Design and assessment of a transonic truss-braced wing aircraft concept

To address the need to reduce the climate impact of the air transport sector, the next generation of commercial airliners will need to be significantly more energy efficient. Alternative configurations to conventional *tube-and-wing* aircraft could help to achieve this goal. The truss-braced wing configuration is particularly promising, as research shows that the addition of a strut can enable higher aspect ratio wings, reducing the induced drag, and thereby increasing the aerodynamic efficiency. Nonetheless, the addition of a strut also has drawbacks, such as an increased wetted area, and has implications on other components, such as the fuselage structural design, the landing gear integration, or the tailplane configuration. This paper therefore presents an assessment of this configuration on conceptual design level to evaluate the potential of truss-braced wing aircraft as an energy-efficient alternative to conventional aircraft. Using low- and mid-fidelity design methods, a coherent TBW aircraft is designed under consideration of relevant constraints and disciplines; critical enabling technologies are identified, modelled, and their effect investigated: From an aerodynamics perspective, the investigations show that the TBW enables lower relative airfoil thickness, reducing the necessary sweep and permitting the use of natural laminar flow without sacrificing cruise speed. To assess the potential of the Truss-braced wing concept depending on the achievable aspect ratio, a design-space exploration is performed for both the TBW and the baseline aircraft to identify the conditions necessary for the TBW to be a competitive alternative.