Blended wing body aircraft

A blended wing body aircraft comprising:

• one or more open-fan engines each including an unducted fan section having a plurality of fan blades;
• and
• a body section blended with a plurality of wing sections each defining an aerodynamic lifting surface, the body section including (a) an upper body, (b) a lower body, and (c) one or more grooves, the one or more grooves including (i) an axial contoured wall extending from the upper body towards the lower body upstream of the one or more open-fan engines at an upper contour angle relative to the upper body, (ii) a bottom surface blending with the axial contoured wall and extending downstream of the axial contoured wall towards an aft end of the body section, the bottom surface extending towards the upper body at a bottom contour angle relative to the lower body, and (iii) a circumferential contoured wall extending from the upper body towards the lower body that blends with the bottom surface and the axial contoured wall, wherein air flows over the body section and the plurality of wing sections and forms a boundary layer over the upper body, the boundary layer being thickest at the one or more grooves,
• wherein the one or more open-fan engines are mounted at least partially within the one or more grooves such that the plurality of fan blades extends beyond the upper body, the one or more open-fan engines are spaced from the bottom surface of the one or more grooves, and the one or more open-fan engines ingest substantially an entirety of the boundary layer, and wherein the one or more open-fan engines are characterized by a propulsor immersion parameter that is defined by a relationship of a height of the one or more open-fan engines from the bottom surface of the one or more grooves to a central longitudinal axis of the one or more open-fan engines, and a diameter of the plurality of fan blades of the one or more open-fan engines, the propulsor immersion parameter being greater than 0.5 and less than or equal to about 1.0.