Aircraft fuel consumption has a direct effect on the aircraft direct operating costs. The pursuit for reduced fuel consumption is a main reason to investigate the aerodynamics, especially the drag, of alternative aircraft configurations. This dissertation reports on an investigation on the aerodynamics of three-surface aircraft at the conceptual design level. A “three-surface aircraft” is characterized by having an additional lifting surface: a main wing, canard and horizontal tail. Contrary to the contemporary conventional and canard aircraft, the three-surface aircraft, having one additional lifting surface, offers potentially a capability to vary, hence optimize, the lift distribution between the surfaces over the center of gravity and weight envelope. The main questions are: Can the drag be reduced relative to conventional and canard aircraft, and how to design and position the lifting surfaces to optimally distribute the lift over and between the three surfaces.