Flight Test of a Shape Memory Alloy Actuated Adaptive Trailing Edge Flap Part 1

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 737-800 wing. 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.

Part 1 of this paper will cover the design, build, and test of the SMA components used in the flight actuator system, including qualification of the SMA components for flight testing. The design and performance objectives will be summarized. Data from previous extensive testing of NiTinol rotary actuators, that form the basis for the design of the flight actuators, will be reviewed. Laboratory tests of the flight design will be compared to performance predictions. Aircraft integration, the test methods used to approve the SMA components for integration and flight, and the test results will be presented.  Issues related to the certification of SMA actuators for aerospace applications will be discussed.