Helicopter
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A helicopter is a type of
In 1942, the Sikorsky R-4 became the first helicopter to reach full-scale production.[1][2]
Although most earlier designs used more than one main rotor, the configuration of a single
Etymology
The English word helicopter is adapted from the French word hélicoptère, coined by Gustave Ponton d'Amécourt in 1861, which originates from the Greek helix (ἕλιξ), genitive helikos (ἕλῐκος), "helix, spiral, whirl, convolution"[3] and pteron (πτερόν) "wing".[4][5] In a process of rebracketing, the word is often (erroneously, from an etymological point of view) perceived by English speakers as consisting of heli- and -copter, leading to words like helipad and quadcopter.[6][7] English language nicknames for "helicopter" include "chopper", "copter", "heli", and "whirlybird". In the United States military, the common slang is "helo" pronounced with a long "e".[clarification needed]
Design characteristics
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more horizontally-spinning rotors.[8] By contrast the autogyro (or gyroplane) and gyrodyne have a free-spinning rotor for all or part of the flight envelope, relying on a separate thrust system to propel the craft forwards, so that the airflow sets the rotor spinning to provide lift. The compound helicopter also has a separate thrust system, but continues to supply power to the rotor throughout normal flight.[citation needed]
Rotor system
The rotor system, or more simply rotor, is the rotating part of a helicopter that 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 horizontal thrust to counteract torque from the main rotors. The rotor consists of a mast, hub and rotor blades.[citation needed]
The mast is a cylindrical metal shaft that extends upwards from the transmission. At the top of the mast is the attachment point for the rotor blades called the hub. Main rotor systems are classified according to how the rotor blades are attached and move relative to the hub. There are three basic types: hingeless, fully articulated, and teetering; although some modern rotor systems use a combination of these.[citation needed]
Anti-torque
Most helicopters have a single main rotor, but torque created by its
Some helicopters use other anti-torque controls instead of the tail rotor, such as the ducted fan (called Fenestron or FANTAIL) and NOTAR. NOTAR provides anti-torque similar to the way a wing develops lift through the use of the Coandă effect on the tail boom.[9]
The use of two or more horizontal rotors turning in opposite directions is another configuration used to counteract the effects of torque on the aircraft without relying on an anti-torque tail rotor. This allows the power normally required to be diverted for the tail rotor to be applied fully to the main rotors, increasing the aircraft's power efficiency and lifting capacity. There are several common configurations that use the counter-rotating effect to benefit the rotorcraft:
- Tandem rotors are two counter-rotating rotors with one mounted behind the other.[citation needed]
- Transverse rotors are pair of counter-rotating rotors transversely mounted at the ends of fixed wings or outrigger structures. Now used on tiltrotors, some early model helicopters had used them.
- Coaxial rotorsare two counter-rotating rotors mounted one above the other with the same axis.
- Intermeshing rotorsare two counter-rotating rotors mounted close to each other at a sufficient angle to let the rotors intermesh over the top of the aircraft without colliding. An aircraft utilizing this is known as a synchropter.
- Multirotors make use of three or more rotors. Specific terms are also used depending on the exact amount of rotors, such as tricopter, quadcopter, hexacopter and octocopter for three rotors, four rotors, six rotors and eight rotors respectively, of which quadcopter is the most common. Multirotors are primarily used on drones and use on aircraft with a human pilot is rare.[citation needed]
Tip jet designs let the rotor push itself through the air and avoid generating torque.[10]
Engines
The number, size and type of engine(s) used on a helicopter determines the size, function and capability of that helicopter design. The earliest helicopter engines were simple mechanical devices, such as rubber bands or spindles, which relegated the size of helicopters to toys and small models. For a half century before the first airplane flight, steam engines were used to forward the development of the understanding of helicopter aerodynamics, but the limited power did not allow for manned flight. The introduction of the internal combustion engine at the end of the 19th century became the watershed for helicopter development as engines began to be developed and produced that were powerful enough to allow for helicopters able to lift humans.[citation needed]
Early helicopter designs utilized custom-built engines or
Turbine engines revolutionized the aviation industry; and the turboshaft engine for helicopter use, pioneered in December 1951 by the aforementioned Kaman K-225, finally gave helicopters an engine with a large amount of power and a low weight penalty. Turboshafts are also more reliable than piston engines, especially when producing the sustained high levels of power required by a helicopter. The turboshaft engine was able to be scaled to the size of the helicopter being designed, so that all but the lightest of helicopter models are powered by turbine engines today.[citation needed]
Special jet engines developed to drive the rotor from the rotor tips are referred to as
Some
There are also human-powered helicopters.
