100 years of a milestone in Aviation: the first flight of the 'Autogiro'
Daniel Cobo-Vuilleumier
Airworthiness & Operational Safety | UAS (Drones) | Aerospace & Defence Systems Engineering
A century ago today, Aviation reached a major milestone: the maiden flight of the first practical rotary-wing aircraft, the Autogiro (gyroplane).
Tests with the C.4 prototype started on January 9th, 1923 at the Getafe aerodrome and, finally, on the 17th a first short flight was performed with this new category of aircraft, patented by the young Spanish engineer Juan de la Cierva Codorniu in 1920, with the experienced pilot Alejandro Gómez Spencer at the controls.
But why the Autogiro?
Let’s start from the beginning, from the childhood of the Autogiro's inventor.?
Juan was born in 1895 in Murcia (Spain), son of the lawyer, politician and businessman Juan de la Cierva y Pe?afiel (who became major of Murcia city and several times Minister of the Spanish government) and María Codorníu Bosch.
Juan witnessed the start of Aviation from a very early age, and soon became a very passionate enthusiast.?So passionate that, at the age of 15, he and two friends decided to create their own ‘aeronautical design office’, called B.C.D. (their surname initials) and build their own planes:?gliders (1910), a powered biplane (BCD-1, which flew pretty well, in 1912) and a monoplane (BCD-2, 1913). Juan was, of course, the chief engineer ;-)
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It was clear to Juan that he would devote his career to design aircraft.
But when the time came to start university there was no School (University) of Aeronautical Engineering in Spain.?So, he decided to study at the School of Public Works Engineering in Madrid, highly regarded at the time.
There, Juan was allowed to develop a very special and indeed atypical final project for his degree in that School: the design of an airplane. But not any airplane, but a 3-engine bomber, the first of its kind to be designed in Spain and one of the first in the world.
Why that airplane? Because he wanted to present the project to the call for proposals by the Spanish MoD to equip the military?with several types of airplanes … and he believed a project like his would be unique. And it certainly was.
Thanks to his father’s position he got someone to finance the project. The result was the C.3, a biplane weighing 5 Tn, powered by three 220 hp engines, which flew in 2019.
However, during the flight test campaign the aircraft crashed (fortunately the pilot survived). Root causes were power issues during flight (no so reliable engines at that time) and lack of pilot multi-engine experience (who could have such experience at that time?)
An accident like that would have discouraged many. But not Juan. He concluded that a radically new design was needed for safe flight. A new kind of aircraft that would not crash due to failure in propulsion power.
He knew that a rotary-wing aircraft would mostly decouple lift from propulsion. But there were very few examples of such aircraft, and all looked extremely complex and inefficient to him. Therefore, he rejected powering rotors and rather looked for an unpowered solution.?
And this is how he started to work on autorotation (a phenomenon already known in nature, e.g., autorotating maple seeds). He found that with a small positive angle of the rotor it was possible the autorotation with a relatively?low aerodynamic speed.
Already in 1920 he patented a new category of aircraft with autorotating rotor that he called Autogiro (with capital letter, as the name is part of the patent). That is, what we know today as gyroplane.
The Autogiro (gyroplane) is a rotary wing aircraft that is propelled like an airplane, but its wing is a rotary one, a rotating rotor by the action of the relative wind that crosses it from bottom up. This requires the aircraft to move in the air, so the aircraft has a powerplant to propel it, as in airplanes. But the Autogiro's rotor is not connected to any engine (as it is the case in helicopters) but it self-rotates freely like a windmill ... it "autorotates", generating lift by this movement relative to the air.
An important thing about autorotation is that it continues as long as the aircraft moves in the air. Therefore, if the propulsion power stops, the aircraft falls but that means it is still moving relative to the air and consequently the rotor keeps autorotating, slowing down the fall as an efficient parachute. This is why helicopters use autorotation in emergency when power fails ... but it is a normal performance in the Autogyro/gyroplane for short/vertical landings.
Initial development and first flight
Juan designed a small-size model aircraft that he tested at the Retiro park in Madrid (he was living nearby) and the results looked very promising!
When moving from this first small-size model to the real prototype, he encountered a major problem: the blade that advances in the direction of movement of the aircraft has more aerodynamic speed than the one that goes back, so one generates more lift than the other and a rolling moment appears, causing the aircraft to tip over.
He failed to solve the asymmetric lift in the first three prototypes C.1, C.2 y C.3. But why did it work well in the model aircraft?
Some biographies indicate that La Cierva found the answer by watching a classical dance show, where he noticed the elasticity of the dancers. Although the anecdote is not confirmed, what is certain is that he realized that the answer was the more elastic behaviour of the model rotor (bamboo wood was used), as that elasticity allowed the blades to flap, thus compensating the lift variation during rotation without transmitting any rolling moment to the aircraft body.
