An Incredibly Deep Dive Into the Fascinating Invention of the Helicopter

“Helicopter’s don’t fly – they just beat the air into submission.” and “Helicopters aren’t aircraft – they’re just ten thousand parts flying in close formation.” are just two of the many tongue-in-cheek sayings which have been levelled at rotorcraft. Yet despite their often ungainly and precarious appearance, it cannot be denied that helicopters are remarkable pieces of engineering, capable of taking off and landing almost anywhere, hovering perfectly still in midair, and maneuvering in any direction with incredible precision. These unique abilities have made helicopters indispensable in dozens of fields, from search and rescue to construction, tourism, policing, journalism, and warfare. Unsurprisingly, this degree of sophistication and adaptability took considerable time and effort to achieve, with nearly four decades separating the first aeroplane flight and the first practical helicopter. But who was responsible for this technological breakthrough? Who were the Wright Brothers of the helicopter? While one man is usually credited with making the helicopter a practical vehicle, like most important technologies, rotorcraft are the product of dozens of different inventors making incremental developments over many decades. This is the story of how mankind achieved the dream of vertical flight.

The fantasy of flying like an insect, hovering and moving freely in any direction, has long captured the human imagination. Possibly inspired by the twirling seeds of the maple tree, the Ancient Chinese created helicopter-like toys called “bamboo dragonflies” composed of two silk rotor blades fixed to a vertical bamboo shaft. A string was wrapped around the shaft and pulled sharply, sending the tiny craft sailing upwards. From China, these toys spread across the Eurasian continent, becoming very popular throughout Europe by the early 14th Century. The first practical advancements in helicopter technology, however, would not be made until nearly 200 years later, by none other than the quintessential Renaissance Man himself – Leonardo da Vinci. In a notebook dating from the 1480s, Leonardo sketched a helicopter design which used an Archimedean screw made of stretched canvas to “drive” itself vertically into the air. According to Leonardo’s notes, a scale model of the vehicle powered by clock springs successfully flew in his workshop, making it the first recorded helicopter to lift off using its own self-contained power source.

After Leonardo, however, helicopter development stalled for another 300 years. Then, in 1784, French naturalist Christian de Launoy created a version of the classic “bamboo dragonfly” toy powered by a self-contained bowstring mechanism, which he demonstrated before the French Academy of Sciences in April of that year. Excited by his invention, Launoy set out to build and fly a full-scale version – only to realize he lacked an adequate power source. Indeed, this problem would continue to plague would-be helicopter designers for another 100 years. Steam engines, with their heavy fireboxes, boilers, and fuel, simply did not have a sufficient power-to-weight ratio to lift themselves off the ground; it would not be until the invention of the internal combustion engine that practical manned, powered flight – both horizontal and vertical – would at last become possible. But this did not stop a few enterprising inventors from trying to crack the problem anyway. In 1847, for example, English inventor W.H. Phillips constructed a model helicopter powered by steam vented out of nozzles at the tips of its twin, contra-rotating aluminium rotor blades. This steam was supplied through a flexible pipe from a ground-based boiler, fired by a mixture of charcoal, gypsum, and potassium nitrate or saltpetre. Author Michael Harrison describes what happened when the device was tested:

“On the Salisbury Plain, when the inventor fed steam to the aerofoils, the helicopter rose so rapidly and with such velocity that it broke connection with the flexible pipe, and took off in unassisted flight. It was never seen again.”

Though incapable of lifting both itself and its steam source off the ground, Phillips’s helicopter was a remarkably prescient design, especially in its use of lightweight aluminium – at the time a very rare and expensive material. It also addressed one of the key design problems inherent to helicopters: countering rotor torque. Thanks to Newton’s Third Law, the torque of the rotors spinning in one direction causes the helicopter fuselage to spin in the opposite direction. Most modern helicopters counter this effect using a small tail rotor, but some, like Phillips’s design, use contra-rotating rotors which cancel out each other’s torque. Rotor torque can also be eliminated by powering the rotors with tip jets rather than a central engine – a method that would be resurrected a century later in experimental helicopter designs like the Hiller Hornet and Fairey Rotodyne.

Less than a decade later in 1863, French inventor Viscount Gustave de Ponton d’Amécourt built his own steam-powered vertical flying machine featuring a lightweight aluminium boiler and bronze pistons. But while d’Amécourt’s device – like all such designs – failed to lift itself off the ground, the inventor did make one long-lasting contribution: combining the Greek words helikos or “spiral” and pteron or “wing” to coin the word helicopter.
The next big swing at the problem of vertical flight was taken in 1885 by inventor extraordinaire Thomas Edison. Initially, Edison planned to power his helicopter with electric motors, only to realize that the batteries of the era were too heavy to fly. Edison thus set about developing his own compact internal combustion engine fuelled not by gasoline but explosive nitrocellulose or “guncotton”. Edison converted paper ticker tape into nitrocellulose by treating it with nitric and sulphuric acid, then fed it using rollers into the cylinders of his engine, where it was ignited electrically. This went about as well as you’d expect, with the flame travelling backwards up the tape and igniting the entire roll, badly burning one of Edison’s assistants. Discouraged by this incident, Edison abandoned the helicopter project and moved on to other things.