Flight controls
A helicopter has four flight control inputs. 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. However, the Robinson R22 and Robinson R44 have a unique teetering bar cyclic control system and a few helicopters have a cyclic control that descends into the cockpit from overhead.[citation needed]
The control is called the cyclic because it changes
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.[citation needed]
A
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. 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. The pedals mechanically change the pitch of the tail rotor altering the amount of thrust produced.[citation needed]
Helicopter rotors are designed to operate in a narrow range of
Compound helicopter
A compound helicopter has an additional system for thrust and, typically, small stub
Flight
There are three basic flight conditions for a helicopter: hover, forward flight and the transition between the two.
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 result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be.[20] 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. 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.[citation needed]
Transition from hover to forward flight
As a helicopter moves from hover to forward flight it enters a state called translational lift which provides extra lift without increasing power. This state, most typically, occurs when the airspeed reaches approximately 16–24 knots (30–44 km/h; 18–28 mph), and may be necessary for a helicopter to obtain flight.[citation needed]
Forward flight
In forward flight a helicopter's flight controls behave more like those of a fixed-wing aircraft. Applying forward pressure on the cyclic 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
Uses
Due to the operating characteristics of the helicopter—its ability to take off and land vertically, and to hover for extended periods of time, as well as the aircraft's handling properties under low
A helicopter used to carry loads connected to long cables or slings is called an aerial crane. Aerial cranes are used to place heavy equipment, like radio transmission towers and large air conditioning units, on the tops of tall buildings, or when an item must be raised up in a remote area, such as a radio tower raised on the top of a hill or mountain. Helicopters are used as aerial cranes in the logging industry to lift trees out of terrain where vehicles cannot travel and where environmental concerns prohibit the building of roads.[22] These operations are referred to as longline because of the long, single sling line used to carry the load.[23] In military service helicopters are often useful for delivery of outsized slung loads that would not fit inside ordinary cargo aircraft: artillery pieces, large machinery (field radars, communications gear, electrical generators), or pallets of bulk cargo. In military operations these payloads are often delivered to remote locations made inaccessible by mountainous or riverine terrain, or naval vessels at sea.[citation needed]
In electronic news gathering, helicopters have provided aerial views of some major news stories, and have been doing so, from the late 1960s. Helicopters have also been used in films, both in front and behind the camera.[24]
The largest single non-combat helicopter operation in history was the disaster management operation following the 1986 Chernobyl nuclear disaster. Hundreds of pilots were involved in airdrop and observation missions, making dozens of sorties a day for several months.[citation needed]
"
Helicopters are used as
Police departments and other law enforcement agencies use helicopters to pursue suspects and patrol the skies. Since helicopters can achieve a unique aerial view, they are often used in conjunction with police on the ground to report on suspects' locations and movements. They are often mounted with lighting and heat-sensing equipment for night pursuits.
