Helicopter
A Canadian Helicopters Bell 206

A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors, each rotor consisting of two or more rotor blades. Helicopters are classified as rotorcraft or rotary-wing aircraft to distinguish them from fixed-wing aircraft because the helicopter derives its source of lift from the rotor blades rotating around a mast. The word 'helicopter' is adapted from the French hélicoptère, coined by Gustave de Ponton d'Amecourt in 1861. Look up helicopter in Wiktionary, the free dictionary. ... Image File history File links Metadata Size of this preview: 800 × 563 pixelsFull resolution (1400 × 985 pixel, file size: 281 KB, MIME type: image/jpeg)Canadian Helicopters Bell 206 I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms... CHC Helicopter Corporation (sometimes known as Canadian Helicopter Corporation or Hélicoptères Canadiens) (TSX: FLY.SV.A TSX: FLY.MV.B NYSE: FLI) is the world’s largest global commercial helicopter operator. ... The Bell Helicopter Model 206 JetRanger is a two-bladed main rotor, turbine powered helicopter with a conventional, two-bladed tail rotor. ... Flying machine redirects here. ... The lift force, lifting force or simply lift is a mechanical force generated by solid objects as they move through a fluid. ... In astronomy, geography, geometry and related sciences and contexts, a plane is said to be horizontal at a given point if it is locally perpendicular to the gradient of the gravity field, i. ... A rotor is the rotating part of a helicopter which generates lift, either vertically in the case of a main rotor, or horizontally in the case of a tail rotor. ... It has been suggested that this article or section be merged with Rotary-wing aircraft. ... Airplane and Aeroplane redirect here. ...

As an aircraft, the primary advantages of the helicopter are due to the rotor blades that revolve through the air, providing lift without requiring the aircraft to move forward the way an airplane does. This creates the ability for the helicopter to take off and land vertically without the need for runways. For this reason, helicopters are often used to operate in congested or isolated areas where airplanes are generally not able to take off or land. The lift from the rotor also allows the helicopter to hover in one area for extended periods of time, and to do so more efficiently than other forms of vertical take-off and landing (VTOL) aircraft, making it useful in accomplishing tasks that airplanes are not able to perform. A Ryanair Boeing 737 takes off from Bristol International Airport, England Take off is the phase of flight where an aircraft transitions from moving along the ground (taxiing) to flying in the air (see flight), usually from a runway. ... MyTravel Airways Airbus A320 landing Landing is the last part of a flight, where a flying animal or aircraft returns to the ground. ... The Hawker Harrier, one of the famous examples of a plane with VTOL capability. ...

Although helicopters were developed and built during the first half century of flight, some even reaching limited production, it wasn't until 1942 that a helicopter designed by Igor Sikorsky became the first helicopter to enter full-scale production, totaling over 400 copies. Even though most previous designs utilized more than one main rotor, it was the single main rotor with antitorque tail rotor configuration of this design that would come to be recognized worldwide as the helicopter. For another meanings and similar spellings, see Sikorsky. ...

History

Since 400 BC, the Chinese have had a bamboo flying top that is used as a children's toy. Eventually, this flying top toy made it to Europe and is depicted in a 1463 European painting.^[1] Pao Phu Tau (抱朴子) was a 4th-century book in China describing some of the ideas inherent to rotary wing aircraft.^[2] A selection of bamboo-copters. ...

In 1493, Leonardo da Vinci first sketched a semi-practical machine that could be described as an "aerial screw".^[3] He wrote that he made small flying models ^[4] but could not stop the rotor from making the whole craft rotate. “Da Vinci” redirects here. ...

In July 1754, Mikhail Lomonosov showed to the Russian Academy of Sciences a small coaxial rotor powered by a wound-up spring, intended to lift meteorological instruments. ^[4] Mikhail Vasilyevich Lomonosov Mikhail Vasilyevich Lomonosov (Михаи́л Васи́льевич Ломоно́сов) (November 19 (November 8, Old Style), 1711 – April 15 (April 4, Old Style), 1765) was a Russian writer and polymath who made important contributions to literature, education, and science. ... Russian Academy of Sciences: main building Russian Academy of Sciences (Росси́йская Акаде́мия Нау́к) is the national academy of Russia. ... Meteorology is the scientific study of the atmosphere that focuses on weather processes and forecasting. ...

In 1783, Christian de Launoy, and his mechanic, Bienvenu, made a model pair of counter-rotating rotors (not coaxial) using turkey's flight feathers as rotor blades, and in 1784 demonstrated it to the French Academy of Sciences. ^[4] Look up Mechanic in Wiktionary, the free dictionary. ... Louis XIV visiting the Académie in 1671 The French Academy of Sciences (Académie des sciences) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. ...

In 1861, the word "helicopter" was coined by Gustave de Ponton d'Amécourt,^[4] a French inventor who demonstrated a small steam-powered model.

From 1860 to 1880, many small helicopter models were designed and made ^[4]. Examples were:

• 1870: Alphonse Pénaud: coaxial rotors, powered by twisted rubber bands.
• 1877: Emmanuel Dieuaide: counter-rotating rotors, steam-powered through a hose from a boiler on the ground.
• 1877: Melikoff: design for a man-carrier, almost certainly not built.
• 1878 or 1879: Dandrieux: counter-rotating rotors, 7.7-pound (3.5-kilogram) steam engine. It rose more than 40 feet (12 meters) and flew for 20 seconds.

In the 1880s, Thomas Edison experimented with small helicopter models in the USA: Alphonse Pénaud (1850–1880) was a major 19th century pioneer of aviation, inventor of the rubber powered model airplane and founder of the aviation industry. ... “Edison” redirects here. ...

• With a guncotton-powered engine: caused damage by explosions, tests ended.
• With an electric motor: showed that a large rotor with low blade area was needed.