Instead, the first real advances in manned vertical flight would be made by two Frenchmen: Louis Bréguet and Paul Cornu. Breguet, born in 1879, was the scion of the wealthy House of Bréguet , acclaimed watchmakers based in the city of Douai. In 1903, Breguet graduated from the École supérieure d’électricité – France’s top engineering school – and two years later became chief engineer in charge of motor services at Maison Bréguet , in charge of manufacturing electric motors. It is around this time that he became obsessed with the idea of vertical flight. Though disappointed that fixed-wing aircraft had beaten helicopters into the air, Bréguet believed that rotorcraft would soon retake the lead, and in 1906 he, along with his brother Jacques and mentor Charles Richet, began constructing a vehicle called the gyroplane in a workshop near the family factory. Powered by a 40-horsepower Antoinette aircraft engine, the gyroplane featured a cruciform body with four tubular-steel struts, at the end of each was mounted a four-bladed, double-stacked rotor. Bréguet’s goals for the craft were ambitious, to say the least: he planned to use it to claim the 50,000-franc Deutsch-Archdeacon prize for the first person to pilot a heavier-than-air craft around a closed 1-kilometre course.

But the road to this goal was far from a smooth one. Development of the gyroplane was plagued with difficulties, from frame collapses to rotor collisions to problems with the temperamental engine. Bréguet also faced skepticism and disapproval from his friends and family, including his factory supervisor Gaston Sciama, who declared:
“I would rather you become an alcoholic than build aircraft!”

Nonetheless, Bréguet persevered, and on September 29, 1907, the gyroplane was wheeled out of the workshop for its first flight test. A young engineer named M. Volumard was selected to pilot the craft – largely because he weighed only 68 kilograms. As four men held tethers connected to each of the four booms, Volumard climbed into the centre of the craft and throttled up the engines, the 32 rotors spinning up into a whirling, roaring blur. Gently the craft rose a metre into the air, hovering there for a minute before settling back to the ground. It was the first time in history a self-powered rotorcraft flew with a person aboard.

Elated, Bréguet continued his experiments, with later models of the gyroplane reaching altitudes of up to 10 metres. However, by this time the Deutsch-Archdeacon prize had already been won by pilot Henri Farman flying a fixed-wing biplane. Furthermore, while Bréguet’s helicopter could rise into the air, it could do little else, lacking any sort of control system to allow the pilot to direct its flight. This was a major engineering challenge that would plague helicopter designers for decades to come. After Breguet’s second helicopter was damaged in a storm in April 1909, he finally decided to abandon the project. But Breguet’s contributions to aviation were far from over. In 1911 he founded Bréguet Aviation, which during the First World War built several highly-successful aircraft for the French armed forces, including the Bréguet 14 – one of the first all-metal aircraft to see combat. He also developed a formula for calculating the range of an aircraft which is still used today. Furthermore, in the 1930s Bréguet Aviation finally succeeded in building a fully-functional experimental helicopter called the Gyroplane Laboratoire, but this accomplishment was quickly overshadowed by developments elsewhere.

Meanwhile, another Frenchman, Paul Cornu, had also begun his own helicopter project, backed by 120 friends contributing 100 francs – $20 in today’s money – each. Cornu’s helicopter was smaller and simpler than Bréguet’s with only two booms with one two-bladed rotor each, powered by a 24 horsepower engine. It also featured a rudimentary control system, consisting of hinged flaps that could be tilted to deflect the rotor wash. During his first test flight on November 13, 1907, Cornu rose to a height of a metre and a half. Trying to steady the craft, Cornu’s brother grabbed the metal frame, only to be lifted into the air itself. The test thus marked not only the first untethered helicopter flight, but also the first two man helicopter flight. Over the next few years, Cornu made over 300 more flight attempts – all of them tethered – but unfortunately his crude control system proved totally inadequate and his research advanced no further. He eventually ran out of money and was forced to return to his regular occupation manufacturing bicycles.
Throughout the 1920s and 30s, a great many inventors experimented with vertical flight, including Etienne Oehmichen and Raul Pateras Pescara in France; Jacob Ellehammer in Denmark; Emile Berliner, A.E. Hunt, and George de Bothezat in the United States; and brothers Nicholas, Doug, and Theodore Froebe in Canada. However, most of these craft were underpowered or lacked an effective directional control system, making them impractical as flying machines. Perhaps the most promising of these early designs was the Petroczy-Karman-Zurovec PKZ-2, designed in 1918 by Austro-Hungarian inventors Wilhelm Zurovec, Theodor von Karman, and Stefan Petroczy. Unlike other contemporary helicopters, the PKZ-1 was designed to be flown tethered, being intended as a safer replacement for increasingly-vulnerable hydrogen-filled observation balloons. Built around a light tubular metal tripod frame, the craft was powered by three 100 horsepower Gnome rotary engines, which drove a pair of contra-rotating rotors mounted above the frame. The pilot/observer, meanwhile, flew in a basket-like cockpit mounted atop the rotors. On the ground, the craft was supported by four inflatable air cushions supplied with air via a pump mounted to the engines, while in flight it was steadied by cables attached to each tripod arm and paid out by winches on the ground. Because a regular bailout would have resulted in the pilot/observer being chopped to mincemeat by the rotors below him, the cockpit was fitted with a primitive ejector seat, consisting of a small cannon that would launch a parachute – and the attached pilot – clear of the whirling blades. Befitting its intended use as a battlefield observation platform, the craft was designed to be easily assembled, disassembled, and transported by a small group of soldiers.

