“Helicopter”的意思、由来-开放百科全书

A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL (Vertical TakeOff and Landing) aircraft cannot perform.

The English word helicopter is adapted from the French word {{lang|fr|hélicoptère}}, coined by Gustave Ponton d'Amécourt in 1861, which originates from the Greek helix ({{lang|grc|ἕλιξ}}) "helix, spiral, whirl, convolution"^[1] and pteron ({{lang|grc|πτερόν}}) "wing".^[2]^[3]^[4]^[5] English language nicknames for helicopter include "chopper", "copter", "helo", "heli", and "whirlybird".

Helicopters were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936. Some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production,^[6] with 131 aircraft built.^[7] Though most earlier designs used more than one main rotor, it is the single main rotor with anti-torque tail rotor configuration that has become the most common helicopter configuration. Tandem rotor helicopters are also in widespread use due to their greater payload capacity. Coaxial helicopters, tiltrotor aircraft, and compound helicopters are all flying today. Quadcopter helicopters pioneered as early as 1907 in France, and other types of multicopter have been developed for specialized applications such as unmanned drones.

History

Early design

The earliest references for vertical flight came from China. Since around 400 BC,^[8] Chinese children have played with bamboo flying toys (or Chinese top).^[9]^[10]^[11] This bamboo-copter is spun by rolling a stick attached to a rotor. The spinning creates lift, and the toy flies when released.^[8] The 4th-century AD Daoist book Baopuzi by Ge Hong (抱朴子 "Master who Embraces Simplicity") reportedly describes some of the ideas inherent to rotary wing aircraft.^[12]

Designs similar to the Chinese helicopter toy appeared in some Renaissance paintings and other works.^[13] In the 18th and early 19th centuries Western scientists developed flying machines based on the Chinese toy.^[15]

It was not until the early 1480s, when Italian polymath Leonardo da Vinci created a design for a machine that could be described as an "aerial screw", that any recorded advancement was made towards vertical flight. His notes suggested that he built small flying models, but there were no indications for any provision to stop the rotor from making the craft rotate.^[14]^[15] As scientific knowledge increased and became more accepted, people continued to pursue the idea of vertical flight.

In July 1754, Russian Mikhail Lomonosov had developed a small coaxial modeled after the Chinese top but powered by a wound-up spring device^[16] and demonstrated it to the Russian Academy of Sciences. It was powered by a spring, and was suggested as a method to lift meteorological instruments. In 1783, Christian de Launoy, and his mechanic, Bienvenu, used a coaxial version of the Chinese top in a model consisting of contrarotating turkey flight feathers^[16] as rotor blades, and in 1784, demonstrated it to the French Academy of Sciences. Sir George Cayley, influenced by a childhood fascination with the Chinese flying top, developed a model of feathers, similar to that of Launoy and Bienvenu, but powered by rubber bands. By the end of the century, he had progressed to using sheets of tin for rotor blades and springs for power. His writings on his experiments and models would become influential on future aviation pioneers.^[14] Alphonse Pénaud would later develop coaxial rotor model helicopter toys in 1870, also powered by rubber bands. One of these toys, given as a gift by their father, would inspire the Wright brothers to pursue the dream of flight.^[17]

In 1861, the word "helicopter" was coined by Gustave de Ponton d'Amécourt, a French inventor who demonstrated a small steam-powered model. While celebrated as an innovative use of a new metal, aluminum, the model never lifted off the ground. D'Amecourt's linguistic contribution would survive to eventually describe the vertical flight he had envisioned. Steam power was popular with other inventors as well. In 1878 the Italian Enrico Forlanini's unmanned vehicle, also powered by a steam engine, rose to a height of {{convert|12|m|ft|abbr=off|sp=us}}, where it hovered for some 20 seconds after a vertical take-off. Emmanuel Dieuaide's steam-powered design featured counter-rotating rotors powered through a hose from a boiler on the ground.^[14] In 1887 Parisian inventor, Gustave Trouvé, built and flew a tethered electric model helicopter.{{citation needed|date=May 2015}}

In July 1901, the maiden flight of Hermann Ganswindt's helicopter took place in Berlin-Schöneberg; this was probably the first motor-driven flight carrying humans. A movie covering the event was taken by Max Skladanowsky, but it remains lost.^[18]