Military forces use
Oil companies charter helicopters to move workers and parts quickly to remote drilling sites located at sea or in remote locations. The speed advantage over boats makes the high operating cost of helicopters cost-effective in ensuring that oil platforms continue to operate. Various companies specialize in this type of operation.[citation needed]
NASA developed Ingenuity, a 1.8 kg (4.0 lb) helicopter used to survey Mars (along with a rover). It began service in February 2021 and was retired due to sustained rotor blade damage in January 2024 after 73 sorties. As the Martian atmosphere is 100 times thinner than Earth's, its two blades spin at close to 3,000 revolutions a minute, approximately 10 times faster than that of a terrestrial helicopter.[27]
Market
In 2017, 926 civil helicopters were shipped for $3.68 billion, led by
By October 2018, the in-service and stored helicopter fleet of 38,570 with civil or government operators was led Robinson Helicopter with 24.7% followed by Airbus Helicopters with 24.4%, then Bell with 20.5 and Leonardo with 8.4%, Russian Helicopters with 7.7%, Sikorsky Aircraft with 7.2%, MD Helicopters with 3.4% and other with 2.2%. The most widespread model is the piston
History
Early design
The earliest references for vertical flight came from China. Since around 400 BC,
Designs similar to the Chinese helicopter toy appeared in some Renaissance paintings and other works.[35] In the 18th and early 19th centuries Western scientists developed flying machines based on the Chinese toy.[36]
It was not until the early 1480s, when Italian polymath Leonardo da Vinci created a design for a machine that could be described as an "aerial screw", that any recorded advancement was made towards vertical flight. His notes suggested that he built small flying models, but there were no indications for any provision to stop the rotor from making the craft rotate.[37][38] As scientific knowledge increased and became more accepted, people continued to pursue the idea of vertical flight.[citation needed]
In July 1754, Russian
In 1861, the word "helicopter" was coined by Gustave de Ponton d'Amécourt, a French inventor who demonstrated a small steam-powered model. While celebrated as an innovative use of a new metal, aluminum, the model never lifted off the ground. D'Amecourt's linguistic contribution would survive to eventually describe the vertical flight he had envisioned. Steam power was popular with other inventors as well. In 1877, the Italian engineer, inventor and aeronautical pioneer Enrico Forlanini developed an unmanned helicopter powered by a steam engine. It rose to a height of 13 meters (43 feet), where it remained for 20 seconds, after a vertical take-off from a park in Milan.[40] Milan has dedicated its city airport to Enrico Forlanini, also named Linate Airport,[41] as well as the nearby park, the Parco Forlanini.[42] Emmanuel Dieuaide's steam-powered design featured counter-rotating rotors powered through a hose from a boiler on the ground.[37] In 1887 Parisian inventor, Gustave Trouvé, built and flew a tethered electric model helicopter.[citation needed]
In July 1901, the maiden flight of Hermann Ganswindt's helicopter took place in Berlin-Schöneberg; this was probably the first heavier-than-air motor-driven flight carrying humans. A movie covering the event was taken by Max Skladanowsky, but it remains lost.[43]
In 1885,
First flights
In 1906, two French brothers, Jacques and
That same year, fellow French inventor Paul Cornu designed and built the Cornu helicopter which used two 6.1-metre (20 ft) counter-rotating rotors driven by a 24 hp (18 kW) Antoinette engine. On 13 November 1907, it lifted its inventor to 0.3 metres (1 ft) and remained aloft for 20 seconds. Even though this flight did not surpass the flight of the Gyroplane No. 1, it was reported to be the first truly free flight with a pilot.[n 1] Cornu's helicopter completed a few more flights and achieved a height of nearly 2.0 metres (6.5 ft), but it proved to be unstable and was abandoned.[1]
In 1909, J. Newton Williams of Derby, Connecticut, and Emile Berliner of Washington, D.C., flew a helicopter "on three occasions" at Berliner's lab in Washington's Brightwood neighborhood.[48]
In 1911, Slovenian philosopher and economist Ivan Slokar patented a helicopter configuration.[49][50][51]
The Danish inventor Jacob Ellehammer built the Ellehammer helicopter in 1912. It consisted of a frame equipped with two counter-rotating discs, each of which was fitted with six vanes around its circumference. After indoor tests, the aircraft was demonstrated outdoors and made several free take-offs. Experiments with the helicopter continued until September 1916, when it tipped over during take-off, destroying its rotors.[52]
During World War I, Austria-Hungary developed the PKZ, an experimental helicopter prototype, with two aircraft built.[citation needed]
Early development
In the early 1920s, Argentine Raúl Pateras-Pescara de Castelluccio, while working in Europe, demonstrated one of the first successful applications of cyclic pitch.[1] Coaxial, contra-rotating, biplane rotors could be warped to cyclically increase and decrease the lift they produced. The rotor hub could also be tilted forward a few degrees, allowing the aircraft to move forward without a separate propeller to push or pull it. Pateras-Pescara was also able to demonstrate the principle of autorotation. By January 1924, Pescara's helicopter No. 1 was tested but was found to be underpowered and could not lift its own weight. His 2F fared better and set a record.[53] The British government funded further research by Pescara which resulted in helicopter No. 3, powered by a 250-horsepower (190 kW) radial engine which could fly for up to ten minutes.[54][55]
