The Evolution of Helicopters

The early history of the helicopter

Vertical flight – the ability of an aircraft to hover, take off and land vertically – traces its origins to ancient China. Historians believe that, as early as around 400 BC, children in China were playing with toys that implemented the concept of vertical lift – gaining height through the use of a propeller.

These toys employed the basic principle we all understand about helicopters: the rotary blade, which was fitted to a shaft that was turned by spinning it in your palms or by pulling a string. However, it wasn’t toys that inspired Leonardo da Vinci to make the famous drawing of his ornithopter flying machine centuries later, but birds. The word ‘ornithopter’ comes from the Greek ornithos (‘bird’) and pteron (‘wing’). He cited the flight of winged animals, especially bats and birds, as inspiration for his 1485 drawing of a human-powered flying device. Unfortunately for da Vinci, his ornithopter didn’t get off the ground until about 300 years later, and even then the first attempts were failures.

The next great milestone in the pursuit of vertical flight was achieved in 1754, by Mikhail Lomonosov, a polymath often described as the Russian da Vinci. Lomonosov designed a machine that he believed would help lift meteorological equipment into the air. The design involved two propellers rotating in opposite directions on the same axis – a principle known as coaxial ­– to avoid the torque from a single propeller causing the machine to spin in the opposite direction.

The next to hop on the vertically-propelled bandwagon (which is a pretty accurate description of what some of these early designs looked like) came from Sir George Cayley, known as ‘The Father of Aviation’. An engineer and inventor, Cayley discovered the four principal forces of flight – weight, lift, drag and thrust ­– and the relationship between them.

Cayley was determined to find a way to get his heavier-than-air vehicles off the ground, and in 1843 he experimented with a design he called the ‘Aerial Carriage’. This machine took a lot of inspiration from da Vinci’s effort – with four umbrella-like propellers that would rotate for lift – although like da Vinci's ornithopter, Cayley’s flying machine never actually flew.

In 1863, vertical flight enthusiast and French scholar, Gustave Vicomte de Ponton d’Amécourt, invented the word ‘helicopteres’ to describe his flying machines. The word was derived from ‘pteron’ and ‘helix’ (the Greek adjective for spiral). But although the craft now had a name, the Frenchman couldn’t get his helicopter off the ground.

Over the next 60 years, inventors and scientists continued to grapple with the problem of vertical flight, including the great inventor Thomas Edison who abandoned the attempt after testing the engine caused an explosion in his laboratory. By the end of the 19th Century, ‘helicopteres’ remained flightless.

Lift-off

In 1903, aviation history was made by attaining powered flight in an aircraft constructed by the Wright Brothers: two self-taught but determined engineers. And four years later another set of brothers – Louis and Jacques Bréguet – finally achieved vertical ascent in a craft they called Gyroplane No.1. It only hovered a short distance above the ground and only for about two minutes, but it was a breakthrough nonetheless, and a more convincing one than French inventor Paul Cornu's helicopter that only stayed in the air for 20 seconds, one foot off the ground.

The following year, vertical flight enthusiast and inventor, Emil Berliner (creator of the gramophone), designed and built a helicopter that not only lifted itself off the ground, but Berliner and his fellow-designer John Newton as well. They hovered at a spectacular three feet above the ground, in a craft consisting of two 36-horsepower engines attached to a platform. Berliner went on to propose the use of a tail rotor as a means of stabilising the aircraft.

Going places

Although helicopters were now getting off the ground, they were unstable and required brave men willing to run alongside them and keep them upright. The enormous variety of designs during this period were proof that mankind was willing to try anything and everything to make vertical flight possible. This video about the history of helicopters shows these fanciful but basically flightless aircraft of the era in action.

The problem of stability was solved by a Spaniard called Juan de la Cierva, who figured out that the blades on a propeller needed to be hinged to allow them to flap and change their speed relative to each other. This was good news for the pilot too, because the blades were held in place by centrifugal forces and not rigidly attached to the rotor, making for a more comfortable experience. In 1923, de la Cierva’s Autogyro No. 4 flew a four-kilometre circuit around Madrid, in what is widely considered the first successful vertical flight.