The PKZ 2 first flew on April 2, 1918, outside Budapest. This and other early tests revealed the craft to be underpowered, struggling and becoming unstable as it rose above 1.2 metres off the ground. This was because most of the lift at low altitudes was generated by the ground effect – a cushion of air trapped between the rotors and ground. Consequently, the engines were replaced with more powerful 120 horsepower le Rhône rotaries, allowing the PKZ-2 to achieve stable flight at altitudes of up to 50 metres. Though instabilities were still encountered, these could be damped out with skilful tensioning of the tethers. On June 18, 1918, Wilhelm Zurovec was ordered to demonstrate the PKZ-2 in front of a delegation of Austo-Hungarian military brass. Though unsatisfied with the state of the design, Zurovec obliged, and the craft made a series of ascents to 8 metres in height. On the last demonstration flight, however, overheating caused the engines to stall and the PKZ-2 crashed to the ground from an altitude of 2 metres, severely damaging the frame and splintering the rotors. The design team reworked the design and were ready to try again in November, but by then the First World War had already ended and the project was cancelled.

In the end, the vehicle that finally cracked the problem of stable, controlled vertical flight was not a true helicopter but rather a strange hybrid whose brief but promising heyday lasted barely two decades and which is largely forgotten today.

So how did we get from a crude contraption capable of only short, uncontrolled hops to the highly capable and adaptable flying machine of today?

As described, before a truly modern helicopter could be built, a number of basic technical problems had first to be overcome. And the man who would finally solve these problems and unlock the secrets of vertical flight was a brilliant and determined Spaniard named Juan de la Cierva.

Born on September 21, 1895 to a wealthy, aristocratic family, Cierva became obsessed with aviation at the age of 8, when he first heard the news of the Wright Brothers’ pioneering flight. In 1910 at the age of 15, he built his own man-carrying glider, which he and his friends piloted on short flights down the side of a hill. But Cierva’s ambition knew no bounds, and the following year he borrowed an engine from French pilot Jean Mauvais and proceeded to build his own powered aircraft, which he dubbed Cangrejo Rojo or “Red Crab”. Amazingly, the homebuilt craft proved remarkably airworthy, and is widely considered to be the first indigenously-built aeroplane to fly in Spain. Unfortunately, however, the glue and paint that Cierva used to assemble and seal the wings was water-soluble, and after a number of successful flights Cangrejo Rojo literally melted away in a rainstorm.

After completing a six-year course in civil engineering, in 1919 Cierva returned to the world of aviation. Using 150,000 pesetas collected from various investors, he built a prototype tri-motor military bomber in the hopes of winning a 30,000 peseta prize and production contracts from the Spanish government. While the prototype performed well, on its second flight the Air Force test pilot, Julio Ríos Argüeso, accidentally stalled and crashed the aircraft. Following this failed venture, Cierva briefly abandoned aviation, marrying and following his father into the civil service. But the crash of his prototype bomber was never far from his mind. Convinced that the aircraft was sound and that the crash was due to pilot error, he began to wonder whether a safer aircraft could be built – one that could safely descend and land from any altitude. After experimenting with a number of toy helicopters, Cierva had a brainwave: if he replaced the wings on a regular aircraft with a rotor, the air moving over the rotor would cause the rotor to spin and generate lift – a phenomenon known as autogyration. If such an aircraft suddenly lost engine power, the lift from the autogyrating rotor would allow it to safely descent and land regardless of altitude. In 1920, Cierva filed a patent for this strange hybrid craft, which he dubbed the autogiro.

