Several ways to fly -------------------------
Leonardo da Vinci produced numerous studies of flight. He began by observing birds of prey gliding, which suggested the idea of a flapping-wing aircraft, the ornithopter. But after various unsuccessful experiments, he abandoned the idea to focus on rigid wings.
He also produced the first sketch of a parachute, as well as a kind of bamboo hang glider that actually flew… albeit only a short distance.
Finally, Leonardo designed the propeller-driven aircraft, or aerial screw, sometimes interpreted as the first helicopter concept. But it would take another two centuries for the helicoid, a surface determined by a helix and an axis, to be formalized mathematically: together with the plane, it is the only ruled minimal surface—that is, one that can be generated by moving a line through space. The first helicopter did not appear until the beginning of the 20th century (in fact, it was a multicopter that bore a striking resemblance to a drone).