First Autogiro Flight in 1923

On January 9, 1923, after four years of experimentation, Juan de la Cierva, (1895-1936), the self-taught Spanish aeronautical engineer developed the articulated rotor, to his invention of the autogiro, which resulted in the world's first successful flight of a stable rotary-wing aircraft, with his C.4 prototype. The first autogiro flight was piloted by Alejandro Gomez Spencer at Cuatro Vientos airfield in Madrid, Spain. 

Juan de la Cierva’s invention of the autogiro in 1920, a single-rotor type of aircraft in which lift is provided by a freely rotating rotor served as the forerunner of the helicopter. This technical breakthrough was necessary for the successful development of the helicopter, which ironically, replaced the autogiro around the time of World War II.