There is a trend in the creative arts called “retrofuturism,” which attempts to replicate depictions of the future produced in an earlier era. As put simply by Elizabeth Guffey in The Oxford Handbook to Science Fiction, “futurism is sometimes called a ‘science’ bent on anticipating what will come, retrofuturism is the remembering of that anticipation.” (Lemay 2014) For those artists, it may be interesting to know that, were they to ask many of the aeronautical experts of the 1920s what the aircraft of the future would look like; they would point to something totally unfamiliar to most people today. First flown in 1923, the Autogyro is a type of rotorcraft with a propeller to give it speed and an unpowered rotor that creates lift using the phenomenon of autorotation. Small, efficient, and safe relative to other aircraft of the day; it was believed by many to be the next major step in aviation. Nearly a century after its first flight, aircraft have circumnavigated the earth and men have walked on the moon; and have done so with the presence of the autogyro missing almost entirely from aviation’s history. To understand the reasons that the unique engineering is absent from modern aircraft designs, the physics of rotorcraft and the history of the Autogyro should be explored.

For a helicopter in flight, air is pulled down through the blades of a powered rotor to create lift. An unpowered rotor will also spin when air flows up through the blades. Should for any reason the rotor lose power, this can be used to sustain rotor velocity so that lift can be generated and controlled flight can be continued to the ground. This principle is called autorotation and, in an autogyro, the rotor is tilted away from the craft’s direction of motion so that moving the craft forward necessarily causes autorotation and creates lift.

A NASA paper published in 1975 provides the equations pertaining to autorotation. For a comprehensive picture of the physics, a curious reader may look to the full text, which is available for free online (Heyson 1975).

The early history of the Autogyro is basically the history of one Spanish engineer: don Juan de la Cierva. He was, of all things, a Civil Engineer near to finishing his education when the Wright brothers first brought their machine to Europe in 1908. Captivated immediately, he would build his own airplane and fly it in 1912. It was named El Cangrejo, or in English, “The Crab,” and is considered to be the first Spanish-built aircraft. He would have mixed success as a designer of aircraft until 1919, when dropping a toy bamboo-copter from his parent’s balcony, he first considered using autorotation to allow aircraft to fly at lower speeds. This was the birth of the concept of the autogyro, or as he first called it, “autogiro” (Lewis 1996)

Cierva recognized immediately that problems would occur due to the torque caused by the rotor. His first design, the Cierva C.1, attempted to accommodate for this by having two counterrotating rotors, one atop the other, to balance the torques. While this design would be used successfully in the future, in the context of the day’s technology it was not effective. The interaction of the air between the blades kept the torque imbalanced. Cierva’s fourth design, the C.4, was the first to solve this problem. For this single-rotor design, he hinged the blades, which negated much of the torque. According to Cierva, he got the idea for this during an opera, a prop for which was a windmill with hinged blades. A subsequent flight of this model attracted some attention when, during a test the engine failed and the pilot was able to autorotate to the ground unharmed and with no damage to the machine- a very difficult task in fixed-wing craft. Don Juan de la Cierva perished in an aircraft accident in 1936 at the age of 41, but not before selling the rights to his design (Lewis 1996).

In the United States, development of the autogyro would be continued by a man named Harold Fredrick Pitcairn. Born in 1897 in Hawthorne, Iowa, Pitcairn began in aviation as an apprentice at Curtiss Aeroplane and Motor Company. He attended the Curtiss Flying School in Newport News in 1916, and in 1927 founded the Pitcairn Aircraft Company as well as Pitcairn Aviation (renamed Eastern Airlines.) In 1929 he purchased the right to license Cierva’s patents for $300,000, and would pursue the development of the autogyro relentlessly. Convinced that autogyros were the future of aviation, he would sell Pitcairn Aviation for $2.5 million for resources with which to pursue their design, and in 1930 was awarded the Collier Trophy for “the development and application of the Autogiro.” His company built autogyros until funding the research became impossible.

On June 26, 1935, the Breguet-Dorand 314 was the first successful helicopter to fly. It incorporated many of the features developed for autogyros, the rights to which were not purchased. Due to the patent infringement, Pitcairn launched a massive lawsuit that would make its way to the supreme court. His company went defunct in 1948, and Harold Pitcairn took his own life in 1960. In 1977, 17 years after his death, the Supreme Court of the United States awarded the Pitcairn Estate $32 million from the US government for rotorcraft control patents used by military rotorcraft (National Aviation Hall of Fame 1995).