Cierva’s first prototype, the C.1, was ready for flight trials by October 1920. During the design process, Cierva realized that due to the airflow over the aircraft, the forward-moving rotor would generate more lift than the rearward-moving one, creating a sideways rolling force. To compensate for this, he fitted C.1 with two rotors spinning in opposite directions, balancing out the lift. The first test flight took place just outside Madrid with Lieutenant Gómez-Acebo, Cierva’s brother-in-law, at the controls. Unfortunately, things immediately went awry as the craft began tilting violently while taxiing. No matter what he tried, Lieutenant Gómez-Acebo could not keep the craft level, and the trial was abandoned. Cierva’s next prototype, the C.2, dispensed with the twin rotors and instead incorporated a system of cams that tilted the blades forward on the forward stroke and rearward on the rearward stroke to balance out the lift. However, this proved ineffective, and on his third prototype, C.3, Cierva added large ailerons on the wings and steel bracing wires to keep the rotors rigid. But while the aircraft briefly succeeded in becoming airborne, the pilot was forced to immediately set down to avoid tipping over.

These results puzzled and frustrated Cierva, for while scale models of the autogiro flew perfectly well, the design somehow stopped working when scaled up. But why?

It was reportedly while watching a performance of the opera Aida that Cierva suddenly realized: the rotors on the models, made of thin wood or rattan, were flexible, allowing them to “flap” and automatically adjust their lift as they spun around. Armed with this insight, Cierva fitted the rotors of his next prototype, the C.4, with hinges. This simple fix immediately solved the problem, and on January 17, 1923, C.4 lifted into the air with Army Lieutenant Alejandro Gómez Spencer at the controls and made a short but successful flight – the first for a fully-controllable rotorcraft – around Getafe Air Base. Encouraged by this success, Cierva continued to refine the design and in 1924 produced the C.6, based on the airframe of an Avro 504 biplane. Unlike in a modern helicopter, the rotor was not controllable and only provided lift, with directional control being achieved with a conventional tailplane and ailerons mounted on stubby wings. On December 12, 1924, the C.6 achieved another milestone for autogiros when it flew between Cuatro Vientos Airfield outside Madrid to the town of Getafe – a distance of 10.5 kilometres. This flight attracted the attention of the British Air Ministry, who in the summer of 1925 offered to buy two examples. However, they first had to be convinced that the autogiro was truly more versatile than conventional aircraft types.

Up until this point, Cierva’s test pilots had been relatively conservative in their handling of this newfangled aircraft. In order to push the autogiro to its limits and show the British what it could do, Cierva needed a truly exceptional pilot. He found one in Frank Courtney of the British de Havilland Company, whose skills were so legendary he was nicknamed “the man with the magic hands.” Initially Courtney was skeptical of the strange new craft, whose rotor had to be started before takeoff via the crude experience of winding a rope around the blade tips. But after a bit of practice he soon came to appreciate the unique capabilities of the autogiro – including the ability to land near-vertically on a designated spot with almost no roll-forward.

In October 1925, Courtney put Cierva’s creation through its paces before a panel of Air Ministry delegates. But while the autogiro breezed through all the Ministry’s requirements with ease, during the final unpowered autogyrating descent from 1,000 feet, Courtney realized he was falling too fast and struck the ground with such force that it left him, to quote:

“as though the world’s biggest elephant had given me a swift kick in the behind.”

Thankfully, much of the impact was absorbed by the collapsing landing gear, leaving Courtney with only minor bruises. Even better, the Air Ministry considered the test a success and purchased two autogiros. Soon after, Cierva moved his operations to England, where he built a factory that produced around 90 autogiros. Far more were built under license abroad, including in Germany, Russia, France, and the United States. 240 were built in Japan alone – the most of any country. To promote his invention, Cierva obtained his pilot’s license and began performing demonstration flights himself, flying a 4,800-kilometre demonstration flight around Europe and making the first rotorcraft crossing of the English Channel on September 18, 1928. The strange aircraft captured the public’s imagination, and was soon pressed into service for all sorts of unique applications. The New Jersey State Forest Service used autogiros for firefighting in the Pine Barrens, several large corporations used them as flying promotional tools, newspapers like The Detroit News and De Moines Register and Tribune used them to fly reporters quickly to the site of major stories, and some cities even used them for rooftop-to-rooftop mail delivery. Police departments also used autogiros for crowd control at large public events, while over in Europe the craft were deployed to the alps for search and rescue, pioneering a role performed today by proper helicopters. Many militaries also saw great potential in the autogiro as an artillery spotter and anti-submarine aircraft, with the Italian Navy conducting trials in January 1935 that showcased the aircraft’s ability to take off and land from even the smallest ships.

But despite its many achievements, the autogiro design still had many kinks to work out – as Frank Courtney would dramatically discover in February 1927. Four months earlier in Berlin, Courtney had landed after a demonstration flight only to find his autogiro’s rotor blades dangerously twisted. He suggested the blades be fitted with vertical hinges to allow them to pivot forward and backwards, but Cierva wouldn’t hear of it. Insisting that the blades had been damaged in shipping, he ordered them replaced and the test flights to carry on as planned. Four months later, however, while flying over Hamble, England, Courtney suddenly heard a disconcerting groan and crack as two of his aircraft’s rotors suddenly snapped off, sending him plummeting to the ground. The impact left him with a concussion and broken ribs, but miraculously he survived. However, he refused to work for Cierva ever again.

