Conceptual Design of a Medium Range Box Wing Aircraft

Author: Daniel Schiktanz

Master Thesis


This thesis covers the conceptual design of a box wing configuration, an unconventional non planar configuration comparable to a joint wing whose wings are connected on the tips by vertical winglets. In this way the wing configuration forms a rectangular box in the front view. The box wing configuration allows for savings in induced drag which results in reduced fuel consumption. Compared to conventional aircraft there are significant differences concerning aerodynamics, flight mechanics and the structural layout. These differences are elaborated and their consequences are applied to the design process. It is shown that the requirements according to longitudinal stability and controllability are a main design driver. The aircraft is very sensitive to shifts of its center of gravity. This issue is solved by a well balanced aircraft layout, comprising of a short fuselage not extending much more forward than the front wing and an engine position close to the center of gravity. For assessing the saving potentials of the box wing configuration a reference aircraft is chosen (the Airbus A320). The design mission and geometry constraints of the reference aircraft are applied to the box wing aircraft so that performance and operational characteristics of both aircraft can be compared. A shorter fuselage and cabin means more seats abreast, so this box wing aircraft becomes a wide body aircraft having two main aisles. This allows for a faster boarding /deboarding. The resulting increase of the cross sectional area of the fuselage permits the accommodation of standard LD3 containers. It is concluded that the designed box wing aircraft consumes 9 % less fuel and requires 2 % less take off thrust for the design mission. With reduced fuel burn the box wing configuration has also a potential of reduced emissions. The maximum take off weight of both aircraft is equal. Unlike other unconventional configurations (e.g. the blended wing body) the box wing is compatible to current airport facilities. It is important to keep in mind that the presented conceptual design is based on simplifying assumptions as well as preliminary calculations and methods. The design has to be checked and confirmed in more detailed investigations. The designed box wing aircraft is not fully optimized yet. Hence it still leaves room for further performance improvements.