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Propeller (aircraft)
An aircraft propeller, also called an airscrew,Beaumont, R.A.; ''Aeronautical Engineering'', Odhams, 1942, Chapter 13, "Airscrews". converts rotary motion from an engine or other power source into a swirling slipstream which pushes the propeller forwards or backwards. It comprises a rotating power-driven hub, to which are attached several radial airfoil-section blades such that the whole assembly rotates about a longitudinal axis. The blade pitch may be fixed, manually variable to a few set positions, or of the automatically variable "constant-speed" type. The propeller attaches to the power source's driveshaft either directly or through reduction gearing. Propellers can be made from wood, metal or composite materials. Propellers are most suitable for use at subsonic airspeeds generally below about , although supersonic speeds were achieved in the McDonnell XF-88B experimental propeller-equipped aircraft. Supersonic tip-speeds are used in some aircraft like the Tupolev Tu-95 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Greek hero's iconography and myths for their literature and art under the name ''Hercules''. In later Western art and literature and in popular culture, ''Hercules'' is more commonly used than ''Heracles'' as the name of the hero. Hercules is a multifaceted figure with contradictory characteristics, which enabled later artists and writers to pick and choose how to represent him. This article provides an introduction to representations of Hercules in the later tradition. Mythology Birth and early life In Roman mythology, although Hercules was seen as the champion of the weak and a great protector, his personal problems started at birth. Juno sent two witches to prevent the birth, but they were tricked by one of Alcmene's servants and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leonardo Da Vinci
Leonardo di ser Piero da Vinci (15 April 14522 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, Drawing, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested on his achievements as a painter, he also became known for #Journals and notes, his notebooks, in which he made drawings and notes on a variety of subjects, including anatomy, astronomy, botany, cartography, painting, and paleontology. Leonardo is widely regarded to have been a genius who epitomized the Renaissance humanism, Renaissance humanist ideal, and his List of works by Leonardo da Vinci, collective works comprise a contribution to later generations of artists matched only by that of his younger contemporary, Michelangelo. Born Legitimacy (family law), out of wedlock to a successful Civil law notary, notary and a lower-class woman in, or near, Vinci, Tuscany, Vinci, he was educated in Florence by the Italian painter and sculptor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sir George Cayley
Sir George Cayley, 6th Baronet (27 December 1773 – 15 December 1857) was an English engineer, inventor, and aviator. He is one of the most important people in the history of aeronautics. Many consider him to be the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight and the first man to create the wire wheel. * * * In 1799, he set forth the concept of the modern aeroplane as a fixed-wing flying machine with separate systems for lift, propulsion, and control. He was a pioneer of aeronautical engineering and is sometimes referred to as "the father of aviation." He identified the four forces which act on a heavier-than-air flying vehicle: weight, lift, drag and thrust. Modern aeroplane design is based on those discoveries and on the importance of cambered wings, also proposed by Cayley. He constructed the first flying model aeroplane and also diagrammed the elements of vertical flight. He also designed t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean-Pierre Blanchard
Jean-Pierre rançoisBlanchard (4 July 1753 – 7 March 1809) was a French inventor, best known as a pioneer of gas balloon flight, who distinguished himself in the conquest of the air in a balloon, in particular the first crossing of the English Channel, on 7 January 1785. Biography 1784 - Flights in Paris Blanchard made his first successful balloon flight in Paris on 2 March 1784, in a hydrogen gas balloon launched from the Champ de Mars. The first successful manned balloon flight had taken place on 21 November 1783, when Pilâtre de Rozier and the Marquis d'Arlandes took off at Palace of Versailles in a free-flying hot air balloon constructed by the Montgolfier brothers. The first manned hydrogen balloon flight had taken place on 1 December 1783, when Professor Jacques Charles and Nicolas-Louis Robert launched '' La Charlière'' from the Jardin des Tuileries in Paris. Blanchard's flight nearly ended in disaster, when one spectator (Dupont de Chambon, a contemporary of N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jean Baptiste Marie Meusnier
Jean Baptiste Marie Charles Meusnier de la Place (Tours, 19 June 1754 — le Pont de Cassel, near Mainz, 13 June 1793) was a French mathematician, engineer and Revolutionary general. He is best known for Meusnier's theorem on the curvature of surfaces, which he formulated while he was at the École Royale du Génie (Royal School of Engineering). He also discovered the helicoid. He worked with Lavoisier on the decomposition of water and the evolution of hydrogen. Dirigible balloon Meusnier is sometimes portrayed as the inventor of the dirigible, because of an uncompleted project he conceived in 1784, not long after the first balloon flights of the Montgolfiers, and presented to the French Academy of Sciences. This concerned an elliptical balloon (''ballonet'') 84 metres long, with a capacity of 1,700 cubic metres, powered by three propellers driven by 80 men. The basket, in the form of a boat, was suspended from the canopy on a system of three ropes. Jacques Charles and ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airship
