Picture above: machine for vertical flight designed by Sir George Cayley, one of the great precursors of flight.
In 1843 Sir George Cayley, the father of British aviation, invented his "Aerial Carriage" which had four "rotors" arranged coaxially in pairs. This strange vehicle was an improve-ment on other contemporary projects, but Sir George did not succeed in finding a suitable engine, so the machine remained on the drawing board.
G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984
Cayley made these drawings for a vertical take-off and landing aircraft in 1843. Although the design looks fanciful by modern standards, it has features that have appeared in successful heli- copters (the wide fanlike rotors resemble those used on the de Bothezat machine flown by the U.S. Army in 1922; the lateral side- by-side arrangement of the rotors is similar to the recordbreaking Focke helicopters built in Germany in the late 1930's). One especially interesting feature is the design of the blades: they flatten down to form a solid disc and act as a wing in forward flight. The bird's- head bowsprit may have been a deliberately humorous touch.
C.Gablehouse "Helicopters and Autogiros", 1969