In 1885, Thomas Edison was given US$1,000 (equivalent to ${{inflation|US|1000|1885|r=-3|fmt=c}} today) by James Gordon Bennett, Jr., to conduct experiments towards developing flight. Edison built a helicopter and used the paper for a stock ticker to create guncotton, with which he attempted to power an internal combustion engine. The helicopter was damaged by explosions and one of his workers was badly burned. Edison reported that it would take a motor with a ratio of three to four pounds per horsepower produced to be successful, based on his experiments.^[19] Ján Bahýľ, a Slovak inventor, adapted the internal combustion engine to power his helicopter model that reached a height of {{convert|0.5|m|ft|abbr=off|sp=us}} in 1901. On 5 May 1905, his helicopter reached {{convert|4|m|ft|abbr=off|sp=us}} in altitude and flew for over {{convert|1,500|m|ft|abbr=off|sp=us}}.^[20] In 1908, Edison patented his own design for a helicopter powered by a gasoline engine with box kites attached to a mast by cables for a rotor,^[21] but it never flew.^[22]

First flights

In 1906, two French brothers, Jacques and Louis Breguet, began experimenting with airfoils for helicopters. In 1907, those experiments resulted in the Gyroplane No.1, possibly as the earliest known example of a quadcopter. Although there is some uncertainty about the date, sometime between 14 August and 29 September 1907, the Gyroplane No. 1 lifted its pilot into the air about {{convert|2|ft|m|sigfig=1|order=flip}} for a minute.^[6] The Gyroplane No.{{nbsp}}1 proved to be extremely unsteady and required a man at each corner of the airframe to hold it steady. For this reason, the flights of the Gyroplane No.{{nbsp}}1 are considered to be the first manned flight of a helicopter, but not a free or untethered flight.

That same year, fellow French inventor Paul Cornu designed and built a Cornu helicopter that used two {{convert|20|ft|m|sigfig=2|adj=on|order=flip}} counter-rotating rotors driven by a {{convert|24|hp|kW|abbr=on|sigfig=2}} Antoinette engine. On 13 November 1907, it lifted its inventor to {{convert|1|ft|m|sigfig=1|order=flip}} and remained aloft for 20 seconds. Even though this flight did not surpass the flight of the Gyroplane No. 1, it was reported to be the first truly free flight with a pilot.^[23] Cornu's helicopter completed a few more flights and achieved a height of nearly {{convert|6.5|ft|m|sigfig=2|order=flip}}, but it proved to be unstable and was abandoned.^[6]

In 1911, Slovenian philosopher and economist Ivan Slokar patented a helicopter configuration.^[24]^[25]^[26]

The Danish inventor Jacob Ellehammer built the Ellehammer helicopter in 1912. It consisted of a frame equipped with two counter-rotating discs, each of which was fitted with six vanes around its circumference. After indoor tests, the aircraft was demonstrated outdoors and made several free take-offs. Experiments with the helicopter continued until September 1916, when it tipped over during take-off, destroying its rotors.^[27]

During World War I, Austria-Hungary developed the PKZ, an experimental helicopter prototype, with two aircraft built.

Early development

In the early 1920s, Argentine Raúl Pateras-Pescara de Castelluccio, while working in Europe, demonstrated one of the first successful applications of cyclic pitch.^[6] Coaxial, contra-rotating, biplane rotors could be warped to cyclically increase and decrease the lift they produced. The rotor hub could also be tilted forward a few degrees, allowing the aircraft to move forward without a separate propeller to push or pull it. Pateras-Pescara was also able to demonstrate the principle of autorotation. By January 1924, Pescara's helicopter No.{{nbsp}}1 was tested but was found to be underpowered and could not lift its own weight. His 2F fared better and set a record.^[28] The British government funded further research by Pescara which resulted in helicopter No. 3, powered by a {{convert|250|hp|adj=on}} radial engine which could fly for up to ten minutes.^[29]^[30]