In the wake of this incident, Cierva took Courtney’s advice and fitted subsequent autogiros with vertical hinges. Other innovations soon followed. Realizing that the rope-based rotor startup system was inefficient and cumbersome, Cierva first tried fitting his autogiros with angled tail fins to deflect the propeller’s airflow into the rotor. When this failed, he then tried connecting the engine to the rotor using a clutch, allowing the pilot to spin up the rotor directly just before takeoff. This was much more successful, and became the standard startup system on all subsequent autogiros. However, the most important development in autogiro technology was made not by Cierva but a pair of German inventors, Walter Rieseler and Walter Kreisler. As previously mentioned, all of Cierva’s original autogyros were flown using ordinary aircraft controls, with the rotor merely providing lift. Rieseler and Kreisler’s machine, however, incorporated full collective and cyclic control of the rotor, allowing the stubby wings of earlier autogiros to be discarded and much greater control of the aircraft to be achieved. This system uses a mechanism called a swash plate to tilt or feather the rotors, varying the lift they produce. In collective control, the blades are all tilted at once, allowing the pilot to ascend and descend without throttling the engine. In cyclic control, by contrast, the blades are only tilted as they sweep past a certain quadrant of the aircraft, allowing the pilot to pitch the aircraft up or down and roll it side to side. The same basic controls are used in regular helicopters to this day. In 1931, E. Burke Wilford purchased Rieseler and Kreisler’s patent and brought it to the United States, where it was built by the Pennsylvania Aircraft company as the Wilford WRK – the first commercial autogiro with fully-controllable rotors. This system was later incorporated into Cierva autogiros, allowing them to make near-vertical “jump” takeoffs like a real helicopter.

As the abilities of autogiros continued to improve, manufacturers increasingly began to see them as the future of aviation. The Pitcairn Aircraft Company, Cierva’s main US licensee, even began promoting its products as the “Model T Ford of the air”, predicting that soon everyone would have an autogiro in their garage. One ad from the early 1930s painted a compelling picture of the extreme convenience a Pitcairn autogiro could provide its – necessarily wealthy – owner:

“The open areas surrounding almost any country club offer room for the owner of the Pitcairn autogiro to fly directly to his golf game.”

To promote their products, Pitcairn loaned a PCA-2 model to legendary aviatrix Amelia Earhart, who used it to set a new women’s autogiro altitude record of 5,614 metres. For his contributions to the design and popularization of the autogyro in the United States, in 1931 the founder of the Pitcairn Aircraft Company, Harold F. Pitcairn, was awarded the prestigious Collier Trophy by President Herbert Hoover. During the ceremony, a Pitcairn Autogiro landed on the White House lawn – the first aircraft to do so.

Sadly, however, Pitcairn’s idyllic vision of the future was not to be, and despite its great promise, the autogyro was destined to become a mere footnote in the history of aviation. Multiple factors contributed to the demise of Cierva’s unique creation, including fundamental problems with the technology itself. Despite Cierva’s original goal of creating an inherently safe aircraft, in practice autogiros proved trickier to fly than expected, injuring or killing many an inexperienced or inattentive pilot. The craft also suffered from an alarming phenomenon known as ground resonance on takeoff and landing, which could cause the rotors to become unbalanced and shake themselves apart.

The autogiro was also a victim of poor timing, with the Wall Street crash of 1929 and subsequent Great Depression causing civilian and military budgets around the world to tighten, squeezing the newfangled rotorcraft out of the market. By the end of the 1930s, autogiros had nearly disappeared from the skies, though a few soldiered on in specialized military roles. During the Second World War, for example, Japan and the Soviet Union used small numbers of autogiros for artillery spotting and submarine hunting, while Britain used them to calibrate the Chain Home radar system that helped save the nation during the 1940 Battle of Britain. An unpowered gyroglider or rotor kite called the Focke-Achgelis Fa 330 was also developed by the Germans for towing behind a surfaced U-boat, allowing the crew to more easily spot approaching enemy ships.

Today, autogiros are used almost exclusively as recreational aircraft, with most being modelled on the 1950s designs of Dr. Igor Bensen with light tubular frames, open cockpits, and rear-mounted pusher propellers. Indeed, in the post-war era these craft were considered exotic enough that a heavily-armed version dubbed Little Nellie was prominently featured in the 1967 James Bond film You Only Live Twice.

As for the visionary creator of the Autogiro, Juan de la Cierva, he tragically died on December 9, 1936 when his KLM flight crashed on takeoff from Croydon airport outside London. Yet while the autogiro did not revolutionize aviation as he had hoped, the many technical problems overcome during its creation certainly did. As we shall shortly see when less than a year before Cierva’s death, one of the earliest pioneers of helicopter research returned to tackle the challenge anew and at last achieved the dream of controlled vertical flight.