In March 1923 Time magazine reported Thomas Edison sent George de Bothezat a congratulations for a successful helicopter test flight. Edison wrote, "So far as I know, you have produced the first successful helicopter." The helicopter was tested at McCook's Field and remained airborne for 2 minutes and 45 seconds at a height of 15 feet.[56]
On 14 April 1924, Frenchman Étienne Oehmichen set the first helicopter world record recognized by the Fédération Aéronautique Internationale (FAI), flying his quadrotor helicopter 360 meters (1,180 ft).[57] On 18 April 1924, Pescara beat Oemichen's record, flying for a distance of 736 meters (2,415 ft)[53] (nearly 0.80 kilometers or .5 miles) in 4 minutes and 11 seconds (about 13 km/h or 8 mph), maintaining a height of 1.8 meters (6 feet).[58] On 4 May, Oehmichen completed the first one-kilometer (0.62 mi) closed-circuit helicopter flight in 7 minutes 40 seconds with his No. 2 machine.[1][59]
In the US, George de Bothezat built the quadrotor helicopter de Bothezat helicopter for the United States Army Air Service but the Army cancelled the program in 1924, and the aircraft was scrapped.[citation needed]
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,[60] with Dutch Army-Air arm Captain Floris Albert van Heijst at the controls. The controls that van Heijst used were von Baumhauer's inventions, the cyclic and collective.[61][62] 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.[citation needed]
In 1927,[63] Engelbert Zaschka from Germany built a helicopter, equipped with two rotors, in which a gyroscope was used to increase stability and serves as an energy accumulator for a gliding flight to make a landing. Zaschka's aircraft, the first helicopter, which ever worked so successfully in miniature, not only rises and descends vertically, but is able to remain stationary at any height.[64][65]
In 1928, Hungarian aviation engineer
In 1930, the Italian engineer Corradino D'Ascanio built his D'AT3, a coaxial helicopter. His relatively large machine had two, two-bladed, counter-rotating rotors. Control was achieved by using auxiliary wings or servo-tabs on the trailing edges of the blades,[68] a concept that was later adopted by other helicopter designers, including Bleeker and Kaman. Three small propellers mounted to the airframe were used for additional pitch, roll, and yaw control. The D'AT3 held modest FAI speed and altitude records for the time, including altitude (18 m or 59 ft), duration (8 minutes 45 seconds) and distance flown (1,078 m or 3,540 ft).[68][69]
First practical rotorcraft
Spanish aeronautical engineer and pilot
Single lift-rotor success
In the Soviet Union, Boris N. Yuriev and Alexei M. Cheremukhin, two aeronautical engineers working at the Tsentralniy Aerogidrodinamicheskiy Institut (TsAGI or the Central Aerohydrodynamic Institute), constructed and flew the TsAGI 1-EA single lift-rotor helicopter, which used an open tubing framework, a four-blade main lift rotor, and twin sets of 1.8-meter (5.9-foot) diameter, two-bladed anti-torque rotors: one set of two at the nose and one set of two at the tail. Powered by two M-2 powerplants, up-rated copies of the Gnome Monosoupape 9 Type B-2 100 CV output rotary engine of World War I, the TsAGI 1-EA made several low altitude flights.[75] By 14 August 1932, Cheremukhin managed to get the 1-EA up to an unofficial altitude of 605 meters (1,985 feet), shattering d'Ascanio's earlier achievement. As the Soviet Union was not yet a member of the FAI, however, Cheremukhin's record remained unrecognized.[76]
The Bréguet-Dorand
American single-rotor beginnings
American inventor
Birth of an industry
During World War II,
In the United States, Russian-born engineer
Developed from the VS-300, Sikorsky's
While LePage and Sikorsky built their helicopters for the military,
Turbine age
In 1951, at the urging of his contacts at the Department of the Navy,
Reliable helicopters capable of stable hover flight were developed decades after fixed-wing aircraft. This is largely due to higher engine power density requirements than fixed-wing aircraft. Improvements in fuels and engines during the first half of the 20th century were a critical factor in helicopter development. The availability of lightweight turboshaft engines in the second half of the 20th century led to the development of larger, faster, and higher-performance helicopters. While smaller and less expensive helicopters still use piston engines, turboshaft engines are the preferred powerplant for helicopters today.[citation needed]
Safety
Maximum speed limit
There are several reasons a helicopter cannot fly as fast as a fixed-wing aircraft. When the helicopter is hovering, the outer tips of the rotor travel at a speed determined by the length of the blade and the rotational speed. 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 speed. 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.[citation needed]
At the same time, the advancing blade creates more lift traveling forward, the retreating blade produces less lift. If the aircraft were to accelerate to the air speed that the blade tips are spinning, the retreating blade passes through air moving at the same speed of the blade and produces no lift at all, resulting in very high torque stresses on the central shaft that can tip down the retreating-blade side of the vehicle, and cause a loss of control. Dual counter-rotating blades prevent this situation due to having two advancing and two retreating blades with balanced forces.[citation needed]
