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Antitorque
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of STOL (Short TakeOff and Landing) or STOVL (Short TakeOff and Vertical Landing) aircraft cannot perform without a runway. In 1942, the Sikorsky R-4 became the first helicopter to reach full-scale production.Munson 1968.Hirschberg, Michael J. and David K. Dailey"Sikorsky". ''US and Russian Helicopter Development in the 20th Century'', American Helicopter Society, International. 7 July 2000. Although most earlier designs used more than one main rotor, the configuration of a single main rotor accompanied by a vertical anti-torque tail rotor (i.e. unicopter, not to be confused with the single-blade monocopter) has become the most common hel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Rotor
A helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which connects through a combination of drive shaft(s) and gearboxes along the tail boom. The blade pitch is typically controlled by the pilot using the helicopter flight controls. Helicopters are one example of rotary-wing aircraft (rotorcraft). The name is derived from the Greek words ''helix'', helik-, meaning spiral; and ''pteron'' meaning wing. Design principles Overview The helicopter rotor is powered by the engine, through the transmission, to the rotating mast. The mast is a cylindrical metal shaft that extends upward from—and is driven by—the transmission. At the top of the mast i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicopter Rotor
A helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight. Each main rotor is mounted on a vertical mast over the top of the helicopter, as opposed to a helicopter tail rotor, which connects through a combination of drive shaft(s) and gearboxes along the tail boom. The blade pitch is typically controlled by the pilot using the helicopter flight controls. Helicopters are one example of rotary-wing aircraft (rotorcraft). The name is derived from the Greek words ''helix'', helik-, meaning spiral; and ''pteron'' meaning wing. Design principles Overview The helicopter rotor is powered by the engine, through the transmission, to the rotating mast. The mast is a cylindrical metal shaft that extends upward from—and is driven by—the transmission. At the top of the mast i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compound Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of STOL (Short TakeOff and Landing) or STOVL (Short TakeOff and Vertical Landing) aircraft cannot perform without a runway. In 1942, the Sikorsky R-4 became the first helicopter to reach full-scale production.Munson 1968.Hirschberg, Michael J. and David K. Dailey"Sikorsky". ''US and Russian Helicopter Development in the 20th Century'', American Helicopter Society, International. 7 July 2000. Although most earlier designs used more than one main rotor, the configuration of a single main rotor accompanied by a vertical anti-torque tail rotor (i.e. unicopter, not to be confused with the single-blade monocopter) has become the most common he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LAPD Bell 206 Jetranger
The Los Angeles Police Department (LAPD), officially known as the City of Los Angeles Police Department, is the municipal Police, police department of Los Angeles, California. With 9,974 police officers and 3,000 civilian staff, it is the third-largest municipal police department in the United States, after the New York City Police Department and the Chicago Police Department. The LAPD has its headquarters at 100 W. 1st St., in the Civic Center, Los Angeles, Civic Center district, not far from the demolished Parker Center it replaced in 2009. The organization of the department is complex, including 21 divisions (stations) grouped in four bureaus in the Office of Operations; multiple divisions within the Detective Bureau in the Office of Special Operations; and specialized units such as SWAT, K-9, mounted police, air support and the Major Crimes Division all within the Counterterrorism and Special Operations Bureau. Further offices support the chief of police in areas such as c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transverse Rotors
Transverse rotor aircraft have two large horizontal rotor assemblies mounted side by side. Single-rotor helicopters (unicopters) need an additional tail rotor or tail exhaust to neutralize the reactional angular momentum produced by the main rotor. Transverse rotor helicopters, however, use counter-rotating rotors, with each cancelling out the other's torque. Counter-rotating rotor blades also won't collide with and destroy each other if they flex into the other rotor's pathway. In addition, transverse rotor configuration has the advantage of higher payload with shorter blades, since there are two sets working to provide lift. Also, all of the power from the engines can be used for lift, whereas a single-rotor helicopter must divert part of its engine power to generate tail thrust. Transverse rotor design with rotatable nacelles are known as tiltrotors while designs where the whole wing rotates are known as tiltwings. List of transverse rotor aircraft Transverse-mounted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kappa
