I touched on the history of the helicopter in a much longer early draft of the Quetzalcoatlus chapter for The Book of Barely Imagined Beings. This is footnote 74 (of 117):
There is, of course, at least one ‘helicopter’ in nature: winged seeds such as that of the sycamore . One of the strangest and least successful flying machines of all time was directly inspired by it. Designed in 1913-14, the Papin-et-Rouilly Gyroptère consisted of rotary engine sucked in air that was piped through a duct inside a single large swept wing where it exited through a nozzle in the trailing edge. This propelled the wing in a clockwise spinning motion around the pilot, who sat in the middle inside a drum mounted on ball bearings, with a doughnut-shaped float underneath. A swiveling air nozzle, which the pilot manipulated to steer the machine, also provided forward thrust. On its first test flight on Lake Cercey in eastern France in 1915, the Gyroptere wing rotated fast enough for the pilot to loose control but not fast enough to take off, and the whole contraption sank.
Helicopters have a longer and stranger history than many people realise. It probably starts with a child’s flying top, the ‘bamboo dragonfly’, which was developed in China in about the year 400 AD. Sophisticated models with, respectively a coaxial rotor and counter rotating rotors using turkey feathers as rotor blades, were demonstrated at the Russian and French academies of science in 1754 and 1783. The word ‘helicopter’ - from the Greek "helicos" meaning helix and "pteron" meaning wing - was coined in the early 1860s by the Viscomte de Ponton d'Amecourt, who demonstrated a small steam-powered model. In 1901 the Slovak inventor Ján Bahýľ developed the first model helicopter powered by an internal combustion engine and in 1905 succeeded in getting it to fly more than 1,500 meters at an altitude of about four meters. And in 1907 two French brothers, Jacques and Louis Breguet, got a piloted craft two feet (0.6 m) into the air for about a minute.
Great strides were made over the next two decades, but the first truly reliable and practical helicopter, the Focke-Wulf Fw 61, didn’t fly until 1936 and was demonstrated indoors at the Deutschlandhalle sports stadium in Berlin in 1938 by Hannah Reitsch, Hitler’s favourite test pilot. Later that year she set an altitude record of 3,427 m and a straight line flight record of 230 km. The Third Reich was the first power to use helicopters in war, with a small number deployed for observation, transport, and medical evacuation.
The first human-powered helicopter, the Da Vinci III, flew on 10th December 1989 at California Polytechnic State University It was airborne for 7.1 seconds and reached a height of 20 cm (a little less than 8 inches). Two people had to hold the craft steady while it was in the air.There were further references to Leonardo da Vinci elsewhere in the text.