Ján Bahýľ, a Slovak inventor, developed a helicopter model powered by an internal combustion engine, that in 1901 reached a height of 0.5 meters. On May 5, 1905 his helicopter reached 4 meters in altitude and flew for over 1500 meters.^[5] Nitrocellulose (Cellulose nitrate, guncotton) is a highly flammable compound formed by nitrating cellulose (e. ... Ján Bahýľ (25 May 1845, Zvolenská Slatina (in Hungarian: Nagyszalatna) (Kingdom of Hungary, today Slovakia) - 13 March 1916, Pressburg (Hungarian: Pozsony, today:Bratislava)) was a Slovak inventor mainly of flying machines. ... The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. ... Year 1901 (MCMI) was a common year starting on Tuesday (link will display calendar) of the Gregorian calendar (or a common year starting on Monday [1] of the 13-day-slower Julian calendar). ... is the 125th day of the year (126th in leap years) in the Gregorian calendar. ... For other uses, see 1905 (disambiguation). ...

In 1906, two French brothers, Jacques and Louis Breguet, began experimenting with airfoils for helicopters and in 1907, those experiments resulted in the Gyroplane No.1, which was the first known man-carrying helicopter. Although there is some discrepancy about the dates, sometime between 14 August and 29 September 1907, the Gyroplane No. 1 lifted its pilot up into the air about two feet (0.6 meters) for a minute.^[6] However, the Gyroplane No. 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. 1 are considered to be the first manned flight of a helicopter, but not a free or untethered flight. 1906 (MCMVI) was a common year starting on Monday (see link for calendar). ... Louis Charles Breguet (January 2, 1880 - May 4, 1955) was a French airplane designer and builder, one of the early aviation pioneers. ... is the 226th day of the year (227th in leap years) in the Gregorian calendar. ... is the 272nd day of the year (273rd in leap years) in the Gregorian calendar. ... Year 1907 (MCMVII) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 13-day-slower Julian calendar). ...

Paul Cornu's helicopter, built in 1907, was the first flying machine to have risen from the ground using rotor blades instead of wings.

In 1906, fellow French inventor Paul Cornu designed and built a helicopter that used two 20-foot (6-meter) counter-rotating rotors driven by a 24-hp (18-kW) Antoinette engine. On November 13, 1907, it lifted its inventor to 1 foot (0.3 meters) and remained aloft for 20 seconds. Although this flight was smaller in its achievement than that of the Breguet brothers, it was greater in accomplishment being that it was the first true free flight with a pilot. The Cornu helicopter would achieve a height of nearly 2 meters but also proved to be unstable and was abandoned after only a few flights.^[7] Image File history File links HE2G8. ... Image File history File links HE2G8. ... Paul Cornu, manufacturing cycles, he was the first piloted free flight in a rotary wing aircraft at Lisieux, Calvados, France on November 13, 1907. ... Paul Cornu, manufacturing cycles, he was the first piloted free flight in a rotary wing aircraft at Lisieux, Calvados, France on November 13, 1907. ... The Antoinette was a short-lived French automobile manufactured by a builder of airplanes and aircraft engines between 1906 and 1908. ... is the 317th day of the year (318th in leap years) in the Gregorian calendar. ... Year 1907 (MCMVII) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 13-day-slower Julian calendar). ...

In the early 1920s, Raul Pateras Pescara, an Argentinian working in Europe, demonstrated one of the first successful applications of cyclic pitch.^[8] His coaxial, contra-rotating, biplane rotors were able to be warped to cyclically increase and decrease the lift they produced; and the rotor hub could also tilt, both allowing the aircraft to move laterally without a separate propeller to push or pull it. Pescara is also credited with demonstrating the principle of autorotation, the method by which helicopters land safely after engine failure. By January 1924, Pescara's helicopter No. 3 was capable of flights up to 10 minutes. Autorotation is the engineering term for the aerodynamics providing lift in a rotor-driven aircraft such as autogyro or helicopter. ... For the rap album, see 1924 (album). ...

On 14 April 1924, one of Pescara's contemporaries, Frenchman Etienne Oemichen, set the first helicopter world record recognized by the Fédération Aéronautique Internationale, flying his helicopter 360 meters (1,181 feet).

On 18 April 1924, Pescara beat Oemichen's record, flying for a distance of 736m (nearly a half mile) in 4 minutes and 11 seconds (about 8 mph, 13 km/h) maintaining a height of six feet.^[9]

On 4 May 1924, Oemichen reclaimed the world record when he flew his No. 2 machine again for a 14-minute flight covering 5,550 feet (1.05 mi, 1.692 km) while climbing to a height of 50 feet (15 meters).^[9] Oemichen also set the 1-km closed-circuit record at 7 minutes 40 seconds.^[10]

During this time, Juan de la Cierva was developing and introducing the first practical autogyro. In 1923, the rotorcraft that became the basis for the modern helicopter began to take shape, in the form of an autogyro.^[11] Cierva discovered aerodynamic and structural deficiencies in his early designs that could cause his autogyros to flip over after takeoff. The flapping hinges Cierva designed allowed the rotor to develop lift equally on the left and right halves of the rotor disk. A crash in 1927 led to the development of the drag hinge.^[11] These two developments allowed for a stable rotor system, not only in a hover, but in forward flight. April 14 is the 104th day of the year (105th in leap years) in the Gregorian calendar, with 261 days remaining. ... For the rap album, see 1924 (album). ... Fédération Aéronautique Internationale The Fédération Aéronautique Internationale (FAI) is a standard setting and record-keeping body for aeronautics and astronautics. ... is the 108th day of the year (109th in leap years) in the Gregorian calendar. ... For the rap album, see 1924 (album). ... Juan de la Cierva (21 September 1895 – 19 December 1936) was a Spanish aeronautical engineer and pilot. ... Modern Autogyro, ELA-07, Casarrubios del Monte Airfield, Spain, 2004. ... Modern Autogyro, ELA-07, Casarrubios del Monte Airfield, Spain, 2004. ...