On 14 April 1924 Frenchman Étienne Oehmichen set the first helicopter world record recognized by the Fédération Aéronautique Internationale (FAI), flying his quadrotor helicopter {{convert|360|m|ft|sp=us}}.^[31] On 18{{nbsp}}April 1924, Pescara beat Oemichen's record, flying for a distance of {{convert|736|m|sp=us}}^[28] (nearly {{convert|.5|mi|order=flip|sp=us|disp=or}}) in 4 minutes and 11 seconds (about {{convert|8|mph|km/h|abbr=on|order=flip|disp=or}}, maintaining a height of {{convert|6|ft|m|abbr=off|sp=us|order=flip}}.^[32] On 4{{nbsp}}May, Oehmichen completed the first {{convert|1|km|adj=on|spell=in|sp=us}} closed-circuit helicopter flight in 7 minutes 40 seconds with his No. 2 machine.^[6]^[33]

In the US, George de Bothezat built the quadrotor helicopter de Bothezat helicopter for the United States Army Air Service but the Army cancelled the program in 1924, and the aircraft was scrapped.{{citation needed|date=February 2013}}

Albert Gillis von Baumhauer, a Dutch aeronautical engineer, began studying rotorcraft design in 1923. His first prototype "flew" ("hopped" and hovered in reality) on 24 September 1925,^[34] with Dutch Army-Air arm Captain Floris Albert van Heijst at the controls. The controls that van Heijst used were von Baumhauer's inventions, the cyclic and collective.^[35]^[36] Patents were granted to von Baumhauer for his cyclic and collective controls by the British ministry of aviation on 31{{nbsp}}January 1927, under patent number 265,272.{{citation needed|date=February 2013}}

In 1927,^[37] Engelbert Zaschka from Germany built a helicopter, equipped with two rotors, in which a gyroscope was used to increase stability and serves as an energy accumulator for a gliding flight to make a landing. Zaschka's plane, the first helicopter, which ever worked so successfully in miniature, not only rises and descends vertically, but is able to remain stationary at any height.^[38]^[39]

In 1928, Hungarian aviation engineer Oszkár Asbóth constructed a helicopter prototype that took off and landed at least 182 times, with a maximum single flight duration of 53 minutes.^[40]^[41]

In 1930, the Italian engineer Corradino D'Ascanio built his D'AT3, a coaxial helicopter. His relatively large machine had two, two-bladed, counter-rotating rotors. Control was achieved by using auxiliary wings or servo-tabs on the trailing edges of the blades,^[42] a concept that was later adopted by other helicopter designers, including Bleeker and Kaman. Three small propellers mounted to the airframe were used for additional pitch, roll, and yaw control. The D'AT3 held modest FAI speed and altitude records for the time, including altitude (18 m or 59 ft), duration (8 minutes 45 seconds) and distance flown (1,078 m or 3,540 ft).^[42]^[43]

In the Soviet Union, Boris N. Yuriev and Alexei M. Cheremukhin, two aeronautical engineers working at the Tsentralniy Aerogidrodinamicheskiy Institut (TsAGI or the Central Aerohydrodynamic Institute), constructed and flew the TsAGI 1-EA single lift-rotor helicopter, which used an open tubing framework, a four-blade main lift rotor, and twin sets of {{convert|1.8|m|ft|abbr=off|sp=us|adj=on}} diameter, two-bladed anti-torque rotors: one set of two at the nose and one set of two at the tail. Powered by two M-2 powerplants, up-rated copies of the Gnome Monosoupape 9 Type B-2 100 CV output rotary engine of World War I, the TsAGI 1-EA made several low altitude flights.^[44] By 14 August 1932, Cheremukhin managed to get the 1-EA up to an unofficial altitude of {{convert|605|m|ft|abbr=off|sp=us}}, shattering d'Ascanio's earlier achievement. As the Soviet Union was not yet a member of the FAI, however, Cheremukhin's record remained unrecognized.^[45]

The Bréguet-Dorand Gyroplane Laboratoire was built in 1933. It was a coaxial helicopter, contra-rotating. After many ground tests and an accident, it first took flight on 26 June 1935. Within a short time, the aircraft was setting records with pilot Maurice Claisse at the controls. On 14 December 1935, he set a record for closed-circuit flight with a {{convert|500|m|ft|abbr=off|sp=us|adj=on}} diameter.^[47] The next year, on 26 September 1936, Claisse set a height record of {{convert|158|m|ft|abbr=off|sp=us}}.^[48] And, finally, on 24 November 1936, he set a flight duration record of one hour, two minutes and 50 seconds^[49] over a {{convert|44|km|mi|abbr=off|sp=us}} closed circuit at 44.7 kilometers per hour (27.8 mph). The aircraft was destroyed in 1943 by an Allied airstrike at Villacoublay airport.^[50]

