The autogiro history
The Autogiro is the greatest Spanish contribution to aviation. Since the achievement of motorized flight by the Wright brothers, it is the only case of design, creation and development of a totally new, original and different flight system: the Rotary Wings.
The creation of the gyroplane is an exceptional case. Juan de la Cierva, starting from an abstract and pragmatic conception of a theoretical nature, was able to create and develop a new type of aircraft with full success: the autogiro.
Juan de la Cierva’s relationship with the pioneers of Spanish Military Aviation and the airfields of Getafe and Cuatro Vientos was very close, and the role of these Air Bases was very significant for the rapid development and success of the Autogiro.
The first flight of a rotary wing aircraft took place on the grounds of the current Getafe Air Base, on January 17th, 1923. It was the fourth autogiro prototype built by Juan de la Cierva, the C-4 and was piloted by Captain Alejandro Gómez Spencer. This was not the only flight that took place there, but the first one that was successful. The trials began with the C-1 in 1920 by Lieutenant Gómez-Acebo, brother-in-law of the great inventor.
After the success of the C-4, the Ministry of War immediately became interested in the gyroplane, and the support the inventor received was very important. The Spanish Military Aviation commissioned him to build a larger experimental gyroplane, using the fuselage of an Avro: the C-6. Juan de la Cierva took advantage of the aeronautical technology park of Cuatro Vientos, one of the best in the world in those years. The star of this infrastructure was the aerodynamic tunnel, one of the largest in the world. The building that housed this aerodynamic tunnel is still functional today, as a workshop of the Maestranza Aérea de Madrid. But not only this kind of support was important, but also that of the people of the Military Aviation, especially Lieutenant Colonel Emilio Herrera, Head of the Aerotechnics laboratory (a very special personality, whose story also deserves to be told) and Captains Gómez Spencer and Lóriga, whose contribution was fundamental for the initial development of the autogiros.
The gyroplane was created under the generative force of in-flight safety. But in developing the gyroplane, Juan de la Cierva did much more: he practically solved something exceptionally complex: the rotor system. Despite the efforts of hundreds of companies around the world (more than 400 in the USA alone in 1919), no helicopter flew effectively until the autogiro rotor began to be used. Even nowadays all helicopters carry a minimum of two Juan de la Cierva patents on their rotors, and if it were not for them, they would not be able to fly.
The lack of further development of this type of aircraft is not a demerit of the gyroplane, but the consequence of following the path of least resistance (if the airplane already flies with greater performance why devote effort to developing the gyroplane …). It is true that the performance, in terms of speed and performance, never matched those of airplanes. But it is also true that the time and effort devoted to the development of the gyroplane has been much less than those used in traditional fixed-wing aviation and helicopters. The basic consideration of flight safety, inherent in the gyroplane, was not universally valued as a key element that validated the cost of its development.
Due to various circumstances, not only the invention of the autogiro took place in Spain (specifically in the Bases of Getafe and Cuatro Vientos) but the subsequent development of the fundamental parts of the rotor, even when its development had already migrated to England, too.
THE MEANING OF THE GYROPLANE
All companies that tried to create gyroplanes (especially Pitcairn in the United States) pursued the universalization of flight, similar to that of the automobile. However, autogiro’s flight safety qualities were not valued then, and the arrival of the helicopter, capable of performing missions that were impossible for the autogiro, relegated it to oblivion.
However, the gyroplane offers the availability of an exceptional tool for the flight tailored to the human being, safe and affordable. And for its exploitation very few human and material resources are required.
Consequently, the gyroplane deserves a standardized place among the usual aircraft types and should be much more universal. However, this will not happen if autogiro’s inherent flight safety is not broadly recognized.
C-30 gyroplane storage line, ready for shipment and distribution in England, 1935.
THE LEGACY OF JUAN DE LA CIERVA
The creation of the gyroplane goes far beyond the simple invention of a new type of aircraft, os which its main value is, as we have already seen, flight safety.
Juan de la Cierva was exceptionally capable, and was overcoming, one after another, all the technical problems that afflicted the first prototypes and promoted the development of the gyroplane until it became a fine and practical aircraft type in the course of just a decade.
Cierva’s gyroplanes were capable of taking off and landing in just a dozen meters, ascending with ease, maneuvering with surprising agility, evolving at extremely reduced speeds and reaching cruising speeds above 160 km / h. Meanwhile the helicopters were evolving to machines that were finally able to land and take off vertically, ascend to a few meters in height, move at speeds of about 15 km / h and with very poor levels of reliability and efficiency.
Only when Dorand first and Focke later used the gyroplane rotor in their helicopters did the helicopter become a viable aircraft.
The C-30P, piloted by Juan de la Cierva in 1934, landing on the deck of the hydro mother ship Dédalo in the port of Valencia (1934).
Thus, Juan de la Cierva not only created the autogyro, but in doing so developed the first complete theory of rotary wings and solved all the technical problems that were presented to him. The current helicopter theory follows the equations and principles of Juan de la Cierva, so the most appropriate thing is to say that Juan de la Cierva is the father of the Rotary Wing, and the creator of the greatest contribution that Spain has ever made to aviation.
THE C-4
The technical problems encountered in the construction of the first gyroplanes were very numerous and complex, to such an extent that this exciting story seems like a real obstacle course. The first of all was something that De la Cierva already knew: the dissymmetry of lift. It is evident that when subjecting a set of rotating wings to a translation speed there will always be one half of the rotor advancing in the air and which will be affected by a much higher relative speed than the other half, which recedes with respect to the speed of translation.
To compensate for this effect, the first gyroplane in history, the C1, had two counter-rotating coaxial rotors arranged.
Autogiro C1 de Juan de la Cierva
When attempting its first take-off the C1 showed that autorotation was a fact, but due to the interference of the air flow coming from the upper rotor, the lower one rotated at a third of the calculated speed and the opposite dissymetries of both rotors were not compensated, so the autogiro turned to the right (the upper rotor was turning right).
Juan de la Cierva tried to control this problem by redesigning the rotor blades, applying a serious negative twist, so that the ends of the blades worked with negative angles of attack (generating downward lift). In this way (greater negative lift in the advancing blade) he expected to compensate for the lift dissymmetry. But it didn’t work. The C2 and C3 also overturned while trying to take off.
The solution was the invention of the flapping hinge. The flapping hinge is, in essence, a hinge arranged horizontally at the root of the blade, which allows it to rise and fall freely. This is the element that made possible the first real flights of the gyroplane, which aroused the interest of different foreign investors. The first flight took place in Getafe on January 17, 1923 and the prototype was the C4, piloted by Captain Alejandro Gómez Spencer.
Juan de la Cierva intended that this model would already fly with some control from the rotor (in roll), but the state of development of the rotor did not allow to culminate that objective, so the first flight was made with the fixed rotor and with the help of some “oars” to roll the autogiro in flight. This form of control with fixed rotor and conventional aircraft surfaces was maintained until the development of Direct Control with the C-19 Mk5 in 1933.
The Autogiro
The Autogiro is the greatest Spanish contribution to aviation. Since the achievement of motorized flight by the Wright brothers, it is the only case of design, creation and development of a totally new, original and different flight system: the Rotary Wings.
