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Aircraft

Aircraft

An aircraft is any machine capable of atmospheric flight. flight. This is a wide-bodied long-haul aircraft]]

Categories and classification

Aircraft fall into two broad categories:

Heavier than air

- Heavier than air aerodynes, including autogyros, helicopters and variants, and conventional fixed-wing aircraft: aeroplanes in Commonwealth English (excluding Canada), airplanes in North American English. Fixed-wing aircraft generally use an internal-combustion engine in the form of a piston engine (with a propeller) or a turbine engine (jet or turboprop), to provide thrust that moves the craft forward through the air. The movement of air over the airfoil produces lift that causes the aircraft to fly. Exceptions are gliders which have no engines and gain their thrust, initially, from winches or tugs and then from gravity and thermal currents. For a glider to maintain its forward speed it must descend in relation to the air (but not necessarily in relation to the ground). Helicopters and autogyros use a spinning rotor (a rotary wing) to provide lift; helicopters also use the rotor to provide thrust. The abbreviation VTOL is applied to aircraft other than helicopters that can take off or land vertically. STOL stands for Short Take Off and Landing. Mainly used internationally.

Lighter than air

STOL
- Lighter than air aerostats: hot air balloons and airships. Aerostats use buoyancy to float in the air in much the same manner as ships float on the water. In particular, these aircraft use a relatively low density gas such as helium, hydrogen or heated air, to displace the air around the craft. The distinction between a balloon and an airship is that an airship has some means of controlling both its forward motion and steering itself, while balloons are carried along with the wind.

Types of aircraft

:See also: List of aircraft There are several ways to classify aircraft. Below, we describe classifications by design, propulsion and usage.

By design

A first division by design among aircraft is between lighter-than-air, aerostat, and heavier-than-air aircraft, aerodyne. Examples of lighter-than-air aircraft include non-steerable balloons, such as hot air balloons and gas balloons, and airships (sometimes called dirigible balloons) such as blimps (that have non-rigid construction) and rigid airships that have a rigid frame. The most successful type of rigid airship was the Zeppelin, although there were some accidents such as the Hindenburg Zeppelin which was destroyed in a fire at Lakehurst, NJ, in 1937. In heavier-than-air aircraft, there are two ways to produce lift: aerodynamic lift and engine lift. In the case of aerodynamic lift, the aircraft is kept in the air by wings or rotors (see aerodynamics). With engine lift, the aircraft defeats gravity by use of vertical thrust greater than its weight. Examples of engine lift aircraft are rockets, and VTOL aircraft such as the Hawker-Siddeley Harrier. Among aerodynamically lifted aircraft, most fall in the category of fixed-wing aircraft, where horizontal airfoils produce lift, by profiting from airflow patterns determined by Bernoulli's equation and, to some extent, the Coanda effect. The forerunner of these type of aircraft is the kite. Kites depend upon the tension between the cord which anchors it to the ground and the force of the wind currents. Much aerodynamic work was done with kites until test aircraft, wind tunnels and now computer modelling programs became available. In a "conventional" configuration, the lift surfaces are placed in front of a control surface or tailplane. The other configuration is the canard where small horizontal control surfaces are placed forward of the wings, near the nose of the aircraft. Canards are becoming more common as supersonic aerodynamics grows more mature and because the forward surface contributes lift during straight-and-level flight. The number of lift surfaces varied in the pre-1950 period, as biplanes (two wings) and triplanes (three wings) were numerous in the early days of aviation. Subsequently most aircraft are monoplanes. This is principally an improvement in structures and not aerodynamics. Other possibilities include the delta-wing, where lift and horizontal control surfaces are often combined, and the flying wing, where there is no separate vertical control surface (e.g. the B-2 Spirit). A variable geometry ('swing-wing') has also been employed in a few examples of combat aircraft (the F-111, Panavia Tornado, F-14 Tomcat and B-1 Lancer, among others). The lifting body configuration is where the body itself produce lift. So far the only significant practical application of the lifting body is in the Space Shuttle, but many aircraft generate lift from nothing other than wings alone. A second category of aerodynamically lifted aircraft are the rotary-wing aircraft. Here, the lift is provided by rotating aerofoils or rotors. The best-known examples are the helicopter, the autogyro and the tiltrotor aircraft (such as the V-22 Osprey). Some craft have reaction-powered rotors with gas jets at the tips but most have one or more lift rotors powered from engine-driven shafts. A further category might encompass the wing-in-ground-effect types, for example the Russian ekranoplan also nicknamed the "Caspian Sea Monster" and hovercraft; most of the latter employing a skirt and achieving limited ground or water clearance to reduce friction and achieve speeds above those achieved by boats of similar weight. A recent innovation is a completely new class of aircraft, the fan wing. This uses a fixed wing with a forced airflow produced by cylindrical fans mounted above. It is (2005) in development in the United Kingdom. And finally the flapping-wing ornithopter is a category of its own. These designs may have potential but are not yet practical.

