This paper presents a numerical aerodynamic study of the stall characteristics and flow separation mechanismsof a blended wing body unmanned aerial vehicle being developed at KTH Royal Institute of Technologyand proposes a bio-inspired leading-edge modification to control the separation mechanism andimprove the aerodynamic performance of the aircraft at high angles of attack. A numerical study of theaircraft was performed at cruise speed, corresponding to Reynold’s number of 1.3x106, employing an UnsteadyReynolds Averaged Navier-Stokes solver with the Spalart-Allmaras turbulence model. Numericalresults indicated that the aircraft is characterized by the presence of an unstable longitudinal vortex – visibleat the stall angle of 9 deg – which breaks up at an angle of attack of 10 deg, resulting in an unsteady,full-chord stall cell in the mid-span region of the wing section. To mitigate this phenomenon, a modificationto the leading edge between 0.4 m and 1.8 m wing spans was implemented inspired by the geometryof the nose of a porpoise whale, effectively generating a porpoise (hump) leading-edge inboard section.Preliminary numerical results indicate an increase in stall angle of attack to ∼13 deg and an in maximumlift coefficient to ∼1.0. Furthermore, the porpoise hump allowed controlling the stall behavior of the aircraftby enforcing a wing tip, trailing-edge separation stall achieved by the generation of an extended flowacceleration region at the leading edge.