Split blended winglet

A method of reducing drag and increasing the range of an aircraft, the aircraft including an upper winglet (906) extending from a wing of the aircraft, the upper winglet including a winglet tip cap (1604), the method comprising: attaching a ventral fin (902) to a bottom surface of one of the upper winglets and the wing, the ventral fin protruding below a wing chord plane and converging in a ventral fin tip configuration comprising a curvature from the ventral fin toward an airflow direction substantially parallel to the wing chord plane; removing the wingtip cap from the top winglet; and attaching a curved blade cover (1616) to the upper flap, the curved blade cover curving toward the airflow direction.