1.
NASA
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President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
2.
Mil Mi-8
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The Mil Mi-8 is a medium twin-turbine helicopter, originally designed by the Soviet Union, and now produced by Russia. In addition to its most common role as a helicopter, the Mi-8 is also used as an airborne command post, armed gunship. Along with the related, more powerful Mil Mi-17, the Mi-8 is among the worlds most-produced helicopters, as of 2015, it is the third most common operational military aircraft in the world. Due to the position of the engine, this enabled Mikhail Mil to justify redesigning the front half of the aircraft around the single engine. The prototype, which was named V-8, was designed in 1958, powered by an AI-242,010 kW Soloviev turboshaft engine, the single engined V-8 prototype had its maiden flight in June 1961 and was first shown on Soviet Aviation Day parade in July 1961. During an official visit to the United States in September 1959, on Khrushchevs return, he ordered the creation of a similar helicopter, which was to be ready for the return visit by the American president, to save face. A luxury version of the Mi-4 was quickly created and Khrushchev took an inspection flight, however, it would be necessary to have a second engine for reliability. In May 1960, the order was given for Mikhail Mil to create his twin engine helicopter, the Sergei Isotov Design Bureau accepted the task of creating the engines. The second prototype flew in September 1961, the aircraft completed its factory based testing in February 1963. The fifth and final prototype was a production prototype for the passenger market. In November 1964, all joint testing had completed and the soviet government began mass production. Production started in the Kazan Production Plant, with the first aircraft completed by the end of 1965 and it was only then that the Soviet military rushed a troop-carrying variant of the Mil Mi-8 into production. By 1967, it had introduced into the Soviet Air Force as the Mi-8. There are numerous variants, including the Mi-8T, which, in addition to carrying 24 troops, is armed with rockets, the Mil Mi-17 export version is employed by around 20 countries, its equivalent in Russian service in the Mi-8M series. The only visible difference between the Mi-8 and Mi-17 is that the rotor is on the starboard side of the Mi-8. Also Mi-17 also has some improved armour plating for its crew, the naval Mil Mi-14 version is also derived from the Mi-8. The Mi-8 is constantly improving and the newest version still remains in production in 2016, the Mi-8 family of helicopters became the main Soviet and later Russian helicopter covering a large range of roles in both peace time and war time. Large fleets of Mi-8 and its derivatives are employed by military and civil operators
3.
Helicopter
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A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and these attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL aircraft cannot perform. English language nicknames for helicopter include chopper, copter, helo, heli, Helicopters were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936. Some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production, with 131 aircraft built. Though most earlier designs used more than one rotor, it is the single main rotor with anti-torque tail rotor configuration that has become the most common helicopter configuration. Tandem rotor helicopters are also in use due to their greater payload capacity. Coaxial helicopters, tiltrotor aircraft, and compound helicopters are all flying today, quadcopter helicopters pioneered as early as 1907 in France, and other types of multicopter have been developed for specialized applications such as unmanned drones. The earliest references for vertical flight came from China, since around 400 BC, Chinese children have played with bamboo flying toys. This bamboo-copter is spun by rolling a stick attached to a rotor, the spinning creates lift, and the toy flies when released. The 4th-century AD Daoist book Baopuzi by Ge Hong reportedly describes some of the ideas inherent to rotary wing aircraft, designs similar to the Chinese helicopter toy appeared in Renaissance paintings and other works. In the 18th and early 19th centuries Western scientists developed flying machines based on the Chinese toy. It was not until the early 1480s, when 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 flying models, but there were no indications for any provision to stop the rotor from making the craft rotate. As scientific knowledge increased and became accepted, people continued to pursue the idea of vertical flight. In July 1754, Russian Mikhail Lomonosov had developed a small coaxial modeled after the Chinese top but powered by a spring device. It was powered by a spring, and was suggested as a method to lift meteorological instruments. Sir George Cayley, influenced by a fascination with the Chinese flying top, developed a model of feathers, similar to that of Launoy and Bienvenu. By the end of the century, he had progressed to using sheets of tin for rotor blades and his writings on his experiments and models would become influential on future aviation pioneers
4.
Cessna 172
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The Cessna 172 Skyhawk is a four-seat, single-engine, high wing, fixed-wing aircraft made by the Cessna Aircraft Company. First flown in 1955, more 172s have been built any other aircraft. Measured by its longevity and popularity, the Cessna 172 is the most successful aircraft in history, Cessna delivered the first production model in 1956 and as of 2015, the company and its partners had built more than 43,000. The aircraft remains in production today, the Skyhawks main competitors have been the Beechcraft Musketeer and Grumman AA-5 series, the Piper Cherokee, and, more recently, the Diamond DA40 and Cirrus SR22. The Cessna 172 started life as a landing gear variant of the taildragger Cessna 170. In January 1955, Cessna flew an improved variant of the Cessna 170, a Continental O-300-A-powered Cessna 170C with larger elevators and a more angular tailfin. Although the variant was tested and certified, Cessna decided to modify it with a landing gear. To reduce the time and cost of certification, the type was added to the Cessna 170 type certificate as the Model 172, later, the 172 was given its own type certificate, 3A12. The 172 became a sales success, and over 1,400 were built in 1956. Early 172s were similar in appearance to the 170s, with the same straight aft fuselage and tall landing gear legs, although the 172 had a straight tailfin while the 170 had a rounded fin and rudder. In 1960, the 172A incorporated revised landing gear and the swept-back tailfin, the final aesthetic development, found in the 1963 172D and all later 172 models, was a lowered rear deck allowing an aft window. Cessna advertised this added rear visibility as Omni-Vision, production halted in the mid-1980s, but resumed in 1996 with the 160 hp Cessna 172R Skyhawk. Cessna supplemented this in 1998 with the 180 hp Cessna 172S Skyhawk SP, the Cessna 172 may be modified via a wide array of supplemental type certificates, including increased engine power and higher gross weights. Available STC engine modifications increase power from 180 to 210 hp, add constant-speed propellers, a Cessna 172 was used in 1958 to set the world record for flight endurance, the record still stands. On December 4,1958, Robert Timm and John Cook took off from McCarran Airfield in Las Vegas, Nevada, in a used Cessna 172, registration number N9172B. They landed back at McCarran Airfield on February 4,1959 after 64 days,22 hours,19 minutes and 5 seconds in flight, the flight was part of a fund-raising effort for the Damon Runyon Cancer Fund. Food and water were transferred by matching speeds with a car on a straight stretch of road in the desert. The drivers steered while a second person matched speeds with the aircraft with his foot on the accelerator pedal
5.
Voodoo (aircraft)
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Voodoo is a highly modified North American P-51 Mustang that was the 2013,2014 and 2016 Unlimited-class champion of the Reno Air Races. The pilot for these wins was Steven Hinton, Jr. of Chino, the P-51D-25-NA was built in 1944 by North American Aviation at Inglewood, California, for the United States Army. The aircraft was transferred to the Royal Canadian Air Force as a Mustang IV with serial number 9289 in February 1951. In February 1951, it went down at Richmond, Virginia, again, in February 1962, the aircraft crashed. In March 1977, the aircraft suffered yet another crash, according to the summarized National Transportation Safety Board narrative from report number SEA77FYE12, There were 2 fatalities. Incident occurred at Olympia Municipal Airport, Olympia, Washington, the aircraft Ground looped or water swerved during the takeoff run. Stalled or mushed during the initial climb, FAA examiner remarks include, Partially completed dual control modification. In 1980, the aircraft was sold to William A. Speer, of La Mesa, California, in 1988, it made its first restored flight. It first raced as #45, then as #55 using the name Pegasus, the plane was sold at auction in December 1994. Bob Button of Button Transportation Inc, wellington, Nevada, owned the plane from 1995 to 1998. He renamed it Voodoo Chile, and raced it as #55, in 1998, the highly modified P-51 raced at the National Championship Air Races in Reno. In 2007, Bob Button retired from air racing after a malfunction. In 2013, Voodoo, still owned by Bob Button, was raced at Reno by Steven Hinton, Jr. who won the gold trophy
6.
Machine
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A machine is a tool containing one or more parts that uses energy to perform an intended action. Machines are usually powered by chemical, thermal, or electrical means, historically, a power tool also required moving parts to classify as a machine. However, the advent of electronics has led to the development of power tools without moving parts that are considered machines, a simple machine is a device that simply transforms the direction or magnitude of a force, but a large number of more complex machines exist. Examples include vehicles, electronic systems, molecular machines, computers, television, the word machine derives from the Latin word machina, which in turn derives from the Greek. The word mechanical comes from the same Greek roots, however, the Ancient Greeks probably have borrowed the word mekhane from the ancient Hebrews. The ancient Greeks were familiar with the Hebrew Scriptures and language, a wider meaning of fabric, structure is found in classical Latin, but not in Greek usage. This meaning is found in late medieval French, and is adopted from the French into English in the mid-16th century, in the 17th century, the word could also mean a scheme or plot, a meaning now expressed by the derived machination. The modern meaning develops out of specialized application of the term to stage engines used in theater and to siege engines. Simple Machines are commonly reckoned to be Six in Number, viz. the Ballance, Leaver, Pulley, Wheel, Wedge, compound Machines, or Engines, are innumerable. The word engine used as a synonym both by Harris and in later language derives ultimately from Latin ingenium ingenuity, an invention, perhaps the first example of a human made device designed to manage power is the hand axe, made by chipping flint to form a wedge. A wedge is a machine that transforms lateral force and movement of the tool into a transverse splitting force. The idea of a simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines, lever, pulley and he discovered the principle of mechanical advantage in the lever. Later Greek philosophers defined the five simple machines and were able to roughly calculate their mechanical advantage. Heron of Alexandria in his work Mechanics lists five mechanisms that can set a load in motion, lever, windlass, pulley, wedge, and screw, however the Greeks understanding was limited to statics and did not include dynamics or the concept of work. In 1586 Flemish engineer Simon Stevin derived the mechanical advantage of the inclined plane, the complete dynamic theory of simple machines was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche. He was the first to understand that simple machines do not create energy, the classic rules of sliding friction in machines were discovered by Leonardo da Vinci, but remained unpublished in his notebooks. They were rediscovered by Guillaume Amontons and were developed by Charles-Augustin de Coulomb. The word mechanical refers to the work that has produced by machines or the machinery
7.
Flight
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Flight is the process by which an object moves, through an atmosphere or beyond it, as in the case of spaceflight. This can be achieved by generating lift, propulsive thrust, aerostatically using buoyancy. Many things fly, from natural aviators such as birds, bats and insects to human inventions such as missiles, aircraft such as airplanes, helicopters and balloons, to rockets such as spacecraft. Humans have managed to construct lighter than air vehicles that raise off the ground and fly, an aerostat is a system that remains aloft primarily through the use of buoyancy to give an aircraft the same overall density as air. Aerostats include free balloons, airships, and moored balloons, an aerostats main structural component is its envelope, a lightweight skin that encloses a volume of lifting gas to provide buoyancy, to which other components are attached. Aerostats are so named because they use aerostatic lift, a buoyant force that does not require movement through the surrounding air mass to effect a lifting force. By contrast, aerodynes primarily use aerodynamic lift, which requires the movement of at least some part of the aircraft through the surrounding air mass. Some things that fly do not generate propulsive thrust through the air, for example, some other things can exploit rising air to climb such as raptors and man-made sailplane gliders. However most other birds and all powered aircraft need a source of propulsion to climb, the only groups of living things that use powered flight are birds, insects, and bats, while many groups have evolved gliding. The extinct Pterosaurs, an order of reptiles contemporaneous with the dinosaurs, were very successful flying animals. Each of these groups wings evolved independently, bats are the only mammals capable of sustaining level flight. Flying frogs use greatly enlarged webbed feet for a similar purpose, flying snakes also use mobile ribs to flatten their body into an aerodynamic shape, with a back and forth motion much the same as they use on the ground. Flying fish can glide using enlarged wing-like fins, and have been observed soaring for hundreds of meters and it is thought that this ability was chosen by natural selection because it was an effective means of escape from underwater predators. The longest recorded flight of a fish was 45 seconds. Most birds fly, with some exceptions, the largest birds, the ostrich and the emu, are earthbound, as were the now-extinct dodos and the Phorusrhacids, which were the dominant predators of South America in the Cenozoic era. The non-flying penguins have wings adapted for use under water and use the same wing movements for swimming that most other birds use for flight, most small flightless birds are native to small islands, and lead a lifestyle where flight would offer little advantage. Among living animals that fly, the wandering albatross has the greatest wingspan, up to 3.5 meters, most species of insects can fly as adults. Insect flight makes use of either of two basic models, creating a leading edge vortex, found in most insects, and using clap and fling
8.