Sikorsky, father of helicopters

In the 1930s, the Germans got cracking on the vertical flight business. Building on de la Cierva’s design, Heinrich Focke and Gerd Achgelis founded a company called Focke-Achgelis that would focus on the production of helicopters.

The main difference between their Fa-61 – also known as the Focke-Wulf 61 – and the Spaniard’s Autogyro No. 4, was that this helicopter had powered rotors. Their success was demonstrated to the world in footage of the helicopter flying around a sports stadium.

But it was Russian-American engineer Igor Sikorsky who earned the title of ‘Father of Helicopters’. After giving up the pursuit of vertical flight decades earlier, in September 1939, Sikorsky took his VS-300 for what turned out to be a very short spin. But a year later an improved version broke the helicopter endurance record by staying airborne for over an hour and a half.

The US government wanted Sikorsky to produce an easily manufactured version of his VS-300. With $50,000 to get the job done, Sikorsky designed the XR-4, which looked much like helicopters do today, with a single main rotor, an auxiliary tail rotor and an enclosed cabin for pilots. It was the first modern helicopter and the first to go into production, with the US and British military buying dozens.

Refinement and innovation

The next few decades would see the helicopter undergoing countless new designs and innovations, as engineers and scientists sought to achieve longer flight times, along with more stability and comfort.

Among the noteworthy successes, the PV-2 designed by Frank N. Piasecki – itself an improvement on the XR-1 model designed by Platt LePage – offered more stability than Sikorsky’s design and was cheaper to build. The Model 47, designed by Larry Bell, featured two extra seats for passengers and a more powerful engine. The Model 47 showed its mettle by eventually evacuating more than 15,000 wounded soldiers from various battlegrounds.

Next came the need for speed. Stanley Hiller, an aviation entrepreneur, developed the first helicopter with entirely metal blades, which allowed the aircraft to fly at much higher speeds. He also piloted the first helicopter to fly across the entire United States – the Hiller 360.

Present-day helicopters

Present-day helicopters are a far cry from what da Vinci had in mind when he drew his bird-inspired ornithopter. Nor did vertical flight replace the car as a means of personal transport, as the early inventors predicted. The helicopter has, however, taken on more and more civilian roles in recent years such as police support work, medical emergencies and firefighting, as well as being used by news teams and as a means for private transport.

Owning a helicopter may be only for the lucky few, but it is relatively easy and more affordable to charter a helicopter ride for business or sightseeing. Helicopter designs are becoming more and more refined and the technology more and more powerful. We have come a long way from the days when hovering a few feet off the ground, for only a few seconds, was considered an aviation milestone.

Your charter helicopter can now carry you across the continent, wait while you complete your business meeting, and whisk you back home in time for supper.

When you consider your helicopter charter options, the name Sikorsky may well come up. Some of the stars of the modern helicopter industry include the Sikorsky X2, which has set a world record for helicopter speed at 415 km/h, and the Sikorsky S-92 that serves as a palace in the sky with the ability to seat 19 passengers in absolute style and comfort.

And if you happen to have a particularly heavy load to move, the Russian-made Mil Mi-26 has so much power it can lift a passenger plane!

With helicopters being so prevalent in our everyday lives, it’s tempting to speculate about the future of vertical flight. Aircraft such as drones and experimental hovercraft even suggest the early dream of helicopters for personal transport may not be so far-fetched after all.

What about the future?

It’s possible that someday we may be flying around above the cities, just like the Jetsons, in our own personal flying machines. The producers of science-fiction books and movies certainly seem to think so. But will we be hovering around on our own Segway-like helicopters to get to work and back? And will personal helicopters or hovercraft ever actually replace the car as a standard means of personal transport? We’ll have to wait and see.

Meanwhile, why not contact us so you can experience the wonder of vertical flight by chartering a private helicopter with ACS today?