Autogyro

Early rotor winged flight suffered failures primarily associated with the unbalanced rolling movement generated when attempting take-off, due to dissymmetry of lift between the advancing and retreating blades. This major difficulty was resolved by Juan de la Cierva's introduction of the flapping hinge. In 1923, de la Cierva's first successful autogyro was flown in Spain by Lt. Gomez Spencer. In 1925 he brought his C.6 to Britain and demonstrated it to the Air Ministry at Farnborough, Hampshire. This machine had a four blade rotor with flapping hinges but relied upon conventional airplane controls for pitch, roll and yaw. It was based upon an Avro 504K fuselage, initial rotation of the rotor was achieved by the rapid uncoiling of a rope passed around stops on the undersides of the blades.

A major problem with the autogyro was driving the rotor before takeoff. Several methods were attempted in addition to the coiled rope system, which could take the rotor speed to 50% of that required, at which point movement along the ground to reach flying speed was necessary, while tilting the rotor to establish autorotation. Another approach was to tilt the tail stabiliser to deflect engine slipstream up through the rotor. The most acceptable solution was finally achieved with the C.19 Mk.4, which was produced in some quantities; a direct drive from the engine to the rotor was fitted, through which the rotor could be accelerated up to speed. The rotor clutch was then disengaged before the takeoff run.

As de la Cierva's autogyros achieved success and acceptance, others began to follow and with them came further innovation. Most important was the development of direct rotor control through cyclic pitch variation, achieved initially by tilting the rotor hub and subsequently by the Austrian engineer Raoul Hafner, by the application of a spider mechanism that acted directly on each rotor blade. The first production direct control autogyro was the C.30, produced in quantity by Avro, Liore et Olivier, and Focke-Wulf.

The production model, called the C.30A by Avro, was built under licence in Britain, France and Germany and was similar to the C.30P. It carried small movable trimming surfaces. Each licensee used nationally built engines and used slightly different names. In all, 143 production C.30s were built, making it by far the most numerous pre-war autogyro.

Between 1933 and 1936, de la Cierva used one C.30A (G-ACWF) to perfect his last contribution to autogyro development before his death in late 1936.^[52] To enable the aircraft to take off without forward ground travel, he produced the "Autodynamic" rotor head, which allowed the rotor to be spun up by the engine in the usual way but to higher than take-off r.p.m at zero rotor incidence and then to reach operational positive pitch suddenly enough to jump some {{convert|20|ft|m|order=flip|sp=us}} upwards.^[53]

Birth of an industry

Heinrich Focke at Focke-Wulf was licensed to produce the Cierva C.30 autogyro in 1933. Focke designed the world's first practical transverse twin-rotor helicopter, the Focke-Wulf Fw 61, which first flew on 26 June 1936. The Fw 61 broke all of the helicopter world records in 1937, demonstrating a flight envelope that had only previously been achieved by the autogyro.

During World War II, Nazi Germany used helicopters in small numbers for observation, transport, and medical evacuation. The Flettner Fl 282 Kolibri synchropter—using the same basic configuration as Anton Flettner's own pioneering Fl 265—was used in the Mediterranean, while the Focke Achgelis Fa 223 Drache twin-rotor helicopter was used in Europe.{{Citation needed|date=July 2010}} Extensive bombing by the Allied forces prevented Germany from producing any helicopters in large quantities during the war.

In the United States, Russian-born engineer Igor Sikorsky and W. Lawrence LePage competed to produce the U.S. military's first helicopter. LePage received the patent rights to develop helicopters patterned after the Fw 61, and built the XR-1.^[54] Meanwhile, Sikorsky settled on a simpler, single rotor design, the VS-300, which turned out to be the first practical single lifting-rotor helicopter design. After experimenting with configurations to counteract the torque produced by the single main rotor, Sikorsky settled on a single, smaller rotor mounted on the tail boom.

