TOP CHOPPER: THE ‘AERIAL SCREW’
Leonardo da Vinci, the Italian polymath, was centuries ahead of his time when it came to human flight. Over 400 years before the first helicopter took off, he sketched his idea for a wood-and-canvas screw-like flyer with blades 2 metres wide. It was never built (like his other flying machines – such as hang gliders, parachutes and a wing-flapping ‘ornithopter’) but the ‘aerial screw’ helped set human imagination skywards.