Winglet and strut configuration study for a slotted, natural-laminar-flow strut-braced transport aircraft

A preliminary design exploration of the NASA-ULI strut-braced aircraft was made. Wing sizing and performance estimations were made in conjunction with the design of a new class of transonic slotted, natural-laminar-flow airfoils. Preliminary computational results indicate the aircraft has the ability to cruise at Mach 0.73 at 40,000 feet. Maximum efficiency during cruise, M^LD^{, is 17.25. The wing was resized from a parent aircraft’s 1477 ft2} to 1350 ft² . The aircraft’s maximum takeoff weight is 140,000 lbs, and the maximum landing weight is 119,000 lbs. Spanwise load distributions were calculated for both the strut and the wing, with twist optimization performed using multi-lifting-line codes coupled with airfoil data from CFD. Further analysis was performed to explore the design space for an aerodynamically load-carrying strut compared to an unloaded one. Finally the addition of winglets to the high-span aircraft were also explored with a FreeWake higher order lifting-line code. Performance improvements from the addition of winglets were on the order of three percent in cruise.