Homebuilt aircraft, also known as amateur-built aircraft or kit planes, are constructed by persons for whom this is not a professional activity. These aircraft may be constructed from "scratch", from plans, or from assembly kits. Overview In the United States, Brazil, Australia, New Zealand and South Africa, homebuilt aircraft may be licensed Experimental under FAA or similar local regulations. With some limitations, the builder(s) of the aircraft must have done it for their own education and recreation rather than for profit. In the U.S., the primary builder can also apply for a repairman's certificate for that airframe. The repairman's certificate allows the holder to perform and sign off on most of the maintenance, repairs, and inspections themselves. Alberto Santos-Dumont was the first to offer for free construction plans, publishing drawings of his Demoiselle in the June 1910 edition of Popular Mechanics. The first aircraft to be offered for sale as plans, rather than a completed airframe, was the Baby Ace in the late 1920s. Homebuilt aircraft gained in popularity in the U.S. in 1924 with the start of the National Air Races, held in Dayton, Ohio. These races required aircraft with useful loads of and engines of 80 cubic inches or less and as a consequence of the class limitations most were amateur-built. The years after Charles Lindbergh's transatlantic flight brought a peak of interest between 1929 and 1933. During this period many aircraft designers, builders and pilots were self-taught and the high accident rate brought public condemnation and increasing regulation to amateur building. The resulting federal standards on design, engineering, stress analysis, use of aircraft-quality hardware and testing of aircraft brought an end to amateur building except in some specialized areas, such as racing. In 1946 Goodyear restarted the National Air Races, including a class for aircraft powered by 200 cubic inch and smaller engines. The midget racer class spread nationally in the U.S. and this led to calls for acceptable standards to allow recreational use of amateur-built aircraft. By the mid-1950s both the U.S. and Canada once again allowed amateur-built aircraft to specified standards and limitations. Homebuilt aircraft are generally small, one to four-seat sportsplanes which employ simple methods of construction. Fabric-covered wood or metal frames and plywood are common in the aircraft structure, but increasingly, fiberglass and other composites as well as full aluminum construction techniques are being used, techniques first pioneered by Hugo Junkers as far