Atmosphere of Earth
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The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earths gravity. The atmosphere of Earth protects life on Earth by absorbing solar radiation, warming the surface through heat retention. By volume, dry air contains 78. 09% nitrogen,20. 95% oxygen,0. 93% argon,0. 04% carbon dioxide, and small amounts of other gases. Air also contains an amount of water vapor, on average around 1% at sea level. The atmosphere has a mass of about 5. 15×1018 kg, the atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km, or 1. 57% of Earths radius, is used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km, several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition. The study of Earths atmosphere and its processes is called atmospheric science, early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann. The three major constituents of air, and therefore of Earths atmosphere, are nitrogen, oxygen, water vapor accounts for roughly 0. 25% of the atmosphere by mass. The remaining gases are often referred to as gases, among which are the greenhouse gases, principally carbon dioxide, methane, nitrous oxide. Filtered air includes trace amounts of other chemical compounds. Various industrial pollutants also may be present as gases or aerosols, such as chlorine, fluorine compounds, sulfur compounds such as hydrogen sulfide and sulfur dioxide may be derived from natural sources or from industrial air pollution. In general, air pressure and density decrease with altitude in the atmosphere, however, temperature has a more complicated profile with altitude, and may remain relatively constant or even increase with altitude in some regions. In this way, Earths atmosphere can be divided into five main layers, excluding the exosphere, Earth has four primary layers, which are the troposphere, stratosphere, mesosphere, and thermosphere. It extends from the exobase, which is located at the top of the thermosphere at an altitude of about 700 km above sea level, to about 10,000 km where it merges into the solar wind. This layer is composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen. The atoms and molecules are so far apart that they can travel hundreds of kilometers without colliding with one another, thus, the exosphere no longer behaves like a gas, and the particles constantly escape into space. These free-moving particles follow ballistic trajectories and may migrate in and out of the magnetosphere or the solar wind, the exosphere is located too far above Earth for any meteorological phenomena to be possible
9.
Buoyancy
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In science, buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid, thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object and this pressure difference results in a net upwards force on the object. For this reason, an object whose density is greater than that of the fluid in which it is submerged tends to sink, If the object is either less dense than the liquid or is shaped appropriately, the force can keep the object afloat. This can occur only in a reference frame, which either has a gravitational field or is accelerating due to a force other than gravity defining a downward direction. In a situation of fluid statics, the net upward force is equal to the magnitude of the weight of fluid displaced by the body. The center of buoyancy of an object is the centroid of the volume of fluid. Archimedes principle is named after Archimedes of Syracuse, who first discovered this law in 212 B. C, more tersely, Buoyancy = weight of displaced fluid. The weight of the fluid is directly proportional to the volume of the displaced fluid. Thus, among completely submerged objects with equal masses, objects with greater volume have greater buoyancy and this is also known as upthrust. Suppose a rocks weight is measured as 10 newtons when suspended by a string in a vacuum with gravity acting upon it, suppose that when the rock is lowered into water, it displaces water of weight 3 newtons. The force it exerts on the string from which it hangs would be 10 newtons minus the 3 newtons of buoyancy force,10 −3 =7 newtons. Buoyancy reduces the apparent weight of objects that have sunk completely to the sea floor and it is generally easier to lift an object up through the water than it is to pull it out of the water. The density of the object relative to the density of the fluid can easily be calculated without measuring any volumes. Density of object density of fluid = weight weight − apparent immersed weight Example, If you drop wood into water, Example, A helium balloon in a moving car. During a period of increasing speed, the air mass inside the car moves in the direction opposite to the cars acceleration, the balloon is also pulled this way. However, because the balloon is buoyant relative to the air, it ends up being pushed out of the way, If the car slows down, the same balloon will begin to drift backward. For the same reason, as the car goes round a curve and this is the equation to calculate the pressure inside a fluid in equilibrium
10.
Lift (force)
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A fluid flowing past the surface of a body exerts a force on it. Lift is the component of force that is perpendicular to the oncoming flow direction. It contrasts with the force, which is the component of the surface force parallel to the flow direction. If the fluid is air, the force is called an aerodynamic force, in water, it is called a hydrodynamic force. Lift is also exploited in the world, and even in the plant world by the seeds of certain trees. When an aircraft is flying straight and level most of the lift opposes gravity, however, when an aircraft is climbing, descending, or banking in a turn the lift is tilted with respect to the vertical. Lift may also be entirely downwards in some aerobatic manoeuvres, or on the wing on a racing car, in this last case, the term downforce is often used. Lift may also be horizontal, for instance on a sail on a sailboat. Aerodynamic lift is distinguished from other kinds of lift in fluids, Aerodynamic lift requires relative motion of the fluid which distinguishes it from aerostatic lift or buoyancy lift as used by balloons, blimps, and dirigibles. An airfoil is a shape that is capable of generating significantly more lift than drag. A flat plate can generate lift, but not as much as a streamlined airfoil, there are several ways to explain how an airfoil generates lift. Some are more complicated or more rigorous than others, some have been shown to be incorrect. For example, there are based directly on Newton’s laws of motion. Either can be used to explain lift, an airfoil generates lift by exerting a downward force on the air as it flows past. According to Newtons third law, the air must exert an equal and opposite force on the airfoil, the air flow changes direction as it passes the airfoil and follows a path that is curved downward. According to Newtons second law, this change in flow direction requires a force applied to the air by the airfoil. Then, according to Newtons third law, the air must exert a force on the airfoil. The overall result is that a force, the lift, is generated opposite to the directional change
11.
Airfoil
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An airfoil or aerofoil is the shape of a wing, blade, or sail. An airfoil-shaped body moved through a fluid produces an aerodynamic force, the component of this force perpendicular to the direction of motion is called lift. The component parallel to the direction of motion is called drag, subsonic flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, often with a symmetric curvature of upper and lower surfaces. Foils of similar function designed with water as the fluid are called hydrofoils. The lift on an airfoil is primarily the result of its angle of attack, when oriented at a suitable angle, the airfoil deflects the oncoming air, resulting in a force on the airfoil in the direction opposite to the deflection. This force is known as force and can be resolved into two components, lift and drag. Most foil shapes require an angle of attack to generate lift. This turning of the air in the vicinity of the airfoil creates curved streamlines, resulting in pressure on one side. The lift force can be related directly to the average top/bottom velocity difference without computing the pressure by using the concept of circulation, a fixed-wing aircrafts wings, horizontal, and vertical stabilizers are built with airfoil-shaped cross sections, as are helicopter rotor blades. Airfoils are also found in propellers, fans, compressors and turbines, sails are also airfoils, and the underwater surfaces of sailboats, such as the centerboard and keel, are similar in cross-section and operate on the same principles as airfoils. Swimming and flying creatures and even many plants and sessile organisms employ airfoils/hydrofoils, common examples being bird wings, the bodies of fish, an airfoil-shaped wing can create downforce on an automobile or other motor vehicle, improving traction. Any object with an angle of attack in a fluid, such as a flat plate. Airfoils are more efficient lifting shapes, able to more lift. A lift and drag curve obtained in wind tunnel testing is shown on the right, the curve represents an airfoil with a positive camber so some lift is produced at zero angle of attack. With increased angle of attack, lift increases in a linear relation. At about 18 degrees this airfoil stalls, and lift falls off quickly beyond that, the drop in lift can be explained by the action of the upper-surface boundary layer, which separates and greatly thickens over the upper surface at and past the stall angle. The thicker boundary layer also causes an increase in pressure drag, so that the overall drag increases sharply near. Airfoil design is a facet of aerodynamics
12.
Powered lift
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Powered lift or powered-lift refers to a type of aircraft that can take off and land vertically and functions differently from a rotorcraft in horizontal flight. The term is used by the United States Federal Aviation Administration for classification purposes. The first powered-lift ratings to be issued by the FAA on a pilot certificate were on 21 August 1997, to pilots of Bell Helicopter and Boeing. A convertiplane is an aircraft which uses rotor power for takeoff and landing. In tiltrotor and tiltwing designs such as the Bell Boeing V-22 Osprey, some designs have a ducted rotor design, in which the rotor is surrounded by a large ring-shaped duct to reduce tip losses. The powered rotors of a tiltrotor are mounted on rotating shafts or nacelles at the end of a fixed wing, for vertical flight, the rotors are angled to provide thrust upwards, lifting the way a helicopter rotor does. As the aircraft speed, the rotors progressively rotate or tilt forward, with the rotors eventually becoming perpendicular to the fuselage of the aircraft. In this mode, the wing provides the lift and the rotor provides thrust, the wings greater efficiency helps the tiltrotor achieve higher speeds than helicopters. The Bell Boeing V-22 Osprey by Bell Helicopter and Boeing is a twin-engine tiltrotor design that has two engines each driving three-blade rotors. The rotors function similar to a helicopter in flight. It first flew on 19 March 1989, the AgustaWestland AW609 tiltrotor is civilian aircraft based on the V-22 Osprey. The aircraft can take off and land vertically with 2 crew and 9 passengers, the aircraft is expected to be certified in 2017. The tiltwing is similar to the tiltrotor, except that the rotor mountings are fixed to the wing, the Vertol VZ-2 was a research aircraft developed in the late 1950s. Unlike other tiltwing aircraft, Vertol designed the VZ-2 using rotors in place of propellers, on 23 July 1958, the aircraft made its first full transition from vertical flight to horizontal flight. By the time the aircraft was retired in 1965, the VZ-2 had accomplished 450 flights, the Boeing X-50 Dragonfly had a two-bladed rotor driven by the engine for takeoff. In horizontal flight the rotor stopped to act like a wing, fixed canard and tail surfaces provided lift during transition, and also stability and control in forward flight. Both examples ended their lives in crashes, the Sikorsky X-Wing had a four-bladed rotor utilizing compressed air to control lift over the surfaces while operating as a helicopter. At higher forward speeds, the rotor would be stopped to continue providing lift as tandem wings in an X configuration, the program was canceled before the aircraft had attempted any flights with the rotor system
13.
Jet engine
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A jet engine is a reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. This broad definition includes airbreathing jet engines and non-airbreathing jet engines, in general, jet engines are combustion engines. In common parlance, the jet engine loosely refers to an internal combustion airbreathing jet engine. These typically feature an air compressor powered by a turbine. Jet aircraft use such engines for long-distance travel, early jet aircraft used turbojet engines which were relatively inefficient for subsonic flight. Modern subsonic jet aircraft usually use more complex high-bypass turbofan engines and these engines offer high speed and greater fuel efficiency than piston and propeller aeroengines over long distances. Jet engines date back to the invention of the aeolipile before the first century AD and this device directed steam power through two nozzles to cause a sphere to spin rapidly on its axis. So far as is known, it did not supply mechanical power, instead, it was seen as a curiosity. However, although powerful, at reasonable flight speeds rockets are very inefficient. The earliest attempts at airbreathing jet engines were hybrid designs in which a power source first compressed air. In one such system, called a thermojet by Secondo Campini but more commonly, motorjet, examples of this type of design were the Caproni Campini N.1, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II. None were entirely successful and the N.1 ended up being slower than the design with a traditional engine. If aircraft performance were ever to increase beyond such a barrier and this was the motivation behind the development of the gas turbine engine, commonly called a jet engine. The key to a jet engine was the gas turbine. The gas turbine was not an idea developed in the 1930s, the first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture, the main problems were safety, reliability, weight and, especially, sustained operation. The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume and his engine was an axial-flow turbojet. Alan Arnold Griffith published An Aerodynamic Theory of Turbine Design in 1926 leading to work at the RAE
14.