Because the advancing blade has higher airspeed than the retreating blade and generates a
Noise
At the end of the 20th century, designers began working on
Vibration
To reduce vibration, all helicopters have rotor adjustments for height and weight. A maladjusted helicopter can easily vibrate so much that it will shake itself apart. Blade height is adjusted by changing the pitch of the blade. Weight is adjusted by adding or removing weights on the rotor head and/or at the blade end caps. 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. Adjustment can be difficult in part because measurement of the vibration is hard, usually requiring sophisticated accelerometers mounted throughout the airframe and gearboxes. The most common blade vibration 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. Health and Usage Monitoring Systems (HUMS) provide vibration monitoring and rotor track and balance solutions to limit vibration.[90] Gearbox vibration most often requires a gearbox overhaul or replacement. Gearbox or drive train vibrations can be extremely harmful to a pilot. The most severe effects are pain, numbness, and loss of tactile discrimination or dexterity.[citation needed]
Loss of tail-rotor effectiveness
For a standard helicopter with a single main rotor, the tips of the main rotor blades produce a vortex ring in the air, which is a spiraling and circularly rotating airflow. As the craft moves forward, these vortices trail off behind the craft.[citation needed]
When hovering with a forward diagonal crosswind, or moving in a forward diagonal direction, the spinning vortices trailing off the main rotor blades will align with the rotation of the tail rotor and cause an instability in flight control.[91]
When the trailing vortices colliding with the tail rotor are rotating in the same direction, this causes a loss of thrust from the tail rotor. When the trailing vortices rotate in the opposite direction of the tail rotor, thrust is increased. Use of the foot pedals is required to adjust the tail rotor's angle of attack, to compensate for these instabilities.[citation needed]
These issues are due to the exposed tail rotor cutting through open air around the rear of the vehicle. This issue disappears when the tail is instead ducted, using an internal impeller enclosed in the tail and a jet of high pressure air sideways out of the tail, as the main rotor vortices can not impact the operation of an internal impeller.[citation needed]
Critical wind azimuth
For a standard helicopter with a single main rotor, maintaining steady flight with a crosswind presents an additional flight control problem, where strong crosswinds from certain angles will increase or decrease lift from the main rotors. This effect is also triggered in a no-wind condition when moving the craft diagonally in various directions, depending on the direction of main rotor rotation.[92]
This can lead to a loss of control and a crash or hard landing when operating at low altitudes, due to the sudden unexpected loss of lift, and insufficient time and distance available to recover.[citation needed]
Transmission
Conventional rotary-wing aircraft use a set of complex mechanical gearboxes to convert the high rotation speed of gas turbines into the low speed required to drive main and tail rotors. Unlike powerplants, mechanical gearboxes cannot be duplicated (for redundancy) and have always been a major weak point in helicopter reliability. In-flight catastrophic gear failures often result in gearbox jamming and subsequent fatalities, whereas loss of lubrication can trigger onboard fire.[citation needed] Another weakness of mechanical gearboxes is their transient power limitation, due to structural fatigue limits. Recent EASA studies point to engines and transmissions as prime cause of crashes just after pilot errors.[93]
By contrast, electromagnetic transmissions do not use any parts in contact; hence lubrication can be drastically simplified, or eliminated. Their inherent redundancy offers good resilience to single point of failure. The absence of gears enables high power transient without impact on service life. The concept of electric propulsion applied to helicopter and electromagnetic drive was brought to reality by Pascal Chretien who designed, built and flew world's first man-carrying, free-flying electric helicopter. The concept was taken from the conceptual computer-aided design model on 10 September 2010 to the first testing at 30% power on 1 March 2011 – less than six months. The aircraft first flew on 12 August 2011. All development was conducted in Venelles, France.[94][95]
Hazards
As with any moving vehicle, unsafe operation could result in loss of control, structural damage, or loss of life. The following is a list of some of the potential hazards for helicopters:
- Settling with power is when the aircraft has insufficient power to arrest its descent. This hazard can develop into vortex ring state if not corrected early.[96]
- Vortex ring state is a hazard induced by a combination of low airspeed, high power setting, and high descent rate. Rotor-tip vortices circulate from the high pressure air below the rotor disk to low pressure air above the disk, so that the helicopter settles into its own descending airflow.[96] Adding more power increases the rate of air circulation and aggravates the situation. It is sometimes confused with settling with power, but they are aerodynamically different.
