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An autogyro, also known as a gyroplane, is a type of rotorcraft that uses an unpowered rotor in free autorotation to develop lift. Forward thrust is provided independently, by an engine-driven propeller. While similar to a helicopter rotor in appearance, the autogyro's rotor must have air flowing across the rotor disc to generate rotation, and the air flows upwards through the rotor disc rather than down.
Juan de la Cierva y Codorníu, 1st Count of la Cierva was a Spanish civil engineer, pilot and aeronautical engineer. His most famous accomplishment was the invention in 1920 of a rotorcraft called Autogiro, a single-rotor type of aircraft that came to be called autogyro in the English language. In 1923, after four years of experimentation, De la Cierva developed the articulated rotor, which resulted in the world's first successful flight of a stable rotary-wing aircraft, with his C.4 prototype.
The Focke-Wulf Fw 61 is often considered the first practical, functional helicopter, first flown in 1936. It was also known as the Fa 61, as Focke began a new company—Focke-Achgelis—in 1937.
The Cierva C.30 is an autogyro designed by Juan de la Cierva and built under licence from the Cierva Autogiro Company by A V Roe & Co Ltd (Avro), Lioré-et-Olivier and Focke-Wulf.
A gyrodyne is a type of VTOL aircraft with a helicopter rotor-like system that is driven by its engine for takeoff and landing only, and includes one or more conventional propeller or jet engines to provide forward thrust during cruising flight. During forward flight the rotor is unpowered and free-spinning, like an autogyro, and lift is provided by a combination of the rotor and conventional wings. The gyrodyne is one of a number of similar concepts which attempt to combine helicopter-like low-speed performance with conventional fixed-wing high-speeds, including tiltrotors and tiltwings.
A rotorcraft or rotary-wing aircraft is a heavier-than-air aircraft with rotary wings or rotor blades, which generate lift by rotating around a vertical mast. Several rotor blades mounted on a single mast are referred to as a rotor. The International Civil Aviation Organization (ICAO) defines a rotorcraft as "supported in flight by the reactions of the air on one or more rotors".
The Cierva C.6 was the sixth autogyro designed by engineer Juan de la Cierva, and the first one to travel a "major" distance. Cierva, the engineer responsible for the invention of the autogyro, had spent all his funds on the research and creation of his first five prototypes. Therefore, in 1923, he turned to the Cuatro Vientos Aerodynamics Laboratory chief, Commander Emilio Herrera, who succeeded in persuading General Francisco Echagüe, the director of the Military Aviation Aeronautics Department, to take over the second stage in the research and development of Cierva's autogyros.
The Pitcairn OP-1 was the first rotary-wing aircraft to be seriously evaluated by any of the world's major air forces. The machine was not a helicopter, nor an airplane, but an autogyro. Pitcairn's model was never put into production for any military.
The Cierva Autogiro Company was a British firm established in 1926 to develop the autogyro. The company was set up to further the designs of Juan de la Cierva, a Spanish engineer and pilot, with the financial backing of James George Weir, a Scottish industrialist and aviator.
The Cierva C.2 was an experimental autogyro built by Juan de la Cierva in Spain in 1921-22. Following the failure of the C.1 the previous year, la Cierva started again from scratch, this time taking the fuselage from a Hanriot biplane and adding a five-bladed single rotor to it. Work was interrupted when Cierva ran out of funds, and the machine was not actually completed until 1922, after his next design, the C.3 had already been built and tested. Attempts to fly the aircraft resulted in repeated crashes, and the machine was rebuilt nine times before being finally abandoned.
The Cierva C.3 was an experimental autogyro built by Juan de la Cierva in Spain in 1921. It was based on the fuselage of a Sommer monoplane, and was actually completed and tested before that aircraft. The C.3 utilised a single, three-bladed rotor in place of the coaxial double rotor tested on the C.1. A few short hops were achieved in testing and Cierva noted a tendency for the machine to want to roll over, thus alerting him to the problem of dissymmetry of lift that he would have to overcome in order to build a successful rotary-wing aircraft. The C.3 was damaged and rebuilt four times before being abandoned without having flown, la Cierva returning to work on the C.2.