By propulsion

ornithopter adapted as a floatplane]] Some types of aircraft, such as the balloon or glider, do not have any propulsion. Balloons drift with the wind, though normally the pilot can control the altitude either by heating the air or by releasing ballast, giving some directional control (since the wind direction changes with altitude). For gliders, takeoff takes place from a high location, or the aircraft is pulled into the air by a ground-based winch or vehicle, or towed aloft by a powered "tug" aircraft. Airships combine a balloon's buoyancy with some kind of propulsion, usually propeller driven. Until World War II, the internal combustion piston engine was virtually the only type of propulsion used for powered aircraft. (See also: Aircraft engine.) The piston engine is still used in the majority of aircraft produced, since it is efficient at the lower altitudes used by small aircraft, but the radial engine (with the cylinders arranged in a circle around the crankshaft) has largely given way to the horizontally-opposed engine (with the cylinders lined up on two sides of the crankshaft). Water cooled V engines, as used in automobiles, were common in high speed aircraft, until they were replaced by jet and turbine power. Piston engines typically operate using avgas or regular gasoline, though some new ones are being designed to operate on diesel or jet fuel. Piston engines normally become less efficient above 7,000-8,000 ft (2100-2400 m) above sea level because there is less oxygen available for combustion; to solve that problem, some piston engines have mechanically powered compressors (blowers) or turbine-powered turbochargers or turbonormalizers that compress the air before feeding it into the engine; these piston engines can often operate efficiently at 20,000 ft (6100 m) above sea level or higher, altitudes that require the use of supplemental oxygen or cabin pressurisation. During the forties and especially following the 1973 energy crisis, development work was done on propellers with swept tips or even scimitar-shaped blades for use in high-speed commercial and military transports. Pressurised aircraft, however, are more likely to use the turbine engine, since it is naturally efficient at higher altitudes and can operate above 40,000 ft. Helicopters also typically use turbine engines. In addition to turbine engines like the turboprop and turbojet, other types of high-altitude, high-performance engines have included the ramjet and the pulse jet. Rocket aircrafts have occasionally been experimented with. They are restricted to rather specialised niches, such as spaceflight, where no oxygen is available for combustion (rockets carry their own oxygen).

By usage

The major distinction in aircraft usage is between military aviation, which includes all uses of aircraft for military purposes (such as combat, patrolling, search and rescue, reconnaissance, transport, and training), and civil aviation, which includes all uses of aircraft for non-military purposes.

Military aircraft

Combat aircraft like fighters or bombers represent only a minority of the category. Many civil aircraft have been produced in separate models for military use, such as the civil Douglas DC-3 airliner, which became the military C-47/C-53/R4D transport in the U.S. military and the Dakota in Britain and the Commonwealth. Even the little fabric-covered two-seater Piper J3 Cub had a military version, the L-4 liaison, observation and trainer aircraft. In the past, gliders and balloons have also been used as military aircraft; for example, balloons were used for observation during the American Civil War and World War I, and cargo gliders were used during World War II to land intruding German troops in many European countries in the 1940/42 period, while Allied troops used them in Europe after D-Day . Combat aircraft themselves, though used a handful of times for reconnaissance and surveillance during the Italo-Turkish War, did not come into widespread use until the Balkan War when first air-dropped bomb was invented and widely used by Bulgarian air force against Turkey. During World War I many types of aircraft were adapted for attacking the ground or enemy vehicles/ships/guns/aircraft, and the first aircraft designed as bombers were born. In order to prevent the enemy from bombing, fighter aircraft were developed to intercept and shoot down enemy aircraft. Tankers were developed after World War II to refuel other aircraft in mid-air, thus increasing their operational range. By the time of the Vietnam War, helicopters had come into widespread military use, especially for transporting and supporting ground troops.

Civil aviation

helicopter]] Civil aviation includes both scheduled airline flights and general aviation, a catch-all covering other kinds of private and commercial use. The vast majority of flights flown around the world each day belong to the general aviation category, ranging from recreational balloon flying to civilian flight training to business trips to firefighting to medevac flights to cargo transportation on freight aircraft. Within general aviation, the major distinction is between private flights (where the pilot is not paid for time or expenses) and commercial flights (where the pilot is paid by a customer or employer). Private pilots use aircraft primarily for personal travel, business travel, or recreation. Usually these private pilots own their own aircraft and take out loans from banks or specialized lenders to purchase them. Commercial general aviation pilots use aircraft for a wide range of tasks, such as flight training, pipeline surveying, passenger and freight transport, policing, crop dusting, and medical transport (medevac). Piston-powered propeller aircraft (single-engine or twin-engine) are especially common for both private and commercial general aviation, but even private pilots occasionally own and operate helicopters like the Bell JetRanger or turboprops like the Beechcraft King Air. Business jets are typically flown by commercial pilots, although there is a new generation of small jets arriving soon for private pilots.

External links

History
- [http://www.nasm.si.edu/ Smithsonian Air and Space Museum] - Excellent online collection with a particular focus on history of aircraft and spacecraft
- [http://invention.psychology.msstate.edu/Tale_of_Airplane/taleplane.html Virtual Museum]
- [http://www.centennialofflight.gov/essay/Prehistory/PH-OV.htm Prehistory of Powered Flight]
- [http://www.hq.nasa.gov/office/pao/History/SP-468/contents.htm The Evolution of Modern Aircraft (NASA)]
- [http://www.check-six.com Check-Six] - Information on historic aircraft crashes including the X-15 and Flying Wing
- [http://www.anythingplanes.net Aircraft community ] Information
- [http://www.aircraft-info.net Aircraft-Info.net]
- [http://www.airliners.net/info/ Airliners.net]
- [http://www.HomebuiltAircraft.com HomebuiltAircraft.com]- Information Portal about Homebuilt Aircraft
- [http://www.DefenceTalk.com Airforces ]
- [http://www.challoner.com/aviation/index.html Series of Photo Essays on British Aviation]
- [http://www.usenet-replayer.com/webrings/aviation.html Pictures of Aircraft] published on Usenet
- [http://www.sulman4paf.tk PAF Procedures and Information, Wallpapers, Picture Gallery, Updated News] Patents
- US[http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=821393.WKU.&OS=PN/821393&RS=PN/821393 821393] -- Flying machine -- O. & W. Wright Category:Aircraft Category:Aviation zh-min-nan:Hui-hêng-ki ko:항공기 ms:Pesawat udara ja:航空機 simple:Aircraft

Machine

For other uses of the term Machine, see Machine (disambiguation) Machine (disambiguation)A machine is any mechanical or organic device that transmits or modifies energy to perform or assist in the performance of tasks. It normally requires some energy source ("input") and accomplishes some sort of work. People have used mechanisms and machines to amplify their abilities since before written records were available. Generally these devices decrease the amount of force required to do a given amount of work, alter the direction of the force, or transform one form of motion or energy into another. The mechanical advantage of a simple machine is the ratio between the force it exerts on the load and the input force applied. This does not entirely describe the machine's performance, as force is required to overcome friction as well. The mechanical efficiency of a machine is the ratio of the actual mechanical advantage (AMA) to the ideal mechanical advantage (IMA). Functioning physical machines are always less than 100% efficient. Modern power tools, automated machine tools, and human-operated power machinery complicate the definition of "machine" greatly. Machines used to transform heat or other energy into mechanical energy are known as engines.