Airplane
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An airplane or aeroplane is a powered, fixed-wing aircraft that is propelled forward by thrust from a jet engine or propeller. Airplanes come in a variety of sizes, shapes, and wing configurations, the broad spectrum of uses for airplanes includes recreation, transportation of goods and people, military, and research. Commercial aviation is a massive industry involving the flying of tens of thousands of daily on airliners. Most airplanes are flown by a pilot on board the aircraft, the Wright brothers invented and flew the first airplane in 1903, recognized as the first sustained and controlled heavier-than-air powered flight. They built on the works of George Cayley dating from 1799, between 1867 and 1896, the German pioneer of human aviation Otto Lilienthal also studied heavier-than-air flight. Following its limited use in World War I, aircraft continued to develop. Airplanes had a presence in all the battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939, the first jet airliner, the de Havilland Comet, was introduced in 1952. The Boeing 707, the first widely successful commercial jet, was in service for more than 50 years. Aéroplane originally referred just to the wing, as it is a plane moving through the air, in an example of synecdoche, the word for the wing came to refer to the entire aircraft. In the United States and Canada, the airplane is used for powered fixed-wing aircraft. In the United Kingdom and most of the Commonwealth, the aeroplane is usually applied to these aircraft. Many stories from antiquity involve flight, such as the Greek legend of Icarus and Daedalus, and this machine may have been suspended for its flight. Some of the earliest recorded attempts with gliders were those by the 9th-century poet Abbas ibn Firnas, leonardo da Vinci researched the wing design of birds and designed a man-powered aircraft in his Codex on the Flight of Birds. In 1799, George Cayley set forth the concept of the airplane as a fixed-wing flying machine with separate systems for lift, propulsion. Cayley was building and flying models of fixed-wing aircraft as early as 1803, in 1856, Frenchman Jean-Marie Le Bris made the first powered flight, by having his glider LAlbatros artificiel pulled by a horse on a beach. Then Alexander F. Mozhaisky also made some innovative designs, in 1883, the American John J. Montgomery made a controlled flight in a glider. Other aviators who made similar flights at that time were Otto Lilienthal, Percy Pilcher, sir Hiram Maxim built a craft that weighed 3.5 tons, with a 110-foot wingspan that was powered by two 360-horsepower steam engines driving two propellers
15.
Airship
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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 large gas bags filled with a gas that is less dense than the surrounding air. In early dirigibles, the gas used was hydrogen, due to its high lifting capacity. Helium gas has almost the same lifting capacity and is not flammable, unlike hydrogen, significant amounts were first discovered in the United States and for a while helium was only used for airships by the United States. Most airships built since the 1960s have used helium, though some have used hot air, the envelope of an airship may form a single gas bag, or may contain a number of internal gas-filled cells. An airship also has engines, crew, and optionally also payload accommodation, the main types of airship are non-rigid, semi-rigid, and rigid. Non-rigid airships, often called blimps, rely on internal pressure to maintain the shape of the airship, semi-rigid airships maintain the envelope shape by internal pressure, but have some form of supporting structure, such as a fixed keel, attached to it. Rigid airships have a structural framework which maintains the shape and carries all structural loads. Rigid airships were first flown by Count Zeppelin and the vast majority of rigid airships built were manufactured by the firm he founded, as a result, rigid airships are called zeppelins. S. Navy helium-filled rigids, the USS Akron and USS Macon respectively, during the pioneer years of aeronautics, terms such as airship, air-ship, air ship and ship of the air meant any kind of navigable or dirigible flying machine. In 1919 Frederick Handley Page was reported as referring to ships of the air, in the 1930s, large intercontinental flying boats were also sometimes referred to as ships of the air or flying-ships. Nowadays the term airship is used only for powered, dirigible balloons, semirigid architecture is the more recent and the late appearance is caused by both advancements about deformable structures and exigiency of reducing weight and volume of the airships. They have a structure that ensure to keep the shape jointly with overpressure of the gas envelope. An aerostat is an aircraft which remain aloft using buoyancy or static lift, Airships are a type of aerostat. The term aerostat has also used to indicate a tethered or moored balloon as opposed to a free-floating balloon. A blimp is a non-rigid aerostat, in American usage it refers specifically to a non-rigid type of dirigible balloon or airship. In British usage it refers to any non-rigid aerostat, including balloons and other kite balloons, having a streamlined shape. The initials LZ, for Luftschiff Zeppelin, usually prefixed their crafts serial identifiers, streamlined Parsifal-shaped rigid airships are usually referred to as Zeppelin, because of the fame that this company has acquired due to the number of airships it produced
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Blimp
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A blimp, or non-rigid airship, is an airship without an internal structural framework or a keel. Unlike semi-rigid and rigid airships, blimps rely on the pressure of the gas inside the envelope. The term is also used to refer to the tethered craft properly known as moored balloons. While often very similar in shape, moored balloons have no propulsion and are tethered to the ground, since blimps keep their shape with internal overpressure, typically the only solid parts are the passenger car and the tail fins. A non-rigid airship that uses heated air instead of a gas as a lifting medium is called a hot-air airship. Volume changes of the gas due to temperature changes or to changes of altitude are compensated for by pumping air into internal ballonets to maintain the overpressure. Without sufficient overpressure, the blimp loses its ability to be steered and is slowed due to increased drag, the propeller air stream can be used to inflate the ballonets and so the hull. In some models, such as the Skyship 600, differential ballonet inflation can provide a measure of pitch trim control, the engines driving the propellers are usually directly attached to the gondola, and in some models are partly steerable. Blimps are the most commonly built airships because they are easy to build. However, because of their hull, their size is limited. A blimp with too long a hull may kink in the middle when the overpressure is insufficient or when maneuvered too fast and this led to the development of semi-rigids and rigid airships. Modern blimps are launched somewhat heavier than air, in contrast to historic blimps, the missing lift is provided by lifting the nose and using engine power, or by angling the engine thrust. Some types also use steerable propellers or ducted fans, operating in a state heavier than air avoids the need to dump ballast at lift-off and also avoids the need to lose costly helium lifting gas on landing. The origin of the word blimp has been the subject of some confusion, ege notes two possible derivations, Colloquially always were referred to as Blimps. Over the years several explanations have been advanced about the origin of this word, the most common is that in the military vernacular the Type B was referred to as limp bag, which was simply abbreviated to blimp. The onomatopoeic derivation, as the sound the airship makes when one taps the envelope with a finger, has recorded in the British Aeronautical Journal. A1943 etymology published in the New York Times supports the British origin during the First World War when the British were experimenting with lighter-than-air craft. Topping researched the origins of the word and concluded that the British had never had a Type B, limp designation, the B-class blimps were patrol airships operated by the United States Navy during and shortly after World War I
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Glider (aircraft)
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A glider is a heavier-than-air aircraft that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and whose free flight does not depend on an engine. Most gliders do not have an engine, although motor-gliders have small engines for extending their flight when necessary, there is a wide variety of types differing in the construction of their wings, aerodynamic efficiency, location of the pilot, controls and intended purpose. Most exploit meteorological phenomena to maintain or even gain height, gliders are principally used for the air sports of gliding, hang gliding and paragliding. However some spacecraft have been designed to descend as gliders and in the past military gliders have been used in warfare, perhaps the simplest and most familiar types are toys such as the paper plane and balsa wood glider. Glider is the agent noun form of the verb to glide and it derives from Middle English gliden, which in turn derived from Old English glīdan. The oldest meaning of glide may have denoted a precipitous running or jumping, scholars are uncertain as to its original derivation, with possible connections to slide, and light having been advanced. Early pre-modern accounts of flight are in most cases difficult to verify and it is whether each craft was a glider, kite or parachute. Often the event is recorded a long time after it allegedly took place. A 17th-century account reports an attempt at flight by the 9th-century poet Abbas Ibn Firnas near Cordoba, according to these reports, both used a set of wings, and both blamed their crash on the lack of a tail. Hezârfen Ahmed Çelebi is alleged to have flown a glider with eagle-like wings over the Bosphorus strait from the Galata Tower to Üsküdar district in Istanbul around 1630–1632. The first heavier-than-air man-carrying aircraft that were based on published scientific principles were Sir George Cayleys series of gliders which achieved brief wing-borne hops from around 1849. Thereafter gliders were built by such as Jean Marie Le Bris, John J. Montgomery, Otto Lilienthal, Percy Pilcher, Octave Chanute. Lilienthal was the first to make repeated successful flights and was the first to use rising air to prolong his flight, using a Montgomery tandem-wing glider, Daniel Maloney was the first to demonstrate high-altitude controlled flight using a balloon-launched glider launched from 4,000 feet in 1905. The Wright Brothers developed a series of three manned gliders after preliminary tests with a kite as they worked towards achieving powered flight and they returned to glider testing in 1911 by removing the motor from one of their later designs. In the inter-war years, recreational gliding flourished in Germany under the auspices of Rhön-Rossitten, in the United States, the Schweizer brothers of Elmira, New York, manufactured sport sailplanes to meet the new demand. Sailplanes continued to evolve in the 1930s, and sport gliding has become the main application of gliders, as their performance improved, gliders began to be used to fly cross-country and now regularly fly hundreds or even thousands of kilometers in a day, if the weather is suitable. Military gliders were developed during World War II by a number of countries for landing troops, a glider – the Colditz Cock – was even built secretly by POWs as a potential escape method at Oflag IV-C near the end of the war in 1944. Foot-launched aircraft had flown by Lilienthal and at the meetings at Wasserkuppe in the 1920s
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Hot air balloon
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A hot air balloon is a lighter than air aircraft consisting of a bag, called an envelope, which contains heated air. Suspended beneath is a gondola or wicker basket, which carries passengers, the heated air inside the envelope makes it buoyant since it has a lower density than the colder air outside the envelope. As with all aircraft, hot air balloons cannot fly beyond the atmosphere, unlike gas balloons, the envelope does not have to be sealed at the bottom, since the air near the bottom of the envelope is at the same pressure as the surrounding air. In modern sport balloons the envelope is made from nylon fabric. The hot air balloon is the first successful human-carrying flight technology, the first hot-air balloon flown in the Americas was launched from the Walnut Street Jail in Philadelphia on January 9,1793 by the French aeronaut Jean Pierre Blanchard. Hot air balloons that can be propelled through the air rather than simply drifting with the wind are known as thermal airships, early unmanned hot air balloons were used in China. Zhuge Liang of the Shu Han kingdom, during the Three Kingdoms era and these lanterns are known as Kongming lanterns. Later that same day, Pilatre de Rozier became the human to ascend into the air, reaching an altitude of 26 m. The first free flight with passengers was made a few weeks later. King Louis XVI had originally decreed that condemned criminals would be the first pilots, the first military use of a hot air balloon happened in 1794 during the battle of Fleurus, when the French used the balloon lEntreprenant for observation. Modern hot air balloons, with a heat source, were developed by Ed Yost, beginning during the 1950s, his work resulted in his first successful flight. The first modern hot air balloon to be made in the United Kingdom was the Bristol Belle, presently, hot air balloons are used primarily for recreation. Hot air balloons are able to fly to extremely high altitudes, on November 26,2005 Vijaypat Singhania set the world altitude record for highest hot air balloon flight, reaching 21,027 m. He took off from downtown Mumbai, India, and landed 240 km south in Panchale, the previous record of 19,811 m had been set by Per Lindstrand on June 6,1988, in Plano, Texas. With a volume of 74 thousand cubic meters, the envelope was the largest ever built for a hot air craft. Designed to fly in the jet streams, the Pacific Flyer recorded the fastest ground speed for a manned balloon at 245 mph. The longest duration record was set by Swiss psychiatrist Bertrand Piccard, Auguste Piccards grandson and it was the first nonstop trip around the world by balloon. The balloon left Château-dOex, Switzerland, on March 1,1999, the two men exceeded distance, endurance, and time records, traveling 19 days,21 hours, and 55 minutes
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Aviation
