Airfoil Decambering for Gust Load Alleviation Using a Bi-stable Hinge

Wing sections with bistable hinges outfitted on trailing edge flaps provide a promising means for passively rejecting gust loads on an aircraft. This study found that there exists a two-way coupling between the aerodynamic loads experienced by the airfoil and the deflection of the bistable hinge and corresponding flap. The current work demonstrates how the energy wells of a bistable hinge system can be configured to introduce decambering of the airfoil when stall limits are approached. By expressing the interdependent coupling between the global flow state and the hinge material properties, a bistable hinge can be designed to produce snap-through transitions when prescribed aerodynamic states are reached. The efficacy of this bistable hinge integration strategy is shown in an experimental campaign, where passive alleviation of aerodynamic loads are produced in the vicinity of airfoil stall limits.