A lightweight, single-seat aircraft with low flight speed and power, used for sport or recreation. Ultralights evolved from hang gliders, and the first models were crude, home-built modifications of the Icarus, a rigid-wing, biplane, tailless hang glider popular in the mid-1970s. Newer ultralights are designed strictly as motorised aircraft and cannot be flown as hang gliders. Ultralights are sold as kits, requiring from 50 to 300 h for construction.