Developed from the VS-300, Sikorsky's R-4 was the first large-scale mass-produced helicopter, with a production order for 100 aircraft. The R-4 was the only Allied helicopter to serve in World War II, when it was used primarily for search and rescue (by the USAAF 1st Air Commando Group) in Burma;^[55] in Alaska; and in other areas with harsh terrain. Total production reached 131 helicopters before the R-4 was replaced by other Sikorsky helicopters such as the R-5 and the R-6. In all, Sikorsky produced over 400 helicopters before the end of World War II.^[56]

While LePage and Sikorsky built their helicopters for the military, Bell Aircraft hired Arthur Young to help build a helicopter using Young's two-blade teetering rotor design, which used a weighted stabilizer bar placed at a 90° angle to the rotor blades. The subsequent Model 30 helicopter showed the design's simplicity and ease of use. The Model 30 was developed into the Bell 47, which became the first helicopter certified for civilian use in the United States. Produced in several countries, the Bell 47 was the most popular helicopter model for nearly 30 years.

Turbine age

In 1951, at the urging of his contacts at the Department of the Navy, Charles Kaman modified his K-225 synchropter — a design for a twin-rotor helicopter concept first pioneered by Anton Flettner in 1939, with the aforementioned Fl 265 piston-engined design in Germany — with a new kind of engine, the turboshaft engine. This adaptation of the turbine engine provided a large amount of power to Kaman's helicopter with a lower weight penalty than piston engines, with their heavy engine blocks and auxiliary components. On 11{{nbsp}}December 1951, the Kaman K-225 became the first turbine-powered helicopter in the world. Two years later, on 26 March 1954, a modified Navy HTK-1, another Kaman helicopter, became the first twin-turbine helicopter to fly.^[57] However, it was the Sud Aviation Alouette II that would become the first helicopter to be produced with a turbine-engine.^[58]

Reliable helicopters capable of stable hover flight were developed decades after fixed-wing aircraft. This is largely due to higher engine power density requirements than fixed-wing aircraft. Improvements in fuels and engines during the first half of the 20th century were a critical factor in helicopter development. The availability of lightweight turboshaft engines in the second half of the 20th century led to the development of larger, faster, and higher-performance helicopters. While smaller and less expensive helicopters still use piston engines, turboshaft engines are the preferred powerplant for helicopters today.

Uses

Due to the operating characteristics of the helicopter—its ability to take off and land vertically, and to hover for extended periods of time, as well as the aircraft's handling properties under low airspeed conditions—it has been chosen to conduct tasks that were previously not possible with other aircraft, or were time- or work-intensive to accomplish on the ground. Today, helicopter uses include transportation of people and cargo, military uses, construction, firefighting, Search and rescue, Tourism, medical transport, law enforcement, agriculture, news and media, and aerial observation, among others.^[59]

A helicopter used to carry loads connected to long cables or slings is called an aerial crane. Aerial cranes are used to place heavy equipment, like radio transmission towers and large air conditioning units, on the tops of tall buildings, or when an item must be raised up in a remote area, such as a radio tower raised on the top of a hill or mountain. Helicopters are used as aerial cranes in the logging industry to lift trees out of terrain where vehicles cannot travel and where environmental concerns prohibit the building of roads.^[60] These operations are referred to as longline because of the long, single sling line used to carry the load.^[61]

The largest single non-combat helicopter operation in history was the disaster management operation following the 1986 Chernobyl nuclear disaster. Hundreds of pilots were involved in airdrop and observation missions, making dozens of sorties a day for several months.

"Helitack" is the use of helicopters to combat wildland fires.^[62] The helicopters are used for aerial firefighting (water bombing) and may be fitted with tanks or carry helibuckets. Helibuckets, such as the Bambi bucket, are usually filled by submerging the bucket into lakes, rivers, reservoirs, or portable tanks. Tanks fitted onto helicopters are filled from a hose while the helicopter is on the ground or water is siphoned from lakes or reservoirs through a hanging snorkel as the helicopter hovers over the water source. Helitack helicopters are also used to deliver firefighters, who rappel down to inaccessible areas, and to resupply firefighters. Common firefighting helicopters include variants of the Bell 205 and the Erickson S-64 Aircrane helitanker.

