User:TheLongTone/History of helicopters

The history of rotorcraft has its origins in toy rotorcraft first made in China. Leonardo da Vinci's aircraft designs included a helicopter, and a number of small experimental craft were made. As with fixed-wing aircraft, serious development did not take place until the development of the internal combustion engine provided a power source with a satisfactory power to weight ratio. However the problems of controlling a rotorcraft proved much harder to solve, and it was not until 1936 that the first fully practical helicopter, the Focke-Wulf Fw 61 was produced.

Early history
The use of a rotor for vertical flight has existed since 400 BC in the form of the bamboo-copter, an ancient Chinese toy. The bamboo-copter is spun by rolling a stick attached to a rotor. The spinning blades create lift, and the toy flies when released. The philosopher Ge Hong's book the Baopuzi (Master Who Embraces Simplicity), written around 317, describes the apocryphal use of a possible rotor in aircraft: "Some have made flying cars [feiche 飛車] with wood from the inner part of the jujube tree, using ox-leather (straps) fastened to returning blades so as to set the machine in motion." The similar "moulinet à noix" (windmill on a nut) did not appear in Europe until the 14th century AD.

Nineteenth century
In July 1754 Mikhail Lomonosov is said to have demonstrated a small clockwork]powered tandem rotor to the [[Russian Academy of Sciences, but no documentation survives.

In 1784 the naturalist Christian de Launoy and his mechanic, Bienvenu, made a model with a pair of counter-rotating rotors powered by a sprung bow drill-like mechanism: this was demonstrated to the French Academy of Sciences on 28 April 1784.

The pioneer of aerodynamic theory Sir George Cayley built a similar model in 1896. Cayley proceeded to build a number of simiar models, and details were published in 1809 in The Mechanics Magazine The word "helicopter" was coined by  Gustave Ponton d’Amécourt, from the ancient Greek words ἕλιξ, ἕλικος, hélix, (spiral) and  πτερόν, pteron (wing). He used the term in a patent application filed on 3 August 1861 in England. D’Amécourt and Gabriel de La Landelle constructed a model powered ny a steam engine, the boiler of which was one of the first uses of aluminium. D'Amecourt's model inspired Jules Verne 1886 novel The Clipper of the Clouds, popularisind the word.

Im 1942 the Englishman W. H. Phillips constructed a model helicopter which avoided the problem of the torque reaction of a shaft-driven rotor by using steam expelled from the rotor tips to produce rotation. Significant as the first model helicopter to fly using an engine rather than a stored mechanical energy. Tip-jet helicopters

Alphonse Pénaud, Achenbach (1874),

1874 the German Wilhelm von Ashenbach built a single-rotor model that was probably the first design to use a tail rotor to counter torque.

In 1877 Enrico Forlanini developed an unmanned helicopter powered by a steam engine. It rose to a height of 13 meters, where it remained for some 20 seconds, after a vertical take-off in Milan. Hiram Maxim's father conceived of a helicopter powered by two counter-rotating rotors, but was unable to find a powerful enough engine to build it. Hiram himself sketched out plans for a helicopter in 1872 before turning his attention to fixed-wing flight.

After unsuccessful tests as a fixed-wing aircraft Thomas Moy adapted his Aerial Steamer into a helicopter. Experiments were made using counterweights to

It did not succeed in lifting its weight off the ground, although

In the 1880s Thomas Edison made a number of experiments with small helicopter models, first useng a gun cotton engine. Deterred by a series of accidents, Edison  later used an electric motor for power. He was one of the first to recognise the need for a large diameter rotor with low blade area to give good hovering efficiency.

Twentieth century
The development of the internal combustion engine made the development of full-sized rotorcraft practical. However, other problems remained, particularly that of control. Early internal combustion engines proved too heavy in relationship to the powere generated to be satisfactory, and serious rotorcraft development only began afetr the First World War.

The Italian Gaetano Crocco, realising that it was necessary to change the pitch of rotor blades as they rotated in order to maintain control in forward flight, patented an early cyclic pitch design in 1906. but did not put his invention to practical use. The Italian Capone produced a number of helicopter designs in the late nineteenth and early twentieth century: one was was built by Howard Wright and sucessful unmanned tethered tests were carried out in Norbury in In 1907 the Frenchmen [[Charles Richet and Louis Breguet built the Gyroplane No. 1; it had four four-bladed rotors attached to a cruciform steel framework, and was powered by an Antoinette. On 29 September 1907 it lifted off in a tethered test flight, becoming the first manned helicopter to rise from the ground. It rose about 60 cm (2 ft) and hovered for a minute. However, it was extremely unstable: Brequet and Richet's next design

Two months later at Lisenux in France, Paul Cornu made the first free flight in a manned rotary-winged craft. The Cornu helicopter was powered by a 24 hp Antoinette engine which drove a pair of two-bladed rotors, lifting to 30 cm (1 ft) and remaining aloft for 20 seconds.

