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Sound Barrier
The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, these effects were seen as constituting a barrier, making faster speeds very difficult or impossible. The term ''sound barrier'' is still sometimes used today to refer to aircraft approaching supersonic flight in this high drag regime. Flying faster than sound produces a sonic boom. In dry air at 20 °C (68 °F), the speed of sound is 343 metres per second (about 767 mph, 1234 km/h or 1,125 ft/s). The term came into use during World War II when pilots of high-speed fighter aircraft experienced the effects of compressibility, a number of adverse aerodynamic effects that deterred further acceleration, seemingly impeding flight at speeds close to the speed of sound. These difficulties represented a barrier to flying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WikiProject Aircraft
A WikiProject, or Wikiproject, is an affinity group for contributors with shared goals within the Wikimedia movement. WikiProjects are prevalent within the largest wiki, Wikipedia, and exist to varying degrees within Wikimedia project, sibling projects such as Wiktionary, Wikiquote, Wikidata, and Wikisource. They also exist in different languages, and translation of articles is a form of their collaboration. During the COVID-19 pandemic, CBS News noted the role of Wikipedia's WikiProject Medicine in maintaining the accuracy of articles related to the disease. Another WikiProject that has drawn attention is WikiProject Women Scientists, which was profiled by ''Smithsonian Magazine, Smithsonian'' for its efforts to improve coverage of women scientists which the profile noted had "helped increase the number of female scientists on Wikipedia from around 1,600 to over 5,000". On Wikipedia Some Wikipedia WikiProjects are substantial enough to engage in cooperative activities with outsi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Firearm
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originated in 10th-century China, when bamboo tubes containing gunpowder and pellet projectiles were mounted on spears to make the portable fire lance, operable by a single person, which was later used effectively as a shock weapon in the siege of De'an in 1132. In the 13th century, fire lance barrels were replaced with metal tubes and transformed into the metal-barreled hand cannon. The technology gradually spread throughout Eurasia during the 14th century. Older firearms typically used black powder as a propellant, but modern firearms use smokeless powder or other explosive propellants. Most modern firearms (with the notable exception of smoothbore shotguns) have rifled barrels to impart spin to the projectile for improved flight stabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armstrong Whitworth Aircraft
Sir W. G. Armstrong Whitworth Aircraft Company, or Armstrong Whitworth Aircraft, was a British list of aircraft manufacturers, aircraft manufacturer. History Armstrong Whitworth Aircraft was established as the Aerial Department of the Armstrong Whitworth, Sir W. G. Armstrong Whitworth & Company engineering group in Newcastle-upon-Tyne in 1912, and from c. 1914 to 1917 employed the Dutch aircraft designer Frederick Koolhoven (hence the "F.K." models).Tapper 1988, pp. 5–10. In 1920, Armstrong Whitworth acquired the aircraft engine, engine and automobile manufacturer Siddeley-Deasy. The engine and automotive businesses of both companies were spun off as Armstrong Siddeley and the aircraft interests as the Sir W. G. Armstrong Whitworth Aircraft Company.Tapper 1988, pp. 17–18. When Vickers Limited, Vickers and Armstrong Whitworth merged in 1927 to form Vickers-Armstrongs, Armstrong Whitworth Aircraft and Armstrong Siddeley were bought out by John Davenport Siddeley, J. D. Sidde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airfoil
An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fluid mechanics), Foils of similar function designed with water as the working fluid are called hydrofoils. When oriented at a suitable angle, a solid body moving through a fluid deflects the oncoming fluid (for fixed-wing aircraft, a downward force), resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as aerodynamic force and can be resolved into two components: lift (perpendicular to the remote freestream velocity) and drag (Parallel (geometry), parallel to the freestream velocity). The lift on an airfoil is primarily the result of its angle of attack. Most foil shapes require a positive angle of attack to generate lift, but Camber (aerodynamics), cambered airfoils can generate lift at zero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Atmosphere
Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes: * The mesosphere, which on Earth lies between the altitudes of about , sometimes considered part of the "middle atmosphere" rather than the upper atmosphere * The thermosphere, which on Earth lies between the altitudes of about * The exosphere, which on Earth lies between the altitudes of about and * The ionosphere, an ionized portion of the upper atmosphere which includes the upper mesosphere, thermosphere, and lower exosphere and on Earth lies between the altitudes of See also * Geospace *Magnetosphere *Near space Near space is the upper region of the Earth's atmosphere between airspace and outer space. It is sometimes referred to as the " edge of space". There is no legal definition for this extent, but typically this is the altitude range from . Rang ... References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorite
A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a Meteoroid#Fireball, fireball, also known as a shooting star; astronomers call the brightest examples "Bolide#Astronomy, bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and impact event, impact Earth are called meteorite falls. All others are known as meteorite finds. Meteorites have traditionally been divided into three broad categories: stony meteorites that are rocks, mainly composed of sil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail
The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to lose their tails (e.g. frogs and hominid primates), the coccyx is the homologous vestigial of the tail. While tails are primarily considered a feature of vertebrates, some invertebrates such as scorpions and springtails, as well as snails and slugs, have tail-like appendages that are also referred to as tails. Tail-shaped objects are sometimes referred to as "caudate" (e.g. lobes of liver#Caudate lobe, caudate lobe, caudate nucleus), and the body part associated with or proximal to the tail are given the adjective "caudal (anatomical term), caudal" (which is considered a more precise anatomical terminology). Function Animal tails are used in a variety of ways. They provide a source of thrust for aquatic locomotion for fish, cetaceans and cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplodocus
''Diplodocus'' (, , or ) is an extinct genus of diplodocid sauropod dinosaurs known from the Late Jurassic of North America. The first fossils of ''Diplodocus'' were discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλός (''diplos'') "double" and δοκός (''dokos'') "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique. The genus of dinosaurs lived in what is now mid-western North America, at the end of the Jurassic period. It is one of the more common dinosaur fossils found in the middle to upper Morrison Formation, with most specimens being found in rocks between about 151.88 and 149.1 million years ago , during the latest Kimmeridgian Age, although it may have made it into the Tithonian., with at least one specimen (AMNH FR 223) being potentially from among the youngest deposits of the formation. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apatosaurus
''Apatosaurus'' (; meaning "deceptive lizard") is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, ''A. ajax'', in 1877, and a second species, ''A. louisae'', was discovered and named by William H. Holland in 1916. ''Apatosaurus'' lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. ''Apatosaurus'' had an average length of , and an average mass of . A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately . The cervical vertebrae of ''Apatosaurus'' are less elongated and more heavily constructed than those of '' Diplodocus'', a diplodocid like ''Apatosaurus'', and the bones of the leg are much stockier despite being longer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brontosaurus
''Brontosaurus'' (; meaning "thunder lizard" from the Ancient Greek, Greek words , "thunder" and , "lizard") is a genus of herbivorous sauropod dinosaur that lived in present-day United States during the Late Jurassic period. It was described by American paleontologist Othniel Charles Marsh in 1879, the type species being dubbed ''B. excelsus'', based on a partial skeleton lacking a skull found in Como Bluff, Wyoming. In subsequent years, two more species of ''Brontosaurus'' were named: ''B. parvus'' in 1902 and ''B. yahnahpin'' in 1994. ''Brontosaurus'' lived about 156 to 146 million years ago (mya) during the Kimmeridgian and Tithonian ages in the Morrison Formation of what is now Utah and Wyoming. For decades, the animal was thought to have been a Synonym (taxonomy), taxonomic synonym of its close relative ''Apatosaurus'', but a 2015 study by Emmanuel Tschopp and colleagues found it to be distinct. It has seen widespread representation in popular culture, being the archetyp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutionary history, evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, Evolution of birds, having evolved from earlier Theropoda, theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomy (biology), taxonomic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomechanics
Biomechanics is the study of the structure, function and motion of the mechanical aspects of biological systems, at any level from whole organisms to Organ (anatomy), organs, Cell (biology), cells and cell organelles, using the methods of mechanics. Biomechanics is a branch of biophysics. Etymology The word "biomechanics" (1899) and the related "biomechanical" (1856) come from the Ancient Greek βίος ''bios'' "life" and μηχανική, ''mēchanikē'' "mechanics", to refer to the study of the mechanical principles of living organisms, particularly their movement and structure. Subfields Biofluid mechanics Biological fluid mechanics, or biofluid mechanics, is the study of both gas and liquid fluid flows in or around biological organisms. An often studied liquid biofluid problem is that of blood flow in the human cardiovascular system. Under certain mathematical circumstances, blood flow can be modeled by the Navier–Stokes equations. ''In vivo'' whole blood is assum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