Simple machines or mechanical components

- Gear
- Lever
- Pulley
- Wedge
- Spring
- Wheel and Axle
- Bearings
- Belts
- Seals
- Chains

Clock

- Atomic clock
- chronometer
- Pendulum clock
- Quartz clock

Compressors and Pumps

- Archimedes screw
- Eductor-jet pump
- Hydraulic ram
- Tuyau
- Vacuum pump

Internal combustion engine

- Gasoline engine
- Diesel engine
- Four-stroke cycle
- Two-stroke cycle
- Wankel engine

External combustion engine

- Steam engine
- Stirling engine

Linkages

- Pantograph
- Peaucellier-Lipkin

Turbine

- Gas turbine
- Jet engine
- Steam turbine
- Water turbine
- Wind generator, Windmill (Air turbine)

Airfoil

- Sail
- Wing
- Rudder
- Flap
- Damper
- Propeller

Rocket

Computing machines

- Calculator
- Analog computer
- Wind tunnel
- Digital computer
- Turing machine

Automated machines

Biological machines

- Virus, Bacterium
- Cell (biology)
- Plant and animal
- Human being
- The mind - controversially Category:Mechanical engineering Category:Manufacturing Category:Electro mechanical engineering Category:Production and manufacturing ja:機械 simple:Machine

Earth's atmosphere

Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly 78% nitrogen and 21% oxygen, with trace amounts of other gases. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night. The atmosphere has no abrupt cut-off. It slowly becomes thinner and fades away into space. There is no definite boundary between the atmosphere and outer space. Three-quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, persons who travel above an altitude of 50.0 miles (80.5 km) are designated as astronauts. An altitude of 120 km (75 mi or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Karman line, at 100 km (62 mi), is also frequently used as the boundary between atmosphere and space.

Temperature and the atmospheric layers

The temperature of the Earth's atmosphere varies with altitude; the mathematical relationship between temperature and altitude varies between the different atmospheric layers:
- troposphere: From the Greek word tropos meaning to turn or mix. The troposphere is the lowest layer of the atmosphere starting at the surface going up to between 7 km at the poles and 17 km at the equator with some variation due to weather factors. The troposphere has a great deal of vertical mixing due to solar heating at the surface. This heating warms air masses, which then rise to release latent heat as sensible heat that further buoys the air mass. This process continues until all water vapor is removed. In the troposphere, on average, temperature decreases with height due to expansive cooling.
- stratosphere: from that 7–17 km range to about 50 km, temperature increasing with height.
- mesosphere: from about 50 km to the range of 80 km to 85 km, temperature decreasing with height.
- thermosphere: from 80–85 km to 640+ km, temperature increasing with height. The boundaries between these regions are named the tropopause, stratopause, and mesopause. The average temperature of the atmosphere at the surface of earth is 14 °C.

Various atmospheric regions

Atmospheric regions are also named in other ways:
- ionosphere — the region containing ions: approximately the mesosphere and thermosphere up to 550 km.
- exosphere — above the ionosphere, where the atmosphere thins out into space.
- magnetosphere — the region where the Earth's magnetic field interacts with the solar wind from the Sun. It extends for tens of thousands of kilometers, with a long tail away from the Sun.
- ozone layer — or ozonosphere, approximately 10 - 50 km, where stratospheric ozone is found. Note that even within this region, ozone is a minor constituent by volume.
- upper atmosphere — the region of the atmosphere above the mesopause.
- Van Allen radiation belts — regions where particles from the Sun become concentrated.

Pressure

:Barometric Formula: (used for airplane flight) barometric formula :Main article: Atmospheric pressure :Nasa mathematical model: NRLMSISE-00 Atmospheric pressure is a direct result of the weight of the air. This means that air pressure varies with location and time because the amount (and weight) of air above the earth varies with location and time. Atmospheric pressure drops by ~50% at an altitude of about 5 km (equivalently, about 50% of the total atmospheric mass is within the lowest 5 km). The average atmospheric pressure, at sea level, is about 101.3 kilopascals (about 14.7 pounds per square inch).

Thickness of the atmosphere

The atmosphere is present to heights of 1000 km. or more. But at this height it is so thin and at such low pressure that it's almost like it isn't there.
- 57.8% of the atmosphere is below the summit of Mount Everest.
- 72% of the atmosphere is below the common flight height of airplanes, (about 10000 m or 32800 ft).
- 99.99999% of the atmosphere is below the highest X-15 plane flight on August 22, 1963 which reached an altitude of 354,300 ft or 108 km. Therefore, most of the atmosphere is below 100 km (99.9999%) although in the rarified region above this there are auroras, and other atmospheric effects.

Composition

aurora
Source for figures above: [http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html NASA]
Carbon dioxide and methane updated (to 1998) by IPCC TAR table 6.1 [http://www.grida.no/climate/ipcc_tar/wg1/221.htm]

Minor components of air not listed above include:
- The mean molecular mass of air is 28.97 g/mol.

