A conceptual design analysis methodology and toolchain was developed for multidisciplinary analysis of box-wing aircraft. This methodology was applied to investigate the effect of wing geometry variation on specific range for various short-range missions. The results were compared with an equivalent, cantilever wing aircraft to determine potential improvement over conventional aircraft designs. The multidisciplinary design analysis incorporated aerodynamic and structural optimisation methods and tools to explore the influence of key geometric parameters and mission requirements on the aerostructural characteristics. The aerodynamic and structural analysis and optimisation, via a design space exploration, was undertaken using vortex-lattice methods and finite element analysis tools developed or integrated in a common framework that facilitates rapid and easy data exchange. This study shows that the geometric parameters of horizontal wing separation, vertical wing separation and aspect ratio are the key design parameters for the box-wing concept and their effect on aircraft performance was analysed in detail. To compare the performance improvement of the box-wing over its conventional counterpart, the same methodology was applied to the conventional aircraft, keeping total wing reference area the same. The wing area was used as the reference parameter as it is driven by take-off distance and would not be affected by cruise performance. The results show that horizontal wing separation should be minimised, and that lower vertical wing separation and aspect ratio for the box-wing led to improved fuel burn. The box-wing had higher structural efficiency with a lower aerodynamic penalty due to the reduction in induced drag that the box-wing offers. To determine the effect of different missions on the box-wing performance, four different missions were analysed and compared, by varying cruise Mach number, altitude, payload and design range. The results indicated that for missions flown at slower cruise Mach numbers and lower altitudes with smaller payloads, a fuel burn reduction of 5% can be achieved with the an optimal box-wing configuration compared to an equivalent conventional configuration. It was shown that the box-wing configuration can be an improvement over its equivalent conventional aircraft configuration in terms of performance, but the fuel burn results are dependent on the mission criteria and the choice of geometric parameters. This indicates that the window of improvement is small and specific, but the box-wing holds significant promise for future development and should be the focus of further, detailed research and analysis.
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