How to create an equivalent behaviour in the real aircraft? In 1922 he patented a new rotor design with flapping hinges. This innovation would be key not only for the Autogiro but also for future helicopters.
During that year, he worked hard on the new prototype C.4. On January 9, 1923, the flight test campaign started at the Getafe aerodrome in Madrid. That is the date that some biographers indicated for the first flight of the Autogiro and the one that became widespread. However, the fact is that La Cierva himself did not make it clear. He reported to the Royal Academy of Sciences that the C.4 took-off on the 10th, but it was on the 17th when the prototype was flown on straight trajectories 2 m above ground, validating the articulated rotor. Also, J. Warleta (probably the best biographer of La Cierva, see ref. 1) said that there is a photograph in La Cierva's album with a footnote indicating January 17 as the first flight. So, this is probably the date that should be used. Anyway, the campaign lasted until the end of January, with official flights to the authorities.
It is worth noting that on January 20th the engine failed in flight and the aircraft landed safely, demonstrating the safe performance provided by the autorotation. La Cierva's original motivation in creating a safer aircraft had been demonstrated.
Further development and ... success?
From the start of the Autogiro development a number of personalities, aviators and technicians had shown great interest in this new flying machine. Institutionally, it was the Spanish Military Aviation that most decisively supported La Cierva (aerodynamic laboratory, materials workshops, pilots...), allowing him to develop various prototypes.
We must highlight the invaluable assistance provided by another brilliant Spanish Aviation pioneer, Emilio Herrera Linares , who, among other things, invented the first astronaut suit. He was the architect of the Aerodynamic Lab in Madrid, where La Cierva tested his first prototypes.
In December 1924, several films on the tests carried out with the C.6 were shown at the Paris Salon, immediately raising international interest in the Autogiro. Already in January 1925 tests were conducted before British aeronautical authorities. That year La Cierva had a busy agenda of foreign contacts, not only British, but also French and US. The Autogyro became an international sensation.
In 1926, the La Cierva Autogiro Company was founded in London, with the financial support of the City, to deal with studies, projects and award of Autogiro production contracts.
In 1927 La Cierva presented another key innovation, the lead-lag hinge, which was able to solve a problem of structural failure in the blades, as a consequence of the forces on the rotor plane and the rigidity in the blade joints with the rotor hub. With this, the Cierva created the two-articulation rotor (flapping and lead-lag hinges), which has been widely used by helicopters.
On September 18, 1928, La Cierva, who had become a pilot to be his own test pilot, crossed the English Channel with a C.8 Mk II, achieving a phenomenal propaganda for the Autogiro (he took as a passenger the director of an important French nautical magazine). He then continued with his promotional tour through several European cities.
On July 11, 1929, the test pilot of Talleres Loring (later AISA) made the Madrid-Lisbon flight with a C.12, in a four-hour flight, setting a record for rotary-wing aircraft (in 1930 helicopter by D'Ascanio, the one with the highest performances, flew just 1 km at a height of 18 m and in 8'45'')
Innovations continued and, in 1929, the C.12 was fitted with a streamlined “scorpion tail” launcher, which deflected the motor current towards the rotor and set it in motion.
In the United States, Harold Pitcairn, a billionaire and aviation enthusiast (founded his own airplane factory and a postal line that would later become Eastern Airlines) became so interested in the Autogyro that he focused his attention and resources on the achievement of the US patent and the creation of the Pitcairn-Cierva Autogiro Company of America. This was the company that probably made more effort to sale Autogiros. They commissioned the design of a mechanical rotor launcher, which was a real success and, in 1931, Pitcairn began selling Autogiros with such a launcher, which was also adopted by the British firm.
Thus, 1931 can be considered the beginning of the commercialization of Autogiros, by Pitcairn-Cierva, the Kellet Autogiro Corp. (another firm that emerged from the "Autogiro fever") and the Bull Aircraft Co. in the US, as well as by the A.V. Roe & Co. Ltd. (Avro airplanes) in the UK, under license from La Cierva Autogiro.
The Autogiro was becoming more and more popular. On April 22, 1931 the Pitcairn-Cierva pilot Jim Ray landed a PCA-2 at the White House, generating great enthusiasm and admiration for the Autogiro among those present and a great media impact. After that, the Autogiro was awarded an Honour Trophy by US president Herbert Hoover.
