Sikorsky Aircraft and it became a part of [[United Aircraft and Transport Corporation]] (now [[United Technologies Corporation]]) in July of that year. [[File:Sikorsky Aircraft Corporation ad Model S-42 Clipper Flying Boat 1937.jpg|thumb|left|upright|Advertisement for [[Sikorsky S-42]] Clipper flying boat from 1937]] In the United States, Igor Sikorsky originally concentrated on the development of multi-engined landplanes and then amphibious aircraft. In the late 1930s, sales declined and United Aircraft merged his division with [[Vought Aircraft]]. He then began work on developing a practical helicopter. After first flying the [[VS-300]] he developed the [[Sikorsky R-4]], the first stable, single-rotor, fully controllable [[helicopter]] to enter full-scale
Igor Sikorsky Kiev Polytechnic Institute. After the academic year, Sikorsky again accompanied his father to Germany in the summer of 1908, where he learned of the accomplishments of the Wright brothers' Flyer and Ferdinand von Zeppelin's dirigible. Sikorsky later said about this event: "Within twenty-four hours, I decided to change my life's work. I would study aviation." By the start of World War I in 1914, Sikorsky's airplane research and production business in Kiev was flourishing, and his factory made bombers during the war. After the Bolshevik revolution began in 1917, Igor Sikorsky fled his homeland, because the new government threatened to