Flight Test of a Shape Memory Alloy Actuated Adaptive Trailing Edge Flap

The Boeing Company has a goal of creating aircraft that are capable of continuous optimization for all flight conditions. Recent advances in SMA actuation and a detailed understanding of wing design were combined to design, build, and safely demonstrate small trailing edge flaps driven by SMA actuation. As part of a 2012 full-scale flight test program a lightweight and compact Shape Memory Alloy (SMA) rotary actuator was integrated into the hinge line of a small flap on the trailing edge of a commercial aircraft wing. This Adaptive Trailing Edge program was part of a Boeing and Federal Aviation Administration (FAA) collaboration. Aerodynamic studies of these small trailing edge flaps show that improved performance requires multiple flap configurations that vary with flight regime. Configurations include small angles of deployment for reduced fuel burn and emissions during high speed cruise and larger angles of deployment for increased lift and lower noise during takeoff and approach. SMA actuation is an ideal compact solution to position these small flaps and increase aircraft performance by simply and efficiently altering the wings aerodynamic characteristics for each flight segment. Closed loop control of the flap’s position, using the SMA actuator, was demonstrated at multiple flight conditions during flight tests. Results of the successful flight test on a 737–800 commercial airplane and the significantly improved performance benefits will be presented. This is the first flight test of an SMA rotary actuator system, which was matured from TRL 4 to TRL 7 during the program.