Heterosphere

Below an altitude of about 100 km, the Earth's atmosphere has a more-or-less uniform composition (apart from water vapor) as described above. However, above about 100 km, the Earth's atmosphere begins to have a composition which varies with altitude. This is essentially because, in the absence of mixing, the density of a gas falls off exponentially with increasing altitude, but at a rate which depends on the molecular mass. Thus higher mass constituents, such as oxygen and nitrogen, fall off more quickly than lighter constituents such as helium, molecular hydrogen, and atomic hydrogen. Thus there is a layer, called the heterosphere, in which the earth's atmosphere has varying composition. As the altitude increases, the atmosphere is dominated successively by helium, molecular hydrogen, and atomic hydrogen. The precise altitude of the heterosphere and the layers it contains varies significantly with temperature.[http://www.oma.be/BIRA-IASB/Public/Research/Thermo/Thermotxt.en.html]

Density and mass

The density of air at sea level is about 1.2 kg/m³. Natural variations of the barometric pressure occur at any one altitude as a consequence of weather. This variation is relatively small for inhabited altitudes but much more pronounced in the outer atmosphere and space due to variable solar radiation The atmospheric density decreases as the altitude increases. This variation can be approximately modeled using the barometric formula. More sophisticated models are used by meteorologists and space agencies to predict weather and orbital decay of satellites. The total mass of the atmosphere is about 5.1 × 10¹⁸ kg, or about 0.9 ppm of the Earth's total mass. The above composition percentages are done by volume. Assuming that the gases act like ideal gases, we can add the percentages p multiplied by their molar masses m, to get a total t = sum (p·m). Any element's percent by mass is then p·m/t. When we do this to the above percentages, we get that, by mass, the composition of the atmosphere is 75.523% N₂, 23.133% O₂, 1.288% Ar, 0.053% CO₂, 0.001267% Ne, 0.00029% CH₄, 0.00033% Kr, 0.000724% He, and 0.0000038 % H₂. ppm This graph is from the NRLMSISE-00 atmosphere model, which has as inputs: latitude, longitude, date, time of day, altitude, solar flux, and the earth's magnetic field daily index.

The evolution of the Earth's atmosphere

model The history of the Earth's atmosphere prior to one billion years ago is poorly understood, but the following presents a plausible sequence of events. This remains an active area of research. The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from two notably different previous compositions. The original atmosphere was primarily helium and hydrogen. Heat (from the still-molten crust, and the sun) dissipated this atmosphere. About 3.5 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes which released steam, carbon dioxide, and ammonia. This led to the "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen (though very recent simulations run at the University of Waterloo and University of Colorado in 2005 suggested that it may have had up to 40% hydrogen [http://newsrelease.uwaterloo.ca/news.php?id=4348]). This second atmosphere had approximately 100 times as much gas as the current atmosphere. It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide, kept the Earth from freezing. During the next few billion years, water vapor condensed to form rain and oceans, which began to dissolve carbon dioxide. Approximately 50% of the carbon dioxide would be absorbed into the oceans. One of the earliest types of bacteria were the cyanobacteria. Fossil evidence indicates that these bacteria existed approximately 3.3 billion years ago and were the first oxygen-producing evolving phototropic organisms. They were responsible for the initial conversion of the earth’s atmosphere from an anoxic state to an oxic state (that is, from a state without oxygen to a state with oxygen). Being the first to carry out oxygenic photosynthesis, they were able to convert carbon dioxide into oxygen, playing a major role in oxygenating the atmosphere. Photosynthesizing plants would later evolve and convert more carbon dioxide into oxygen. Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. As oxygen was released, it reacted with ammonia to create nitrogen; in addition, bacteria would also convert ammonia into nitrogen. As more plants appeared, the levels of oxygen increased significantly, while carbon dioxide levels dropped. At first the oxygen combined with various elements (such as iron), but eventually oxygen accumulated in the atmosphere, resulting in mass extinctions and further evolution. With the appearance of an ozone layer (ozone is an allotrope of oxygen) lifeforms were better protected from ultraviolet radiation. This oxygen-nitrogen atmosphere is the "third atmosphere".

References

- [http://www.oma.be/BIRA-IASB/Public/Research/Thermo/Thermotxt.en.html The thermosphere: a part of the heterosphere], by J. Vercheval (viewed 1 Apr 2005)

External links

- [http://nssdc.gsfc.nasa.gov/space/model/models_home.html#atmo NASA atmosphere models]
- [http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html NASA's Earth Fact Sheet]
- [http://atmospheres.agu.org/ American Geophysical Union: Atmospheric Sciences]
- [http://www.srh.noaa.gov/srh/jetstream/atmos/layers.htm Layers of the Atmosphere] Category:Atmospheric sciences Category:Atmosphere Category:Environments ko:대기권 ms:Atmosfera ja:大気

Flight

Flight is the process of flying: either movement through the air by aerodynamically generating lift or aerostatically using buoyancy, or movement beyond earth's atmosphere by spacecraft.

Animal flight

spacecraft The most successful groups of living things that fly are insects, birds, and bats. Each of these groups' wings evolved separately from different structures. Pterosaurs were a group of flying vertebrates contemporaneous with the dinosaurs. Bats are the only mammals capable of true flight. However, there are several gliding mammals which are able to glide from tree to tree using fleshy membranes between their limbs; some can travel hundreds of metres in this way with very little loss of height. Flying tree frogs use greatly enlarged webbed feet for a similar purpose, and there are flying lizards which employ their unusually wide, flattened rib-cages to the same end. Certain snakes also use a flattened rib-cage to fly, 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 metres using the updraft on the leading edges of waves. It is thought that they evolved this ability to help them escape from underwater predators. Most birds fly (see bird flight), with some exceptions. The largest birds, the ostrich and the emu, are earthbound, as were the now-extinct dodos, while the non-flying penguins have adapted their wings for use under water. Most small flightless birds are native to small islands, and lead a lifestyle where flight would confer little advantage. The Peregrine Falcon is the fastest animal in the world; its terminal velocity exceeds 320 km/h (199 mph) while diving down on its prey. Among living animals that fly, the wandering albatross has the greatest wingspan, up to 3.5 metres (11.5 feet), and the trumpeter swan perhaps the greatest weight, at 17 kilograms (38 pounds). Among the many species of insects, some fly and others do not (See insect flight).