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Aviation is the practical aspect or art of aeronautics, being the design, development, production, operation and use of aircraft, especially heavier than air aircraft. The word aviation was coined by French writer and former naval officer Gabriel La Landelle in 1863, from the verb avier, itself derived from the Latin word avis and the suffix -ation. The modern age of aviation began with the first untethered human lighter-than-air flight on November 21,1783, the practicality of balloons was limited because they could only travel downwind. It was immediately recognized that a steerable, or dirigible, balloon was required, jean-Pierre Blanchard flew the first human-powered dirigible in 1784 and crossed the English Channel in one in 1785. Rigid airships became the first aircraft to transport passengers and cargo over great distances, the best known aircraft of this type were manufactured by the German Zeppelin company. The most successful Zeppelin was the Graf Zeppelin and it flew over one million miles, including an around-the-world flight in August 1929. However, the dominance of the Zeppelins over the airplanes of that period, the Golden Age of the airships ended on May 6,1937 when the Hindenburg caught fire, killing 36 people. The cause of the Hindenburg accident was blamed on the use of hydrogen instead of helium as the lift gas. An internal investigation by the manufacturer revealed the coating used to protect the material over the frame was highly flammable. Changes to the coating formulation reduced the risk of further Hindenburg type accidents, although there have been periodic initiatives to revive their use, airships have seen only niche application since that time. In 1799 Sir George Cayley set forth the concept of the airplane as a fixed-wing flying machine with separate systems for lift, propulsion. Seven years later, on 14 October 1897, Aders Avion III was tested without success in front of two officials from the French War ministry, the report on the trials was not publicized until 1910, as they had been a military secret. In November 1906 Ader claimed to have made a flight on 14 October 1897. Although widely believed at the time, these claims were later discredited, however, the most widely accepted date is December 17,1903 by the Wright brothers. The Wright brothers were the first to fly in a powered and controlled aircraft, previous flights were gliders or free flight, but the Wright brothers combined both, setting the new standard in aviation records. Aircraft began to transport people and cargo as designs grew larger, the Wright brothers took aloft the first passenger, Charles Furnas, one of their mechanics, on May 14,1908. By the beginning of World War II, many towns and cities had built airports, the war brought many innovations to aviation, including the first jet aircraft and the first liquid-fueled rockets. Manufacturers such as Cessna, Piper, and Beechcraft expanded production to provide aircraft for the new middle-class market
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Aircrew
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Aircrew, also called flight crew, are personnel who operate an aircraft while in flight. The composition of a flights crew depends on the type of aircraft, plus the duration, in commercial aviation, the aircrew are called flight crew. Historical flightdeck positions include, Captain, the designated as the Pilot-In-Command. First Officer, another pilot who is not the pilot-in-command, and is seated to the right of the captain. Second Officer, a person lower in rank to the First Officer, the rank of Second Officer was traditionally a Flight Engineer, who was often the person who handled the engine controls. In the 21st century second officers on some airlines are pilots who act as relief on long haul flights. Third Officer, a person lower in rank to a Second Officer, largely redundant in the present day. The number of crew members assigned to a flight depends in part on the length of the flight. Flight Engineer, an originally called an Air Mechanic. On older aircraft, typically between the late-1920s and the 1970s, the Flight Engineer was the member responsible for engines, systems. The Flight Engineers position is commonly staffed as a Second Officer, Flight engineers can still be found in the present day, used on airline or air freight operations still flying such older aircraft. The position is typically crewed by a dual-licensed Pilot-Flight Engineer in the present day, the airborne sensor operator is considered a principal flight crew or aircrew member. Navigator, also called Air Navigators or Flight Navigators, modern electronic navigation systems made the navigator redundant by the early 1980s. Aircraft cabin crew members can consist of, Purser or In-flight Service Manager or Cabin Services Director, is responsible for the crew as a team leader. Flight attendant or Cabin Crew, is the member responsible for the safety of passengers. Historically during the era of commercial aviation, the position was staffed by young cabin boys who assisted passengers. Cabin boys were replaced by female nurses, originally called stewardesses, the medical background requirement for the flight attendant position was later dropped. Flight medic, is a specialized paramedic employed on air ambulance aircraft or flights, on non-cargo aircraft, weight and balance tasks are performed by the flight crew
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Aircraft pilot
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A pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Other aircrew members such as attendants, mechanics and ground crew, are not classified as aviators. In recognition of the qualifications and responsibilities, most militaries and many airlines worldwide award aviator badges to their pilots. The first recorded use of the aviator was in 1887, as a variation of aviation, from the Latin avis. The term aviatrix, now archaic, was used for a female aviator. These terms were used more in the days of aviation, when airplanes were extremely rare. For example, a 1905 reference work described the Wright brothers first airplane, The weight, the Aéro-Club de France delivered the first certificate to Louis Blériot in 1908—followed by Glenn Curtiss, Léon Delagrange, and Robert Esnault-Pelterie. The absolute authority given to the pilot in command derives from that of a ships captain, when flying for an airline, pilots are usually referred to as airline pilots, with the pilot in command often referred to as the captain. While the flight decks of U. S. and European airliners do have ex-military pilots, military training and flying, while rigorous, is fundamentally different in many ways from civilian piloting. Pilots licensing in Canada is similar to the United States, the Aeronautics Act of 1985 and Canadian Aviation Regulations provide rules for pilots in Canada. Retirement age is provided by each airline with some set to age 60, in 1930, the Air Commerce Act established pilot licensing requirements for American civil aviation. Commercial airline pilots in the United States have a retirement age of 65. Military pilots fly with the forces of a government or nation-state. Their tasks involve combat and non-combat operations, including direct hostile engagements, military pilots undergo specialized training, often with weapons. Examples of military pilots include fighter pilots, bomber pilots, transport pilots, military pilots also serve as flight crews on aircraft for government personnel, such as Air Force One and Air Force Two in the United States. Military pilots are trained with a different syllabus than civilian pilots and this is due to the different aircraft, flight goals, flight situations and chains of responsibility. Many military pilots do transfer to civilian-pilot qualification after they leave the military, the person controlling a remotely piloted UAV may be referred to as its pilot or operator. Most jurisdictions have restrictions on the use of UAVs which have limited their use in controlled airspace, UAVs have mostly been limited to military
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Unmanned aerial vehicle
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An unmanned aerial vehicle, commonly known as a drone, is an aircraft without a human pilot aboard. UAVs are a component of an unmanned aircraft system, which include a UAV, a controller. The flight of UAVs may operate with various degrees of autonomy, either under control by a human operator, or fully or intermittently autonomously. Compared to manned aircraft, UAVs are often preferred for missions too dull, civilian drones now vastly outnumber military drones, with estimates of over a million sold by 2015. Multiple terms are used for unmanned vehicles, which generally refer to the same concept. The term drone, more used by the public, was coined in reference to the resemblance of navigation. The term has encountered opposition from aviation professionals and government regulators. This term emphasizes the importance of other than the aircraft. It includes elements such as ground stations, data links. A similar term is a vehicle system remotely piloted aerial vehicle. Many similar terms are in use, therefore, missiles are not considered UAVs because the vehicle itself is a weapon that is not reused, though it is also unmanned and in some cases remotely guided. The relation of UAVs to remote controlled model aircraft is unclear, UAVs may or may not include model aircraft. Some jurisdictions base their definition on size or weight, however, a radio-controlled aircraft becomes a drone with the addition of an autopilot artificial intelligence, and ceases to be a drone when an AI is removed. In 1849 Austria sent unmanned, bomb-filled balloons to attack Venice, UAV innovations started in the early 1900s and originally focused on providing practice targets for training military personnel. UAV development continued during World War I, when the Dayton-Wright Airplane Company invented a pilotless aerial torpedo that would explode at a preset time, the earliest attempt at a powered UAV was A. M. Lows Aerial Target in 1916. Nikola Tesla described a fleet of unmanned aerial vehicles in 1915. Advances followed during and after World War I, including the Hewitt-Sperry Automatic Airplane, the first scaled remote piloted vehicle was developed by film star and model-airplane enthusiast Reginald Denny in 1935. More emerged during World War II – used both to train gunners and to fly attack missions
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Powered aircraft
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A powered aircraft is an aircraft that uses onboard propulsion with mechanical power generated by an aircraft engine of some kind. Aircraft propulsion nearly always either a type of propeller, or a form of jet propulsion. Other potential propulsion techniques such as ornithopters are very rarely used, a propeller or airscrew comprises a set of small, wing-like aerofoil blades set around a central hub which spins on an axis aligned in the direction of travel. The blades are set at an angle to the airflow. A tractor design mounts the propeller in front of the power source, although the pusher design allows cleaner airflow over the wing, tractor configuration is more common because it allows cleaner airflow to the propeller and provides a better weight distribution. Contra-rotating propellers have one close behind another on the same axis. A variation on the propeller is to use many broad blades to create a fan, such fans are usually surrounded by a ring-shaped fairing or duct, as ducted fans. Many kinds of plant have been used to drive propellers. The earliest designs used man power to give dirigible balloons some degree of control, attempts to achieve heavier-than-air man-powered flight did not succeed fully until Paul MacCreadys Gossamer Condor in 1977. The first powered flight of an aircraft was made in a steam-powered dirigible by Henri Giffard in 1852, attempts to marry a practical lightweight steam engine to a practical fixed-wing airframe did not succeed until much later, by which time the internal combustion engine was already dominant. The piston engine is used in the majority of smaller aircraft produced, since it is efficient at the lower altitudes. Turbine engines need not be used as jets, but may be geared to drive a propeller in the form of a turboprop, modern helicopters also typically use turbine engines to power the rotor. Turbines provide more power for less weight than piston engines, and are suited to small-to-medium size aircraft or larger. Some turboprop designs mount the propeller directly on a turbine shaft. Other less common sources include, Electric motors, often linked to solar panels to create a solar-powered aircraft. Rubber bands, wound many times to store energy, are used for flying models. Rotorcraft have spinning blades called a rotor which spins in the plane to provide lift. Forward thrust is obtained by angling the rotor disc slightly forward so that a proportion of its lift is directed backwards
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History of aviation
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Kite flying in China dates back to several hundred years BC and slowly spread around the world. It is thought to be the earliest example of man-made flight, Leonardo da Vincis 15th-century dream of flight found expression in several rational but unscientific designs, though he did not attempt to construct any of them. Balloons, both free-flying and tethered, began to be used for military purposes from the end of the 18th century, with the French government establishing Balloon Companies during the Revolution. The modern aeroplane with its tail was established by 1909. After World War II, the boats were in their turn replaced by land planes. In the latter part of the 20th century the advent of digital electronics produced great advances in flight instrumentation, the 21st century saw the large-scale use of pilotless drones for military, civilian and leisure use. With digital controls, inherently unstable aircraft such as flying wings became possible, the origin of mankinds desire to fly is lost in the distant past. From the earliest legends there have been stories of men strapping birdlike wings, stiffened cloaks or other devices to themselves, the Greek legend of Daedalus and Icarus is one of the earliest known, others originated from India, China and the European Dark Ages. During this early period the issues of lift, stability and control were not understood, eilmer of Malmesbury soon followed and many others have continued to do so over the centuries. As late as 1811, Albrecht Berblinger constructed an ornithopter and jumped into the Danube at Ulm, the kite may have been the first form of man-made aircraft. It was invented in China possibly as far back as the 5th century BC by Mozi, later designs often emulated flying insects, birds, and other beasts, both real and mythical. Some were fitted with strings and whistles to make sounds while flying. Ancient and medieval Chinese sources describe kites being used to measure distances, test the wind, lift men, signal, Kites spread from China around the world. After its introduction into India, the further evolved into the fighter kite. Man-carrying kites are believed to have been used extensively in ancient China, an early recorded flight was that of the prisoner Yuan Huangtou, a Chinese prince, in the 6th Century AD. Stories of man-carrying kites also occur in Japan, following the introduction of the kite from China around the seventh century AD and it is said that at one time there was a Japanese law against man-carrying kites. The use of a rotor for vertical flight has existed since 400 BC in the form of the bamboo-copter, the similar moulinet à noix appeared in Europe in the 14th century AD. From ancient times the Chinese have understood that hot air rises and have applied the principle to a type of hot air balloon called a sky lantern
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Early flying machines