In 1922, Albert Gillis von Baumhauer, a Dutch aeronautical engineer, started studying VTOL rotor craft. His first prototype 'flew' ('hopped' and hovered really) on September 24, 1925, with Dutch Army-Air arm Captain Floris Albert van Heijst at the controls. The controls that Captain van Heijst used were Von Baumhauer's inventions, the cyclic and collective. Patents were granted to Von Baumhauer by the British Ministry of Aviation on January 31, 1927, under number 265,272. The Hawker Harrier, one of the famous examples of a plane with VTOL capability. ... is the 267th day of the year (268th in leap years) in the Gregorian calendar. ... Year 1925 (MCMXXV) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar. ... is the 31st day of the year in the Gregorian calendar. ... Year 1927 (MCMXXVII) was a common year starting on Saturday (link will display full calendar) of the Gregorian calendar. ...

In 1930 the Italian engineer Corradino d'Ascanio built 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,^[12] 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. This machine held modest FAI speed and altitude records for the time, including altitude (18 m), duration (8 minutes 45 seconds) and distance flown (1,078 m).^[12]

In 1931, Soviet aeronautical engineers Boris Yuriev and Alexei Cheremukhin began experiments with the TsAGI 1-EA helicopter. A single rotor helicopter, with dual forward and aft anti-torque propellers, it reached an altitude of 605 meters (1,984 ft) on August 14, 1932 with Cheremukhin at the controls.^[13] TsAGI is a transliteration of the Russian abbreviation for Центра́льный аэрогидродинами́ческий институ́т (ЦАГИ) or Tsentralniy Aerogidrodinamicheskiy Institut, the Central Aerohydrodynamic Institute. ... is the 226th day of the year (227th in leap years) in the Gregorian calendar. ... Year 1932 (MCMXXXII) was a leap year starting on Friday (the link will display full 1932 calendar) of the Gregorian calendar. ...

In 1935 Louis Breguet flew the Gyroplane Laboratoire, a twin coaxial rotor helicopter (like a Kamov). It had a tailplane. Its blades had cyclic pitch and collective pitch blade control. During tests on 26 September 1936, it reached 120km/h and an altitude of 158m. A flight on 24 November 1936 lasted more than one hour at 44.7km/h. The last prototype was destroyed in 1943 by an Allied air strike at Villacoublay airport. Louis Charles Breguet (January 2, 1880 - May 4, 1955) was a French airplane designer and builder, one of the early aviation pioneers. ... The Gyroplane Laboratoire is considered by some to be the first, practicable helicopter in the world. ... Kamov projects, 1999 Nikolai Ilyich Kamov started building his first rotor-winged aircraft in 1929, together with N. K. Skrzhinskii. ... Tailplane or horizontal stabilizer of a Boeing 737 A tailplane, also known as horizontal stabilizer, is a small lifting surface located behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed wing aircraft such as helicopters and gyroplanes. ... Cyclic pitch refers to a method of aligning the angle of attack of the rotor blades on a rotary-winged aircraft, such as a Helicopter, Autogiro or Gyrodyne. ... Refers to the pitch (or angle) of blades of a helicopter to direct movement. ... In general, allies are people or groups that have joined an alliance and are working together to achieve some common purpose. ... Strategic bombing is a military strategem used in a total war style campaign that attempts to destroy the economic ability of a nation-state to wage war. ... Vélizy-Villacoublay is a commune in the southwestern suburbs of Paris, France. ...

In 1936, the German Focke-Wulf Fw 61 became the first useful helicopter. The Fw 61 broke all of the helicopter world records in 1937. It was like a fixed-wing aircraft including a a tailplane and front propeller but with the wings replaced by long sideways struts with counter-rotating rotors on their ends. Nazi Germany used helicopters in small numbers during World War II. The Focke-Wulf Fw 61 was the first fully controllable helicopter. ... Nazism in history Nazi ideology Nazism and race Outside Germany Related subjects Lists Politics Portal         Nazism, or National Socialism (German: Nationalsozialismus), refers primarily to the totalitarian ideology and practices of the Nazi Party (National Socialist German Workers Party, German: Nationalsozialistische Deutsche Arbeiterpartei or NSDAP) under Adolf Hitler. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000...

The German Flettner Fl 282 Kolibri synchropter's hull was more like a modern helicopter's in shape, with no tail rotor, and counter-rotating intermeshing rotors set close together on the cabin top, each tilted outwards so that its blades would not hit the other rotor's shaft top. Models such as it were used in the Mediterranean Sea. Flettner was a German helicopter manufacturer during World War II, founded by Anton Flettner. ... The Flettner Fl 282 Kolibri is a single-seat open cockpit helicopter produced by Anton Flettner of Germany. ... Intermeshing rotor or synchropter helicopters have two sets of contra-rotating propellers mounted on axles mounted at slightly oblique angles so that the blades intermesh without colliding. ... Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. ... Composite satellite image of the Mediterranean Sea. ...

The German Focke Achgelis Fa 223 Drache was used in Europe. It was like a fixed-wing aircraft with long sideways rotor struts instead of wings, and tailplane, and no front propeller. Focke-Achgelis was a German helicopter company founded in 1937 by Henrich Focke, and Gerd Achgelis. ... This article or section does not cite any references or sources. ...

Sikorsky Aircraft's first helicopter (the Vought-Sikorsky 300) flew, first tethered in 1939, and then free in 1940. It had one main rotor and a tail rotor. Sikorsky is an American aircraft and helicopter manufacturer. ... ...

In May 1942, mass production of the the Sikorsky R-4 began for the United States Army. It was the first mass produced helicopter in the world.^[14] The R-4 was used in Burma for rescue duties during World War II.^[15] It was also used by the Royal Air Force, the first British military unit to be equipped with helicopters being the Helicopter Training School, formed in January 1945 at RAF Andover with nine Sikorsky R-4B Hoverfly I helicopters. Sikorsky R-4B at National Museum of the United States Air Force The Sikorsky R-4 was the worlds third production helicopter, after the German Focke-Achgelis FA 223 Drache and the Flettner Fl 282, It was the United States Air Forces first service helicopter. ... “RAF” redirects here. ... , For both the types of transport aircraft called Andover used by the RAF, see Avro Andover (1920s) and Hawker Siddeley Andover (1960s-present day). ... Sikorsky R-4B at National Museum of the United States Air Force The Sikorsky R-4 was the worlds third production helicopter, after the German Focke-Achgelis FA 223 Drache and the Flettner Fl 282, It was the United States Air Forces first service helicopter. ...

