Impact of Horizontal Tail Position on Turbulence Transition Around Vertical Tail

The research and development of natural laminar flow (NLF) wing designs can minimize airframe drag. This investigation extends to the design of NLF vertical tails for a reference subsonic civil aircraft under cruise conditions. Although parameters unrelated to design are treated as constant, practical aircraft development requires performance optimization across all airframe components rather than isolated elements. This study examines how the presence and positioning of a horizontal tail affect the turbulent transition and aerodynamic properties of a NLF vertical tail. Adjusting the presence and location of the horizontal tail alters the flowfield around the vertical tail and modifies the spatial pressure distribution, which corresponds to changes in flow acceleration and deceleration. Compared to the baseline configuration, positioning the horizontal tail upstream and vertically higher locally delays transition. The laminar flow extent ranges from approximately 45 to 48% across the configurations, while the transition characteristics are notably affected. The drag coefficient decreases, whereas the lift and moment coefficients and the lift-to-drag ratio also decrease. These results demonstrate that modifying the relative positioning of adjacent components can alter pressure distributions and transition characteristics without changing the geometry of the target component.