Conceptual design and evaluation of blended-wing-body aircraft

Blended wing body (BWB) aircraft represent a paradigm shift in jet transport aircraft design that promise benefits over conventional aircraft. A method is presented to enable the conceptual design of BWB aircraft, enabling comparison studies with tube-and-wing aircraft (TAW) based on the same top-level requirements and analysis fidelity. The aim of this work is to make comparative studies between the blended-wing-body aircraft and its conventional tube-and-wing counterpart based upon the same design requirements at conceptual level. By developing a novel geometric parametrisation of the blended wing body, the design possibilities have been increased while maintaining straightforward shaping manipulation and robustness. The mass estimation methods that have been implemented are verified and validated to be within approximately 5% of reference blended wing bodies. Drag estimations perform less accurately with drag being overpredicted by approximately 20%. The cause of this over prediction was largely due to empirical corrections for miscellaneous and unaccounted drag sources as well as induced drag predicted by a vortex-lattice method. Test-case BWB and TAW aircraft were formed in the 150, 250 and 400 passenger classes. The comparisons of the resulting aircraft show that the blended wing body have reduced mass, improved aerodynamic efficiency and higher fuel economy. Trends also show that the improvements over tube-and-wing aircraft increase with aircraft size.