For this prototype which he built at Madrid, La Cierva used the fuselage of a Deperdussin, a French monoplane of pre-World War I vintage, on which were mounted two contra-rotating four-bladed rotors. The C.1 had a vertical surface above the rotor to give lateral control. This model never flew, since it proved impossible to control: the lift from the two rotors was unbalanced because of mutual interference.

P.Lambermont "Helicopters and Autogyros of the World", 1958

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