An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air. In early dirigibles, the lifting gas used was hydrogen, due to its high lifting capacity and ready availability. Helium gas has almost the same lifting capacity and is not flammable, unlike hydrogen, but is rare and relatively expensive. Significant amounts were first discovered in the United States and for a while helium was only available for airships in that country. Most airships built since the 1960s have used helium, though some have used hot air.A few airships after World War II used hydrogen. The first British airship to use helium was the ''Chitty Bang Bang'' of 1967. The envelope of an airship may form the gasbag, or it may contain a number of gas-filled cells. An airship also has engines, crew, and optionally also payload accommodatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Academy Of Sciences
The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at the forefront of scientific developments in Europe in the 17th and 18th centuries, and is one of the earliest Academies of Sciences. Currently headed by Patrick Flandrin (President of the Academy), it is one of the five Academies of the Institut de France. History The Academy of Sciences traces its origin to Colbert's plan to create a general academy. He chose a small group of scholars who met on 22 December 1666 in the King's library, near the present-day Bibliothèque Nationals, and thereafter held twice-weekly working meetings there in the two rooms assigned to the group. The first 30 years of the Academy's existence were relatively informal, since no statutes had as yet been laid down for the institution. In contrast to its Bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turkey (bird)
The turkey is a large bird in the genus ''Meleagris'', native to North America. There are two extant turkey species: the wild turkey (''Meleagris gallopavo'') of eastern and central North America and the ocellated turkey (''Meleagris ocellata'') of the Yucatán Peninsula in Mexico. Males of both turkey species have a distinctive fleshy wattle, called a snood, that hangs from the top of the beak. They are among the largest birds in their ranges. As with many large ground-feeding birds (order Galliformes), the male is bigger and much more colorful than the female. Native to North America, the wild species was bred as domesticated turkey by indigenous peoples. It was this domesticated turkey that later reached Eurasia, during the Columbian exchange. In English, "turkey" probably got its name from the domesticated variety being imported to Britain in ships coming from the Turkish Levant via Spain. The British at the time therefore associated the bird with the country Turk ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanic
A mechanic is an artisan, skilled tradesperson, or technician who uses tools to build, maintain, or repair machinery, especially cars. Duties Most mechanics specialize in a particular field, such as auto body mechanics, air conditioning and refrigeration mechanics, auto mechanics, bicycle mechanics, boiler mechanics, and other areas. A mechanic is typically certified by a trade association or regional government power. Mechanics may be separated into two classes based on the type of machines they work on, heavyweight and lightweight. Heavyweight work is on larger machines or heavy equipment, such as tractors and trailers, while lightweight work is on smaller items, such as automotive engines. Automotive mechanics/automotive technicians Automotive technicians (the modern term of reference) have many trades within. Some may specialize in the electrical diagnosis, while others may specialize in the mechanical aspects. Other mechanical areas include: brakes and steer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christian De Launoy
Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χριστός), a translation of the Biblical Hebrew term '' mashiach'' (מָשִׁיחַ) (usually rendered as ''messiah'' in English). While there are diverse interpretations of Christianity which sometimes conflict, they are united in believing that Jesus has a unique significance. The term ''Christian'' used as an adjective is descriptive of anything associated with Christianity or Christian churches, or in a proverbial sense "all that is noble, and good, and Christ-like." It does not have a meaning of 'of Christ' or 'related or pertaining to Christ'. According to a 2011 Pew Research Center survey, there were 2.2 billion Christians around the world in 2010, up from about 600 million in 1910. Today, about 37% of all Christians live in the Ame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorological
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not begin until the 18th century. The 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data. It was not until after the elucidation of the laws of physics, and more particularly in the latter half of the 20th century the development of the computer (allowing for the automated solution of a great many modelling equations) that significant breakthroughs in weather forecasting were achieved. An important branch of weather forecasting is marine weather forecasting as it relates to maritime and coastal safety, in which weather effects also include atmospheric interactions with large bodies of water. Meteorological phe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Russian Academy Of Sciences
The Russian Academy of Sciences (RAS; russian: Росси́йская акаде́мия нау́к (РАН) ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across the Russian Federation; and additional scientific and social units such as libraries, publishing units, and hospitals. Peter the Great established the Academy (then the St. Petersburg Academy of Sciences) in 1724 with guidance from Gottfried Leibniz. From its establishment, the Academy benefitted from a slate of foreign scholars as professors; the Academy then gained its first clear set of goals from the 1747 Charter. The Academy functioned as a university and research center throughout the mid-18th century until the university was dissolved, leaving research as the main pillar of the institution. The rest of the 18th century continuing on through the 19th century consisted of many published academic works from Academy scholars and a few ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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