On this note, as we covered earlier, in the early 1900s French inventor Louis Bréguet constructed the gyroplane, one of the first helicopters to actually lift off the ground. However, the problem of actually controlling the craft proved too daunting, and in 1911 Bréguet abandoned the project and turned his attention to building conventional aircraft. But in 1930, inspired by the breakthroughs made in autogiro design, Bréguet decided that technology had advanced enough to have another go at the holy grail of aviation. Too busy to pursue the project himself, Breguet instead established a subsidiary called the Syndicate for Gyroplane Studies, and placed in charge a young engineer named Rene Dorand.

Over the next three years, Dorand and his team constructed an experimental helicopter called the Gyroplane-Laboratoire, based on the fuselage of a surplus Breguet 19 biplane. Featuring twin contra-rotating rotors to cancel out torque, the craft incorporated all the latest technological advancements pioneered by autogiros, including double-hinged rotor roots for stability and swash plates to allow both cyclic and collective rotor control. In November 1933, after months of ground tests, the helicopter was finally ready for its maiden flight. As a group of investors looked on, former army pilot Maurice Claisse climbed into the cockpit and slowly powered up the engine. But as the rotors neared takeoff speed, the craft began to rock wildly from side to side. Suddenly it pitched completely onto its side, smashing its rotors to pieces and sending onlookers running for safety. While Claisse managed to escape without injury, the helicopter was badly damaged. Undeterred, Dorand repaired the craft, and on June 26, 1935, the Gyroplane-Laboratoire made its first successful flight, flying at speeds of 50 kilometres per hour under nearly complete control. It was the first untethered, fully-controlled helicopter flight in history.

The pioneering flight attracted the attention of the French Air Ministry, who agreed to underwrite further flight trials and award Breguet a million-Franc bonus if the helicopter could meet a set of stringent performance requirements, such as flying around a set course, banking within a 100 metre wide corridor, flying nonstop for over an hour, and achieving a speed of 100 kilometres per hour. In December 1935, Maurice Claisse met the first requirement by navigating the Ministry’s 550-metre course, laid out at Villacoublay airfield just outside Paris. A week later he succeeded in flying at 100 kilometres an hour, but at the end of the flight the helicopter became unstable and the rotors collided, severely damaging the craft. Nonetheless, the Ministry declared the speed requirement met. Over the following year, Claisse would smash a number of helicopter records, reaching an altitude of 158 metres, staying aloft for 1 hour and 2 minutes, and hovering in place for 10 minutes straight. But while these feats satisfied all the Air Ministry’s performance requirements and earned Breguet his one-million-Franc bonus, his helicopter was far from production-ready; on his record-breaking endurance flight, Claisse reported that the craft “shook me like a bag of walnuts.” Sadly, Breguet would never get to refine the design, for the looming world war forced him to focus his efforts on producing bombers for the French Air Force. The honour of producing the world’s first practical production helicopters would instead pass to France’s mortal enemy – Germany.

The first major helicopter pioneer in Germany was Heinrich Focke, who, along with Georg Wulf, had founded the Focke-Wulf aircraft company in 1923. In 1933, Focke was expelled from the company for his anti-Nazi views, and formed his own small firm to build autogiros. However he soon realized that autogiros were a technological dead end, and turned his attention to perfecting a proper helicopter. Together with engineer and test pilot Gerd Achgelis, Focke constructed an unmanned flying model and then a full-scale prototype called the Fa-61. Built around the fuselage of a Focke-Wulf Fw-44 training biplane, the craft was fitted with a pair of tubular steel outriggers supporting twin contra-rotating propellers. These were driven via a system of shafts by a conventional 7-cylinder radial engine, which was fitted with a propeller large enough to cool the cylinders in hovering flight, but which provided negligible forward thrust. The Fa-61 first flew on June 26, 1936 with test pilot Ewald Rohlfs at the controls, and immediately began smashing every record set by the Breguet Gyroplane-Laboratoire, reaching a maximum altitude of 2,300 metres and travelling 230 kilometres in a straight line. The craft soon attracted the attention of the Nazi government, who handed it over to celebrity test pilot Hannah Reitsch. At a trade show in February 1938, Reitsch flew nightly demonstrations inside Berlin’s cavernous Deutschlandhalle sports arena, wowing massive crowds with the Fa-61’s impressive maneuverability and hovering ability. Recognizing the potential of helicopters in warfare, the government allowed Focke and Achgelis to form their own company, and placed an order for a military helicopter capable of lifting 500 kilograms of useful load.