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Early flying machines include all forms of aircraft studied or constructed before the development of the modern aeroplane by 1910. The story of modern flight begins more than a century before the first successful manned aeroplane, the Greek legend of Daedalus and Icarus is one of the earliest to come down to us. According to Ovid, Daedalus tied feathers together to mimic the wings of a bird, other ancient legends include the Indian Vimana flying palace or chariot, Ezekiels Chariot, various stories about Magic carpets, and mythical British King Bladud, who conjured up flying wings. Eventually some tried to build real flying devices, typically birdlike wings, in the 1st century AD, Chinese Emperor Wang Mang recruited a specialist scout to be bound with bird feathers, he is claimed to have glided about 100 meters. In 559 AD, Yuan Huangtou is said to have landed safely following an enforced tower jump, in 1010 AD, English monk Eilmer of Malmesbury flew from the tower of Malmesbury Abbey in a primitive glider. Eilmer was said to have flown over 200 yards before landing, breaking both his legs, Eilmer later remarked that the only reason he did not fly further was that he forgot to give his machine a tail. This burst of activity was followed by a lull of several centuries, jumping revived in 1496 with Seccio breaking both arms in Nuremberg. In 1507, John Damian strapped on wings covered with feathers and jumped from the walls of Stirling Castle in Scotland, breaking his thigh. Similar attempts continued until the early 19th century, with never more than partial success, francis Willughbys suggestion, published in 1676, that human legs were more comparable to birds wings in strength than arms, had only occasional influence. As late as 1811, Albrecht Berblinger constructed an ornithopter and jumped into the Danube at Ulm, the kite was invented in China, possibly as far back as the 5th century BC by Mozi and Lu Ban. These leaf kites were constructed by stretching silk over a bamboo framework. The earliest known Chinese kites were flat and often rectangular, later, tailless kites incorporated a stabilizing bowline. Designs often emulated flying insects, birds, and other beasts, some were fitted with strings and whistles to make musical sounds while flying. In 549 AD, a made of paper was used as a message for a rescue mission. Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men, signalling, after its introduction into India, the kite further evolved into the fighter kite. Traditionally these are small, unstable single line flat kites where line tension alone is used for control, Kites also spread throughout Polynesia, as far as New Zealand. Anthropomorphic kites made from cloth and wood were used in ceremonies to send prayers to the gods. By 1634 kites had reached the West, with an illustration of a kite with a tail appearing in Bates Mysteries of nature
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Aviation in World War I
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World War I was the first major conflict involving the large-use of aircraft. Tethered observation balloons had already employed in several wars. Germany employed Zeppelins for reconnaissance over the North Sea and Baltic and also for strategic bombing raids over Britain, aeroplanes were just coming into military use at the outset of the war. Initially, they were used mostly for reconnaissance, pilots and engineers learned from experience, leading to the development of many specialized types, including fighters, bombers, and ground-attack aeroplanes. Ace fighter pilots were portrayed as modern knights, and many became popular heroes, the war also saw the appointment of high-ranking officers to direct the belligerent nations air war effort. This legislation was rooted in a fear that airplanes would be used to attack undefended cities, at the start of the war, there was some debate over the usefulness of aircraft in warfare. Many senior officers, in particular, remained sceptical, early scepticism and low expectations quickly turned to unrealistic demands beyond the capabilities of the primitive aircraft available. Even so, air reconnaissance played a role in the war of movement of 1914. On 22 August 1914, British Captain L. E. O, wadham reported German General Alexander von Klucks army was preparing to surround the BEF, contradicting all other intelligence. The British High Command took note of the report and started to withdraw toward Mons, later, during the First Battle of the Marne, observation aircraft discovered weak points and exposed flanks in the German lines, allowing the allies to take advantage of them. In Germany the great successes of the early Zeppelin airships had largely overshadowed the importance of heavier-than-air aircraft, out of a paper strength of about 230 aircraft belonging to the army in August 1914 only 180 or so were of any use. The French military aviation exercises of 1911,1912, and 1913 had pioneered cooperation with the cavalry and artillery, Great Britain had started late and initially relied largely on the French aircraft industry, especially for aircraft engines. The initial British contribution to the total allied airwar effort in August 1914 was three squadrons with about 30 serviceable machines. By the end of the war, Great Britain had formed the worlds first air force to be independent of either army or naval control, by the end of 1914 the line between the Germans and the Allies stretched from the North Sea to the Alps. The initial war of movement largely ceased, and the front became static, three main functions of short range reconnaissance squadrons had emerged by March 1915. The first was photographic reconnaissance, building up a complete map of the enemy trench system. The first air cameras used glass plates, artillery spotting enabled the ranging of artillery on targets invisible to the gunners. Radio telephony was not yet practical from an aircraft, so communication was a problem, by March 1915, a two-seater on artillery observation duties was typically equipped with a primitive radio transmitter transmitting using Morse code, but had no receiver
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Aviation between the World Wars
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By the outbreak of World War II in 1939 the biplane was all but obsolete. This revolution was possible by the continuing development of lightweight aero engines of increasing power. The jet engine began development during the 1930s but would not see operational use until later. During this period civil aviation became widespread and many daring and dramatic feats took place such as flights, air races. Many commercial airlines were started during this period, a number of nations operated airships between the two world wars, including Britain, the United States, Germany, Italy, France, the Soviet Union and Japan. This period marked the age of the airship. Before the First World War, pioneers such as the German Zeppelin company had begun passenger services, in 1919 the British airship R34 flew a double crossing of the Atlantic and in 1926 the Italian semi-rigid airship, Norge was the first aircraft confirmed to fly over the North Pole. The first American-built rigid airship, the USS Shenandoah, flew in 1923, the Shenandoah was the first to use helium, which was in such short supply that the one airship contained most of the worlds reserves. The US Navy explored the idea of using airships as airborne aircraft carriers, whereas the British had experimented with an aircraft trapeze on the R33 many years before, the Americans built hangars into two new airships and even designed specialist airplanes for them. The USS Akron and Macon were the worlds largest airships at the time, although successful, the idea was not taken further. By the time the Navy started to develop a doctrine for using these airships. More significantly, the seaplane had become mature and was considered a better investment. The Empire State Building, then the tallest building in the world, was completed in 1931 with a dirigible mast, the most famous airships today are the passenger-carrying rigid airships made by the German Zeppelin company, especially the Graf Zeppelin of 1928 and the Hindenburg of 1936. The Graf Zeppelin was intended to stimulate interest in passenger airships and its engines ran on blau gas, similar to propane, which was stored in large gas bags below the hydrogen cells. Since its density was similar to that of air, it avoided any weight change as fuel was used, the Graf Zeppelin became the first aircraft to fly all the way around the world. Airship operations suffered a series of highly publicised fatal accidents, notably to the British R101 in 1930, following the Hindenburg disaster, the age of the great airships was effectively over.13 to be built and accepted into service. Unusually for such a highly stressed wing at that time it was made of wood. The Comet was powered by two race-tuned but otherwise standard production de Havilland Gipsy Six engines with an output of 460 hp
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Air warfare of World War II
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The air warfare of World War II was a major component in all theatres and, together with Anti-aircraft warfare, consumed a large fraction of the industrial output of the major powers. By contrast, Britain and the United States took an approach that greatly emphasised strategic bombing, and to a degree, tactical control of the battlefield by air. They both built a force of large, long-range bombers that could carry the air war to the enemys homeland. Simultaneously, they built tactical air forces that could win air superiority over the battlefields and they both built a powerful naval-air component based on aircraft carriers, as did Japan, these played the central role in the war at sea. Before 1939, all operated under largely theoretical models of air warfare. Italian theorist Giulio Douhet in the 1920s summarised the faith that airmen during, Many said it alone could win wars, as the bomber will always get through. The Americans were confident that the Boeing B-17 Flying Fortress bomber could reach targets, protected by its own weapons, Japanese aviation pioneers felt that they had developed the finest naval aviators in the world. The Luftwaffe was the German Air Force, the pride of Nazi Germany under its leader Hermann Göring, it learned new combat techniques in the Spanish Civil War and was seen by Adolf Hitler as the decisive strategic weapon he needed. Its advanced technology and rapid growth led to exaggerated fears in the 1930s that helped to persuade the British, in the war the Luftwaffe performed well in 1939–41, as its Stuka dive bombers terrified enemy infantry units. The Messerschmitt Me 262 jet fighter did not enter service until July 1944, the Luftwaffe could not deal with the faster P-51 Mustang escort fighters after 1943, or Britains increasingly lethal defensive fighter screen after the Battle of Britain. When the Luftwaffes fuel supply ran dry in 1944 due to the oil campaign of World War II, it was reduced to anti-aircraft flak roles, by 1944 it operated 39,000 flak batteries staffed with a million people in uniform, both men and women. They did attempt some strategic bombing in the east with the problematic Heinkel He 177A and their one success was destroying an airbase at Poltava Air Base, Ukraine during the Allied Operation Frantic, which housed 43 new B-17 bombers and a million tons of aviation fuel. Although Germanys allies, especially Italy and Finland, had air forces of their own, the British had their own very well-developed theory of strategic bombing, and built the long-range bombers to implement it. Once it became clear that Germany was a threat, the RAF started on an expansion, with many airfields being set up. From 42 squadrons with 800 aircraft in 1934, the RAF had reached 157 squadrons and 3,700 aircraft by 1939 and they combined the newly developed radar with communications centres to direct their fighter defences. Their medium bombers were capable of reaching the German industrial centre of the Ruhr, the RAF underwent rapid expansion following the outbreak of war against Germany in 1939. This included the training in other Commonwealth nations of half of British and Commonwealth aircrews and it was the second largest in Europe. The RAF also integrated Polish and other airmen who had escaped from Hitlers Europe, in Europe, the RAF was in operational control of Commonwealth aircrews and Commonwealth squadrons although these retained some degree of independence
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Post-war
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A post-war period or postwar period is the interval immediately following the end of a war. A post-war period can become an interwar period or interbellum, when a war between the same parties resumes at a later date, by contrast, a post-war period marks the cessation of conflict entirely. The term post-war can have different meanings in different countries and refer to a period determined by local considerations based on the effect of the war there. Considering the post-war era as equivalent to the Cold War era, post-war sometimes includes the 1980s, putting the end at December 1991, the 1990s are rarely considered to be part of the post-war era. Interbellum Interwar Post 9/11 era Postbellum Pre-war Reconstruction Era of the U. S
30.
Aerostat
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An aerostat is a lighter than air craft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships, a balloon may be free-flying or tethered. Especially with airships, the gasbags are often protected by an outer envelope, aerostats are so named because they use aerostatic lift which is a buoyant force that does not require movement through the surrounding air mass. This contrasts with the heavy aerodynes that primarily use aerodynamic lift which requires the movement of a surface through the surrounding air mass. The term has also used in a narrower sense, to refer to the statically tethered balloon in contrast to the free-flying airship. This article uses the term in its broader sense, in conventional usage, the term aerostat refers to any aircraft that remains aloft primarily using aerostatic buoyancy. Historically, all aerostats were called balloons, powered types capable of horizontal flight were referred to as dirigible balloons or simply dirigibles. These powered aerostats later came to be called airships, with the term reserved for unpowered types. More recently, the US Government Accountability Office has used the term aerostat in a different sense, a balloon is an aerostat which has no means of propulsion and must be either tethered on a long cable or allowed to drift freely with the wind. Although a free balloon travels at the speed of the wind, it is travelling with the wind so to a passenger the air feels calm, to change its altitude above ground it must either adjust the amount of lift or discard ballast weight. Notable uses of free-flying balloons include meteorological balloons and sport balloons, a tethered balloon is held down by one or more mooring lines or tethers. It has sufficient lift to hold the line taut and its altitude is controlled by winching the line in or out, a tethered balloon does feel the wind. A round balloon is unstable and bobs about in strong winds, both kite balloons and non-rigid airships are sometimes called blimps. Notable uses of tethered balloons include observation balloons and barrage balloons, an airship is a powered, free-flying aerostat that can be steered. Airships divide into rigid, semi-rigid and non-rigid types, with these last often known as Blimps, a rigid airship has an outer framework or skin surrounding the lifting gas bags inside it, The outer envelope keeps its shape even if the gasbags are deflated. The great Zeppelin airships of the century were rigid types. A non-rigid airship or blimp deflates like a balloon as it loses gas, the Goodyear blimps are still a common sight in the USA. A semi-rigid airship has a gas bag like a non-rigid
31.