Why, then, did the autogyro not become the next major step in the history of aviation as Harold Pitcairn predicted? In part, it was because very few people at the time saw clearly the direction that flying would take, and those who did were outspoken. An excerpt from the court martial of Colonel Billy Mitchell illustrates this particularly well.

Prosecutor: “You say that, in future wars, soldiers will invade by leaping in parachutes from airplanes. Would you care to reveal who gave you this startling information?”

Mitchel: “No one gave it to me. It is quite obvious to anyone with the slightest foresight.”

Prosecutor: “Is it your actual belief that the country is vulnerable to attack from the air?”

Mitchel: “In the foreseeable future.”

Prosecutor: “Colonel Mitchel, do you have any idea of the width of the Atlantic ocean?

Mitchel: “Approximately 3,000 miles.”

Prosecutor: “And the Pacific Ocean?”

Mitchel: “I know what you’re getting at, and I tell you that it will not be long before airplanes fly nonstop across both oceans.”

Prosecutor: “You say that airplanes traveling at 1,000 miles per hour will fight each other in the stratosphere. Do you have any comprehension how fast 1,000 miles per hour is?”

Mitchel: “Of course I do.”

Prosecutor: Do you know that is faster than the speed of sound?

Mitchel: Approximately 250 miles faster than the speed of sound.

Prosecutor: You say that the Hawaiian Islands, our base at Pearl Harbor, will fall victim to an air attack. Does your crystal ball reveal by what enemy this mythical attack will be made? By whom, Colonel? By whom?

Mitchel: The attack will be made by the Japanese. (Pell 2004)

The autogyro was an excellent fit for the technology of the day. It could fly slow, needed only a relatively small motor, and could safely autorotate to the ground if the engine failed. In that context, it is understandable why at the time it was thought by many to be the next big development. From our millennial vantage point we have a different picture of things. Engines would become more reliable and lightweight, solving the problems for which the autogyro was designed and paving the way for powered rotorcraft. With aircraft soon to be crossing oceans, the ability to fly slowly would become far less important than the ability to fly very fast; and developments in warfare would require craft to move quickly and support the weight of munitions- the slow-moving autogyro would have been an easy target in the coming wars.

Another factor that led to the demise of the autogyro was, in no small part, the deaths of its two major contributors. Beyond Cierva and Pitcairn, no one was working on the technology. Paul Bergen Abbott, previous Editor/Publisher of Rotorcraft Magazine, has his own theory on the issue.

As the world began moving toward World War II, the rivalry between the United States and Germany grew to a fierce level … In 1938 Germany demonstrated the Focke-Achgelis F.61 helicopter, a side-by-side-rotor model, by flying it publicly inside a building and making headlines all over the world. This infuriated the powers-that-be in the United States, and soon thereafter the government attention and development funds were shifted entirely to helicopter development. (Abbott 1996)

Autogyros are still made today, though in no large numbers. Because of their low cost to purchase and maintain relative to helicopters, it is estimated that around 1,000 are in use by police departments around the world (Osborne 2011). Care should be taken not to conflate their numbers with their significance, as had Cierva and Pitcairn not perused the autogyro, the development of the helicopter would certainly have been severely delayed, possibly by decades. While they are seen as somewhat of a novelty today, their development was critical to the progress of aviation.

Bibliography

Abbott, Paul Bergen, interview by Jeff Lewis. 1996. Email from the Editor/Publisher of Rotorcraft Magazine

Heyson, Harry H. 1975. Momentum Analysis of Helicopters and Autogyros in Inclined Descent, with Comments on Operational Restrictions. Washington, D.C.: National Aeronautics and Space Administration.

Lemay, Elizabeth Guffey and Kate C. 2014. “Retrofuturism and Steampunk.” The Oxford Handbook to Science Fiction 434.

Lewis, Jeff. 1996. Autogyro History and Theory. Accessed November 20, 2015. http://www.jefflewis.net/autogyros.html.

National Aviation Hall of Fame. 1995. Harold Pitcairn. Accessed December 2, 2015. http://www.nationalaviation.org/pitcairn-harold/.

Osborne, Tony. 2011. “Autogyro debuts in the sky over Texas.” Shepard Media Rotorhub. Accessed December 2, 2015. https://www.shephardmedia.com/news/rotorhub/alea-2011-autogyro-debuts-in-the-sky-over-texas/9585/.

Legends of Airpower Episode 103: Billy Mitchell . Directed by The Military Channel. Performed by Gene Pell.