“Helicopter” Sketch
, 1493
In 1493, Leonardo da Vinci drew this sketch of the “aerial screw," inspired by observing maple seeds that slow their fall by rotating. While this early design was not without its flaws – it was far too heavy to fly and called for the manual cranking of wooden shafts to generate force – its core principles underpinned the flight of the first viable helicopter by Igor Sikorsky some 450 years later.