In fiction

- Dumbo, the Disney-created elephant, employs his comically oversized ears as wings for flight.
- Many dragons are depicted with wings capable of flight.
- Superman is a well known superhero in comic books, cartoons, and films; unaided flight is among the various super powers he is portrayed to obtain from the yellow rays of earth's sun. Most flight-capable fictional comic book superheroes are said to fly by sheer will rather than by telekinetically levitating themselves. Jean Grey of the X-men is an exception who uses telekinesis to levitate slightly above ground. telekinesis

Mechanical flight

Flying machines are aircraft, including aeroplanes, helicopters, airships and balloons, and spacecraft. In the case of an aeroplane flight involves
- Taxiing
- Take off
- Climb
- Cruise
- Descent
- Landing See aviation history for the history of mechanical flight.

Autogyro

An autogyro (only an autogiro™ when produced by the Cierva Autogiro Company or one of its licensees (see below), sometimes called a gyroplane, gyrocopter™, or rotaplane) is an aircraft supported in flight by an unpowered rotor. Though the autogyro resembles a helicopter, it is driven in flight by an engine-powered propeller similar to that of an airplane. Often mistakenly characterized as a hybrid between an airplane and helicopter, the autogyro is a distinct type of aircraft that made its first successful flight on 17 January 1923 at Cuatro Vientos Airfield in Madrid, Spain, predating the first successful helicopter by 13 years. All helicopters utilize rotor technology first developed for the autogiro: the helicopter owes its existence to the brilliant work conducted by Juan de la Cierva and his associates. helicopter

General characteristics

Autogyros can take off and land in significantly smaller areas compared to airplanes, and depending on the model, can operate from helipads. When fitted with a jump start feature, an autogyro can takeoff from a standing start into forward flight, accelerate in ground effect, then commence a climb; hovering capability is not available however since the rotor is always declutched before the autogyro leaves the ground. If rotor collective pitch control is provided, an autogyro can execute a collective flare; otherwise landings are always made with a cyclic flare. Certificated autogyros flown by trained and qualified pilots are notably safe. As intended by la Cierva, the rotor always turns regardless of the airspeed of the aircraft, though as airspeed decreases rotor rpm reduces to a minimum value at zero airspeed. Reduction of engine power increases the descent rate, though the autogyro remains fully stable and controllable. Directional control, provided by a rudder, can become nonexistent at low airspeed and low propeller thrust. For example, the Air and Space 18A gyroplane rudder rapidly loses effectiveness below 50mph airspeed when the engine is throttled. Most autogyros are neither efficient nor very fast (for one exception see Wing Commander Ken Wallis, below - around 120mph on 60bhp). Fixed-wing aircraft are faster and use less fuel over the same distance, helicopters generally require more power (and hence fuel) than a fixed wing aircraft (or autogyro) for the same top speed/load etc. It must be noted, however, that large scale autogyro development ceased prior to WW2 and with few exceptions has not benefitted from rotary wing developments applied to helicopters. Gyroplanes are typically more maneuverable than fixed-wing aircraft, but do not hover as does a helicopter. When helicopters became practical, autogyros were neglected for nearly 30 years. They were however at one time used extensively by major newspapers and by the US Postal Service for mail service between the Camden, NJ airport and the top of the post office building in downtown Philadelphia, PA. As the infrastructure for service, repair, training and building increases the number of autogyro users may increase. Autogyros can be of tractor configuration with the engine(s) and propeller(s) at the front of the fuselage, or pusher configuration with the engine(s) and propeller(s) at the rear of the fuselage. Early autogyros were fitted with fixed rotor hubs, small fixed-wings and airplane-type control surfaces. At the low airspeed at which autogyros can easily operate, the airplane-type control surfaces became ineffective and could readily lead to loss of control, particularly during landing. The direct control rotor hub, which could be tilted in any direction by the pilot, was first developed on the Cierva C.19 Mk.V and saw production on the Cierva C.30 series of 1934. Rotor drives initially took the form of a rope wrapped around the rotor axle and then pulled by a team of men to accelerate the rotor prior to a long taxi to bring the rotor up to speed sufficient for takeoff. The next innovation was a fully deflectable horizontal stabilizer that directed propeller slipstream into the rotor. Cierva license, Pitcairn-Cierva Autogiro Company of Willow Grove, PA, finally solved the problem with a light mechanical transmission driven by the engine. The Groen Brothers Hawk 4 of the late 1992 is advertised as possessing Ultra-Short Take-Off and Landing (USTOL) capabilty, enabling the aircraft to take off and land within a very short distance (25 feet). This is merely a new name for performance autogyros have always possessed.

