Ján Bahýľ (25.5.1856 Zvolenská Slatina - 13.3.1916 Bratislava) was an inventor working with flying machines. He was responsible for 17 inventions, including a petrol-engined helicopter and an airtrubine baloon. After completing elementary education he trained as a draughtsman at the State School in Banska Štiavnica and graduated from the military academy in Vienna. He was an officer in the Austro-Hungarian army and its chief construction engineer and specialist in building military fortifications. He worked in Bratislava, Lvov, Cracow, Dubrovnik and elsewhere. From 1892 onwards he conducted tests with a helicopter prototype of his own construction. On 13th August, 1895 his helicopter design was patented. It was 6,5 m long, weighed 50 kg. and hovered 50 cm above the ground. In 1903 Bahýľ's helicopter reached a height of 1,5 metres above the ground and four years later, four metres. On 15th June, 1905 it was registred by the International Aviation Organisation.