Balloon (aeronautics)
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In aeronautics, a balloon is an unpowered aerostat, which remains aloft or floats due to its buoyancy. A balloon may be free, moving with the wind, or tethered to a fixed point and it is distinct from an airship, which is a powered aerostat that can propel itself through the air in a controlled manner. Many balloons have a basket, gondola or capsule suspended beneath the envelope for carrying people or equipment. A balloon is conceptually the simplest of all flying machines, the balloon is a fabric envelope filled with a gas that is lighter than the surrounding atmosphere. As the entire balloon is less dense than its surroundings, it rises, taking along with it a basket, attached underneath, which carries passengers or payload. Although a balloon has no propulsion system, a degree of control is possible through making the balloon rise or sink in altitude to find favorable wind directions. There are three types of balloon, The hot air balloon or Montgolfière obtains its buoyancy by heating the air inside the balloon. The Rozière type has both heated and unheated lifting gases in separate gasbags and this type of balloon is sometimes used for long-distance record flights, such as the recent circumnavigations, but is not otherwise in use. Both the hot air, or Montgolfière, balloon and the gas balloon are still in common use, Montgolfière balloons are relatively inexpensive, as they do not require high-grade materials for their envelopes, and they are popular for balloonist sport activity. The first tethered manned balloon flight was by a larger Montgolfier balloon, the first free balloon flight was by the same Montgolfier balloon on 21 November 1783. When heated, air expands, so a given volume of space contains less air and this makes it lighter and, if its lifting power is greater than the weight of the balloon containing it, it will lift the balloon upwards. A hot air balloon can stay up while it has fuel for its burner. The Montgolfiers early hot air balloons used a solid-fuel brazier which proved less practical than the balloons that had followed almost immediately. In the 1950s, the convenience and low cost of bottled gas burners led to a revival of hot air ballooning for sport and leisure. A man-carrying balloon using the gas hydrogen for buoyancy was made by Professor Jacques Charles and flown less than a month after the Montgolfier flight. In the 19th century, it was common to use gas to fill balloons, this was not as light as pure hydrogen gas, having about half the lifting power. Light gas balloons are predominant in scientific applications, as they are capable of reaching much higher altitudes for longer periods of time. They are generally filled with helium, although hydrogen has more lifting power, it is explosive in an atmosphere rich in oxygen
32.
Helium
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Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and its boiling point is the lowest among all the elements. Its abundance is similar to figure in the Sun and in Jupiter. This is due to the high nuclear binding energy of helium-4 with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of nuclear fusion and radioactive decay. Most helium in the universe is helium-4, and is believed to have formed during the Big Bang. Large amounts of new helium are being created by fusion of hydrogen in stars. Helium is named for the Greek god of the Sun, Helios and it was first detected as an unknown yellow spectral line signature in sunlight during a solar eclipse in 1868 by French astronomer Jules Janssen. Janssen is jointly credited with detecting the element along with Norman Lockyer, Janssen observed during the solar eclipse of 1868 while Lockyer observed from Britain. Lockyer was the first to propose that the line was due to a new element, the formal discovery of the element was made in 1895 by two Swedish chemists, Per Teodor Cleve and Nils Abraham Langlet, who found helium emanating from the uranium ore cleveite. In 1903, large reserves of helium were found in gas fields in parts of the United States. Liquid helium is used in cryogenics, particularly in the cooling of superconducting magnets, a well-known but minor use is as a lifting gas in balloons and airships. As with any gas whose density differs from that of air, inhaling a small volume of helium temporarily changes the timbre, on Earth it is relatively rare—5.2 ppm by volume in the atmosphere. Most terrestrial helium present today is created by the radioactive decay of heavy radioactive elements. Previously, terrestrial helium—a non-renewable resource, because once released into the atmosphere it readily escapes into space—was thought to be in short supply. The first evidence of helium was observed on August 18,1868, the line was detected by French astronomer Jules Janssen during a total solar eclipse in Guntur, India. This line was assumed to be sodium. He concluded that it was caused by an element in the Sun unknown on Earth, Lockyer and English chemist Edward Frankland named the element with the Greek word for the Sun, ἥλιος
33.
Hydrogen
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Hydrogen is a chemical element with chemical symbol H and atomic number 1. With a standard weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form is the most abundant chemical substance in the Universe, non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton, the universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays an important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a charge when it is known as a hydride. The hydrogen cation is written as though composed of a bare proton, Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Industrial production is mainly from steam reforming natural gas, and less often from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market, Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen gas is flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol,2 H2 + O2 →2 H2O +572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%, the explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C, the detection of a burning hydrogen leak may require a flame detector, such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames, the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. The visible orange flames in that incident were the result of a mixture of hydrogen to oxygen combined with carbon compounds from the airship skin. H2 reacts with every oxidizing element, the ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, however, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity. The most complicated treatments allow for the effects of special relativity
34.
Sky lantern
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A sky lantern, also known as Kongming lantern or Chinese lantern, is a small hot air balloon made of paper, with an opening at the bottom where a small fire is suspended. In Asia and elsewhere around the world, sky lanterns have been made for centuries. The name sky lantern is a translation of the Chinese name, in China and Taiwan, sky lanterns are traditionally made from oiled rice paper on a bamboo frame. The source of hot air may be a candle or fuel cell composed of a waxy flammable material. The general design is a thin shell, which may be from about 30 cm to a couple of metres across. The opening is usually about 10 to 30 cm wide, and is surrounded by a collar that serves to suspend the flame source. In Thailand, sky lanterns are traditionally made from oiled rice paper on a bamboo frame. They may also be constructed from other lightweight papers, the source of hot air is usually a small candle or fuel cell composed of a waxy flammable material lit and which usually stays lit despite the surrounding air currents. The Thai name is khom loi, many areas of Asia, however, do not permit sky lanterns because of widespread fire hazards as well as danger to livestock. A design that was fairly common was two pyramids joined by the base sometimes with a cube or prism inserted in the middle, the candle was usually a packet of paraffin or rosin tightly wrapped in cloth and bound with wire. When lit, the heats the air inside the lantern, thus lowering its density. The sky lantern is only airborne for as long as the flame stays alight, traditionally, however, their invention is attributed to the sage and military strategist Zhuge Liang whose reverent term of address was Kongming. He is said to have used a message written on a sky lantern to summon help on an occasion when he was surrounded by enemy troops, for this reason they are still known in China as Kongming lanterns. Sky lanterns are an explanation for some UFO sightings through the years. In ancient China, sky lanterns were used in wars. However, later on, non-military applications were employed as they became popular with children at festivals and these lanterns were subsequently incorporated into festivals like the Chinese Mid-Autumn and Lantern Festivals. Pingxi District in New Taipei City of Taiwan holds an annual Lantern Festival in which sky lanterns are released into the sky with peoples wishes written on the lantern. The Lanna people of northern Thailand use floating lanterns year round, for celebrations, one very important festival in which sky lanterns are used is the Yi Peng festival, which is held on a full moon of the 2nd month of the Lanna calendar
35.
Kite
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A kite is traditionally a tethered heavier-than-air craft with wing surfaces that react against the air to create lift and drag. A kite consists of wings, tethers, pulleys, and anchors, Kites often have a bridle to guide the face of the kite at the correct angle so the wind can lift it. A kites wing also may be so designed so a bridle is not needed, when kiting a sailplane for launch, a kite may have fixed or moving anchors. Untraditionally in technical kiting, a kite consists of tether-set-coupled wing sets, even in technical kiting, though, the lift that sustains the kite in flight is generated when air moves around the kites surface, producing low pressure above and high pressure below the wings. The interaction with the wind also generates horizontal drag along the direction of the wind, the resultant force vector from the lift and drag force components is opposed by the tension of one or more of the lines or tethers to which the kite is attached. The anchor point of the line may be static or moving. The same principles of fluid flow apply in liquids and kites are used under water. A hybrid tethered craft comprising both a lighter-than-air balloon as well as a lifting surface is called a kytoon. Kites have a long and varied history and many different types are flown individually, Kites may be flown for recreation, art or other practical uses. Sport kites can be flown in aerial ballet, sometimes as part of a competition, even Man-lifting kites have been made. The kite has been claimed as the invention of the 5th-century BC Chinese philosophers Mozi, by 549 AD paper kites were certainly being flown, as it was recorded that in that year a paper kite was used as a message for a rescue mission. Ancient and medieval Chinese sources describe kites being used for measuring distances, testing the wind, lifting men, signaling, the earliest known Chinese kites were flat and often rectangular. Later, tailless kites incorporated a stabilizing bowline, Kites were decorated with mythological motifs and legendary figures, some were fitted with strings and whistles to make musical sounds while flying. From China, kites were introduced to Cambodia, Thailand, India, Japan, Korea, after its introduction into India, the kite further evolved into the fighter kite, known as the patang in India, where thousands are flown every year on festivals such as Makar Sankranti. Kites were known throughout Polynesia, as far as New Zealand, anthropomorphic kites made from cloth and wood were used in religious ceremonies to send prayers to the gods. Polynesian kite traditions are used by anthropologists get an idea of early primitive Asian traditions that are believed to have at one time existed in Asia, Kites were late to arrive in Europe, although windsock-like banners were known and used by the Romans. Stories of kites were first brought to Europe by Marco Polo towards the end of the 13th century, although they were initially regarded as mere curiosities, by the 18th and 19th centuries kites were being used as vehicles for scientific research. In 1750 Benjamin Franklin published a proposal for an experiment to prove that lightning was caused by electricity by flying a kite in a storm that appeared capable of becoming a lightning storm
36.
History of science and technology in China
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Among the earliest inventions were the abacus, the shadow clock, and the first items such as Kongming lanterns. The Tang Dynasty in particular, was a time of great innovation, a good deal of exchange occurred between Western and Chinese discoveries up to the Qing Dynasty. In the 19th and 20th century the introduction of Western technology was a factor in the modernization of China. Much of the early Western work in the history of science in China was done by Joseph Needham, the Warring States period began 2500 years ago at the time of the invention of the crossbow. Needham notes that the invention of the crossbow far outstripped the progress in defensive armor, at this time, there were also many nascent schools of thought in China — the Hundred Schools of Thought, scattered among many polities. The schools served as communities which advised the rulers of these states, mo Di introduced concepts useful to one of those rulers, such as defensive fortification. One of these concepts, fa was extended by the School of Names, the development of a school of logic was cut short by the defeat of Mohisms political sponsors by the Qin Dynasty, and the subsumption of fa as law rather than method by the Legalists. You conquered the empire on horseback, but from horseback you will never succeed in ruling it, derived from Taoist philosophy, one of the newest longstanding contributions of the ancient Chinese are in Traditional Chinese medicine, including acupuncture and herbal medicine. These claims, however, are disputed and rely on much supposition. The Book of Silk was the first definitive atlas of comets and it listed 29 comets that appeared over a period of about 300 years, with renderings of comets describing an event its appearance corresponded to. In architecture, the pinnacle of Chinese technology manifested itself in the Great Wall of China, typical Chinese architecture changed little from the succeeding Han Dynasty until the 19th century. The Qin Dynasty also developed the crossbow, which became the mainstream weapon in Europe. Several remains of crossbows have been found among the soldiers of the Terracotta Army in the tomb of Qin Shi Huang, the Eastern Han Dynasty scholar and astronomer Zhang Heng invented the first water-powered rotating armillary sphere, and catalogued 2500 stars and over 100 constellations. In 132, he invented the first seismological detector, called the Houfeng Didong Yi, according to the History of Later Han Dynasty, this seismograph was an urn-like instrument, which would drop one of eight balls to indicate when and in which direction an earthquake had occurred. On June 13,2005, Chinese seismologists announced that they had created a replica of the instrument, the mechanical engineer Ma Jun was another impressive figure from ancient China. However, Ma Juns most impressive invention was the south-pointing chariot and it incorporated the use of a differential gear in order to apply equal amount of torque to wheels rotating at different speeds, a device that is found in all modern automobiles. Sliding calipers were invented in China almost 2,000 years ago, the Chinese civilization was the earliest civilization to experiment successfully with aviation, with the kite and Kongming lantern being the first flying machines. The Four Great Inventions are the compass, gunpowder, papermaking and printing, paper and printing were developed first
37.