The Cierva C.4 was an experimental autogiro built by Juan de la Cierva in Spain in 1922 which early the following year became the first autogyro to fly successfully. Failures of De la Cierva's attempts to compensate for dissymmetry of lift with the C.1, C.2, and C.3 autogiros, led him to consider alternate means of enabling an autogyro to fly without rolling over. He noted that the problems experienced with his full-size aircraft were not present in the models that he had successfully flown, and considered the difference between the full-size and small-scale rotors. The rotors used on his model were made of bamboo and were thus far more flexible than the ones on his full-size aircraft. While attending an opera he realized that the flexibility eliminated the moments acting on the hub and associated instability. Trained as a civil engineer, Cierva was aware that a cantilever structure hinged to its attachment point generated no moment, and he designed a rotor the blades of which were mounted to the hub through hinges to permit their vertical oscillation.
The Cierva C.8 was an experimental autogyro built by Juan de la Cierva in England in 1926 in association with Avro. Like Cierva's earlier autogyros, the C.8s were based on existing fixed-wing aircraft fuselages – in this case, the Avro 552.
The Cierva C.17 was a British experimental autogyro built by Cierva Autogiro Company in England in 1928, in association with Avro. It was an attempt to build upon the successful Cierva C.8 design using the smaller, more streamlined fuselage of an Avro Avian IIIA as a starting point. The type was found to be underpowered, and when the first attempt at fitting a more powerful engine still did not result in acceptable performance, the design was abandoned.
The Cierva C.19 was a 1930s British two-seat autogyro, designed by Spanish engineer Juan de la Cierva. It was built by Avro as the Avro Type 620. It proved to be the most successful and widely produced of the early de la Cierva designs.
The Pitcairn PCA-2 was an autogyro developed in the United States in the early 1930s. It was Harold F. Pitcairn's first autogyro design to sell in quantity. It had a conventional design for its day – an airplane-like fuselage with two open cockpits in tandem, and an engine mounted tractor-fashion in the nose. The lift by the four-blade main rotor was augmented by stubby, low-set monoplane wings that also carried the control surfaces. The wingtips featured considerable dihedral that acted as winglets for added stability.
The Cierva C.40 was a British autogyro designed by G.B.L. Ellis, Otto Reder, and Dr. J.A.J Bennett and was assembled by the British Aircraft Manufacturing Company at London Air Park, Hanworth.
The Cierva C.29 was a five-seat British cabin autogyro built in 1934 as a joint venture between Westland Aircraft and Cierva. The rotor system and rotors were designed by Cierva and the fuselage by Westland. It was powered by a 600 hp (447 kW) Armstrong Siddeley Panther II engine with a two-bladed tractor propeller; the engine also drove the three-bladed rotor via a clutched shaft. The C.29 suffered from ground resonance during ground running and was not flown. It was later acquired for evaluation by the Royal Aircraft Establishment but it was unable to cure the resonance problem and the autogyro was scrapped in 1939.
The Westland CL.20 was a two-seat autogyro designed and built by Westland Aircraft between 1934 and 1938. One flying prototype and six airframes were built, which had control problems and insufficient lift. Before these problems could be solved the programme was abandoned and the prototype was scrapped in 1938.
The TsAGI A-4, sometimes anglicised as CAHI A-4 or ZAGI A-4, was an early Russian autogyro, influenced by Cierva designs and delivered in small numbers to the Soviet Air Force in 1934.
References
- Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. p. 254.
- World Aircraft Information Files. London: Bright Star Publishing. pp. File 891 Sheet 28.
- Leishman, J. Gordon (2006). Principles of Helicopter Aerodynamics. Cambridge: Cambridge University Press. p. 699.
