Da Vinci sketched the oldest known plans for a human-powered aircraft in 1485. Yet it wasn’t until 1977 that the first one truly flew. Flight requires lift, when the net air pressure pushing upward counteracts the craft’s weight. For years, many assumed that flight required more lift and more power than the human body alone could provide (although the admonitions did little to stop myriad failed attempts). But inventors persisted. Aircraft fly using three basic configurations: fixed wing, flapping wing, and rotors. In the last 50 years, inventors have conquered fixed-wing and flapping flight. Now they are on the verge of overcoming the greatest challenge yet: vertical takeoff.