The transonic truss-braced-wing configuration (TTBW) and cruise-slotted wing are two advanced technologies with the potential to significantly improve the aerodynamic efficiency of next-generation transport aircraft. The TTBW achieves reduced induced drag through the use of an ultra-high-aspect-ratio wing supported by a truss, while the cruise-slotted wing employs slotted airfoils to mitigate shock formation and boundary-layer separation at transonic flight conditions. However, it remains to be seen whether these technologies can be combined while retaining their individual benefits. To address this question, this paper investigates the aerodynamic design and performance of a cruise-slotted TTBW configuration through the application of aerodynamic shape optimization based on the Reynolds-averaged Navier–Stokes equations. Aerodynamic shape optimization is also applied to the aerodynamic design of a nonslotted TTBW reference aircraft. Results indicate that aerodynamic shape optimization is successful in achieving an aerodynamically efficient cruise-slotted TTBW design for fully turbulent flow, with similar features to those of the optimized nonslotted TTBW. In terms of aerodynamic performance, the optimized cruise-slotted TTBW experiences 3.0% more drag at Mach 0.80 than the nonslotted variant but benefits from a more gradual drag rise as the operating Mach number increases. This trend persists even when both configurations are optimized for higher design Mach numbers. However, the low wave drag of both sets of optimized designs mitigates the airfoil technology factor advantage of the cruise-slotted wing, resulting in lower maximum aerodynamic range efficiency compared to the nonslotted wing.
Chau et al. (Wed,) studied this question.