- Retreating blade stall is experienced during high speed flight and is the most common limiting factor of a helicopter's forward speed.
- Ground resonance is a self-reinforcing vibration that occurs when the lead/lag spacing of the blades of an articulated rotor system becomes irregular.
- Low-G condition is an abrupt change from a positive G-force state to a negative G-force state that results in loss of lift (unloaded disc) and subsequent roll over. If aft cyclic is applied while the disc is unloaded, the main rotor could strike the tail causing catastrophic failure.[97]
- Dynamic rollover in which the helicopter pivots around one of the skids and 'pulls' itself onto its side (almost like a fixed-wing aircraft ground loop).
- height-velocity diagram.
- Tail rotor failures which occur from either a mechanical malfunction of the tail rotor control system or a loss of tail rotor thrust authority, called "loss of tail-rotor effectiveness" (LTE).
- Brownout in dusty conditions or whiteoutin snowy conditions.
- Low rotor RPM, is when the engine cannot drive the blades at sufficient RPM to maintain flight.
- Rotor overspeed, which can over-stress the rotor hub pitch bearings (brinelling) and, if severe enough, cause blade separation from the aircraft.
- Wire and tree strikes due to low altitude operations and take-offs and landings in remote locations.[98]
- Controlled flight into terrain in which the aircraft is flown into the ground unintentionally due to a lack of situational awareness.
- Mast bumping in some helicopters[99]
List of fatal crashes
Date | Operator | Aircraft | Event and location | Death toll |
---|---|---|---|---|
19 August 2002 | Russia | Mil Mi-26 | Shot down over Chechnya | 127[100] |
9 December 1982 | Nicaragua | Mil Mi-8 | Shot down by Sandinistan rebels while carrying 88 people. All 84 passengers were killed and all four crew members survived.[101] | 84 |
4 February 1997 | Israel | Sikorsky CH-53 Sea Stallion (x2) | Collision over Israel | 73 |
14 December 1992 | Russia (Russian Air Force) | Mil Mi-8 | Shot down by Georgian forces in Abkhazia using SA-14 MANPADs, despite heavy escort. Three crew and 58 passengers, composed of mainly Russian refugees.[102]
|
61 |
4 October 1993 | Georgia | Mil Mi-8 | Shot down when transporting 60 refugees from eastern Abkhazia; all on board were killed.[102][failed verification] | 60 |
10 May 1977 | Israel | CH-53 | Jordan Valley |
54 |
8 January 1968 | United States | Sikorsky CH-53A Sea Stallion, USMC | Crash near Đông Hà Combat Base in South Vietnam. All five crew and 41 passengers were killed. | 46[103] |
11 July 1972 | United States | Sikorsky CH-53D Sea Stallion, USMC | Shot down by missile near Quảng Trị in South Vietnam. Six US Marines and 50 Vietnamese Marines on board. Three US Marines and 43 Vietnamese Marines were killed. | 46[104] |
11 September 1982 | United States | U.S. Army |
Crash at an air show in Mannheim, then located in West Germany. | 46[105] |
6 November 1986 | British International Helicopters | Boeing 234LR Chinook | Shetland Islands |
45 |
28 January 1992 | Azerbaijan | Mil Mi-8 | Shootdown | 44 |
3 July 2009 | Pakistan (Pakistan Army) | Mil Mi-17 | Crash | 41 |
6 August 2011 | United States | CH-47 Chinook | Shootdown , Afghanistan |
38[106] |
18 August 1971 | United States | CH-47 Chinook, US Army | Crash near Pegnitz, then located in West Germany. All four crew and 33 passengers were killed. | 37[107] |
26 January 2005 | United States | Sikorsky CH-53E Super Stallion, USMC | Ar Rutbah, Iraq |
31[108] |
World records
Record type | Record | Helicopter | Pilot(s) | Date | Location | Note | Ref. |
