Leonardo da Vinci's proposed helicopter, late 15th century.

This model has been constructed from a sketch for a helicopter design by Leonardo da Vinci (1452-1519). The ancient Chinese made hand-spun toys that rose upward like a helicopter when revolved rapidly, but Leonardo's helicopter is the earliest known design to envision a machine to carry a man and its own 'power unit'. Like many other designs after his, Leonardo's worked theoretically but would have been impractical in full-sized form.