The result was the Focke-Achgelis Fa-223 Drache or “Dragon”, effectively an upscaled version of the Fa-61 with a 12-metre fuselage and twin 12-metre rotors mounted on tubular outriggers and powered by a 1,000 horsepower radial engine. The Drache was first flown on August 3, 1940, and proved even more capable than its designers had hoped, reaching altitudes of over 7,000 metres and speeds of 180 kilometres an hour. It could also lift a full metric ton of payload at low altitudes. Full-scale production began in 1942, but only seven machines had been assembled when, in July 1944, an Allied bombing raid destroyed the Focke-Achgelis factory in Laupheim. Though a new production line was later established at Berlin’s Tempelhof airport, Germany’s rapidly deteriorating strategic situation meant that no Drachen saw operational use before the end of the war. However, on September 6, 1945, former Luftwaffe pilot Helmut Gerstenhauer flew a British-captured example from Cherbourg, France to RAF Beaulieu in England, making the world’s first helicopter flight across the English Channel.

At around the same time Focke and Achgelis were awarded the contract for the Drache, another German engineer, Anton Flettner, was developing another, even more advanced helicopter. Like the Drache, Flettner’s helicopter used twin rotors to cancel out torque; however, to save space and weight, he placed their shafts close together on the fuselage and designed a complex gearbox to allow the rotors to intermesh without colliding. In 1937, Flettner was awarded a contract by the Kriegsmarine to produce 30 examples for use as fleet reconnaissance and light transport craft. The helicopter, known as the Fl-282 Kolibri or “Hummingbird”, first flew in 1941, and proved an extremely capable aircraft, capable of reaching speeds of 144 kilometres per hour and altitudes of 4,000 metres and carrying 400 kilograms of useful load. It was also extremely agile both in hover and level flight; in one trial, Luftwaffe fighter aircraft attempted to intercept the Kolibri, but the nimble helicopter proved nearly impossible to catch. In another, it successfully took off and landed from the gun turret of a Kriegsmarine cruiser in heavy seas, proving its utility as a naval aircraft. Yet despite its great promise, circumstances conspired to prevent the Kolibri from seeing any actual action. In 1944 the Flettner factory was bombed after only 24 units had been produced; the majority of these were sent to Rangsdorf in Northeast Germany where they saw some use as artillery spotters, but most were destroyed by enemy fire before the war ended.

And so, the honour of being the first nation to deploy a helicopter in combat would go not to the French or the Germans, but rather to the Americans, thanks to an eccentric and tenacious Russian immigrant whose name has become synonymous with rotary-wing flight.

Igor Ivanovich Sikorsky was born into a wealthy family in Kyiv, Ukraine, in what was then the Russian Empire. From an early age, Sikorsky was fascinated by mechanical devices and flight, and by his teenage years had constructed numerous rubber-band-powered flying model aircraft, a propeller-powered sled, and a prototype helicopter. While the helicopter was plagued by vibration and too underpowered to lift itself off the ground, Sikorsky would remain obsessed with cracking the secrets of vertical flight for the rest of his life.

By the time the First World War broke out in 1914, Sikorsky was Russia’s premier aircraft designer and manufacturer, producing some of the largest and most advanced designs in the world, including the massive Russky Vityaz airliner – the world’s first successful four-engined aircraft – and its military variant, the Ilya Muromets heavy bomber. But after the 1917 Revolution, Sikorsky – whose family had close ties to the deposed Royal Family – was forced to flee Russia to avoid Bolshevik persecution. He moved first to France and then the United States, arriving in New York City on March 30, 1919. A strong believer in free enterprise, he said of his adopted nation:

“I found what I had hoped for: a dynamic, forceful, progressive country.”

After several years teaching mathematics at a night school for Russian immigrants, in 1923 Sikorsky bought a chicken farm in Long Island and founded the Aero Engineering Corporation. The company – later renamed the Sikorsky Aviation Corporation – produced a variety of unsuccessful aircraft designs before introducing their first hit: the eight-passenger S-38 amphibian. 101 were manufactured, with examples being purchased by prominent celebrities like pilot Charles Lindbergh, industrialist Howard Hughes, documentary filmmakers Marin and Osa Johnson, and Herbert Johnson Jr. of the Johnson Wax company. Sikorsky later designed the S-42 Clipper flying boat, which helped launch the global empire of Pan American Airways. In 1929, Sikorsky Aircraft became a subsidiary of the United Aircraft and Transport Corporation and moved its headquarters to Stratford, Connecticut. Unfortunately, just as Sikorsky was poised to reach new heights of innovation, the Stock Market Crash and Great Depression hit his new parent company hard, and he was soon informed that the Vought-Sikorsky aircraft division was being shut down. But there was still a ray of hope, for the company told Sikorsky that they would fund any personal research project he wanted to undertake – provided it was not too expensive. Sikorsky immediately decided to work on helicopters, and asked to be allowed to retain his engineering team.