History

Juan de la Cierva, a Spanish engineer and aeronautical enthusiast, invented the first successful rotorcraft, which he named autogiro in 1923. His craft used a tractor-mounted forward propeller and engine, a rotor mounted on a mast, and a horizontal and vertical stabilizer. His first three designs, C.1, C.2, and C.3, were unstable due to aerodynamic and structural deficiencies in their rotors. His fourth design, the C.4, fitted with flapping hinges to attach each rotor blade to the hub, made the first successful flight of a rotary-wing aircraft, piloted by Alejandro Gomez Spencer, on 17 January 1923. The C.4 was fitted with conventional airplane ailerons, elevators and rudder for control. During a later test flight, the engine failed shortly after takeoff and the aircraft descended slowly and steeply to a safe landing, validating la Cierva's efforts to produce an aircraft that could be flown safely at low airspeeds. Juan de la Cierva This success eventually became well known and after further limited Autogiro development in Spain, la Cierva accepted an offer from Scottish industrialist James G. Weir to establish the Cierva Autogiro Company in England following a 20 October 1925 demonstration to the British Air Ministry at Farnborough. Test pilot for these flights was Frank T. Courtney. From this point on, Britain became the world center of rotary-wing aircraft development. A crash due to blade root failure in February 1927 led to an improvement in rotor hub design. Adjacent the flapping hinge a drag hinge was incorporated to allow each blade to slightly oscillate horizontally and relieve inplane stresses generated as a byproduct of flapping motion. Development work on means to accelerate the rotor prior to takeoff was also undertaken. Efforts with the C.11 in Spain showed that development of a light and efficient mechanical rotor transmission was not a trivial undertaking and led to the adoption of the intermediate expedient of inclining the horizontal stabilizer to redirect the propeller slipstream into the rotor while on the ground. This feature was later introduced on the production C.19 series of 1929. Further Autogiro development led to the Cierva C.8 L.IV which on 18 September 1928 made the first rotary-wing aircraft crossing of the English Channel followed by an extensive tour of Europe. US industrialist Harold F. Pitcairn had in 1925 visited la Cierva in Spain upon learning of the successful flights of the Autogiro; in 1928 he visited la Cierva in England after taking a C.8 L.IV test flight piloted by Arthur H.C.A. Rawson and being particularly impressed with the Autogiro's safe vertical descent capability, purchased a C.8 L.IV with a Wright Whirlwind engine. Arriving in the United States on 11 December 1928 accompanied by Rawson, this Autogiro was redesignated C.8W. (Further editing of the following to continue) The Cierva "Autodynamic" rotor used drag hinges with offset axes to perform this to good effect with great simplicity, but the Pitcairn collective pitch control advanced the "jump" ability. The C-19 technology was licensed to a number of manufacturers, including Harold Pitcairn in the U.S. (in 1928) and Focke-Achgelis of Germany. In 1931 Amelia Earhart flew a Pitcairn PCA-2 to a then world altitude record of 18,415 feet (5613 m). In World War II, Germany pioneered a very small gyroglider "rotor-kite", the Focke-Achgelis Fa 330 "Bachstelze" (Water-wagtail), towed by submarines to provide aerial surveillance. It's reported that German gyro pilots were often forgotten in the heat of battle when the submarine dived suddenly. The Japanese also developed the Kayaba Ka-1 Autogyro for reconnaissance, artillery-spotting, and anti-submarine uses. The autogyro was resurrected post WW2 when Dr. Igor Bensen (a doctor of Divinity) saw a captured German U-Boat's gyroglider, and was fascinated by its characteristics. At work he was tasked with the analysis of the British "Rotachute" gyro glider designed by expatriate Austrian Raoul Hafner. This led him to adapt the design for his own purposes and eventually market the B-7. Post WW2 autogyros, such as the Bensen B-8M gyrocopter, generally use a pusher configuration for simplicity and to increase visibility for the pilot. For greater simplicity, they generally lack both variable-pitch rotors and powered rotors. It must be noted that Bensen autogyros and its derivatives have established an abysmal safety record due to their deficient stability and control characteristics greatly worsened by use of a teetering rotor, and their marketing as a build it yourself and teach yourself how to fly it aircraft. Three FAA-certified designs, Umbaugh U-18/Air and Space 18A of 1965, Avian 2-180 of 1967, and McCulloch J-2 or 1972 have for various reasons been commercial failures.

Bensen's design

The Bensen Gyrocopter™, the protoype of many post WW2 gyroplanes, actually consists of three versions, the B-6, B-7 and B-8. All three were designed in both unpowered and powered forms. The basic design is a simple frame of square aluminum or galvanized steel tubing, reinforced with triangles of lighter tubing. It is arranged so that the stress falls on the tubes, or special fittings, not the bolts. All welds or soldered structural joints should be inspected. The rotor is on the top of the vertical mast. The outlying fixed wheels are mounted on an axle (of tubing). The front-to-back keel (more tubing) mounts the forward wheel (which casters), seat, other tubes, engine and a vertical stabilizer. Some versions mount seaplane-style floats and successfully land and take off from water. It is common for the vertical stabilizer to drag on the ground unless it is cut away. This is also why many frames have a small wheel mounted on the back end of the keel. Many light gyroplane rotors are made from aluminum, though GRP-based composite blades (Sport Copter, Averso, Revolution, RAF eg) and GRP-skinned blades are increasing in number. Even aircraft-quality birch was specified in early Bensen designs, and a wood/steel composite is still used in the world speed record holding Wallis.

Flight Controls

There are only three flight controls: a control stick, rudder pedals and a throttle. Modern designs typically use a between-legs control stick instead, and the precession is handled by a mechanical linkage so that left and right stick motions are more intuitive than Bensen's simple design. Another control is a simple set of rudder pedals that move the hinged back half of the vertical stabilizer, similar to a rudder on a fixed wing aircraft. This lets the pilot keep the craft lined up in the desired direction of motion. The stabilizer is mounted behind the pusher propeller, so one can steer the craft on the ground and during takeoff. Some builders use a pushrod between the rudder bar and stabilizer. Others use cables. Some simple autogyros, including Bensen's G-6, do not use controllable-vertical stabilizers at all. They are fixed - this works for towed gyro gliders, but not for powered gyros. The throttle and choke are usually levers mounted where convenient- often under the seat. The rotor generates more lift on the leading side and less on the lagging side, and this causes the rotor to tilt backwards with forward airspeed (helicopters tilt their rotor in the opposite way as they use their rotor to drag the vehicle through the air, whereas an autogyros's blades are unpowered). This increases drag and has a lot to do with the relatively low top speed that Autogyros can reach.

