Integrated propulsion systems and methods for blended wing aircraft are disclosed. In one embodiment, a propulsion system at least one engine operatively disposed within an engine flow duct having an engine inlet and an engine exhaust aperture, and at least one fan operatively disposed within a fan flow duct having a fan inlet and a fan exhaust aperture. The engine and fan rotational axes extending at least approximately along a lengthwise direction of the aircraft, the fan flow duct being separate from the engine flow duct. A transmission assembly is operatively coupled between the at least one engine and the at least one fan, the transmission assembly being configured to transmit a rotary output from the at least one engine to rotate the at least one fan.