Helicopters are used as air ambulances for emergency medical assistance in situations when an ambulance cannot easily or quickly reach the scene, or cannot transport the patient to a medical facility in time. Helicopters are also used when patients need to be transported between medical facilities and air transportation is the most practical method. An air ambulance helicopter is equipped to stabilize and provide limited medical treatment to a patient while in flight. The use of helicopters as air ambulances is often referred to as "MEDEVAC", and patients are referred to as being "airlifted", or "medevaced". This use was pioneered in the Korean war, when time to reach a medical facility was reduced to three hours from the eight hours needed in World War II, and further reduced to two hours by the Vietnam war.^[63]

Police departments and other law enforcement agencies use helicopters to pursue suspects. Since helicopters can achieve a unique aerial view, they are often used in conjunction with police on the ground to report on suspects' locations and movements. They are often mounted with lighting and heat-sensing equipment for night pursuits.

Military forces use attack helicopters to conduct aerial attacks on ground targets. Such helicopters are mounted with missile launchers and miniguns. Transport helicopters are used to ferry troops and supplies where the lack of an airstrip would make transport via fixed-wing aircraft impossible. The use of transport helicopters to deliver troops as an attack force on an objective is referred to as "air assault". Unmanned aerial systems (UAS) helicopter systems of varying sizes are developed by companies for military reconnaissance and surveillance duties. Naval forces also use helicopters equipped with dipping sonar for anti-submarine warfare, since they can operate from small ships.

Oil companies charter helicopters to move workers and parts quickly to remote drilling sites located at sea or in remote locations. The speed advantage over boats makes the high operating cost of helicopters cost-effective in ensuring that oil platforms continue to operate. Various companies specialize in this type of operation.

Market

In 2017, 926 civil helicopters were shipped for $3.68 Billion, led by Airbus Helicopters with $1.87 Billion for 369 rotorcraft, Leonardo Helicopters with $806 Million for 102 (first three quarters only), Bell Helicopter with $696 Million for 132, then Robinson Helicopter with $161 Million for 305.^[65]

By October 2018, the in-service and stored helicopter fleet of 38,570 with civil or government operators was led Robinson Helicopter with 24.7% followed by Airbus Helicopters with 24.4%, then Bell with 20.5 and Leonardo with 8.4%, Russian Helicopters with 7.7%, Sikorsky Aircraft with 7.2%, MD Helicopters with 3.4% and other with 2.2%.