Kappa (uppercase Κ, lowercase κ or cursive ; el, κάππα, ''káppa'') is the 10th letter of the Greek alphabet, representing the voiceless velar plosive sound in Ancient and Modern Greek. In the system of Greek numerals, has a value of 20. It was derived from the Phoenician letter kaph . Letters that arose from kappa include the Roman K and Cyrillic К. The uppercase form is identical to the Latin K. Greek proper names and placenames containing kappa are often written in English with "c" due to the Romans' transliterations into the Latin alphabet: Constantinople, Corinth, Crete. All formal modern romanizations of Greek now use the letter "k", however. The cursive form is generally a simple font variant of lower-case kappa, but it is encoded separately in Unicode for occasions where it is used as a separate symbol in math and science. In mathematics, the kappa curve is named after this letter; the tangents of this curve were first calculated by Isaac Barrow in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genitive Case
In grammar, the genitive case (abbreviated ) is the grammatical case that marks a word, usually a noun, as modifying another word, also usually a noun—thus indicating an attributive relationship of one noun to the other noun. A genitive can also serve purposes indicating other relationships. For example, some verbs may feature arguments in the genitive case; and the genitive case may also have adverbial uses (see adverbial genitive). Genitive construction includes the genitive case, but is a broader category. Placing a modifying noun in the genitive case is one way of indicating that it is related to a head noun, in a genitive construction. However, there are other ways to indicate a genitive construction. For example, many Afroasiatic languages place the head noun (rather than the modifying noun) in the construct state. Possessive grammatical constructions, including the possessive case, may be regarded as a subset of genitive construction. For example, the genitive constru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Language
Greek ( el, label=Modern Greek, Ελληνικά, Elliniká, ; grc, Ἑλληνική, Hellēnikḗ) is an independent branch of the Indo-European family of languages, native to Greece, Cyprus, southern Italy (Calabria and Salento), southern Albania, and other regions of the Balkans, the Black Sea coast, Asia Minor, and the Eastern Mediterranean. It has the longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system is the Greek alphabet, which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic, and many other writing systems. The Greek language holds a very important place in the history of the Western world. Beginning with the epics of Homer, ancient Greek literature includes many works of lasting impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unmanned Aerial Vehicle
An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without any human pilot, crew, or passengers on board. UAVs are a component of an unmanned aircraft system (UAS), which includes adding a ground-based controller and a system of communications with the UAV. The flight of UAVs may operate under remote control by a human operator, as remotely-piloted aircraft (RPA), or with various degrees of autonomy, such as autopilot assistance, up to fully autonomous aircraft that have no provision for human intervention. UAVs were originally developed through the twentieth century for military missions too "dull, dirty or dangerous" for humans, and by the twenty-first, they had become essential assets to most militaries. As control technologies improved and costs fell, their use expanded to many non-military applications.Hu, J.; Bhowmick, P.; Jang, I.; Arvin, F.; Lanzon, A.,A Decentralized Cluster Formation Containment Framework for Multirobot Systems IEEE Tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multicopter
A multirotor or multicopter is a rotorcraft with more than two lift-generating rotors. An advantage of multirotor aircraft is the simpler rotor mechanics required for flight control. Unlike single- and double-rotor helicopters which use complex variable pitch rotors whose pitch varies as the blade rotates for flight stability and control, multirotors often use fixed- pitch blades; control of vehicle motion is achieved by varying the relative speed of each rotor to change the thrust and torque produced by each. Due to their ease of both construction and control, multirotor aircraft are frequently used in radio control aircraft and unmanned aerial vehicle (UAV) (drone) projects in which the names tricopter, quadcopter, hexacopter and octocopter are frequently used to refer to 3-, 4-, 6- and 8-rotor rotorcraft, respectively. There is also the X8 (also called ''octo-quad'') configuration that is similar to the quadracopter design, except that it has eight rotors; the lower of whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