---|---|---|---|---|---|---|---|
Speed | 400.87 km/h (249.09 mph) | Westland Lynx | John Trevor Egginton (UK) | 11 August 1986 | UK | [109] | |
Distance without landing | 3,561.55 km (2,213.04 mi) | Hughes YOH-6A | Robert G. Ferry (USA) | 6 April 1966 | United States | [110] | |
Around-the-world speed | 136.7 km/h (84.9 mph) | Agusta A109S Grand | Scott Kasprowicz (USA) | 18 August 2008 | From and to New York City via Europe, Russia, Alaska, Canada |
No in-flight refueling | [111] |
Highest altitude without payload | 12,442 m (40,820 ft) | Aerospatiale Lama |
Jean Boulet (France) | 21 June 1972 | France | [112] | |
Highest level flight altitude | 11,010 m (36,120 ft) | Sikorsky CH-54 Tarhe | James K. Church | 4 November 1971 | United States | [113] | |
Altitude with 40- payload |
2,255 m (7,398 ft) | Mil V-12 | Vasily Kolochenko, et al. | 6 August 1969 | USSR | [114] | |
Highest takeoff (turbine) | 8,848 m (29,029 ft) | Eurocopter AS350 |
Didier Delsalle | 14 May 2005 | Nepal | Mount Everest | [115] |
Highest takeoff (piston) | 4,300.7 m (14,110 ft) | Robinson R44 | Mark Young | 12 October 2009 | United States | Pike's Peak, Colorado | [116] |
First manned electric flight | Purely electric hover | Solution F Prototype | Pascal Chretien | 12 August 2011 | France | Venelles | [117] |
Longest human-powered lift | Pedalling, lift 64 s endurance, 3.3 m height; diagonal width: 46.9 m | AeroVelo Atlas, 4 rotors | Todd Reichert | 13 June 2013 | Canada | Indoor soccer stadium; Igor I. Sikorsky Competition winner | [118] |
See also
- Attack helicopter
- Backpack helicopter
- Cyclogyro
- Disk loading
- Helicopter dynamics
- Helicopter height–velocity diagram
- Helicopter manufacturer
- Helicopter Underwater Escape Training
- Jesus nut, the top central big nut that holds the rotor on
- List of helicopter airlines
- List of rotorcraft
- Transverse flow effect
- Utility helicopter
- Wire strike protection system
- Tiltrotor
References
Notes
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Bibliography
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- Frawley, Gerard. The International Directory of Civil Aircraft, 2003–2004. Fyshwick, Canberra, Act, Australia: Aerospace Publications Pty Ltd., 2003, p. 155. ISBN 1-875671-58-7.
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- Rotorcraft Flying Handbook. Washington: Skyhorse Publishing, Inc., 2007. ISBN 1-60239-060-6.
- Rotorcraft Flying Handbook: FAA Manual H-8083-21. Washington, D.C.: Federal Aviation Administration (Flight Standards Division), U.S. Dept. of Transportation, 2001. ISBN 1-56027-404-2.
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- Watkinson, John. Art of the Helicopter. Oxford: Elsevier Butterworth-Heinemann, 2004. ISBN 0-7506-5715-4
- Wragg, David W. Helicopters at War: A Pictorial History. London: R. Hale, 1983. ISBN 0-7090-0858-9.
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External links
- "Helicopterpage.com – How Helicopters Work" Complete site explaining different aspects of helicopters and how they work.
- "Planes That Go Straight Up". 1935 article about early development and research into helicopters.
- "Flights — of the Imagination". 1918 article on helicopter design concepts.
- "Twin Windmill Blades Fly Wingless Ship" Popular Mechanics, April 1936
- Silent (Russian-language intertitled) video about the Cheremukhin/Yuriev TsAGI 1-EA pioneer helicopter
- American Helicopter Society
- Graham Warwick (17 June 2016). "How The Helicopter Has Developed". Aviation Week & Space Technology. Getting from idea to reality took far longer for the helicopter than for the fixed-wing aircraft.