In 1943 the VS300 was introduced to the US Navy.

In March 1946, the Bell 47 designed by Arthur Young became the first helicopter to be licensed for certified civilian use in the United States. In 1967, the Bell 206 became the most successful commercial helicopter ever built, with more hours and more industry records than any other aircraft in the world. The Bell 47 was the first helicopter to be certified for civil use on 8 March 1946. ... Arthur Middleton Young (November 3, 1905–1995) was inventor of the Bell helicopter, as well as a cosmologist, philosopher and author. ... The Bell Helicopter Model 206 JetRanger is a two-bladed main rotor, turbine powered helicopter with a conventional, two-bladed tail rotor. ...

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, pioneered by the Kaman K-225 synchropter, [1], which first flew with gas turbine power late in 1951, led to the development of larger, faster, and higher-performance helicopters. Turboshaft engines are the preferred powerplant for all but the smallest and least expensive helicopters today. Schematic diagram showing the operation of a simplified turboshaft engine. ...

Uses of helicopters

A Polish Army's PZL SW-4 Tawny Owl.

Image File history File linksMetadata Download high-resolution version (1340x672, 354 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Polish Air Force Equipment of the Polish Army PZL SW-4 Puszczyk Timeline of Polish science and technology... Image File history File linksMetadata Download high-resolution version (1340x672, 354 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Polish Air Force Equipment of the Polish Army PZL SW-4 Puszczyk Timeline of Polish science and technology... Polish Air Force (Siły Powietrzne Rzeczypospolitej Polskiej, Siły Powietrzne RP). ... PZL SW-4 prototype PZL SW-4 #0203 of Polish Air Force The PZL SW-4 is a Polish light single-engine multipurpose helicopter manufactured by PZL Świdnik. ...

Aerial cranes

Main article: Aerial crane

One of the most unusual commercial uses of helicopters is the aerial crane or skycrane. As aerial cranes, helicopters carry loads connected to long cables or slings in order to place heavy equipment such as 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, far from the nearest road. One of the most unusual commercial uses of helicopters is the aerial crane or skycrane. ...

Helicopters were first used as aerial cranes in the 1950s, but it was not until the 1960s that the popularity of the use of skycranes in the construction and other industries began to catch on. The most popular use of helicopters as aerial cranes is in the logging industry to lift large trees out of rugged terrain where vehicles aren't able to reach, or where environmental concerns prohibit the building of roads. These operations are referred to as longline because of the long, single sling line used to carry the load.

Aerial firefighting

A Kern County (California) Fire Department Bell 205 drops water during a training exercise at the Mojave Spaceport.

Main article: helitack

Aerial firefighting (or water bombing) is a method to combat wildfires that often uses helicopters. Helicopters may be fitted with tanks or carry buckets or deliver firefighters who rappel to the ground below. Buckets are usually filled by submerging in lakes, rivers, reservoirs, or portable tanks. The most popular of the buckets is the flexible Bambi bucket. Tanks may be filled on the ground or water may be siphoned from lakes or reservoirs through a hanging snorkel. Helicopters are also used to resupply firefighters on the ground with tools, food, water and other supplies. Popular firefighting helicopters include variants of the Bell 204 and the Erickson S-64 Aircrane helitanker. The Erickson helitanker also has a sea snorkel for filling while in flight. Image File history File links Metadata Size of this preview: 800 × 583 pixelsFull resolution (2008 × 1464 pixel, file size: 559 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Metadata Size of this preview: 800 × 583 pixelsFull resolution (2008 × 1464 pixel, file size: 559 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Kern County is a county located in the southern Central Valley of California. ... Firefighter with an axe A firefighter, sometimes still called a fireman though women have increasingly joined firefighting units, is a person who is trained and equipped to put out fires, rescue people and in some areas provide emergency medical services. ... The Mojave Spaceport (IATA: MHV, ICAO: KMHV) , also known as the Mojave Airport and Civilian Aerospace Test Center, is located in Mojave, California, at an elevation of 2,791 feet. ... Santa Barbara County helitack crew and a Bell 212 on the Day Fire. ... A USMC CH-53 Super Stallion drops water from a Bambi Bucket during a training excercise. ... CH-54 Tarhe carrying an M551 Sheridan tank on a sling mount in Vietnam. ...

Air ambulance

Main article: Air ambulance

Helicopters are often used as an air ambulance for emergency medical assistance in situations where either a traditional ambulance cannot easily or quickly reach the scene or when a patient needs to be transported at a distance where air transportation is most practical. Air ambulance crews are supplied with equipment that enables them to provide medical treatment to a critically injured or ill patient. The use of helicopters as an air ambulance is sometimes referred to as MEDEVAC, or patients are referred to as being "airlifted", or "medevaced". Ontario Health air ambulance An air ambulance is an aircraft used for emergency medical assistance in situations where either a traditional ambulance cannot easily or quickly reach the scene or the patient needs to be repositioned at a distance where air transportation is most practical. ... A [PC-12] of the Royal Flying Doctor Service of Australia. ...

Law enforcement

Main article: Police aircraft

Police departments and other law enforcement agencies use helicopters to search for and pursue suspects. Since helicopters can achieve a unique aerial view and don't need to negotiate ground obstacles, 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. MBB/Kawasaki BK 117 B2 (North Rhine-Westphalia), Germany. ... Image of a small dog taken in mid-infrared (thermal) light (false-color). ...

Military helicopters

Main article: Military helicopters

Indian Army's HAL Dhruv.

Military forces use helicopters to conduct aerial attacks on ground targets. Such helicopters are mounted with missile launchers and miniguns. Militaries also use transport helicopters to ferry troops in and out of constrained combat zones where the lack of an airstrip would make transport via fixed-wing aircraft impossible. This article or section is in need of attention from an expert on the subject. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1024 × 768 pixel, file size: 146 KB, MIME type: image/jpeg) Para drop operation using HAL Dhruv helicopter. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1024 × 768 pixel, file size: 146 KB, MIME type: image/jpeg) Para drop operation using HAL Dhruv helicopter. ... This article is about the post-independence Indian Army. ... The HAL Dhruv (Sanskrit:Pole Star) is a multi-role advanced helicopter made by Hindustan Aeronautics Limited (HAL). ... Rocket launcher or missile launcher can mean: Bazooka Multiple rocket launcher Shoulder-launched missile weapon Transporter erector launcher (TEL) for large missiles Rocket propelled grenade launcher Categories: | ... A helicopter-mounted minigun A minigun is a multibarreled machine gun with a high rate of fire (several thousand rounds per minute), employing Gatling-style rotating barrels. ... An airstrip is a kind of airport that consists only of a runway with perhaps fueling equipment. ...

Motion picture photography

Main article: Motion picture photography

In the United States, use of helicopters in making films and television can fall under the safety rules set by collective bargaining. For instance, bargaining agents have guidelines that all aerial coordinators and/or pilots in command possess a current FAA approved Motion Picture and Television Operations Manual.^[16] This article needs additional references or sources for verification. ... Film may refer to: photographic film a motion picture in academics, the study of motion pictures as an art form a thin skin or membrane, or any covering or coating, whether transparent or opaque a thin layer of liquid, either on a solid or liquid surface or free-standing Film...

News gathering

Main article: electronic news gathering

Helicopters are often used by news services to observe scenes where newsworthy incidents have occurred. The helicopter can carry a camera to capture an aerial view of a scene, to be recorded for later broadcast or transmitted to a newsroom for live broadcast. News helicopters are most often used to report on traffic conditions of local roads, highways, and bridges. In 1974, Joseph Flaherty, then vice-president at CBS Inc. ...

Other uses

• Search and Rescue
• Aerial still photography
• Logging
• Transport
• Civilian touring/personal pleasure

Search and Rescue (acronym SAR) is an operation mounted by emergency services, often well-trained volunteers, to find someone believed to be in distress, lost, sick or injured either in a remote or difficult to access area, such as mountains, desert or forest (Wilderness search and rescue), or at sea... The Georgian terrace of Royal Crescent (Bath, England) from a hot air balloon Intersection of E42 and E451 from an aircraft soon after takeoff from Frankfurt International Airport Moreton Island in Queensland, Australia Aerial photography is the taking of photographs from the air with a camera mounted, or hand held... Logging is the process in which trees are cut down usually as part of a timber harvest which is good for the environment. ...

Helicopter configurations

Most helicopters have a single main rotor but require a separate rotor to overcome torque. This is accomplished through a variable pitch, antitorque rotor or tail rotor. This is the design that Igor Sikorsky settled on for his VS-300 helicopter and it has become the recognized convention for helicopter design, although designs do vary. When viewed from above, designs from Germany, United Kingdom and the United States are said to rotate counter-clockwise, all others are said to rotate clockwise. This can make it difficult when discussing aerodynamic effects on the main rotor between different designs, since the effects may manifest on opposite sides of each aircraft. For another meanings and similar spellings, see Sikorsky. ... ...

Antitorque

Antitorque
Torque effect on a helicopter

For a helicopter with a single main rotor, torque develops as the engine turns the rotor, creating a torque effect which causes the body of the helicopter to turn in the opposite direction of the rotor. To eliminate this effect, some sort of antitorque control must be used, with a sufficient margin of power available to allow the helicopter to maintain its heading and provide yaw control. The three most common controls used today are the traditional tail rotor, Eurocopter's Fenestron (also called a fantail), and MD Helicopters' NOTAR. Image File history File links Size of this preview: 765 × 599 pixels Full resolution (923 × 723 pixel, file size: 52 KB, MIME type: image/jpeg) Description of helicopter torque effect. ... Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque (or often called a moment) can informally be thought of as rotational force or angular force which causes a change in rotational motion. ... This gyroscope remains upright while spinning due to its angular momentum. ... Fenestron on Eurocopter EC120B A Fenestron (or Fantail) is a totally enclosed tail rotor of a helicopter that has a tail rotor configuration. ... MD Helicopters is an aerospace company that produces helicopters primarily for commerical use. ... MD 900 (German police) NOTAR, an acronym for NO TAil Rotor, is a helicopter stabilization process developed by McDonnell Douglas Helicopter Systems which eliminates the use of tail rotors on helicopters, yielding quieter and safer operation. ...

Tail rotor of an SA 330 Puma

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Tail rotor

The tail rotor is a smaller rotor mounted vertically or near-vertical on the tail of a traditional single-rotor helicopter. The tail rotor either pushes or pulls against the tail to counter the torque. The tail rotor drive system consists of a drive shaft powered from the main transmission and a gearbox mounted at the end of the tail boom. The drive shaft may consist of one long shaft or a series of shorter shafts connected at both ends with flexible couplings. The flexible couplings allow the drive shaft to flex with the tail boom. The gearbox at the end of the tailboom provides an angled drive for the tail rotor and may also include gearing to adjust the output to the optimum RPM for the tail rotor. On some larger helicopters, intermediate gearboxes are used to transition the tail rotor drive shaft from along the tailboom or tailcone to the top of the tail rotor pylon which also serves as a vertical stabilizing airfoil to alleviate the power requirement for the tail rotor in forward flight. It may also serve to provide limited antitorque within certain airspeed ranges in the event that the tail rotor or the tail rotor flight controls fail. rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On...

Fenestron

Main article: Fenestron

Fenestron on a EC 120B

A Fenestron (or Fantail) is a ducted fan mounted on the tail boom of the helicopter and used in place of a tail rotor. Its housing is integral with the tail skin, and while conventional tail rotors typically possess a maximum of 5 rotor blades, Fenestrons have between 8 and 18 blades. These are arranged in varying distance, so that the noise is distributed over different frequencies and thus appears quieter. The housing allows a higher rotational speed than a conventional rotor and therefore it can have a smaller size than a conventional rotor. Fenestron on Eurocopter EC120B A Fenestron (or Fantail) is a totally enclosed tail rotor of a helicopter that has a tail rotor configuration. ... The fenestron (tail-rotor shrouding) of Eurocopter EC120B, built 2002, photographed at the Heli-Day, Kemble Airfield, England, in August 2003. ... The fenestron (tail-rotor shrouding) of Eurocopter EC120B, built 2002, photographed at the Heli-Day, Kemble Airfield, England, in August 2003. ... A ducted fan is an arrangement of a propeller-driven aircraft where the propeller is mounted inside the fuselage, within a duct. ...

The Fenestron tail rotor was used for the first time at the end of the 1960s on the second experimental model of Sud Aviation's SA 340, and on the later model Aérospatiale SA 341 Gazelle. Besides Eurocopter and its predecessors, a ducted fan tail rotor was also used on the canceled military helicopter project, the United States Army's RAH-66 Comanche. The 1960s decade refers to the years from 1960 to 1969, inclusive. ... Sud Aviation was a French state-owned aircraft manufacturer, originating from the merger of SNCASE (Société Nationale de Constructions Aéronautiques du Sud-Est) and SNCASO (Société Nationale de Constructions Aéronautiques du Sud-Ouest) on March 1, 1957. ... The Gazelle is a French-designed helicopter, created by the company Sud Aviation, that later became Aérospatiale, and later still Eurocopter. ... The Eurocopter Group is a global helicopter manufacturing and support company formed in 1992 from the merger of the helicopter divisions of French Aérospatiale and German DaimlerChrysler Aerospace AG (DASA). ... The United States Army is the largest and oldest branch of the armed forces of the United States. ... The Boeing/Sikorsky RAH-66 Comanche was an advanced U.S. Army military helicopter intended for the armed reconnaissance role, incorporating stealth techniques. ...

NOTAR

Main article: NOTAR

NOTAR, an acronym for NO TAil Rotor, is a relatively new helicopter anti-torque system originally developed by Hughes Helicopters and currently produced by MD Helicopters which eliminates the use of the tail rotor on a helicopter. MD 900 (German police) NOTAR, an acronym for NO TAil Rotor, is a helicopter stabilization process developed by McDonnell Douglas Helicopter Systems which eliminates the use of tail rotors on helicopters, yielding quieter and safer operation. ... Hughes Helicopters was a major manufacturer of military helicopters, now part of The Boeing Company. ... Traditional Tail rotor of an Aérospatiale Puma The tail rotor of a helicopter is mounted on the tail of a traditional single-rotor helicopter, close to perpendicular to the main rotor. ...

Diagram showing the movement of air through the NOTAR system.

Although the concept, which uses the Coandă effect, took some time to refine, the NOTAR system is simple in theory and works to provide antitorque the same way a wing develops lift.^[17] A variable pitch fan is enclosed in the aft fuselage section immediately forward of the tail boom and driven by the main rotor transmission. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Coanda effect as demonstrated with a spoon and a water stream. ... MD 900 (German police) NOTAR, an acronym for NO TAil Rotor, is a helicopter stabilization process developed by McDonnell Douglas Helicopter Systems which eliminates the use of tail rotors on helicopters, yielding quieter and safer operation. ...

MD Helicopters 520N NOTAR

This fan forces low pressure air through two slots on the left side of the tailboom, causing the downwash from the main rotor to hug the tailboom, producing lift, and thus a measure of antitorque proportional to the amount of airflow from the rotorwash. This is augmented by a direct jet thruster (which also provides directional yaw control) and vertical stabilizers. Image File history File linksMetadata Size of this preview: 800 × 600 pixels Full resolution (2816 × 2112 pixel, file size: 1. ... Image File history File linksMetadata Size of this preview: 800 × 600 pixels Full resolution (2816 × 2112 pixel, file size: 1. ...

Development of the NOTAR system dates back to 1975 when engineers at Hughes Helicopters began concept development work.^[17] In December 1981 Hughes flew a OH-6A fitted with NOTAR for the first time.^[18] A more heavily modified prototype demonstrator first flew in March 1986 and successfully completed an advanced flight-test program, validating the system for future application in helicopter design.^[19] Hughes Helicopters was a major manufacturer of military helicopters, now part of The Boeing Company. ... The Hughes H-6 is a family of light utility civilian and assault helicopters of the United States Army. ...

There are three production helicopters that utilize the NOTAR system, all produced by MD Helicopters:

• MD 520N - a NOTAR variant of the Hughes/MD500 series helicopter is seen in the movie Mission: Impossible
• MD 600N - a larger version of the MD 520N, is seen in the James Bond film Die Another Day
• MD Explorer - a twin-engine, 8-seat light helicopter.

The MD Helicopters MD 500 series is a family of light utility civilian and military helicopters. ... The MD Helicopters MD 500 series is a family of light utility civilian and military helicopters. ... Mission: Impossible (1996) is a film directed by Brian De Palma and featuring Tom Cruise, based on the television series Mission: Impossible. ... The MD Helicopters MD 600N is a light utility civilian helicopter. ... For the theme song of the same movie, performed by Madonna, see Die Another Day (song). ... MD-900 (N900MH) Helicopter Noise Abatement Test MD 902 Explorer of the Kent Air Ambulance The MD Helicopters MD Explorer is a light twin utility helicopter. ...

Dual rotors (contra-rotating)

Contra-rotating rotors, are rotorcraft configurations with a pair or more of large horizontal rotors turning in opposite directions to counteract the effects of torque on the aircraft without relying on an antitorque tail rotor. Primarily, there are three common configurations that utilize the contra-rotating effect to benefit the rotorcraft; tandem rotors are two rotors with one mounted behind the other, coaxial rotors are two rotors that are mounted one above the other with the same axis, and intermeshing rotors are two rotors that are mounted close to each other at enough angle to allow the rotors to intermesh over the top of the aircraft. Another configuration found on tiltrotors and some earlier helicopters is called transverse rotors where the pair of rotors is mounted at each end of a wing-type structure or outriggers. It has been suggested that this article or section be merged with Rotary-wing aircraft. ... A rotor is the rotating part of a helicopter which generates lift, either vertically in the case of a main rotor, or horizontally in the case of a tail rotor. ...

CH-47 Chinook

Image File history File linksMetadata Download high resolution version (3000x2000, 798 KB) Summary Licensing File links The following pages link to this file: Spanish Army FAMET Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ... Image File history File linksMetadata Download high resolution version (3000x2000, 798 KB) Summary Licensing File links The following pages link to this file: Spanish Army FAMET Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ... The Boeing CH-47 Chinook is a versatile, twin-engine, tandem rotor heavy-lift helicopter. ...

Tandem

Main article: Tandem rotors

Tandem rotors are two horizontal main rotor assemblies mounted one behind the other with the rear rotor mounted slightly higher than the front rotor. Tandem rotors achieve pitch attitude changes to accelerate and decelerate the helicopter through a process called differential collective pitch. To pitch forward and accelerate, the rear rotor increases collective pitch, raising the tail and the front rotor decreases collective pitch, simultaneously dipping the nose. To pitch upward while decelerating (or moving rearward), the front rotor increases collective pitch to raise the nose and the rear rotor decreases collective pitch to lower the tail. Yaw control is developed through opposing cyclic pitch in each rotor; to pivot right, the front rotor tilts right and the rear rotor tilts left, and to pivot left, the front rotor tilts left and the rear rotor tilts right. Tandem rotor helicopters have two large horizontal rotor assemblies instead of one main assembly and a smaller tail rotor. ...

Coaxial

Main article: Coaxial rotors

Kamov Ka-50

Coaxial rotors are a pair of rotors turning in opposite directions, but mounted on a mast, with the same axis of rotation, one above the other. The advantage of the coaxial rotor is that, in forward flight, the lift provided by the advancing halves of each rotor compensates for the retreating half of the other, eliminating one of the key effects of dissymmetry of lift; retreating blade stall. However, other design considerations plague coaxial rotors. There is an increased mechanical complexity of the rotor system because it requires linkages and swashplates for two rotor systems. Add that each rotor system needs to be turned in opposite directions means that the mast itself is more complex, and provisions for making pitch changes to the upper rotor system must pass through the lower rotor system. Kamov Ka-50 Coaxial rotor Miltary Attack Helicopter In the field of helicopter design there are three principal arrangements of the rotor blades, the traditional single rotor with tail rotor, the tandem twin rotors (two separate sets of rotor blades turning in opposite senses), and coaxial twin rotors, AKA Dual... Image File history File linksMetadata Size of this preview: 800 × 600 pixels Full resolution (2592 × 1944 pixel, file size: 581 KB, MIME type: image/jpeg) Kamov Ka-50 File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Helicopter User... Image File history File linksMetadata Size of this preview: 800 × 600 pixels Full resolution (2592 × 1944 pixel, file size: 581 KB, MIME type: image/jpeg) Kamov Ka-50 File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Helicopter User... This article does not cite any references or sources. ... A swashplate is a device that translates the pilots (or autopilots) commands via the helicopter flight controls into motion of the main rotor blades. ...

HH-43 Huskie

Image File history File links Size of this preview: 728 × 600 pixels Full resolution (2300 × 1895 pixel, file size: 366 KB, MIME type: image/jpeg) Fire protection specialists fight a fire as an HH-43B Husky helicopter hovers overhead to create a continuous downward air current, assisting the crew members. ... Image File history File links Size of this preview: 728 × 600 pixels Full resolution (2300 × 1895 pixel, file size: 366 KB, MIME type: image/jpeg) Fire protection specialists fight a fire as an HH-43B Husky helicopter hovers overhead to create a continuous downward air current, assisting the crew members. ... The Kaman HH-43 Huskie is a helicopter used by the United States Air Force, the United States Navy and the United States Marine Corps in the 1950s through 1970s. ...

Intermeshing

Main article: Intermeshing rotors

Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. This configuration is sometimes referred to as a synchropter. Intermeshing rotors have high stability and powerful lifting capability. The arrangement was successfully used in Nazi Germany for a small anti-submarine warfare helicopter, the Flettner Fl 282 Kolibri. During the Cold War, the American company, Kaman Aircraft produced the HH-43 Huskie for the USAF firefighting and rescue missions. The latest Kaman model, the Kaman K-MAX, is a dedicated sky crane design. Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. ... “A/S” redirects here. ... The Flettner Fl 282 Kolibri is a single-seat open cockpit helicopter produced by Anton Flettner of Germany. ... For other uses, see Cold War (disambiguation). ... Kaman Aircraft was founded in 1945 by Charles Kaman. ... The Kaman HH-43 Huskie is a helicopter used by the United States Air Force, the United States Navy and the United States Marine Corps in the 1950s through 1970s. ... Seal of the Air Force. ... The Kaman K-MAX (also known as the K-1200) is a purpose-built helicopter with intermeshing rotors specializing in external load operations. ...

Transverse

Mi-12

Transverse rotors are mounted on the end of wings or outriggers, perpendicular to the body of the aircraft. Similar to tandem rotors and intermeshing rotors, the transverse rotor also utilizes differential collective pitch. But like the intermeshing rotors, the transverse rotors use the concept for changes in the roll attitude of the rotorcraft. This configuration is found on two of the first viable helicopters, the Focke-Wulf Fw 61 and the Focke-Achgelis Fa 223, as well as the world's largest helicopter ever built, the Mil Mi-12. It is also the configuration found on tiltrotors, such as Bell's XV-15 and the newer V-22 Osprey. Image File history File linksMetadata Size of this preview: 800 × 533 pixels Full resolution (3888 × 2592 pixel, file size: 4. ... Image File history File linksMetadata Size of this preview: 800 × 533 pixels Full resolution (3888 × 2592 pixel, file size: 4. ... Mil Mi-12 (behind a T-10, prototype of the Su-27) The Soviet made Mil Mi-12 (Also known as the V-12, NATO reporting name Homer) is the largest helicopter ever built. ... The Focke-Wulf Fw 61 was the first fully controllable helicopter. ... Fa 223 V 11 during tests in Travemünde The Focke-Achgelis FA 223 Drache (Dragon) was a helicopter that was developed by Germany during World War II, notable for being the first helicopter to attain production status. ... The Mil Mi-12 (Also known as the V-12, NATO reporting name Homer) was a Soviet heavy transport helicopter. ... XV-15 at National Air and Space Museum The Bell XV-15 was the first successful experimental tiltrotor VTOL airplane. ... The V-22 Osprey is a joint service, multimission, military tiltrotor aircraft with both a vertical takeoff and landing (VTOL) and short takeoff and landing capability (STOL). ...

