Aeroelastic Studies on a Folding Wing Configuration

Abstract

Morphing aircraft can change shape and size substantially in-flight to enable a single vehicle to perform multiple mission roles. The majority of shape change occurs in the wing, resulting in a wide variety of changes in aerodynamic and structural features. In addition, as the wing moves during flight, the stiffness is reduced. One strong candidate for morphing wing design is a folding wing configuration. Several parametric studies were performed to identify aeroelastic features and potential peculiarities of a generic folding wing configuration. Study parameters include inboard and outboard wing folding angles, hinge line flexibility, and sweep angle of the outboard wing. Both the inboard and outboard hinge moments were also computed throughout the wing folding procedure while maintaining 1-g trim flight condition. This information was used to compute the energy requirement for folding the wing as a function of Mach number and aircraft center of gravity (c.g.) position. As a preprocessor, MATLAB is used to generate high fidelity structure and aerodynamic models. MATLAB generates input files for both ZAERO and MSC/NASTRAN to perform aeroelastic analysis. These studies show that as inboard wing folding angle increases the flutter dynamic pressure also increases. For the extended wing configuration, the flutter dynamic pressure is much more sensitive to changes in inboard hinge stiffness than outboard hinge stiffness. For the fully folded wing configuration, however, the outboard hinge stiffness affects flutter results more than that the inboard one. Results of the trim study show that minimum hinge actuation energy for the wing folding can be achieved at lower Mach number and most forward c.g. position.