An outflow valve is provided. The outflow valve includes a frame and a first door rotatably coupled to the frame. The first door has a first side opposite a second side and a bellmouth. The bellmouth is defined by a super-ellipse, with a major axis of the super-ellipse substantially parallel to the second side and a minor axis of the super-ellipse substantially perpendicular to the second side. The outflow valve also includes a second door rotatably coupled to the frame. The first door and the second door are substantially simultaneously movable between at least a first position and a second position.