Flight characteristics

Autogyros are often regarded by fixed-wing aircraft pilots as "dangerously unstable", which is certainly true when its pilot is, as is so often the case, self-taught with no professional flight instruction received whatsoever. Piloted properly, a certificated autogyro is significantly safer than any other type of aircraft because it cannot stall, since the rotor of a autogyro is always spinning. If translational airspeed becomes zero, the autogyro will descend vertically to the ground, rotor still spinning. Though safe for the pilot and passengers, landing from a vertical descent usually results in damage to the autogyro. One weakness in certain types of autogyro is pitch instability (pitch is the tilting up or down of the craft as viewed from the front or the back). Pitch instability can be a problem because autogyros lose rotor control authority in negative-G forces (positive-G forces push people into their seats; negative-G forces make people float out of them, such as driving over a hump back bridge at high speed in an automobile). Negative-G forces "unload the rotor" and rotor control authority is lost. A flying autogyro hangs from the rotor much like an object hung from a string. As long as the plane is hanging from the rotor, stability is maintained. The instant zero or negative-Gs are introduced, rotor speed begins to decay and the forces stabilizing the plane are lost. Negative-Gs can be caused by Pilot-Induced Oscillation, or PIO. PIO happens when a pilot adjusts his pitch too much too quickly, then makes a countering control input to bring the pitch back. The countering input often overcompensates, and the autogyro begins to buck like a bronco. You can see a similar effect when some learner-drivers are doing kangaroo-hops in a car with a stick shift and clutch. This is most likely at higher engine throttle settings. If the pilot continues to fight the plane, the rotor (which is flexible) can slow down due to the lack of positive G force, and can flop down and strike the spinning propeller, which destroys both and sends the autogyro into an uncontrolled fall. The way to avoid this during an incipient PIO is to apply gentle back pressure on the stick (to raise the nose in pitch) and cut engine power. Note that this is the exact opposite of what fixed-wing pilots are trained to do when in trouble, which has led to some unfortunate accidents and the autogyro's undeserved reputation for being "dangerous." Another danger is "bunting over" or a Power Push-Over (PPO). An autogyro's vertical airspeed (climb or sink rate) is directly coupled to airspeed. Increase forward airspeed, increase rate of climb. In order to maintain level flight at high engine throttle settings, the pilot must tilt the rotor forward to prevent climbing and maintain level flight. The rotor thus becomes more nearly horizontal, and the control stick becomes more sensitive. Too much forward stick, and the autogyro's rotor can aim down towards the ground. When this happens, negative-Gs occur, rotor speed drops too low to provide lift, and a high-thrustline autogyro is then pitched forward by the propeller thrust and tumbles end-over-end in a somersault. It is virtually impossible to regain control after a full PPO. Two factors can lead to pitch instability: no or too small horizontal stabilizers (h-stabs) on too short a tail and high thrustline propeller placement which destabilises the force diagram. A large h-stab, ideally in the prop wash (where the propeller blows on it) will reduce the tendency of an autogyro to bunt over as a result of improper control input by damping the control response. If the propeller thrustline in an autogyro is high -- meaning the axis of propeller power is above the center of gravity for the aircraft -- the autogyro tends to pitch forward under sudden power application (see PPOs above, as for why this is Bad). (Unfortunately, Bensen-type autogyros have a notably high thrustline.) If the thrustline is low, the autogyro tends to pitch up under sudden power application, which is harmless. It's difficult to have a low thrustline without a really tall autogyro (such as a "Dominator" style) however, so most autogyro designs simply try to get the thrustline as low as possible though still being slightly above the center of gravity. In spite of these dangers, most autogyros are designed to reduce them. Also, the majority of autogyro pilot training involves avoidance of PIO and PPOs. Autogyro rotors usually feature a teeter-hinge in the middle. Picture a autogyro or helicopter from above, rotor spinning clockwise. If the aircraft is flying forward, the rotor tips on the left are traveling faster than the aircraft, while those on the right are actually going backwards relative to the craft. If the rotor blades were fixed, this would produce uneven lift -- more lift on the left side, since those blades are traveling faster. The teeter hinge on each blade lets it "flap" up and down. As the blade swings on the left, the increased speed makes it flap up with a greater angle of attack to the relative wind. This increases drag and reduces lift. As it swings to the right, it's now going slower, relative to forward speed. This reduced drag lets it flap down and get a better bite into the air, increasing lift. Pitch is controlled by a conventional joystick coupled to the rotor. Pulling back on the stick tilts the rotor back, increasing lift and decreasing forward airspeed. Pushing forward on the stick decreases lift and increases airspeed, as long as it is not pushed much beyond horizontal (see PPO above). The plane's direction is controlled by rudder pedals.

Records and Application

As of 2002, Wing Commander Ken Wallis, an enthusiast who has built several gyroplanes, holds or has held most of the type's record performances. These include the speed record of 111.7mph (186km/h), and the straight-line distance record of 543.27 miles (905km). The record picture is continually changing, and on 16 November 2002, Ken Wallis increased the speed record to 207.7 km/h - and simultaneously set another world record as the oldest pilot to set a world record! See: [http://records.fai.org/pilot.asp?from=rotorcraft&id=335] Ken Wallis also built and flew one of the most famous autogyros - "Little Nellie" - in the James Bond movie "You Only Live Twice".
- Hours flown :Autogyros are often used to herd range animals. An autogyro 'cowboy' holds the world record for total hours in the air each week. The Bensen design has also been used by hobbyists, sight-seers and scientists (for game counting).
- Speed :The CarterCopter fixed wing/autogyro hybrid has been unofficially flown in tests at speeds above 170 mph. The claimed theoretical top speed for this general design is in excess of 450 mph. :In the late 1950s, the Fairey Rotodyne, another hybrid was capable of 213 mph. Andy Keech made a TransContinental flight from Kitty Hawk, N.C. to San Diego, Ca. in October 2003 and set 3 World Records. The 3 records are for 'speed over a recognised course', and are verified by tower personnel or by Official Observers of the U.S. National Aeronautic Association:
- Sub-class : E-3a (Autogyros : take-off weight less than 500 kg) :Category : General :Group 1 : piston engine
- Speed over a recognised course : 16.45 km/h, :::Date of flight: 12 October 2003 :::Pilot: Andrew C. KEECH (USA) :::Course/place: Kitty Hawk, NC (USA) - San Diego, CA (USA)
- Speed over a recognised course : 31.89 km/h :::Date of flight: 22 October 2003 :::Pilot: Andrew C. KEECH (USA) :::Course/place: San Diego, CA (USA) - Kitty Hawk, NC (USA)
- Speed over a recognised course, round trip : 16.42 km/h :::Date of flight: 22 October 2003 :::Pilot: Andrew C. KEECH (USA) :::Course/place: Kitty Hawk, NC (USA) - San Diego, CA (USA) and return