See also

References

Notes

1. ^GEN {{lang|grc|ἕλικος}} helikos (the κ being romanised as a c); see {{LSJ|e(/lic2|ἕλιξ}} and {{LSJ|e(/lic1|ἕλιξ (as an adjective)|ref}}.
2. ^{{LSJ|ptero/n|πτερόν|shortref}}.
3. ^{{OEtymD|helicopter}}
4. ^For various reasons, the word is often erroneously, from an etymological point of view, analysed by English speakers into heli- and copter; see {{cite web|url=http://www.thefreedictionary.com/helicopter|website=The Free Dictionary|title=helicopter}}
5. ^Cottez 1980, p. 181.
6. ^¹²³⁴Munson 1968.
7. ^Hirschberg, Michael J. and David K. Dailey, "Sikorsky" {{webarchive|url=https://web.archive.org/web/20071218045128/http://www.vtol.org/History.htm |date=18 December 2007 }}. US and Russian Helicopter Development In the 20th Century, American Helicopter Society, International. 7 July 2000.
8. ^¹Leishman, J. Gordon. Principles of Helicopter Aerodynamics. Cambridge aerospace series, 18. Cambridge: Cambridge University Press, 2006. {{ISBN|978-0-521-85860-1}}. {{cite web|url=http://terpconnect.umd.edu/~leishman/Aero/history.html |title=Archived copy |accessdate=15 July 2014 |deadurl=yes |archiveurl=https://web.archive.org/web/20140713201846/http://terpconnect.umd.edu/~leishman/Aero/history.html |archivedate=13 July 2014 }} Web extract
9. ^"Early Helicopter History." Aerospaceweb.org. Retrieved: 12 December 2010
10. ^{{cite book|title=Taking Flight: Inventing the Aerial Age, from Antiquity Through the First World War|url=https://books.google.com/books?id=YRqV_PayIKIC&pg=PA22|date=8 May 2003|publisher=Oxford University Press|isbn=978-0-19-516035-2|pages=22–23}}
11. ^Goebel, Greg. {{cite web|url=http://www.vectorsite.net/avheli_1.html |title="The Invention Of The Helicopter." |accessdate=11 November 2008 |deadurl=bot: unknown |archiveurl=https://web.archive.org/web/20110629140626/http://www.vectorsite.net/avheli_1.html |archivedate=29 June 2011 }} Vectorsite.net. Retrieved: 11 November 2008
12. ^Fay, John. "Helicopter Pioneers – Evolution of Rotary Wing Aircraft." Helicopter History Site. Retrieved: 28 November 2007
13. ^Donald F. Lach. (1977). [https://books.google.com/books?id=N0xD7BYXv_YC Asia in the making of Europe. Volume II, A Century of Wonder]. p. 403
14. ^¹²Rumerman, Judy. "Early Helicopter Technology." Centennial of Flight Commission, 2003. Retrieved 12 December 2010
15. ^Pilotfriend.com "Leonardo da Vinci's Helical Air Screw." Pilotfriend.com. Retrieved 12 December 2010
16. ^¹²Leishman, J. Gordon (2006). [https://books.google.com/books?id=nMV-TkaX-9cC&lpg=PP1&dq=Principles%20of%20Helicopter%20Aerodynamics Principles of Helicopter Aerodynamics]. Cambridge University Press. p. 8. {{ISBN|0-521-85860-7}}
17. ^[https://www.loc.gov/teachers/classroommaterials/primarysourcesets/flight/pdf/teacher_guide.pdf The Inventive Wright Brothers]
18. ^{{cite web|url=http://helikopterhysteriezwo.blogspot.jp/2012/06/moments-in-helicopter-history-9.html|title=Moments in Helicopter History (9) – Hermann Ganswindt|website=helikopterhysteriezwo.blogspot.jp}}
19. ^Bryan, George S. Edison: the Man and His Work. New York: Garden City Publishers, 1926. p. 249
20. ^"Pioneers – 1900/1930." Helicopter History Site. Retrieved: 3 May 2007
21. ^¹{{cite web|url=https://www.google.de/patents/US970616|title=Patent US970616 - Flying-machine.|publisher=|accessdate=30 March 2016}}
22. ^Dowd, George L. "Flops of famous inventors". Popular Science, December 1930
23. ^Leishman, Dr. J. Gordon, Technical Fellow of AHS International. "Paper." 64th Annual Forum of the American Helicopter Society International, on the aerodynamic capability of Cornu's design, arguing that the aircraft lacked the power and rotor loading to lift free of the ground in manned flight.
24. ^{{cite web|url=http://www.slovenska-biografija.si/oseba/sbi584468/|title=Slokar, Ivan (1884–1970)|author=Slovenska akademija znanosti in umetnosti|publisher=|accessdate=30 March 2016}}
25. ^{{cite web|url=http://www.ajdovscina.si/ajdovscina/zgodovina/pomembne_osebnosti/2015082013191757/%20Ivan%20Slokar%20-%20letalski%20izumitelj,%20gospodarstvenik,%20jezikoslovec%20(1884%20-%201970)/|title=Ivan Slokar - letalski izumitelj, gospodarstvenik, jezikoslovec (1884 - 1970)|author=Občina Ajdovščina|publisher=|accessdate=30 March 2016}}
26. ^{{cite web|url=https://openlibrary.org/books/OL19750086M/Sto_slovenskih_znanstvenikov_zdravnikov_in_tehnikov|title=Sto slovenskih znanstvenikov, zdravnikov in tehnikov (Open Library)|publisher=|accessdate=30 March 2016}}
27. ^Taylor, Michael J. H. Jane's Encyclopedia of Aviation, p. 348. London: Studio Editions, 1989.
28. ^¹"FAI Record ID #13094 - Straight distance. Class E former G (Helicopters), piston {{webarchive|url=https://web.archive.org/web/20141006093603/http://www.fai.org/fai-record-file/?recordId=13094 |date=6 October 2014 }}" Fédération Aéronautique Internationale (FAI). Retrieved: 21 September 2014.
29. ^[https://books.google.com/books?id=9ycDAAAAMBAJ&pg=PA70&dq=1930+plane+%22Popular&hl=en&ei=5SWNTvvhIM63tge6lc2DDA&sa=X&oi=book_result&ct=result&resnum=3&sqi=2&ved=0CEAQ6AEwAg#v=onepage&q=1930%20plane%20%22Popular&f=true "New Helicopter Rises in Vertical Flight."] Popular Science, November 1930, p. 70.
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