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Loss Of Tail-rotor Effectiveness
Loss of tail-rotor effectiveness (LTE)Rotorcraft Flying Handbook Section 11-12, Federal Aviation Administration, Skyhorse Publishing (July 2007) occurs when the tail rotor of a helicopter is exposed to wind forces that prevent it from carrying out its function—that of cancelling the torque of the engine and transmission. Any low-airspeed high-power environment provides an opportunity for it to occur. Causes Environmental factors which can lead to LTE include higher operating-density altitudes or temperatures, and high winds. A high gross weight can also create an LTE-conducive situation. Causative wind-directions may include: # Main rotor disk interference - Main-rotor disk vortices are pushed into the tail rotor by wind. This can occur with wind coming from 10 o'clock on North American (counter-clockwise) rotors and from 2 o'clock on clockwise rotors. The wind pushes the dirty air and vortices generated from the main-rotor into the tail-rotor, preventing the tail rotor fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Rotor Disk Vortex Interference
Main may refer to: Geography * Main River (other) **Most commonly the Main (river) in Germany * Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries *''The Main'', the diverse core running through Montreal, Quebec, Canada, also separating the Two Solitudes *Main (lunar crater), located near the north pole of the Moon *Main (Martian crater) People and organisations * Main (surname), a list of people with this family name *Ma'in, alternate spelling for the Minaeans, an ancient people of modern-day Yemen *Main (band), a British ambient band formed in 1991 * Chas. T. Main, an American engineering and hydroelectric company founded in 1893 *MAIN (Mountain Area Information Network), former operator of WPVM-LP (MAIN-FM) in Asheville, North Carolina, U.S. Ships * ''Main'' (ship), an iron sailing ship launched in 1884 * SS ''Main'', list of steamships with this name * ''Main'' (A515), a moder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weathercock Stability
A wind vane, weather vane, or weathercock is an instrument used for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word ''vane'' comes from the Old English word , meaning "flag". Although partly functional, wind vanes are generally decorative, often featuring the traditional cockerel design with letters indicating the points of the compass. Other common motifs include ships, arrows, and horses. Not all wind vanes have pointers. In a sufficiently strong wind, the head of the arrow or cockerel (or equivalent) will indicate the direction from which the wind is blowing. Wind vanes are also found on small wind turbines to keep the wind turbine pointing into the wind. History The oldest textual reference in China to a weather vane comes from the ''Huainanzi'' dating from around 139 BC, which mentions a thread or streamer that another commentator interprets as "wind-observing fan" (, ). The Tower of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail Rotor Vortex Ring State
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds. While tails are primarily a feature of vertebrates, some invertebrates including scorpions and springtails, as well as snails and slugs, have tail-like appendages that are sometimes referred to as tails. Tailed objects are sometimes referred to as "caudate" and the part of the body associated with or proximal to the tail are given the adjective "caudal". Function Animal tails are used in a variety of ways. They provide a source of locomotion for fish and some other forms of marine life. Many land animals use their tails to brush away flies and other biting insects. Most canines use their tails to comunicate mood and intention . Some species, including cats and kangaroos, use their tails for balance; and some, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail Rotor
The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor's rotation. The tail rotor's position and distance from the helicopter's center of mass allow it to develop enough thrust leverage to counter the reactional torque exerted on the fuselage by the spinning of the main rotor. Without the tail rotor or other anti-torque mechanisms (e.g. NOTAR), the helicopter would be constantly spinning in the opposite direction of the main rotor when flying. Tail rotors are simpler than main rotors since they require only collective changes in pitch to vary thrust. The pitch of the tail rotor blades is adjustable by the pilot via the anti-torque pedals, which also provide directional control by allowing the pilot to rotate the helicopter around its vertical axis. Its drive system consists of a shaft powered from the mai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of the body. The concept originated with the studies by Archimedes of the usage of levers, which is reflected in his famous quote: "''Give me a lever and a place to stand and I will move the Earth''". Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object around a specific axis. Torque is defined as the product of the magnitude of the perpendicular component of the force and the distance of the line of action of a force from the point around which it is being determined. The law of conservation of energy can also be used to understand torque. The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. When being referred to as moment of force, it is commonly denoted by . In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yaw Angle
The Euler angles are three angles introduced by Leonhard Euler to describe the orientation of a rigid body with respect to a fixed coordinate system.Novi Commentarii academiae scientiarum Petropolitanae 20, 1776, pp. 189–207 (E478PDF/ref> They can also represent the orientation of a mobile frame of reference in physics or the orientation of a general basis in 3-dimensional linear algebra. Alternative forms were later introduced by Peter Guthrie Tait and George H. Bryan intended for use in aeronautics and engineering. Chained rotations equivalence Euler angles can be defined by elemental geometry or by composition of rotations. The geometrical definition demonstrates that three composed ''elemental rotations'' (rotations about the axes of a coordinate system) are always sufficient to reach any target frame. The three elemental rotations may be extrinsic (rotations about the axes ''xyz'' of the original coordinate system, which is assumed to remain motionless), or intrinsic ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autorotation (helicopter)
Autorotation is a state of flight in which the main rotor system of a helicopter or other rotary-wing aircraft turns by the action of air moving up through the rotor, as with an autogyro, rather than engine power driving the rotor. Bensen, Igor.How they fly – Bensen explains all" ''Gyrocopters UK''. Accessed: 10 April 2014. Quote: "air.. (is) deflected downward"Charnov, Bruce HCierva, Pitcairn and the Legacy of Rotary-Wing Flight ''Hofstra University''. Accessed: 22 November 2011. The term ''autorotation'' dates to a period of early helicopter development between 1915 and 1920, and refers to the rotors turning without the engine."Autorotation", ''Dictionary.com Unabridged (v 1.1)''. Random House, Inc. 17 April 2007 It is analogous to the |
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