Aerodynamic Considerations in the Design of Truss-Braced-Wing Aircraft

This paper describes a study of the effects of several key aerodynamic considerations on the conceptual design of minimum-fuel/emissions, long-range transport, transonic, truss-braced-wing aircraft configurations. This unconventional configuration has a large benefit over conventional cantilever wing configurations. The truss system enables an increased aspect ratio with lower sweep, thickness ratio, and chords, thus exploiting natural laminar flow. The design problem is solved by a multidisciplinary optimization process, which takes into account both aerodynamic and structural considerations. This paper contains several studies, each of which investigates the dependency of the design space on a specific aerodynamic parameter such as the extent of laminar flow on the wing, cruise Mach number, maximum cruise two-dimensional lift coefficient, supercritical characteristics of the airfoil, winglet influence, and intersection fairing design. In addition, various fuselage drag-reduction technologies are investigated: fuselage relaminarization, surface riblets, tailless arrangements, and Goldschmied propulsion apparatus. All of these studies illustrate the large potential of the truss-braced wing along with additional drag-reduction technologies, which may substantially decrease the fuel weight and vehicle emissions.