler, with longer, thinner spans, stabilisers and more fuel-efficient control surfaces. The same technology allows a wing to change shape for different flight conditions, including improving supersonic performance.

Testing Progress

SMA actuators were first tested on the remotely controlled Prototype Technology-Evaluation Research Aircraft before being installed on the F/A-18 Hornet wing.