The Italian polymath Leonardo da Vinci drew his design for an "aerial screw" in the late 1480s, while he was employed as a military engineer by

Ludovico Sforza Ludovico Maria Sforza (; 27 July 1452 – 27 May 1508), also known as Ludovico il Moro (; "the Moor"). "Arbiter of Italy", according to the expression used by Guicciardini,

Duke of Milan The following is a list of rulers of Milan from the 13th century to 1814, after which it was incorporated into the Kingdom of Lombardy–Venetia by the Congress of Vienna. Before elevation to duchy Until 1259, Milan was a free commune that elect ...

from 1494 to 1499. The original drawing is part of a manuscript dated to 1487 to 1490 and appears on folio 83-verso of , part of the papers removed from the Biblioteca Ambrosiana in 1795 by

Napoleon Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...

and still held by the Institut de France in Paris. Da Vinci biographer Walter Isaacson has expressed the belief that it was “devised for a theatrical spectacle”. The "aerial screw" was one of several aerial machines drawn by Leonardo, including an early

parachute A parachute is a device used to slow the motion of an object through an atmosphere by creating drag or, in a ram-air parachute, aerodynamic lift. A major application is to support people, for recreation or as a safety device for aviators, who ...

, an ornithopter and a hang glider. The pen-and-ink sketch outlines an idea for a flying machine similar to a modern helicopter, with a spiral rotor or "aerial screw" based on a water screw, but intended to push against the fluid of the air instead of water. The design comprises a large structure, built on a solid circular platform, with a central vertical pole supported by three diagonal members meeting at a small circular plate about half way up the pole. The upper half of the pole is the supportive axis for a large spiralling sail of linen with a radius of about , stiffened with starch. The inner edge of the sail winds clockwise around the pole, while the outer edge of the sail is connected by ropes or wires to a ring that rotates around the lower platform. The design envisions a crew of several people on the wooden platform running around the central pole while holding handles that rotate the sail. Leonardo's annotations suggest that a linen aerial screw, if turned quickly enough, would push against the air and lift the structure into the air. The notes indicate that Leonardo built small flying models of the aerial screw, but there were no indications for any provision to stop the reaction against the rotation of the sail from making the craft itself rotate in the opposite direction. It is conceivable that Leonardo could have constructed small working models, but a full-size working version could not have been realised for want of sufficiently light but strong materials, and a powerful enough drive for the screw. The

bamboo helicopter The bamboo-copter, also known as the bamboo dragonfly or Chinese top (Chinese ''zhuqingting'' (竹蜻蜓), Japanese ''taketonbo'' ), is a toy helicopter rotor that flies up when its shaft is rapidly spun. This helicopter-like top originated in ...

, a toy flying machine based on similar principles, had been known in China since about 300 BC. The modern helicopter owes more to the bamboo helicopter than to Leonardo's aerial screw. In 2022 a drone based on Leonardo's design flew. Macchina volante - Museo scienza tecnologia Milano 09392 01.jpg, Model in the Museo Nazionale Scienza e Tecnologia Leonardo da Vinci, Milan DaVinci Helix Hubschraubermuseum Bueckeburg.jpg, Model in the Hubschraubermuseum Bückeburg

References

Folio83-verso, Manuscrit B
Institut de France

Leonardo3 Museum Leonardo3 is an interactive museum and exhibition center at Galleria Vittorio Emanuele II, Piazza della Scala, Milano, Italy. The museum is devoted to Italy’s notable personality Leonardo da Vinci and portrays him both as an artist and inventor ...

Leonardo da Vinci's helicopter: 15th-century flight of fancy led to modern aeronautics
''The Conversation'', 3 May 2019
Leonardo da Vinci's Aerial Screw
COVE, 22 May 2019 {{Leonardo da Vinci Helicopters Leonardo da Vinci