The first helicopters

This helicopter, designed by George De Bothezat and Ivan Jerome, made its first public flight on December 18, 1922, at McCook Field near Dayton, Ohio.

This helicopter, built by Etiénne Oehmichen, had four lifting airscrews and five auxiliary propellers. It set flight records in 1924.

In Etiénne Oehmichen's first attempt at vertical flight, around 1920, he built a twin-rotor helicopter that had insufficient power to fly. He solved the problem by adding a balloon to the machine.