A ducted fan propulsion comprises a duct with a cutout and a movable duct section that is moved between a retracted position within the cutout and am extended position relative to the duct. An actuator is disposed within the duct wall and is connected to the movable duct section with actuating linkage. A control linkage connects the movable duct section to the cutout edges. The movable duct section is extended when the ducted fan propulsion transitions from vertical takeoff to a level flight or transitions from level flight to a vertical landing. The movable duct section is retracted into cutout an becomes integrated with the duct during level flight.