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The famous inventor Thomas A. Edison, who considered airplanes unsafe machines, after watching the Autogiro flying, he praised this new aircraft with the following words (ref. 3):
"That's the answer, that's the answer" "The [Autogiro is the] greatest advance that could have been made in aviation after the Wright Brothers flight" (Thomas A. Edison)
While Americans and the British were eager to sell Autogiros, La Cierva seemed rather focused on a frantic race to perfect his invention, which became an issue for the Autogiro marketing, since when a new model was ready to be launched on the market, it was already obsolete in the face of the new developments by La Cierva. This may be highlighted as a main factor affecting the commercial success of the Autogiro.
Nevertheless, several units were sold to different companies (Champions Spark Plugs, Standard Oil, Detroit News...), institutions (NACA, US Navy) and individuals (Amelia Earhart set an altitude record with a PCA-2).
That creative fever of La Cierva resulted in two important innovations: direct control and direct take-off.
La Cierva himself demonstrated the VTOL characteristics taking off and landing a C.30 from the deck of the Spanish aircraft carrier "Dédalo" on March 7, 1934.
On December 9, 1936, La Cierva took a KLM flight at Croydon (UK) to fly to Amsterdam. The DC-2 crashed after take-off and almost all occupants died, including La Cierva.
The Autogiro would become orphan. Ironically, La Cierva had died in an airplane accident after having devoted his entire career to create a safer aircraft than airplanes.
The Autogiro after the death of his inventor
After La Cierva's death, the British firm (Cierva Autogiro Company) developed the C.40, the first to incorporate direct take-off as standard. But with World War II, the production of gyroplanes in the UK practically stopped, although they played an important and rather unknown role: the calibration of British radars (the first in service in the world).
In 1940 Raoul Haffner designed the Rotachute, a small unpowered gyroplane conceived to be launched from an airplane and introduce agents into the enemy lines. On the other side, Henrich Focke, designer of the world's first operational helicopter (Fa 61, 1937), created the Fa 330 Bachstelze (1942), a similar aircraft to Haffner's but to be used as an observation point for German submarines.
In the US, Kellet sold several YO-60 gyroplanes to the Army for liaison and observation missions.
But after the war, most rotary wing efforts focused on the helicopter.
In 1957 the Rotodyne flew, an ambitious project by the British firm Fairey: a gyroplane in cruise flight and a helicopter during takeoff and landing, and capable of transporting 40 passengers. It was a promising concept and tests were successful, but the programme was eventually cancelled, as it failed to attract orders, in part due to concerns over the high levels of noise generated by the rotor tip jets (to spin the rotor instead of using the normal shaft drive, thus having no torque on the airframe and, therefore, not requiring a tail rotor)
The revival of interest in the gyroplane was largely due to Igor Bensen (then chief engineer at Kaman Aircraft Co.), who in the early 1950s created the B-8 Gyroglider, an ultralight unpowered gyroplane inspired by those of Haffner and Focke, which was followed by the motorized version of the Gyrocopter, the most popular amateur-built aircraft in the world (more than 10,000 of them have flown) and on which today's sports gyroplanes are based.
Another singular character was Kenneth Wallis, also a designer of light gyroplanes (among them, the Little Nellie, which appears in a Bond movie), and who holds almost all the records with this type of aircraft.
In the 1970s, a serious attempt to give a new life to the gyroplane outside the field of sport aviation was carried out by the Spanish company Aeronáutica Industrial, S.A. (AISA). They designed the GN gyroplane: 4-seat, metallic construction of semi-monocoque type, equipped with a Lycoming engine of 3000 hp (at 2700 RPM), four-blade rotor with flapping and (lead-lag hinges), collective pitch control and cyclical, and with jump take-off capability (engaging the rotor to the engine). Maiden flight took place on July 21, 1982. But on September 15 of that year, during its first traffic, it suffered an accident in which it was seriously damaged ... but demonstrated the good survivability provided by the autorotation, which saved the pilot's life. Nissan, then owner of AISA, decided to cancel the project.
Another very interesting gyroplane project by AISA was actually led by Juan de La Cierva Hoces, nephew of the Autogiro's inventor: the AISA GT, a small unmanned gyroplane that raised the interest of the US Department of Defense, which wanted to use it in the Vietnam War. .. but the interest disappeared with the end of the war.
Some remarkable and current initiatives outside sport aviation are the following couple of examples in the US:
And of course we must not forget the myriad of gyroplane enthusiasts around the world that love flying in their light sport gyroplanes made by ELA Aviación , Magni Gyro and many others ...
We can conclude that, clearly, 100 years after the first successful flight of the Autogiro, it lives on and autorotation continues to be at the core of innovative projects as well as saving lives, this being the best tribute to Juan de la Cierva.
Bibliographic references: