A helicopter is an aircraft that is lifted and propelled by one or more horizontal rotors, each rotor consisting of two or more rotor blades. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout In the context of a Fluid flow relative to a body the lift force is the component of the Aerodynamic force that is Perpendicular to the flow In Astronomy, Geography, Geometry and related sciences and contexts a plane is said to be horizontal at a given point if it is locally A helicopter rotor is the rotating part of a Helicopter which generates an aerodynamic Force. 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. Classes of rotorcraft Helicopter See also Helicopter A helicopter is a rotorcraft whose rotors are driven by the engine(s throughout the flight Overview Fixed-wing aircraft range from small training and recreational aircraft to Wide-body aircraft and military cargo aircraft. The word 'helicopter' is adapted from the French hélicoptère, coined by Gustave de Ponton d'Amecourt in 1861. French ( français,) is a Romance language spoken around the world by 118 million people as a native language and by about 180 to 260 million people It is linked to the Greek words helix/helik- (ἕλικ-) = "spiral" or "turning" and pteron (πτερόν) = "wing". ^[1][2]

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. This creates the ability for the helicopter to take off and land vertically without the need for runways. Takeoff is the phase of Flight in which an Aircraft goes through a transition from moving along the ground ( Taxiing) to flying in the air usually Landing is the last part of a Flight, where a flying Animal, Aircraft, or Spacecraft returns to the ground For this reason, helicopters are often used in congested or isolated areas where fixed-wing aircraft are not able to take off or land. The lift from the rotor also allows the helicopter to hover in one area and to do so more efficiently than other forms of vertical takeoff and landing (VTOL) aircraft, allowing it to accomplish tasks that fixed-wing aircraft are unable to perform. Takeoff is the phase of Flight in which an Aircraft goes through a transition from moving along the ground ( Taxiing) to flying in the air usually VTOL is an abbreviation for Vertical Take-Off and Landing. VTOL describes Fixed-wing aircraft that can lift off vertically

Although helicopters were developed and built during the first half-century of flight, some even reaching limited production, it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production,^[3] with 131 aircraft built. Igor Sikorsky (25 May 1889 &ndash 26 October 1972 was born Igor Ivanovich Sikorsky (Игорь Иванович Сикорский Mass production (also called flow production, repetitive flow production, series production, or serial production) is the production of ^[4] Even though most previous designs used 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. The tail rotor of a Helicopter is mounted on the tail of a traditional single-rotor helicopter close to perpendicular to the main rotor.

Contents 1 History 1.1 First flights 1.2 Early development 1.3 Birth of an industry 1.4 Turbine age 2 Uses 2.1 Other uses 3 Rotor configurations 3.1 Single main rotor 3.1.1 Tail rotor 3.1.2 Ducted fan 3.1.3 NOTAR 3.1.4 Tip jets 3.2 Dual rotors (contra-rotating) 3.2.1 Tandem 3.2.2 Coaxial 3.2.3 Intermeshing 3.2.4 Transverse 4 Helicopter rotor system 4.1 Semirigid 4.2 Fully articulated 4.3 Rigid 4.4 Combination 5 Controlling flight 5.1 Flight conditions 6 Alternative power sources 7 Limitations 8 Hazards of helicopter flight 8.1 Deadliest helicopter crashes 9 See also 10 References 10.1 Notes 10.2 Bibliography 11 External links

History

Since 400 AD, Chinese children have played with bamboo flying tops. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Bamboo-copter (竹蜻蜓 "bamboo dragonfly" is a Chinese children's Toy invented around 400 CE. This toy made its way to Europe and is depicted in a 1463 European painting. ^[5] Pao Phu Tau (抱朴子) was a 4th-century book in China reported to describe some of the ideas inherent to rotary wing aircraft:^[6]

“

Someone asked the master about the principles of mounting to dangerous heights and traveling into the vast inane. The Master said, "Some have made flying cars 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. Ziziphus zizyphus (from Greek ζίζυφον - zizuphon, syn Z "[7]

”

Leonardo da Vinci conceived a machine that could be described as an "aerial screw". Leonardo di ser Piero da Vinci ( April 15 1452 – May 2 1519 was an Italian Polymath, having been a scientist Mathematician, Engineer ^[8] He wrote that he made small flying models ^[9] but could not stop the rotor from making the whole craft rotate. Later machines would more closely resemble the ancient bamboo flying top, with spinning wings rather than screws.

In July 1754, Mikhail Lomonosov showed the Russian Academy of Sciences a small coaxial rotor powered by a wound-up spring, intended to lift meteorological instruments. Mikhail Vasilyevich Lomonosov (Михаи́л Васи́льевич Ломоно́сов () was a Russian Polymath, scientist The Russian Academy of Sciences (Российская Академия Наук Rossi'iskaya Akade'miya Nau'k, shortened to PAH RAN) consists of the National Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary ^[9]

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. A mechanic is a person who uses Tools to repair things (generally machinery or works to keep things operating properly A turkey is either of two extant Species of large Birds in the Genus Meleagris native to North America. The French Academy of Sciences ( French: Académie des sciences) is a Learned society, founded in 1666 by Louis XIV at the ^[9]

In 1861, the word "helicopter" was coined by Gustave de Ponton d'Amécourt,^[9] a French inventor who demonstrated a small steam-powered model. This article is about the country For a topic outline on this subject see List of basic France topics.

From 1860 to 1880, many small helicopter models were designed and made. ^[9] These included Alphonse Pénaud's model coaxial rotors, powered by twisted rubber bands (1870). Alphonse Pénaud ( May 31, 1850 &ndash October 22, 1880) was a 19th-century French pioneer of Aviation, inventor Enrico Forlanini's unmanned helicopter was powered by a steam engine. Enrico Forlanini ( December 13 1848 - October 9 1930) was an Italian engineer inventor and aeronautical pioneer well known It was the first of its type that rose to a height of 13 meters, where it remained for some 20 seconds, after a vertical take-off from a park in Milan (1877). Emmanuel Dieuaide's design featured counter-rotating rotors and was steam-powered through a hose from a boiler on the ground (1877). Melikoff designed a "man carrier," but it was almost certainly not built (1877). Dandrieux's design had counter-rotating rotors and a 7. 7-pound (3. 5-kilogram) steam engine. It rose more than 40 feet (12 meters) and flew for 20 seconds (circa 1878).

In the 1880s, Thomas Edison experimented with small helicopter models in the USA. First he used a guncotton-powered engine, but it caused damage by explosions, and tests were ended. Nitrocellulose (also cellulose nitrate, flash paper) is a highly flammable compound formed by Nitrating Cellulose through exposure to Next he used an electric motor. His tests showed that a large rotor with low blade area was needed.

Ján Bahýľ, a Slovak inventor, developed a model helicopter powered by an internal combustion engine, that in 1901 reached a height of 0. Ján Bahýľ ( 25 May 1845, Zvolenská Slatina (Nagyszalatna ( Kingdom of Hungary, today Slovakia } The Slovaks or Slovakians are a western Slavic People that primarily inhabit Slovakia and speak the Slovak language, which is 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 Year 1901 ( MCMI) was a Common year starting on Tuesday (link will display calendar of the Gregorian calendar (or a Common year starting 5 meters. On 5 May 1905, his helicopter reached four meters in altitude and flew for over 1,500 meters. Events 553 - The Second Council of Constantinople begins 1215 - Rebel Barons renounce their allegiance to King John Year 1905 ( MCMV) was a Common year starting on Sunday (link will display full calendar of the Gregorian calendar (or a Common year starting ^[10]

First flights

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. For the Grande école formerly known as the Breguet School see ESIEE Louis Charles Breguet ( January 2, 1880 in 1. Although there is some uncertainty about the dates, sometime between 14 August and 29 September 1907, the Gyroplane No. Events 1183 - Taira no Munemori and the Taira clan take the young Emperor Antoku and the three sacred treasures Events 522 BC - Darius I of Persia kills the Magian usurper Gaumâta securing his hold as king of the Persian Empire. Year 1907 ( MCMVII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common year 1 lifted its pilot up into the air about two feet (0. 6 meters) for a minute. ^[3] 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.

That same year, 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. Paul Cornu (born 1881 in Lisieux, France, died 6 June, 1944) was a French engineer who manufactured Bicycles by trade Antoinette was a short-lived (1903-1912 French manufacturer of light Gasoline Engines which were quite advanced for that period On 13 November 1907, it lifted its inventor to 1 foot (0. Events 1002 - English king Ethelred orders the killing of all Danes in England, known today as the St Year 1907 ( MCMVII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common year 3 meters) and remained aloft for 20 seconds. Even though this flight did not surpass the flight of the Gyroplane No. 1, it was the first truly free flight with a pilot. Cornu's helicopter would complete a few more flights and achieve a height of nearly 6. 5 feet (2 meters), but it proved to be unstable and was abandoned. ^[3]

Early development

In the early 1920s, Raúl Pateras Pescara, an Argentinian working in Europe, demonstrated one of the first successful applications of cyclic pitch. Raúl Pateras Pescara de Castelluccio (born in Buenos Aires in 1890 and died in Paris in 1966 Marquis of Pateras-Pescara was an Argentine ^[3] 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. In Aviation, the word autorotation is applied to operation of Fixed-wing aircraft and Rotary-wing aircraft. By January 1924, Pescara's helicopter No. 3 was capable of flights up to 10 minutes.

One of Pescara's contemporaries, Frenchman Etienne Oemichen, set the first helicopter world record recognized by the Fédération Aéronautique Internationale (FAI) on 14 April 1924, flying his helicopter 360 meters (1,181 feet). The Fédération Aéronautique Internationale (FAI is the world governing body for Air sports and Aeronautics and Astronautics world records Events 43 BC - Battle of Forum Gallorum: Mark Antony, besieging Julius Caesar 's assassin Decimus Junius Brutus in Year 1924 ( MCMXXIV) was a Leap year starting on Tuesday (link will display the full calendar of the Gregorian calendar. On 18 April 1924, Pescara beat Oemichen's record, flying for a distance of 736 m (nearly a half mile) in 4 minutes and 11 seconds (about 8 mph, 13 km/h) maintaining a height of six feet. Events 1025 - Bolesław Chrobry is crowned in Gniezno, becoming the first King of Poland. Year 1924 ( MCMXXIV) was a Leap year starting on Tuesday (link will display the full calendar of the Gregorian calendar. ^[11] Not to be outdone, Oemichen reclaimed the world record on 4 May when he flew his No. Events 1256 - The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV 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). ^[11] Oemichen also set the 1-km closed-circuit record at 7 minutes 40 seconds. ^[3]

Meanwhile, Juan de la Cierva was developing the first practical rotorcraft in Spain. Juan de la Cierva (21 September 1895 – 9 December 1936 was a Spanish Civil engineer and pilot In 1923, the aircraft that would become the basis for the modern helicopter rotor began to take shape in the form of an autogyro, Cierva's C. A helicopter rotor is the rotating part of a Helicopter which generates an aerodynamic Force. Configuration An autogyro is characterised by a free-spinning rotor that turns due to passage of air upwards through the rotor 4. ^[12] Cierva had discovered aerodynamic and structural deficiencies in his early designs that could cause his autogyros to flip over after takeoff. The flapping hinges that Cierva designed for the C. 4 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 a drag hinge to relieve further stress on the rotor from its flapping motion. ^[12] These two developments allowed for a stable rotor system, not only in a hover, but in forward flight.

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, with Dutch Army-Air arm Captain Floris Albert van Heijst at the controls. Events 622 - Prophet Muhammad completes his hegira from Mecca to Medina. Year 1925 ( MCMXXV) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar. The controls that Captain van Heijst used were Von Baumhauer's inventions, the cyclic and collective. A Helicopter pilot manipulates the helicopter flight controls in order to achieve controlled aerodynamic Flight. Patents were granted to von Baumhauer for his cyclic and collective controls by the British ministry of aviation on 31 January 1927, under patent number 265,272. Events 1504 - France cedes Naples to Aragon. 1606 - Gunpowder Plot: Guy Fawkes 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 his D'AT3, a coaxial helicopter. General Corradino D'Ascanio ( Popoli, Pescara February 1, 1891 — Pisa, August 6, 1981) was an Italian 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,^[13] 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), duration (8 minutes 45 seconds) and distance flown (1,078 m). ^[13]

The Bréguet-Dorand Gyroplane Laboratoire was built in 1933. The Gyroplane Laboratoire is considered by some to be the first practicable Helicopter in the world After many ground tests and an accident, it first took flight on 26 June 1935. Events 363 - Roman Emperor Julian is killed during the retreat from the Sassanid Empire. Year 1935 ( MCMXXXV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. 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 500 m diameter. Events 1287 - St Lucia's flood: The Zuider Zee sea wall in the Netherlands collapses killing over 50000 people Year 1935 ( MCMXXXV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. The next year, on 26 September 1936, Claisse set a height record of 158 m. Events 46 BC - Julius Caesar dedicates a Year 1936 ( MCMXXXVI) was a Leap year starting on Wednesday (link will display the full calendar of the Gregorian calendar. And, finally, on 24 November 1936, he set a flight duration record of one hour, two minutes and 5 seconds over a 44 km closed circuit at 44. Events 380 - Theodosius I makes his adventus, or formal Year 1936 ( MCMXXXVI) was a Leap year starting on Wednesday (link will display the full calendar of the Gregorian calendar. 7 km/h. The aircraft was destroyed in 1943 by an Allied air strike at Villacoublay airport. In general allies are people groups or nations that have joined together in an association for mutual benefit or to achieve some common purpose Strategic bombing is a Military strategy used in a Total war with the goal of defeating an enemy nation-state by destroying its economic ability to wage war rather Vélizy-Villacoublay is a commune in the southwestern suburbs of Paris, France.

Birth of an industry

Despite the success of the Gyroplane Laboratoire, the German Focke-Wulf Fw 61, first flown in 1936, would eclipse its accomplishments. Los Angeles (lɑˈsændʒələs los ˈaŋxeles in Spanish) is the largest City in the state of California and the American West WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout 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. In Aerodynamics, the flight envelope or performance envelope of an Aircraft refers to the capabilities of a design in terms of speed and altitude In February 1938, Hanna Reitsch became the first female helicopter pilot, exhibiting the Fw 61 before crowds in the Deutschlandhalle. Hanna Reitsch ( 29 March 1912 &ndash 24 August 1979) was a German Aviatrix who was once Adolf Hitler 's Deutschlandhalle is an Arena in Berlin, Germany. Built primarily for the 1936 Summer Olympics it was opened in 1935 and holds 8764 people

Nazi Germany would use helicopters in small numbers during World War II for observation, transport, and medical evacuation. Nazi Germany and the Third Reich are the common English names for Germany under the regime of Adolf Hitler and the National Socialist German Workers World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including The Flettner Fl 282 Kolibri synchropter was used in the Mediterranean Sea, while the Focke Achgelis Fa 223 Drache was used in Europe. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout 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 WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Extensive bombing by the Allied forces prevented Germany from producing any helicopters in large quantities during the war. The Allies of World War II were the countries officially opposed to the Axis powers during the Second World War.

In the United States, Igor Sikorsky and W. Igor Sikorsky (25 May 1889 &ndash 26 October 1972 was born Igor Ivanovich Sikorsky (Игорь Иванович Сикорский Lawrence LePage, were competing to produce the United States military's first helicopter. Prior to the war, LePage had received the patent rights to develop helicopters patterned after the Fw 61, and built the XR-1, utilizing the transverse rotor layout. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout ^[14] Meanwhile, Sikorsky, had settled on a simpler, single rotor design, the VS-300. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout After experimenting with configurations to counteract the torque produced by the single main rotor, he settled on a single, smaller rotor mounted vertically on the tailboom.

Developed from the VS-300, Sikorsky's R-4 became the first mass produced helicopter with a production order for 100 aircraft. The Sikorsky R-4 was "the world's first mass produced Helicopter and the United States Air Force 's first service helicopter" Development The R-4 was the only Allied helicopter to see service in World War II, primarily being used for rescue in Burma, Alaska, and other areas with harsh terrain. Total production would reach 131 helicopters before the R-4 was replaced by other Sikorsky helicopters such as the R-5 and the R-6. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout In all, Sikorsky would produce over 400 helicopters before the end of World War II. ^[15]

As LePage and Sikorsky were building their helicopters for the military, Bell Aircraft hired Arthur Young to help build a helicopter using Young's semi-rigid, teetering-blade rotor design, which used a weighted stabilizing bar. This article is about Arthur M Young the inventor and philosopher The subsequent Model 30 helicopter demonstrated the simplicity and ease of the design. The Model 30 was developed into the Bell 47, which became the first aircraft certificated for civilian use in the United States. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Produced in several countries, the Bell 47 would become 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 H. Kaman modified his Ka-225 helicopter with a new kind of engine, the turboshaft engine. A turboshaft engine is a form of Gas turbine which is optimized to produce Shaft power, rather than Jet thrust. This adaptation of the turbine engine provided a large amount of horsepower to the helicopter with a lower weight penalty than piston engines, with their heavy engine blocks and auxiliary components. On 11 December 1951, the Ka-225 became the first turbine-powered helicopter in the world. Events 359 - Honoratus, the first known Prefect of the City of Constantinople, takes office Year 1951 ( MCMLI) was a Common year starting on Monday. Events of 1951 January Two years later, on 26 March 1954, a modified Navy HTK-1, another Kaman helicopter, became the first twin-turbine helicopter to fly. Events 1026 - Pope John XIX crowns Conrad II as Holy Roman Emperor. Year 1954 ( MCMLIV) was a Common year starting on Friday (link will display full 1954 Gregorian calendar) However, it was the Sud Aviation Alouette II that would become the first helicopter to be produced with a turbine-engine. Sud Aviation was a French state-owned Aircraft manufacturer, originating from the merger of Sud-Est (SNCASE or Société nationale des constructions WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout ^[16]

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. A turboshaft engine is a form of Gas turbine which is optimized to produce Shaft power, rather than Jet thrust. While smaller and less expensive helicopters still use piston engines, turboshaft engines are the preferred powerplant for helicopters today.

Uses

Due to the unique operating characteristics of the helicopter—its ability to takeoff 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. Airspeed is the speed of an Aircraft relative to the air There are several different measures of airspeed indicated airspeed calibrated airspeed equivalent airspeed and true Today, helicopters are used for transportation, for construction, for firefighting, search and rescue, and a variety of other jobs that require its special capabilities.

Sikorsky S-64 Skycrane	Kern County (California) Fire Department Bell 205 dropping water on fire	Polish police Bell 206	Canadian helicopter taking off from the Greenland Ice Sheet
A Sikorsky S76-C+, known as the "Traumahawk Air Ambulance" in Palm Beach County, FL

A helicopter used to carry loads connected to long cables or slings is called an aerial crane. For an overview of the whole Huey family of aircraft see Bell Huey WikipediaWikiProject Aircraft. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The Greenland Ice Sheet is a vast body of ice covering 171 million km² roughly 80% of the surface of Greenland. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout ---- The Traumahawks of Palm Beach County FL are two identical 1999 Sikorsky S76-C+. Palm Beach County is located in the state of Florida. As of 2007 the county had a population of 1351236 according to the University of Florida Bureau of Economic One of the most unusual commercial uses of Helicopters is the aerial crane or skycrane. 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. These operations are referred to as longline because of the long, single sling line used to carry the load.

Helitack is the use of helicopters to combat wildland fires. Helitack refers to "helicopter-delivered fire resources" and is the system of managing and using Helicopters and their crews to perform Aerial firefighting Wildland fire suppression refers to the firefighting tactics used to suppress wildfires The helicopters are used for aerial firefighting (or water bombing) and may be fitted with tanks or carry helibuckets. Aerial firefighting is a method to combat Wildfires using aircraft A helicopter bucket is a specialised bucket suspended on a cable carried by a Helicopter to deliver water for Aerial firefighting. 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. Abseiling (German abseilen, "to rope down" rappelling in American and British English is the controlled descent down a rope in Rock climbing Common firefighting helicopters include variants of the Bell 205 and the Erickson S-64 Aircrane helitanker. For an overview of the whole Huey family of aircraft see Bell Huey WikipediaWikiProject Aircraft.

Helicopters are used as air ambulances for emergency medical assistance in situations when an ambulance cannot easily or quickly reach the scene. An air ambulance is an Aircraft used for emergency medical assistance in situations where either a traditional Ambulance cannot easily or quickly reach An ambulance is a Vehicle for transporting sick or injured people to from or between places of treatment for an Illness or Injury. Helicopters are also used when a patient needs to be transported between medical facilities and air transportation is the most practical method for the safety of the patient. Air ambulance helicopters are equipped to provide medical treatment to a patient while in flight. The use of helicopters as an air ambulance is often referred to as MEDEVAC, and patients are referred to as being "airlifted", or "medevaced". Medical evacuation, often termed MEDEVAC or medivac, is the timely and efficient movement and en route care provided by medical personnel to the wounded being

Oil companies charter helicopters to move workers and parts quickly to remote drilling sites located out to sea or in remote locations. The speed over boats makes the high operating cost of helicopters cost effective to ensure that oil platforms continue to flow. Companies such as CHC Helicopter, Bristow Helicopters, and Air Logistics specialize in this type of operation. CHC Helicopter Corporation (sometimes known as Canadian Helicopter Corporation, Canadian Helicopters or Hélicoptères Canadiens) () is the world’s Bristow Helicopters ( NYSE: BRS is a British helicopter airline based at Aberdeen Airport, Scotland.

Police departments and other law enforcement agencies use helicopters to pursue suspects. A police aircraft is an airplane or Helicopter used in Police operations 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. A thermographic camera, sometimes called a FLIR (Forward Looking InfraRed or an infrared camera less specifically is a device that forms an image using Infrared

Military forces use attack helicopters to conduct aerial attacks on ground targets. An attack helicopter, also known as a Helicopter Gunship, is a Military helicopter armed for attacking targets on the ground Such helicopters are mounted with missile launchers and miniguns. The minigun is a multi-barrel Machine gun with a high rate of fire (several thousand Rounds per minute) employing Gatling -style rotating barrels and an Transport helicopters are used to ferry troops and supplies where the lack of an airstrip would make transport via fixed-wing aircraft impossible. An airport is a location where Aircraft such as airplanes, Helicopters and blimps take off and land The use of transport helicopters to deliver troops as an attack force on an objective is referred to as Air Assault. An Air Assault is a Tactical or Operational manoeuvre of an Infantry unit Airlifted by Helicopters usually to fulfil an Aerial Unmanned Aerial Systems (UAS) helicopter systems of varying sizes are being developed by companies for military reconnaissance and surveillance duties. An unmanned aerial vehicle (UAV is an unpiloted Aircraft. UAVs can be remote controlled or fly autonomously based on pre-programmed flight plans or more complex dynamic Reconnaissance (also scouting) is a military and medical term denoting exploration conducted to gain information Surveillance aircraft are military Aircraft used for monitoring enemy activity usually carrying no armament

Other uses

• Aerial photography
• Motion picture photography
• Electronic news gathering
• Search and Rescue
• Tourism or personal pleasure
• Transport

Rotor configurations

Most helicopters have a single, main rotor but require a separate rotor to overcome torque. Aerial photography is the taking of Photographs of the ground from an elevated position ENG is a Broadcasting (usually Television) industry acronym which stands for electronic news gathering. For the TV series of this title see Search and Rescue (TV series. Tourism is Travel for Recreational or Leisure purposes The World Tourism Organization defines tourists as people who "travel Transport or transportation is the movement of people and goods from one place to another 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. Igor Sikorsky (25 May 1889 &ndash 26 October 1972 was born Igor Ivanovich Sikorsky (Игорь Иванович Сикорский WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout 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.

Single main rotor

With a single main rotor helicopter, the creation of torque as the engine turns the rotor creates a torque effect that causes the body of the helicopter to turn in the opposite direction of the rotor. A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about In Physics, the angular momentum of a particle about an origin is a vector quantity equal to the mass of the particle multiplied by the Cross product of the position 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. A Fenestron is a fully enclosed Tail rotor of a Helicopter that is essentially a Ducted fan. MD Helicopters is an aerospace company that produces helicopters primarily for commercial use NOTAR, an acronym for NO TA il R otor is a Helicopter anti-torque system (see the helicopter article for more details developed by

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 rotational speed typically measured in rotations per minute (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.

Ducted fan

Main article: Fenestron

Fenestron and FANTAIL^[17] are trademarks for a ducted fan mounted at the end of the tail boom of the helicopter and used in place of a tail rotor. A Fenestron is a fully enclosed Tail rotor of a Helicopter that is essentially a Ducted fan. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual A ducted fan is a propulsion arrangement whereby a fan which is a type of Propeller, is mounted within a cylindrical shroud or duct Ducted fans have between eight and 18 blades arranged with irregular spacing, so that the noise is distributed over different frequencies. The housing is integral with the aircraft skin and allows a high rotational speed, therefore a ducted fan can have a smaller size than a conventional tail rotor.

The Fenestron was used for the first time at the end of the 1960s on the second experimental model of Sud Aviation's SA 340, and produced on the later model Aérospatiale SA 341 Gazelle. The 1960s decade refers to the years from the beginning of 1960 to the end of 1969 Aérospatiale was a French Aerospace manufacturer that primarily built both civilian and military Aircraft and Rockets The company was created in 1970 WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout 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, as the FANTAIL. The Eurocopter Group is a European Helicopter manufacturing and support company formed in 1992 from the merger of German Daimler-Benz Aerospace The United States Army is a military organization whose primary mission is to "provide necessary forces and capabilities. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout

NOTAR

Main article: NOTAR

NOTAR, an acronym for NO TAil Rotor, is a helicopter anti-torque system that eliminates the use of the tail rotor on a helicopter. NOTAR, an acronym for NO TA il R otor is a Helicopter anti-torque system (see the helicopter article for more details developed by Although the concept took some time to refine, the NOTAR system is simple in theory and works to provide antitorque the same way a wing develops lift using the Coandă effect. The Coandă effect ('kwandə is the tendency of a Fluid jet to stay attached to an adjacent curved surface that is very well shaped. ^[18] A variable pitch fan is enclosed in the aft fuselage section immediately forward of the tail boom and driven by the main rotor transmission. This fan forces low pressure air through two slots on the right 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.

Development of the NOTAR system dates back to 1975 when engineers at Hughes Helicopters began concept development work. Hughes Helicopters was a major manufacturer of military and civil Helicopters from the 1950s to the 1980s ^[18] In December 1981 Hughes flew a OH-6A fitted with NOTAR for the first time. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout ^[19] 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. ^[20] There are currently three production helicopters that incorporate the NOTAR design, all produced by MD Helicopters. This antitorque design also improves safety by eliminating the opportunity for personnel to walk into the tail rotor.

Tip jets

Main article: Tip jet

Another single main rotor configuration without a tail rotor is the tip jet rotor, where the 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 turbojet, ramjet or rocket thrusters. Tip jet refers to the jet Nozzles located at the tip of some Helicopter rotor blades TurboJET (噴射飛航 is the brand name for the operations of the Hong Kong -based Shun Tak-China Travel Ship Management Limited (信德中旅船務管理有限公司 A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of Jet engine that contains no major Moving parts. A rocket engine is a Jet engine that uses only Propellant mass for forming its high speed propulsive jet. 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. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The Fairey Jet Gyrodyne and 40-seat Fairey Rotodyne flew very well indeed. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Possibly the most unusual was the rocket tipped Rotary Rocket Roton ATV. Rotary Rocket Inc, was a rocketry company headquartered in a facility at Mojave Airport that developed the Roton concept in the late 1990s as a fully reusable None have made it into production.

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. Classes of rotorcraft Helicopter See also Helicopter A helicopter is a rotorcraft whose rotors are driven by the engine(s throughout the flight Primarily, there are three common configurations that use 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.

Tandem

Main article: Tandem rotors

Tandem rotors are two horizontal main rotor assemblies mounted one behind the other. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Tandem rotor (sometimes referred to as dual rotor) Helicopters have two large Horizontal rotor assemblies a twin rotor system instead of one 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.

Coaxial

Main article: Coaxial rotors

Coaxial rotors are a pair of rotors turning in opposite directions on the same masthead. "Black Shark" redirects here For the species of fish see Kitefin shark. 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. This article is about the swashplate in helicopters see also the Swashplate article which describes all uses of the mechanism 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.

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. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout 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 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. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Anti-submarine warfare (ASW or in older form A/S is a branch of Naval warfare that uses surface Warships Aircraft, space craft or other Submarines WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout During the Cold War, the American company, Kaman Aircraft produced the HH-43 Huskie for the USAF firefighting and rescue missions. Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the Kaman Aircraft is an American Aerospace company with headquarters in Bloomfield Connecticut. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The latest Kaman model, the Kaman K-MAX, is a dedicated sky crane design. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout

Transverse

Transverse rotors are mounted on the end of wings or outriggers, perpendicular to the body of the aircraft. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Similar to tandem rotors and intermeshing rotors, the transverse rotor also uses 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. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout It is also the configuration found on tiltrotors, such as Bell's XV-15 and the newer V-22 Osprey. Overview As the name implies a tiltrotor aircraft uses tiltable rotating Propellers or proprotors, for lift and propulsion. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout

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 helicopter rotor is the rotating part of a Helicopter which generates an aerodynamic Force. In the context of a Fluid flow relative to a body the lift force is the component of the Aerodynamic force that is Perpendicular to the flow 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. Overview As the name implies a tiltrotor aircraft uses tiltable rotating Propellers or proprotors, for lift and propulsion.

The rotor consists of a mast, hub and rotor blades. 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

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.

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. Dissymmetry of lift in Helicopter Aerodynamics refers to an uneven amount of lift on opposite sides of the rotor disc 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. In physics the Coriolis effect is an apparent deflection of moving objects when they are viewed from a Rotating frame of reference. 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.

Rigid

In a rigid rotor system, the blades, hub, and mast are rigid with respect to each other. The rigid rotor system is mechanically simpler than the fully articulated rotor system. There are no vertical or horizontal hinges so the blades cannot flap or drag, but they can be feathered. Operating loads from flapping and lead/lag forces must be absorbed by bending rather than through hinges. By flexing, the blades themselves compensate for the forces which previously required rugged hinges. The result is a rotor system that has less lag in the control response, because the rotor has much less oscillation. ^[21] The rigid rotor system also negates the danger of mast bumping inherent in semi-rigid rotors. ^[22]

Combination

Modern rotor systems may use the combined principles of the rotor systems mentioned above. Some rotor hubs incorporate a flexible hub, which allows for blade bending (flexing) without the need for bearings or hinges. These systems, called "flextures",^[23] are usually constructed from composite material. Elastomeric bearings may also be used in place of conventional roller bearings. Elastomeric bearings are bearings constructed from a rubber type material and have limited movement that is perfectly suited for helicopter applications. Flextures and elastomeric bearings require no lubrication and, therefore, require less maintenance. They also absorb vibration, which means less fatigue and longer service life for the helicopter components.

Controlling flight

Main article: Helicopter flight controls

A helicopter has four flight control inputs. A Helicopter pilot manipulates the helicopter flight controls in order to achieve controlled aerodynamic Flight. These are the cyclic, the collective, the anti-torque pedals, and the throttle. The cyclic control is usually located between the pilot's legs and is commonly called the cyclic stick or just cyclic. On most helicopters, the cyclic is similar to a joystick. Although, the Robinson R22 and R44 have a unique teetering bar cyclic control system and a few helicopters have a cyclic control that descends into the cockpit from overhead. The Robinson Helicopter Company of Torrance California is the largest manufacturer of civil Helicopters in the world WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout

The control is called the cyclic because it changes the pitch of the rotor blades cyclically. Blade pitch or simply pitch refers to turning the Angle of attack of the blades of a Propeller into or out of the wind to control the production or absorption The result is to tilt the rotor disk in a particular direction, resulting in the helicopter moving in that direction. If the pilot pushes the cyclic forward, the rotor disk tilts forward, and the rotor produces a thrust in the forward direction. If the pilot pushes the cyclic to the side, the rotor disk tilts to that side and produces thrust in that direction, causing the helicopter to hover sideways.

The collective pitch control or collective is located on the left side of the pilot's seat with a settable friction control to prevent inadvertent movement. The collective changes the pitch angle of all the main rotor blades collectively (i. e. all at the same time) and independently of their position. Therefore, if a collective input is made, all the blades change equally, and the result is the helicopter increasing or decreasing in altitude.

The anti-torque pedals are located in the same position as the rudder pedals in a fixed-wing aircraft, and serve a similar purpose, namely to control the direction in which the nose of the aircraft is pointed. A rudder is a device used to steer a Ship, Boat, Submarine, Hovercraft, or other conveyance that move through a fluid (generally air or Application of the pedal in a given direction changes the pitch of the tail rotor blades, increasing or reducing the thrust produced by the tail rotor and causing the nose to yaw in the direction of the applied pedal. Flight dynamics is the science of air and space vehicle orientation and control in three dimensions The pedals mechanically change the pitch of the tail rotor altering the amount of thrust produced.

Helicopter rotors are designed to operate at a specific RPM. The throttle controls the power produced by the engine, which is connected to the rotor by a transmission. The purpose of the throttle is to maintain enough engine power to keep the rotor RPM within allowable limits in order to keep the rotor producing enough lift for flight. In single-engine helicopters, the throttle control is a motorcycle-style twist grip mounted on the collective control, while dual-engine helicopters have a power lever for each engine.

A Swashplate transmits the pilot commands to the main rotor blades for articulated rotors. This article is about the swashplate in helicopters see also the Swashplate article which describes all uses of the mechanism

Flight conditions

There are two basic flight conditions for a helicopter; hover and forward flight. Flight is the process by which an object achieves sustained movement either through the Air (or movement beyond Earth's atmosphere, in the case of

• Hover

Hovering is the most challenging part of flying a helicopter. This is because a helicopter generates its own gusty air while in a hover, which acts against the fuselage and flight control surfaces. The fuselage (from the French fuselé "spindle-shaped" is an Aircraft 's main body section that holds crew and passengers or Cargo The end result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be. Despite the complexity of the task, the control inputs in a hover are simple. The cyclic is used to eliminate drift in the horizontal plane, that is to control forward and back, right and left. The collective is used to maintain altitude. The pedals are used to control nose direction or heading. In Navigation, a course is the intended path of a vehicle over the surface of the Earth It is the interaction of these controls that makes hovering so difficult, since an adjustment in any one control requires an adjustment of the other two, creating a cycle of constant correction.

• Forward flight

In forward flight a helicopter's flight controls behave more like that in a fixed-wing aircraft. Displacing the cyclic forward will cause the nose to pitch down, with a resultant increase in airspeed and loss of altitude. Aft cyclic will cause the nose to pitch up, slowing the helicopter and causing it to climb. Increasing collective (power) while maintaining a constant airspeed will induce a climb while decreasing collective will cause a descent. Coordinating these two inputs, down collective plus aft cyclic or up collective plus forward cyclic, will result in airspeed changes while maintaining a constant altitude. The pedals serve the same function in both a helicopter and a fixed-wing aircraft, to maintain balanced flight. This is done by applying a pedal input in whichever direction is necessary to center the ball in the turn and bank indicator. In Aviation, the turn and bank indicator shows the rate of turn and the coordination (slip or skid of the turn

Alternative power sources

The Rotomotion SR20 is a small, unmanned helicopter which is powered by electric batteries. An unmanned aerial vehicle (UAV is an unpiloted Aircraft. UAVs can be remote controlled or fly autonomously based on pre-programmed flight plans or more complex dynamic The SR20 can carry a payload of 10 pounds for 12 to 24 minutes based on battery configuration. ^[24]

Limitations

A-Star pulling rope through skywire traveller

Boeing CH-47 Chinook

The Bristol Type 192 Belvedere

HAL Dhruv helicopters of the Indian Air Force Sarang aerobatics team

The main limitation of the helicopter is its slow speed. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The Indian Air Force (Devanāgarī भारतीय वायु सेना IAST Bhartiya Vāyu Senā is the air arm of the Armed Forces of India and has the Sarang ( Sanskrit: सारंग - Peacock) is the Helicopter formation display team of the Indian Air Force. There are several reasons why a helicopter cannot fly as fast as a fixed wing aircraft. When the helicopter is at rest, the outer tips of the rotor travel at a speed determined by the length of the blade and the RPM. In a moving helicopter, however, the speed of the blades relative to the air depends on the speed of the helicopter as well as on their rotational velocity. The airspeed of the advancing rotor blade is much higher than that of the helicopter itself. It is possible for this blade to exceed the speed of sound, and thus produce vastly increased drag and vibration. Sound is a vibration that travels through an elastic medium as a Wave. See Wave drag. Wave drag is an Aerodynamics term that refers to a sudden and very powerful form of drag that appears on aircraft and blade tips moving at high-subsonic and supersonic

Because the advancing blade has higher airspeed than the retreating blade and generates a dissymmetry of lift, rotor blades are designed to "flap" – lift and twist in such a way that the advancing blade flaps up and develops a smaller angle of attack. Dissymmetry of lift in Helicopter Aerodynamics refers to an uneven amount of lift on opposite sides of the rotor disc Conversely, the retreating blade flaps down, develops a higher angle of attack, and generates more lift. At high speeds, the force on the rotors is such that they "flap" excessively and the retreating blade can reach too high an angle and stall. For this reason, the maximum safe forward speed of a helicopter is given a design rating called V_NE, Velocity, Never Exceed. In Aviation, V-speeds or Velocity-speeds are standard terms used to define Airspeeds important or useful to the operation of Aircraft, such

During the closing years of the 20th century designers began working on helicopter noise reduction. The twentieth century of the Common Era began on Helicopter noise reduction is a topic of research into designing Helicopters which can be operated more quietly reducing the public-relations problems with night-flying Urban communities have often expressed great dislike of noisy aircraft, and police and passenger helicopters can be unpopular. The redesigns followed the closure of some city heliports and government action to constrain flight paths in national parks and other places of natural beauty. A national park is a reserve of land usually declared and owned by a national Government, protected from most Human development and pollution

Helicopters vibrate. An unadjusted helicopter can easily vibrate so much that it will shake itself apart. To reduce vibration, all helicopters have rotor adjustments for height and pitch. Most also have vibration dampers for height and pitch. Some also use mechanical feedback systems to sense and counter vibration. Usually the feedback system uses a mass as a "stable reference" and a linkage from the mass operates a flap to adjust the rotor's angle of attack to counter the vibration. Angle of attack ( AOA, \alpha Greek letter alpha) is a term used in Aerodynamics to describe the Angle between the Adjustment is difficult in part because measurement of the vibration is hard. The most common adjustment measurement system is to use a stroboscopic flash lamp, and observe painted markings or coloured reflectors on the underside of the rotor blades. The traditional low-tech system is to mount coloured chalk on the rotor tips, and see how they mark a linen sheet.

Hazards of helicopter flight

As with any moving vehicle, unsafe operation could result in loss of control, structural damage, or fatality. The following is a list of some of the potential hazards for helicopters:

• Settling with power, also known as a vortex ring state, is essentially when the aircraft settles into its own downwash, unable to climb out of the condition due to the effect of the turbulent air on the aerodynamics of the rotor. Settling with Power, also known as Vortex Ring State, is a hazardous condition of helicopter flight where the Helicopter settles (descends in spite A vortex ring, also called a toroidal vortex, is a region of rotating Fluid moving through the same or different fluid where the flow pattern takes on a
• Retreating blade stall
• Ground resonance (affects helicopters with rotor systems having lead-lag natural frequency less than the blade rotation frequency). Retreating blade stall is a hazardous flight condition in Helicopters and other rotary wing Aircraft, where the rotor blade rotating away from the direction of flight Ground resonance, in fully articulated multi-bladed Helicopters is a hazardous condition during Touchdown or at other times when the helicopter is running while sitting
• Low-G condition (affects two-bladed main rotor helicopters)
• Dynamic rollover
• Operating within the shaded area of the height-velocity diagram
• Tail rotor failure. Low- g condition is a phase of aerodynamic Flight where the airframe is temporarily unloaded A Helicopter is susceptible to a lateral rolling tendencycalled dynamic rollover, when lifting off the surface The Height-Velocity diagram or H/V curve is a Graph charting the safe/unsafe flight profiles relevant to a specific Helicopter.
• Brownout or whiteout in snow condition

Deadliest helicopter crashes

1. Khankala attack - Mi-26 shot down over Chechnya in 2002; 127 killed. In aviation a brownout (or brown-out) is an in-flight visibility restriction due to dust or sand in the air Whiteout is a Weather condition in which visibility and contrast are severely reduced by Snow and diffuse lighting from overcast Clouds There are three "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. On August 19, 2002, a Russian made Igla shoulder-fired Surface-to-air missile hit an overloaded Mil Mi-26 Helicopter WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout The Chechen Republic (ˈʧɛʧɨn rɪˈpʌblɨk Чече́нская Респу́блика Chechenskaya Respublika; Нохчийн Республика Noxçiyn Respublika
2. 1997 Israeli helicopter disaster - MH-53 crash in Israel in 1997; 73 killed. The 1997 Israeli helicopter disaster, occurred on 4 February 1997 and left 73 IDF soldiers dead after two Sikorsky CH-53 helicopters collided over She'ar Yashuv WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout
3. 1977 Israeli CH-53 crash - CH-53 crash near Yitav in the Jordan Valley on 10 May 1977; 54 killed. On May 10 1977 an Israeli Air Force Sikorsky CH-53 Yas'ur helicopter crashed during an exercise in the Jordan Valley, killing Mevo'ot Yericho (מְבוֹאוֹת יְרִיחוֹ (lit "Doorway to Jericho" founded in 1999 is a communal settlement located in the West Bank Events 1291 - Scottish Nobles recognize the authority of Edward I of England. Also 1977 (album by Ash. Year 1977 ( MCMLXXVII) was a Common year starting on Saturday (link displays
4. 1986 Sumburgh disaster - a British International Helicopters Boeing 234LR Commercial Chinook, Shetland Islands; 45 killed. Year 1986 ( MCMLXXXVI) was a Common year starting on Wednesday (link displays 1986 Gregorian calendar) The Sumburgh disaster was the crash of a Boeing 234LR Chinook Helicopter on 6 November 1986 with a loss of 43 passengers and two crew members British International Helicopters (Veritair Limited is an Airline based at Penzance heliport in Cornwall, England, United Kingdom WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Shetland (formerly spelled Zetland, from etland; Old Norse non Hjaltland; Sealtainn is an Archipelago off the northeast coast of
5. 1968 Los Angeles Airways Flight 417 - a Los Angeles Airways Sikorsky S-61L crashed enroute to the Disneyland Heliport; 21 killed. Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar. Los Angeles Airways Flight 417 crashed on August 14, 1968 in the city of Compton, California. Los Angeles Airways ( LAA) was a Helicopter Airline that was based in Los Angeles, California. WikipediaWikiProject Aircraft. Please see WikipediaWikiProject Aircraft/page content for recommended layout Disneyland, marketed as the happiest place on Earth, is an American Theme park in Anaheim, California, owned and operated by the Walt

See also

• Autogyro
• Autorotation (helicopter)
• Backpack helicopter
• Heliport
• Gyrodyne
• Jesus nut (the top central big nut that holds the rotor on)
• List of helicopter models
• Transverse Flow Effect
• VTOL

References

Notes

Bibliography

External links

• American Helicopter Society
• Army Aviation Association of America
• Helicopter Links - companies, organizations, museums, trade/air shows
• Helicopter at HowStuffWorks
• Helicopter Association International
• Helicopter history site
• Helicopter photo gallery
• Rotary Action - guide to helicopters in movies and TV
• Image of a Chinese flying top
• US patent #1848389 - Sikorsky's helicopter patent (requires Quicktime plugin).

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