USS Akron (ZRS-4)
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USS Akron was a helium-filled rigid airship of the U. S. Navy which operated between September 1931 and April 1933. She was the worlds first purpose-built flying aircraft carrier, carrying F9C Sparrowhawk fighter planes which could be launched and recovered while she was in flight, with an overall length of 785 ft, the Akron and her sister ship the Macon were among the largest flying objects ever built. The Akron was destroyed in a thunderstorm off the coast of New Jersey on the morning of 4 April 1933, killing 73 of the 76 crewmen and this accident involved the greatest loss of life in any airship crash. The airships skeleton was built of the new lightweight alloy duralumin 17-SRT, the frame introduced several novel features compared with traditional Zeppelin designs. Rather than being single-girder diamond trusses with radial wire bracing, the rings of the Akron were self-supporting deep frames. The inherent strength of these frames allowed Chief Designer, Dr Karl Arnstein, instead, the fins of the Akron were cantilevered, mounted entirely externally to the main structure. Each keel provided a walkway running almost the length of the ship. The main rings were spaced at 22.5 m and between each pair were three intermediate rings of lighter construction, in keeping with conventional practice, station numbers on the airship were measured in meters from zero at the rudder post, positive forward and negative aft. Thus the tip of the tail was at station -23.75, each ring frame formed a polygon with 36 corners and these were numbered from 1 to 18 port and starboard. Thus a position on the hull could be referred to, for example, while Germany, France and Britain used goldbeaters skin to gas-proof their gasbags, the Akron used Goodyear Tire and Rubbers rubberised cotton, heavier but much cheaper and more durable. Half the gas cells used an experimental cotton-based fabric impregnated with a gelatin-latex compound and this was more expensive than the rubberised cotton but lighter than goldbeaters skin. It was so successful all the gasbags of the Macon were made from it. There were 12 gas cells, numbered 0 to XI, using Roman numerals, while the air volume of the hull was 7,401,260 cu ft, the total volume of the gas cells at 100 percent fill was 6,850,000 cu ft. At a normal 95 percent fill with helium of standard purity, each engine turned a two-bladed,16 ft 4 in diameter, fixed pitch, wooden propeller via a driveshaft and bevel gearing which allowed the propeller to swivel from the vertical plane to the horizontal. With the engines ability to reverse, this allowed thrust to be applied forward, aft and it appears from photographs that the four propellers on each side were contra-rotating, each one turning the opposite way to the one ahead of it. Thus it would appear that the designers were aware that running the propellers in the air disturbed by the one ahead was not ideal and this was to prove problematical in service, inducing considerable vibration, especially noticeable in the emergency control position in the lower fin. By 1933, the Akron had two of her propellers replaced by advanced, ground-adjustable, three-bladed, metal propellers. These promised an increase and were adopted as standard for the Macon
38.
Frederick Handley Page
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Sir Frederick Handley Page, CBE, FRAeS was an English industrialist who was a pioneer in the aircraft industry and became known as the father of the heavy bomber. His company Handley Page Limited was best known for its large aircraft such as the Handley Page 0/400 and Halifax bombers, the latter was the flagship of the Imperial Airways fleet between the wars and remarkable at the time for having been involved in no passenger deaths. He is also known for his invention, with Gustav Lachmann, Frederick Handley Page was the uncle of World War II flying ace Geoffrey Page. Handley Page was born in Cheltenham, the son of Frederick Joseph Page. He was educated at Cheltenham Grammar School, in 1902, against his parents wishes, he moved to London to study electrical engineering at Finsbury Technical College. On qualifying in 1906 he was appointed head designer at Johnson & Phillips Ltd, in 1907 he joined the Royal Aeronautical Society where he met the artist and aviation pioneer José Weiss. Weiss was performing experiments with using an inherently stable wing design based on the seed-pods of the Zanonia macrocarpa which he was to patent in 1908. R. Low, who would become an aircraft designer for Vickers. He immediately set up his own business, with an office in Woolwich, after some searching for a suitable flying ground he leased a small stretch of marshland and a shed at Creekmouth in Essex. Here he constructed his first aircraft, a canard configuration glider with a tricycle undercarriage, in June 1909 he established his business as a limited company, with an authorised capital of £10,000. Handley Page also set about designing and building his first powered aircraft, as well as complete aircraft, the company also supplied metal fixings for aircraft and aircraft propellers, two of which were used by one of the Willows airships. After it was exhibited at Olympia, Handley Page set about attempting to learn to fly using the Bluebird, a brief straight flight was first achieved on 26 May 1910, but after a few more similar efforts Handley Pages first attempt at a turn ended in a crash. Here he had a built, and he also sold the Bluebird to the Institute for use as an instructional airframe. Shortly after the outbreak of the First World War in 1914 Handley Page was invited by Murray Sueter to the Admiralty to discuss Naval air requirements. The result was a specification for a large twin-engined aircraft, capable of carrying 600 lb of bombs, the eventual result was the Handley Page 0/100, first flown in December 1915 and the start of the Handley Page companys reputation for building large aircraft. During the war it was developed into the 0/400 and 0/1500 bombers. In 1917 Handley Page and his aerodynamicist R. O, bothwell started wind-tunnel experiments intended to combine the low drag of high aspect ratio wings with the delayed stall at high angles of attack of a low aspect ratio wing. The first attempts involved using a divided into separate square panels by slots running chordwise
39.
Rigid airship
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Rigid airships are often commonly called Zeppelins, though this technically refers only to airships built by the Luftschifbau Zeppelin company. Rigid airships were produced and relatively successfully employed from the beginning of the 1900s to the end of the 1930s, Rigid airships consist of a structural framework usually covered in doped fabric containing a number of gasbags or cells containing a lifting gas. The noble gas helium was used by American airships in the 1920s and 30s and is used in all modern airships, similarly, by flying nose-down down-force can be generated, this may be done to prevent the airship rising above its pressure height. Typically airships start a flight with their gasbags inflated to about 95% capacity, by 1874 several people had conceived of a rigid dirigible. The Frenchman Joseph Spiess had patented a rigid airship design in 1873, Count Zeppelin had outlined his thoughts of a rigid airship in diary entries from 25 March 1874 through to 1890 when he resigned from the military. David Schwarz had thought about building an airship in the 1880s and had started design work in 1891. It was not until after Schwarzs death in 1897 that his airship, built with help from the industrialist Carl Berg. With Bergs aluminium, Zeppelin was able to start building his first airship in 1899, ferdinand von Zeppelin completed his first airship, the LZ1 in July 1900. Constructed in a shed on Lake Constance, it was 128.02 m long,11.73 m in diameter with a volume of 11,298 m3 and was powered by two 11 kW Daimler engines. The first flight, lasting 20 minutes, was made on 2 July, after repairs and modifications two further flights were made in October 1900. These experiments failed to attract any investors, and Count Zeppelin did not complete his design, LZ2. This made only a flight on 17 January 1906. After both engines failed it made a landing in the Allgäu mountains, where a storm subsequently damaged it beyond repair. A similar design, the LZ3 was soon completed and this performed well enough to interest the German Army, but they required an airship capable of flying for 24 hours. This was beyond the capability of LZ3, so a larger craft and this was 136 m long,12.95 m in diameter and powered by two Daimler engines delivering a total of 156 kW. LZ4 first flew on 20 June 1908, and on 1 July made a spectacular 12 hour cross-country flight during which it was flown over Switzerland to Zürich, the 24-hour trial was started on 4 August, but was interrupted by the failure of one of the engines. It was moored near Echterdingen in order to make repairs but a storm arose and it away from its moorings, was blown into some trees. The disaster took place in front of an estimated 40 to 50 thousand spectators, seven were operated by DELAG, the first airline in the world
40.
Zeppelin
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A Zeppelin was a type of rigid airship named after the German Count Ferdinand von Zeppelin who pioneered rigid airship development at the beginning of the 20th century. Zeppelins notions were first formulated in 1874 and developed in detail in 1893 and they were patented in Germany in 1895 and in the United States in 1899. After the outstanding success of the Zeppelin design, the word came to be commonly used to refer to all rigid airships. Zeppelins were first flown commercially in 1910 by Deutsche Luftschiffahrts-AG, the worlds first airline in revenue service, by mid-1914, DELAG had carried over 10,000 fare-paying passengers on over 1,500 flights. During World War I the German military made use of Zeppelins as bombers and scouts. The defeat of Germany in 1918 temporarily slowed down the airship business, an exception was made allowing the construction of one airship for the US Navy, which saved the company from extinction. In 1926 the restrictions on airship construction were lifted and with the aid of donations from the public and this revived the companys fortunes, and during the 1930s the airships Graf Zeppelin and the larger LZ129 Hindenburg operated regular transatlantic flights from Germany to North America and Brazil. The Hindenburg disaster in 1937, along political and economic issues. The principal feature of Zeppelins design was a rigid metal framework made up from transverse rings. The advantage of design was that the aircraft could be much larger than non-rigid airships. The framework of most Zeppelins was made of duralumin, early Zeppelins used rubberised cotton for the gasbags, but most later craft used goldbeaters skin, made from the intestines of cattle. The first Zeppelins had long cylindrical hulls with tapered ends and complex multi-plane fins and they were propelled by several engines, mounted in gondolas or engine cars, which were attached to the outside of the structural framework. Some of these could provide reverse thrust for manoeuvring while mooring, early models had a comparatively small externally mounted gondola for passengers and crew which was attached to the bottom of the frame. This space was never heated so passengers during trips across the North Atlantic or Siberia were forced to bundle themselves in blankets, the flight ceiling was so low that no pressurization of the cabins was necessary, though the Hindenburg did maintain a pressurized air-locked smoking room. Access to the Zeppelin was achieved in a number of ways, the Graf Zeppelins gondola was accessed while the vessel was on the ground, via gangways. This describes a large rigidly framed outer envelope containing several separate gasbags and he had previously encountered Union Army balloons in 1863 when he visited the United States as a military observer during the American Civil War. Count Zeppelin began to pursue his project after his early retirement from the military in 1890 at the age of 52. Convinced of the importance of aviation, he started working on various designs in 1891
41.
Hindenburg disaster
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Of the 97 people on board, there were 35 fatalities. One worker on the ground was killed, raising the final death toll to 36. The disaster was the subject of spectacular newsreel coverage, photographs, and Herbert Morrisons recorded radio eyewitness reports from the landing field, a variety of hypotheses have been put forward for both the cause of ignition and the initial fuel for the ensuing fire. The incident shattered public confidence in the giant, passenger-carrying rigid airship, the American Airlines company had contracted with the operators of the Hindenburg to shuttle the passengers from Lakehurst to Newark for connections to airplane flights. Although carrying only half its capacity of passengers and crewmen for the accident flight. Many of the passengers tickets to Germany were planning to attend the coronation of King George VI. The airship was hours behind schedule when she passed over Boston on the morning of May 6, after passing over the field at 4,00 p. m. Captain Pruss took passengers on a tour over the seasides of New Jersey while waiting for the weather to clear. After finally being notified at 6,22 p. m. that the storms had passed, around 7,00 p. m. local time, at an altitude of 650 feet, the Hindenburg made its final approach to the Lakehurst Naval Air Station. This was to be a landing, known as a flying moor, because the airship would drop its landing ropes and mooring cable at a high altitude. This type of landing maneuver would reduce the number of ground crewmen, although the high landing was a common procedure for American airships, the Hindenburg had only performed this maneuver a few times in 1936 while landing in Lakehurst. At 7,09, the made a sharp full-speed left turn to the west around the landing field because the ground crew was not ready. At 7,11, it turned back toward the landing field, all engines idled ahead and the airship began to slow. Captain Pruss ordered aft engines full astern at 7,14 while at an altitude of 394 ft, at 7,17, the wind shifted direction from east to southwest, and Captain Pruss ordered a second sharp turn starboard, making an s-shaped flightpath towards the mooring mast. At 7,18, as the turn progressed, Pruss ordered 300,300 and 500 kg of water ballast in successive drops because the airship was stern-heavy. The forward gas cells were also valved, as these measures failed to bring the ship in trim, six men were then sent to the bow to trim the airship. At 7,21, while the Hindenburg was at an altitude of 295 feet, the lines were dropped from the bow. The port line was overtightened as it was connected to the post of the ground winch, the starboard line had still not been connected
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Dirigible
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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 large gas bags filled with a gas that is less dense than the surrounding air. In early dirigibles, the gas used was hydrogen, due to its high lifting capacity. Helium gas has almost the same lifting capacity and is not flammable, unlike hydrogen, significant amounts were first discovered in the United States and for a while helium was only used for airships by the United States. Most airships built since the 1960s have used helium, though some have used hot air, the envelope of an airship may form a single gas bag, or may contain a number of internal gas-filled cells. An airship also has engines, crew, and optionally also payload accommodation, the main types of airship are non-rigid, semi-rigid, and rigid. Non-rigid airships, often called blimps, rely on internal pressure to maintain the shape of the airship, semi-rigid airships maintain the envelope shape by internal pressure, but have some form of supporting structure, such as a fixed keel, attached to it. Rigid airships have a structural framework which maintains the shape and carries all structural loads. Rigid airships were first flown by Count Zeppelin and the vast majority of rigid airships built were manufactured by the firm he founded, as a result, rigid airships are called zeppelins. S. Navy helium-filled rigids, the USS Akron and USS Macon respectively, during the pioneer years of aeronautics, terms such as airship, air-ship, air ship and ship of the air meant any kind of navigable or dirigible flying machine. In 1919 Frederick Handley Page was reported as referring to ships of the air, in the 1930s, large intercontinental flying boats were also sometimes referred to as ships of the air or flying-ships. Nowadays the term airship is used only for powered, dirigible balloons, semirigid architecture is the more recent and the late appearance is caused by both advancements about deformable structures and exigiency of reducing weight and volume of the airships. They have a structure that ensure to keep the shape jointly with overpressure of the gas envelope. An aerostat is an aircraft which remain aloft using buoyancy or static lift, Airships are a type of aerostat. The term aerostat has also used to indicate a tethered or moored balloon as opposed to a free-floating balloon. A blimp is a non-rigid aerostat, in American usage it refers specifically to a non-rigid type of dirigible balloon or airship. In British usage it refers to any non-rigid aerostat, including balloons and other kite balloons, having a streamlined shape. The initials LZ, for Luftschiff Zeppelin, usually prefixed their crafts serial identifiers, streamlined Parsifal-shaped rigid airships are usually referred to as Zeppelin, because of the fame that this company has acquired due to the number of airships it produced
43.