In 1931, Sikorsky filed a patent for the simplest possible design for a helicopter: one with only a single rotor mounted to the fuselage. To counter rotor torque, the craft was fitted with a small vertically-mounted rotor on the end of its tail. Shortly thereafter, Sikorsky built a test stand powered by a motorcycle engine to test different rotor designs and soon began constructing a full-scale flying prototype which he dubbed the VS-300. Eight metres long and powered by a 75 horsepower engine, it was built on an open tubular frame so that repairs and modifications could easily be performed. While Sikorsky initially planned to achieve full directional control by varying the angle of the rotors – that is, via cyclic control – this proved difficult to perfect, so instead he mounted a pair of smaller horizontal rotors to short outriggers. By powering these up separately or together, he could make the helicopter fly forwards, backwards, or sideways.

The VS-300, nicknamed “Igor’s nightmare” by its creators, made its first tethered flight on September 14, 1939. Like many early helicopters, it was plagued by violent vibrations. The helicopter flew untethered in November of that same year, making a number of 2-minute hops before a rogue gust of wind caused it to topple over, smashing the rotors. Undeterred, Sikorsky pressed forward, quipping that:

“I must take the blame for our occasional flight trouble if I am to accept any of the credit for the helicopter’s success later.”

After repairing the damaged craft, Sikorsky made his first free flight in the VS-300 on May 30, 1940. Performance was much improved over previous versions, with the craft hovering so still that a person could easily take objects in and out of a basket attached to its nose. But there was one tiny problem: while the VS-300 could easily fly backwards, sideways, up, and down, the one direction it couldn’t fly was straight forward. This was because the downdraft from the main rotors would deflect off the ground and interact with the outrigger rotors, causing severe vibrations. It was a major shortcoming, but one Sikorsky was certain he would eventually overcome. But he was running out of time, for the U.S. Army Air Corps – the client Sikorsky most wanted to court – had already awarded a $300,000 contract to the rival Platt-LePage Aircraft company to develop a copy of the pioneering German Fa-61 helicopter.

Feeling the added pressure, Sikorsky’s team continued to refine the VS-300, though progress was slow. As test pilot Captain Hollingsworth Gregory later recalled:

“More than anything else, the VS-300 reminded me of a bucking bronco. She was ornery. When I wanted her to go down she went up. When I tried to back her up she persisted on going forward. About the only thing she was agreeable to was getting down again and that was probably because she wanted to get fed and pampered by the mechanics and her maker.”

But the ungainly craft’s performance was steadily improving. On May 6, 1941, the VS-300 set a new hover endurance record, beating the Fa-61’s 1937 record by a full 12 minutes. And in June of that year, Sikorsky finally decided to ditch the inefficient and troublesome outrigger rotors and mount the anti-forge tail rotor on a short pylon, returning the VS-300 to the simple, elegant configuration he had detailed in his original patent. The results were extraordinary: suddenly the VS-300 became the machine Sikorsky had always dreamed about, able to hover smoothly and fly nimbly in any direction – even forward:

“I had never been in a machine that was as pleasant to flight as this light helicopter was, with a completely open cockpit. It was like a dream to feel the machine lift you gently up in the air, float smoothly over one spot, move up or down, and move not only forward or backward but in any direction.”

Such was the improvement in performance that the Army Air Corps, despite having invested heavily in the Platt-Lepage design, switched its support to Sikorsky and awarded him a contract to produce helicopters for military use. Production of the finalized design, designated the YR-4, began in 1942, with 400 being produced by the end of the war. In April 1944, the YR-4 became the first mass-produced helicopter to see active military service when one took part in a daring rescue operation in the Burmese jungle. On April 22, an American pilot was flying three British soldiers out of the jungle in a Stinson L-1 liaison aircraft when engine trouble forced him down 50 kilometres from the nearest airfield. With the passengers too injured to carry out from the crash site, U.S. Army Lieutenant Carter Harman of the 1st Air Commando Group was called in to fly them out using his brand-new YR-4. It was a hazardous assignment: the crash site was small and the hot, humid jungle air greatly reduced the helicopter’s lifting power, forcing Lieutenant Harman to fly one man out at a time and make rapid transitions from vertical to horizontal flight to avoid crashing into the surrounding trees. To reduce strain on his engine, Harman did not fly the casualties all the wayback to base, and instead dropped them in a dry riverbed 16 kilometres away where they were picked up and flown the rest of the way by a light aircraft. Despite these precautions, however, Harman’s engine began to overheat, and he was forced to fly back to base and return the next day. Nonetheless, all four men were successfully recovered, bringing to a close history’s first helicopter combat rescue. Of the helicopter’s combat debut, Colonel Philip G. Cochran, commanding officer of the 1st Air Commando Group, would note:

“Today the ‘egg-beater’ went into action and the damn thing acted like it had good sense.”

From these humble beginnings, the helicopter would go on to become an invaluable tool in both war and peace, being used in all manner of roles including search and rescue, transport, ground attack, construction, policing, and traffic reporting. Today, helicopters are such a common sight that it is easy to forget how difficult the problem of controlled vertical flight was to crack – so difficult that the first practical helicopter did not fly until three decades after the first practical aeroplane. So the next time you see a helicopter whir past, take a moment to appreciate what a miracle of engineering it truly is.

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