100 Years of Autogyros

Text and photography by Divan Muller

1922 was a pivotal year in the history of autogyros. Let's take a look back and see what has made these unique-looking aircraft stand the test of time.

What is an autogyro?

That said, what exactly is an autogyro? Unlike helicopters, autogyros can be defined as aircraft that achieve lift with a free-spinning rotor. An engine produces thrust through a separate propeller, either pulling or pushing the aircraft. Helicopters, on the other hand, rely on a rotor to provide thrust and lift. That is why helicopters require a tail rotor to counter the torque of the main rotor. With autogyros, rotor blades are turned by air moving upwards through the blades. This phenomenon is referred to as autorotation, which means that autogyros cannot stall. At slow speeds, where fixed-wing aircraft would stall, autogyros simply descend. Autogyros have another advantage in that they have a high 'wing loading', making them surprisingly stable whilst flying through turbulent air. These factors, in addition to excellent visibility from the cockpit, make autogyros exceptional photographic platforms, and extremely useful in a useful in a variety of roles that involve observation and aerial inspection.

History

Autogyros have been safely taking to the skies for almost a century, yet most people don’t know the role these unusual flying machines played in history. The concept of an aircraft with rotating wings has been around for more than 200 years, that is if one excludes manuscripts of Leonardo da Vinci and other inventors that date back to the 1400s and earlier. It is generally accepted that the first model of a helicopter was flown in France in 1784, although there is a chance that a Russian, named Mikhail Vasilyevich, may have accomplished a similar feat as early as 1754. During the 1800s and early 1900s, many inventors and engineers attempted to get their contraptions, which resembled horizontal windmills, off the ground, but without much success. These pioneers were quick to discover the inherent instability of an aircraft with moving wings, not to mention the problem of providing a machine with enough power to lift itself and a pilot off the ground.

The future of rotary-wing aircraft seemed quite dark, until Don Juan de la Cierva came on the scene. This resourceful engineer had already built Spain’s first successful fixed-wing aircraft and, after one of his prototype aircraft crashed, was moved to find a safer way to fly. His solution was the ‘autogiro’, a combination of a fixed-wing aircraft and a helicopter. The Cierva C.4 was completed and tested in 1922, culminating in a successful maiden flight on January 9, 1923. The secret behind the C.4’s success was Cierva’s concept of hinged rotor blades. Changing the angle of rotor blades allowed more or less lift to be produced as required. Cierva developed several other models in which he introduced more novel concepts, many of which are still used in modern helicopter designs. Cierva also proved to the world just how capable autogyros could be, such as one occasion when he flew one of his aircraft across the English Channel, or when he flew almost 5,000 km across Europe.

By the late 1920s, with Cierva’s help, gyroplanes were being manufactured in Britain, the United States and other countries. The C.30 was Cierva’s most successful design. It relied on direct control to manoeuvre, instead of the use of ailerons. Also, it was the first autogyro capable of a ‘jump take-off’, which meant it could take off vertically. This involved pre-rotating the rotor, a procedure still used by modern autogyros. More than 80 of these C.30s were built, of which many were used in air forces/ Some of these were produced under licence by Britain’s A.V. Roe, for example, while others were produced in France and Germany. The version built be A.V. Roe was powered by a 140 hp engine and could reach a speed of about 90 kts at sea level.

Meanwhile, several gyroplane milestones were being reached across the world. In 1931, Amelia Earheart set an autogyro altitude record of more than 18,000 ft, and in 1935, an autogyro landed on the Fiume, an Italian cruiser, becoming the first aircraft to land on a ship other than an aircraft carrier. The world’s first rotary-wing airmail route was started in 1939 and consisted of autogyros flying from one post office to the next.

Juan de la Cierva - Public Domain

In Moscow, the Soviet Union used its engineers, such as Kamov, Skrzhinskii, Kuznetsov and Mil, to design its own autogyros. The first noteworthy autogyro to be designed in the Soviet Union was Kamov’s A-7. This aircraft was armed with 7.62 mm machine guns and was used in a reconnaissance role and to support troops in World War II. More models were developed for anti-submarine warfare and leaflet dropping, but the Soviets weren’t the only ones who used autogyros in combat.

During the 1930s, the US sent marines to Nicaragua. Pitcairn autogyros were taken along to be used for examining fields as possible landing areas for other aircraft, and to extract wounded soldiers from the frontlines.

Meanwhile, Japan used its Kayaba Ka-1s as army observation aircraft and for anti-submarine warfare, as they could armed with bombs or depth charges. Other air forces in Europe mainly used autogyros in general purpose roles. That said, Germany used Fa 330 rotor kites as observation platforms by towing them with U-Boats. Autogyros in the Royal Air Force were used for radar calibration and army cooperation training, in addition to more common general-purpose duties.

Ever since the end of World War II, and especially in our modern times, autogyros have been used primarily as recreational aircraft. Well, in the 1950s, the Fairey Rotodyne nearly changed the course of gyroplane development. It was a convertiplane, combining the flight characteristics of a helicopter and autogyro. With seating capacity for more than forty passengers, the Rotodyne was essentially a small airliner. It was powered by two Napier Eland turboprop engines, providing 2 800 shp each. In forward flight, four large rotor blades spun freely, as with normal autogyros, but during take-offs and landings, the rotor was powered by compressed air. To achieve this, the air was channelled through tubes inside the rotor blades, exiting through rotor tip combustion chambers. The Rotodyne completed its maiden flight on 6 November 1957. It had a top speed of more than 160 kts and a range of 725 km. Work on a larger version, capable of carrying 75 passengers and powered by Rolls-Royce Tyne turboprops commenced, but the programme was cancelled in 1962. The most common reason given for the cancellation was the fact that, as a tipjet rotorcraft, the Rotodyne was incredibly noisy during take-offs and landings. However, the aircraft was funded by the British government, which may have scrapped the programme due to a lack of interest from prospective operators.

One can only wonder how different history, especially with regards to autogyro development, would have been if Juan de la Cierva, who was arguably the most passionate about the subject, had not died in a (fixed-wing) airliner crash in 1936, at the age of 41.