Tip jets

The most unusual helicopter configuration is the tip jet rotor, where a single main rotor is not driven by the mast, but from nozzles on the tip of the rotor blade; which are either pressurized from a fuselage-mounted gas turbine or have their own pulsejet, ramjet or rocket thrusters. Although this method is simple and eliminates torque, the prototypes that have been built are less fuel efficient than conventional helicopters and produce more noise. One example, the Percival P.74, was not even able to leave the ground, and the Hiller YH-32 Hornet had good lifting capability but was otherwise poor. The Fairey Jet Gyrodyne and 40-seat Fairey Rotodyne flew very well indeed. Possibly the most unusual was the Rotary Rocket Roton ATV. None have made it into production. A pulse jet engine is a very simple form of internal combustion engine wherein the combustion occurs in pulses and the propulsive effort is a reaction to the rearward flow of hot gasses. ... A ramjet, sometimes referred to as a stovepipe jet, is a type of jet engine. ... A cold (un-ignited) rocket engine test at NASA A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. ... Hunting Percival P.74 c. ... The Hiller YH-32 Hornet was built by Hiller Aircraft in the early 1950s. ... The Fairey Jet Gyrodyne was a British experimental gyrodyne aircraft, a form of compound helicopter related to autogyros, built by Fairey Aviation. ... The Fairey Rotodyne was a British compound autogyro intended for commercial and military applications in the 1950s and early 1960s. ... The Roton was a launch vehicle design for a cone-shaped single-stage-to-orbit (SSTO) fully reusable manned spacecraft. ...

Helicopter rotor system

Main article: Helicopter rotor

The rotor system, or more simply rotor, is the rotating part of a helicopter which generates lift. A rotor system may be mounted horizontally as main rotors are, providing lift vertically, or it may be mounted vertically, such as a tail rotor, to provide lift horizontally as thrust to counteract torque effect. In the case of tiltrotors, the rotor is mounted on a nacelle that rotates at the edge of the wing to transition the rotor from a horizontal mounted position, providing lift horizontally as thrust, to a vertical mounted position providing lift exactly as a helicopter. A rotor is the rotating part of a helicopter which generates lift, either vertically in the case of a main rotor, or horizontally in the case of a tail rotor. ... The lift force, lifting force or simply lift is a mechanical force generated by solid objects as they move through a fluid. ... This article or section does not cite its references or sources. ...

The rotor consists of a mast, hub and rotorblades. The mast is a cylindrical metal shaft which extends upwards from and is driven by the transmission. At the top of the mast is the attachment point for the rotor blades called the hub. The rotor blades are then attached to the hub by a number of different methods. Main rotor systems are classified according to how the main rotor blades are attached and move relative to the main rotor hub. There are three basic classifications: semirigid, rigid, or fully articulated, although some modern rotor systems use an engineered combination of these types.

Semirigid

Robinson Helicopter R44 Raven II

A semirigid rotor system allows for two different movements, flapping and feathering. This system is normally comprised of two blades, which are rigidly attached to the rotor hub. The hub is then attached to the rotor mast by a trunnion bearing or teetering hinge and is free to tilt with respect to the main rotor shaft. This allows the blades to see-saw or flap together. As one blade flaps down, the other flaps up. Feathering is accomplished by the feathering hinge, which changes the pitch angle of the blade. Since there is no vertical drag hinge, lead-lag forces are absorbed through blade bending. Image File history File links Size of this preview: 800 × 546 pixelsFull resolution (2418 × 1650 pixel, file size: 2. ... Image File history File links Size of this preview: 800 × 546 pixelsFull resolution (2418 × 1650 pixel, file size: 2. ... Robinson R44 Helicopter The Robinson Helicopter Company of Torrance, California manufactures more civil helicopters than any other company in the world. ...

Helicopters with semi-rigid rotors are vulnerable to a condition known as mast bumping which can cause the rotor flap stops to shear the mast. Mast bumping is normally encountered during low-G maneuvers, so it is written into the operator's handbook to avoid any low-G conditions.

Fully articulated

In a fully articulated rotor system, each rotor blade is attached to the rotor hub through a series of hinges, which allow the blade to move independently of the others. These rotor systems usually have three or more blades. The blades are allowed to flap, feather, and lead or lag independently of each other. The horizontal hinge, called the flapping hinge, allows the blade to move up and down. This movement is called flapping and is designed to compensate for dissymmetry of lift. The flapping hinge may be located at varying distances from the rotor hub, and there may be more than one hinge. The vertical hinge, called the lead-lag or drag hinge, allows the blade to move back and forth. This movement is called lead-lag, dragging, or hunting. Dampers are usually used to prevent excess back and forth movement around the drag hinge. The purpose of the drag hinge and dampers is to compensate for the acceleration and deceleration caused by Coriolis Effect. Each blade can also be feathered, that is, rotated around its spanwise axis. Feathering the blade means changing the pitch angle of the blade. By changing the pitch angle of the blades you can control the thrust and direction of the main rotor disc. It has been suggested that Dissymetry of Lift be merged into this article or section. ... In the inertial frame of reference (upper part of the picture), the black object moves in a straight line. ...

Rigid

In a rigid rotor system, the blades, hub, and mast are