1923 De Bothezat helicopter, four six-bladed rotors 18 December 1922 flying for 1 minute 42 seconds and reaching a height if 6&nbspft

Étienne Oehmichen, after experiments with a balloon provid a twin-rotor helicopter to provide additional lift. A later design had four lifting airscrews and five auxiliary propellers. On 14 April 1924, he flew this, powered by a 180&nbsp (134-kilowatt) Rhone engine, 1,181 ft (360 meters), the first helicopter distance record ratified by the Federation Aeronautique Internationale. On 4 May he was the first to fly a helicopter at least one kilometer (0.6 mile) in a closed circuit in a 5,550-foot (1.692-kilometer) flight that lasted 14 minutes and rose to 50 feet (15 meters).

In 1924 Albert von Baumhauer, a Dutch aeronautical engineer, began studying rotorcraft design in 1923, and produced a helicopter that although only flown with limied success is historically significant because it used a sideways-acting tail rotor to counteract the torque of the main rotor.

The first practical rotorcraft were the autogyros developed by the Spanish aeronautical engineer Juan de la Cierva. In these the rotor was not driven directly by the engine but windmilled in the slipstream from a front-mounted propeller. Crucially, experiments with autogyros led to the discovery by Cierva of the necessity to incorporate a hinge into the rotor hub allowing the blades to flap up and down to compensate for the difference in the lift produced by the blades on either side when the aircraft was moving.

In Russia, the TsAGI's 1-EA, made its first tethered flights in August 1930. This had a single 4-blade lifting rotor and small sideways rotors at the nose and tail. Controllability of the 1-EA was poor, but it had an excellent performance and endurance and on 14 August 1932 it was flown to a record height of 605m. In 1930, the Soviet Union introduced the most promising design to date with the Aerodynamic and Hydrodynamic Central Institute’s (TSAGI) 1-EA. This single-rotor design featured a swashplate and adequate power and lifting rotors. However, the design lacked adequate dampers and other refinements and progress in refining the design was slow.

In 1929 Breguet filed a series of patents which addressed the flight stabilization of rotorcraft, and in 1931 he created the Syndicat d'Etudes de Gyroplane ("Syndicate for Gyroplane Studies"), with Rene Dorand as technical director. The Gyroplane Laboratoire, coaxial rotors flew on 26 June 1935. Within a short time the pilot, Maurice Claisse, had set a number of rotorcraft records: on 14 December 1935 a closed-circuit flight over a 500 m diameter circuit, on 26 September 1936 an altitude record of 58 m and on 24 November 1936 a duration record of 1 h2 m05 s hours over a 44 km closed circuit at a speed of 44.7 kph. Maximum speed 120 km/h

The first practical helicopter was the Focke-Wulf Fw 61, first flown on June 26, 1936. This had a pair of cotr-rotating rotors mounted on outriggers eithe side of the fuselage, which was adapted from that of the Fw 44. A small propeller at the front of the aircraft was fitted primarily to ensure an adequate flow of cooling air over the engine: the aircraft was propelled by the forward tilt of its rotors. The Fw 61 set a number of records, including an altitude record of 3427 m and was also flown by Hanna Reitsch in a spectacular indoor demonstration flights at the Deutschlandhalle in Berlin in 1938.

The Fw 61 formed the basis of the world's first production helicopter, the Fw

Like Breguet, Igor Sikorsky had abandoned early rotorcraft experimentation in favour of fixed-wing development and returned to the idea in the 1930s. His first experimental machine, the Vought-Sikorsky VS-300 was test flown by Sikorsky on 14 September 1939 but had to be tethered by cables due to its inherent instability.

The cyclic pitch control was found to be difficult to perfect, and led to Sikorsky disabling the cyclic pitch mechanism and adding two smaller lifting rotors to either side aft of the tail boom. Varying the pitch of these rotors in unison provided pitch control: roll control was provided by differential control. Sikorsky fitted utility floats (also called pontoons) to the VS-300 and performed a water landing and takeoff On 6 May 1941, the VS-300 beat the world endurance record held by the Focke-Wulf Fw 61, staying aloft for 1 hr 32 min  26.1 seconds.

By 1941 a new cyclic control system had been developed giving it satisfactory control, and the design was refined into the Sikorsky R-4, which beame the first helicopter to be used by the American and British armed forces.

On 22–23 April 1944 U.S. Army Lieutenant Carter Harman of the 1st Air Commando Group made the first combat rescue by helicopter using a YR-4B in the China-Burma-India theater. Despite the high altitude, humidity, and capacity for only a single passenger, Harman rescued a downed liaison aircraft pilot and his three passengers in two flights.

The first tip jet helicopter to fly was built by Freidrich von Dobelhoff using a piston engine to drive a compressor to in 1942