World War II
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World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the worlds countries—including all of the great powers—eventually forming two opposing alliances, the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. Marked by mass deaths of civilians, including the Holocaust and the bombing of industrial and population centres. These made World War II the deadliest conflict in human history, from late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, and formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Poland, Finland, Romania and the Baltic states. In December 1941, Japan attacked the United States and European colonies in the Pacific Ocean, and quickly conquered much of the Western Pacific. The Axis advance halted in 1942 when Japan lost the critical Battle of Midway, near Hawaii, in 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained all of its territorial losses and invaded Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in South Central China and Burma, while the Allies crippled the Japanese Navy, thus ended the war in Asia, cementing the total victory of the Allies. World War II altered the political alignment and social structure of the world, the United Nations was established to foster international co-operation and prevent future conflicts. The victorious great powers—the United States, the Soviet Union, China, the United Kingdom, the Soviet Union and the United States emerged as rival superpowers, setting the stage for the Cold War, which lasted for the next 46 years. Meanwhile, the influence of European great powers waned, while the decolonisation of Asia, most countries whose industries had been damaged moved towards economic recovery. Political integration, especially in Europe, emerged as an effort to end pre-war enmities, the start of the war in Europe is generally held to be 1 September 1939, beginning with the German invasion of Poland, Britain and France declared war on Germany two days later. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or even the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously and this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935. The British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the forces of Mongolia and the Soviet Union from May to September 1939, the exact date of the wars end is also not universally agreed upon. It was generally accepted at the time that the war ended with the armistice of 14 August 1945, rather than the formal surrender of Japan
44.
Aerodynamics
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Aerodynamics, from Greek ἀήρ aer + δυναμική, the study of the motion of air, particularly its interaction with a solid object, such as an airplane wing. Aerodynamics is a sub-field of fluid dynamics and gas dynamics, the term aerodynamics is often used synonymously with gas dynamics, the difference being that gas dynamics applies to the study of the motion of all gases, and is not limited to air. The formal study of aerodynamics began in the sense in the eighteenth century. Most of the efforts in aerodynamics were directed toward achieving heavier-than-air flight. Recent work in aerodynamics has focused on issues related to flow, turbulence. Fundamental concepts of continuum, drag, and pressure gradients appear in the work of Aristotle, in 1726, Sir Isaac Newton became the first person to develop a theory of air resistance, making him one of the first aerodynamicists. In 1757, Leonhard Euler published the more general Euler equations which could be applied to both compressible and incompressible flows, the Euler equations were extended to incorporate the effects of viscosity in the first half of the 1800s, resulting in the Navier-Stokes equations. The Navier-Stokes equations are the most general governing equations of fluid flow, in 1871, Francis Herbert Wenham constructed the first wind tunnel, allowing precise measurements of aerodynamic forces. Drag theories were developed by Jean le Rond dAlembert, Gustav Kirchhoff, in 1889, Charles Renard, a French aeronautical engineer, became the first person to reasonably predict the power needed for sustained flight. Otto Lilienthal, the first person to become successful with glider flights, was also the first to propose thin, curved airfoils that would produce high lift. Building on these developments as well as carried out in their own wind tunnel. During the time of the first flights, Frederick W. Lanchester, Martin Wilhelm Kutta, Kutta and Zhukovsky went on to develop a two-dimensional wing theory. Expanding upon the work of Lanchester, Ludwig Prandtl is credited with developing the mathematics behind thin-airfoil, as aircraft speed increased, designers began to encounter challenges associated with air compressibility at speeds near or greater than the speed of sound. The differences in air flows under such conditions leds to problems in control, increased drag due to shock waves. The ratio of the speed to the speed of sound was named the Mach number after Ernst Mach who was one of the first to investigate the properties of supersonic flow. Theodore von Kármán and Hugh Latimer Dryden introduced the term transonic to describe flow speeds around Mach 1 where drag increases rapidly, by the time the sound barrier was broken, aerodynamicists understanding of the subsonic and low supersonic flow had matured. The Cold War prompted the design of an line of high performance aircraft. Understanding the motion of air around an object enables the calculation of forces, in many aerodynamics problems, the forces of interest are the fundamental forces of flight, lift, drag, thrust, and weight
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Wing
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A wing is a type of fin that produces lift, while moving through air or some other fluid. As such, wings have a shape, a streamlined cross-sectional shape. A wings aerodynamic efficiency is expressed as its lift-to-drag ratio, the lift a wing generates at a given speed and angle of attack can be one to two orders of magnitude greater than the total drag on the wing. A high lift-to-drag ratio requires a significantly smaller thrust to propel the wings through the air at sufficient lift, lifting structures used in water, include various foils, including hydrofoils. Hydrodynamics is the science, rather than aerodynamics. Applications of underwater foils occur in hydroplanes, sailboats and submarines, the word wing from the Old Norse vængr for many centuries referred mainly to the foremost limbs of birds. In nature wings have evolved in dinosaurs, birds, mammals, fish, reptiles, Wing forms in nature The design and analysis of the wings of aircraft is one of the principal applications of the science of aerodynamics, which is a branch of fluid mechanics. The properties of the airflow around any moving object can - in principle - be found by solving the Navier-Stokes equations of fluid dynamics, however, except for simple geometries these equations are notoriously difficult to solve. Fortunately, simpler explanations can be described, for a wing to produce lift, it must be oriented at a suitable angle of attack relative to the flow of air past the wing. When this occurs the wing deflects the airflow downwards, turning the air as it passes the wing, since the wing exerts a force on the air to change its direction, the air must exert a force on the wing, equal in size but opposite in direction. This force manifests itself as differing air pressures at different points on the surface of the wing, a region of lower-than-normal air pressure is generated over the top surface of the wing, with a higher pressure on the bottom of the wing. The lower air pressure on the top of the wing generates a smaller force on the top of the wing than the upward force generated by the higher air pressure on the bottom of the wing. Hence, a net force acts on the wing. This force is called the lift generated by the wing, the different velocities of the air passing by the wing, the air pressure differences, the change in direction of the airflow, and the lift on the wing are intrinsically one phenomenon. It is, therefore, possible to lift from any of the other three. For example, the lift can be calculated from the differences, or from different velocities of the air above and below the wing. Fluid dynamics offers other approaches to solving these problems—and all produce the same answers if done correctly, air velocity on the bottom of a wing is higher than that on the top, while the wing is generating lift. Wings with a cross section are the norm in subsonic flight
46.
Fixed-wing aircraft
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A fixed-wing aircraft is an aircraft, such as an aeroplane, which is capable of flight using wings that generate lift caused by the vehicles forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft, in which the form a rotor mounted on a spinning shaft. Glider fixed-wing aircraft, including free-flying gliders of various kinds and tethered kites, powered fixed-wing aircraft that gain forward thrust from an engine include powered paragliders, powered hang gliders and some ground effect vehicles. The wings of an aircraft are not necessarily rigid, kites, hang-gliders, variable-sweep wing aircraft. Most fixed-wing aircraft are flown by a pilot on board the aircraft, kites were used approximately 2,800 years ago in China, where materials ideal for kite building were readily available. Some authors hold that leaf kites were being flown much earlier in what is now Indonesia, by at least 549 AD paper kites were being flown, as it was recorded in that year a paper kite was used as a message for a rescue mission. Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men, signaling, and communication for military operations. Stories of kites were brought to Europe by Marco Polo towards the end of the 13th century, although they were initially regarded as mere curiosities, by the 18th and 19th centuries kites were being used as vehicles for scientific research. This machine may have been suspended for its flight, some of the earliest recorded attempts with gliders were those by the 9th-century poet Abbas Ibn Firnas and the 11th-century monk Eilmer of Malmesbury, both experiments injured their pilots. In 1799, Sir George Cayley set forth the concept of the aeroplane as a fixed-wing flying machine with separate systems for lift, propulsion. Cayley was building and flying models of fixed-wing aircraft as early as 1803, in 1856, Frenchman Jean-Marie Le Bris made the first powered flight, by having his glider LAlbatros artificiel pulled by a horse on a beach. In 1884, the American John J. Montgomery made controlled flights in a glider as a part of a series of gliders built between 1883-1886, other aviators who made similar flights at that time were Otto Lilienthal, Percy Pilcher, and Octave Chanute. In the 1890s, Lawrence Hargrave conducted research on wing structures and his box kite designs were widely adopted. Although he also developed a type of aircraft engine, he did not create. Sir Hiram Maxim built a craft that weighed 3.5 tons, in 1894, his machine was tested with overhead rails to prevent it from rising. The test showed that it had enough lift to take off, the craft was uncontrollable, which Maxim, it is presumed, realized, because he subsequently abandoned work on it. By 1905, the Wright Flyer III was capable of fully controllable, stable flight for substantial periods, the flight was certified by the FAI. This was the first controlled flight, to be officially recognised, the Bleriot VIII design of 1908 was an early aircraft design that had the modern monoplane tractor configuration
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Rotorcraft
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A rotorcraft or rotary-wing aircraft is a heavier-than-air flying machine that uses lift generated by wings, called rotary wings or rotor blades, that revolve around a mast. Several rotor blades mounted on a single mast are referred to as a rotor, the International Civil Aviation Organization defines a rotorcraft as supported in flight by the reactions of the air on one or more rotors. Rotorcraft generally include those aircraft where one or more rotors are required to provide lift throughout the flight, such as helicopters, cyclocopters, autogyros. Compound rotorcraft may also include additional thrust engines or propellers and static lifting surfaces, helicopters have several different configurations of one or more main rotors. A cyclocopter is a rotorcraft whose rotors are driven by the engine throughout the flight. At the present time flying model prototypes have been built in China, US, S. Korea, while similar to a helicopter rotor in appearance, the autogyros rotor must have air flowing up and through the rotor disk in order to generate rotation. Early autogyros resembled the fixed-wing aircraft of the day, with wings, late-model autogyros feature a rear-mounted engine and propeller in a pusher configuration. The autogyro was invented in 1920 by Juan de la Cierva, the autogyro with pusher propeller was first tested by Etienne Dormoy with his Buhl A-1 Autogyro. As power is increased to the propeller, less power is required by the rotor to provide forward thrust resulting in reduced pitch angles and rotor blade flapping. At cruise speeds with most or all of the thrust being provided by the propellers, a rotor kite or gyroglider is an unpowered rotary-wing aircraft. Like an autogyro or helicopter, it relies on lift created by one or more sets of rotors in order to fly, a rotary wing is characterised by the number of blades. Typically this is two and six per driveshaft. A rotorcraft may have one or more rotors, various rotor configurations have been used, One rotor. Powered rotors require compensation for the reaction causing yaw, except in the case of tipjet drive. These typically rotate in opposite directions cancelling the torque reaction so that no tail rotor or other yaw stabiliser is needed and these rotors can be laid out as Tandem – One in front of the other. Coaxial – One rotor disc above the other, with drive shafts. An uncommon configuration, the 1948 Cierva Air Horse had three rotors as it was not believed a single rotor of sufficient strength could be built for its size. All three rotors turned in the direction and yaw compensation was provided by inclining each rotor axis to generate rotor thrust components that opposed torque
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