Kits

Many autogyros are assembled from kits. Kits with all parts, ready to assemble, are listed for US$19,550 as of 18th July 2002. This is extremely inexpensive for an aircraft. This includes an engine, the major expense. It can be reduced. Some people are clever at scrounging materials. However, scrounging increases one's construction time and program risk. Buying both the engine and rotor hub is recommended by most vendors. Some people who actually completed an autogyro have said that it took them about a year, working in their spare time. Careful estimates place most build times at 100 to 200 hours. Kit vendors often say that since it has relatively few parts, hobbyists can assemble it more rapidly and correctly than most fixed-wing kit aircraft. Kit vendors recommend working on it every day for an hour or two.

Warnings

Most vendors recommend that a new pilot have at least ten hours of instruction by a rated instructor in small fixed-wing aircraft, followed by at least two hours of instruction in a dual-place autogyro with an experienced instructor. An autogyro is more similar to a fixed-wing aircraft than to a helicopter. One must be able to land safely and reliably before attempting to fly any aircraft alone. Autogyros are relatively safe, but not foolproof. There were 19 fatal autogyro accidents reported to the FAA between 1996 and 2001. Autogyros are aircraft. Do not neglect safety precautions: training, instrumentation, flight rules, preflight checklists and periodic inspections and maintenance. In the United States private, recreational, and commercial pilot licenses with rotorcraft category and gyroplane class rating are issued, or the rating is added to an existing license for other aircraft; holders of sport pilot licenses can also qualify to fly autogyros. Requirements include completing required training times, passing written exams, and successfully doing oral and practical tests. Sport pilot license in-flight tests can be conducted in single-seat aircraft, but a "single place only" limitation is placed on the certificate in such cases. "Learning to fly the rotor" is a vital ingredient for safe flight in an autogyro - models and rotary kites can help the learning process, and towed gyro-gliders and boom-trainers are ideal tools for this as well as being cheap to build and fly.

Fixed-wing aircraft

Fixed-wing aircraft is a term used to refer to what are more commonly known as airplanes in North American English and aeroplanes in Commonwealth English. An airplane is a heavier than air aircraft where any movement of the wings in relation to the aircraft is not used to generate lift. All aircraft wings flex and some aircraft have wings that can tilt, sweep back or fold but if none of these movements are used to generate lift the wing is considered to be a "fixed-wing". Fixed-wing aircraft include a large range of craft designed for many purposes from small trainers and recreational airplanes to large airliners and military cargo aircraft. Some aircraft use fixed wings to provide lift only part of the time and may or may not be referred to as fixed-wing. Airplanes have no ability to drive on the ground for extended time periods. cargo aircraft, an example of a fixed-wing aircraft]] The term also embraces a minority of aircraft with folding wings that are intended to fold when on the ground. This is usually in order to to ease stowage or facilitate transport on, for example, a vehicle trailer or the powered lift connecting the hangar deck of an aircraft carrier to its flight deck. It also embraces an even smaller number of aircraft, such as the General Dynamics F-111 Aardvark, Grumman F-14 Tomcat and the Panavia Tornado, which can vary the sweep angle of their wings during flight. In the early days of their development, these were termed "variable geometry" aircraft. When the wings of these aircraft are fully swept, usually for high speed cruise, the trailing edges of their wings abut the leading edges of their tailplanes, giving an impression of a single delta wing if viewed from above or below. There are also rare examples of aircraft which can vary the angle of incidence of their wings in flight, such the F-8 Crusader, which are also considered to be "fixed-wing". Two characteristics common to all the airplanes are the necessity of constant air flow over the wings for lifting of the aircraft, and an open area free of obstacles where they can, with sufficient space, take off or land. The majority of airplanes, however, also need an airport with enough infrastructure to receive adequate maintenance, restocking, refueling and for the loading and unloading of crew, cargo and/or passengers, when these are present in sufficient amounts. While the vast majority of airplanes land and take off on land, some are capable of take off and landing on ice, snow and calm water. The airplane is currently the fastest method of civil and military transport on the planet. Commercial jet airplanes can reach up to 875 km/h, and cover one fourth of the terrestrial sphere in a matter of hours, and single-engine airplanes are easily capable of reaching 175 km/h or more at cruise speed. Supersonic airplanes, currently only military, research and a few private aircraft, can reach speeds that sometime surpass the speed of the sound.

Conventional airplanes

Conventional airplanes from small planes such as the Bumble Bee II and Cessna 140, to a gigantic Antonov 225, consist of a longitudinal fuselage, one or more front wings to provide the majority of lift, a tailplane for stability and a one or more vertical surfaces at the tail for stability.

Fixed parts

- Each wing is a single wing structure attached to or integrated into the fuselage of the aircraft. Sometimes the half of a wing on either side of the fuselage is referred to as a wing, e.g. left wing and right wing. Most airplanes are monoplanes having one wing structure for providing lift. Biplanes (two wings) or triplanes (three wing) have been popular in the past and some are still made for special purposes like aerobatics. The wing is also where it generally stores the fuel necessary for the engine(s) of the aircraft.
- The fuselage (or main body): in smaller aircraft, the necessary fuel for the engine(s) of the aircraft is stored in the main body.
- An engine (or engines): Also known as powerplants, engines serve to propel the aircraft on the ground and the air. Airplanes use a wide variety of engines, including turbine, reciprocating, and radial engines. The engines are usually located under or on the wings or attached to the fuselage. A few aircraft have engines attached to the vertical or horizontal stabilizer.
- The tailplane is a small wing that provides positive or negative lift to stabilize the aircraft in flight. Most often it is configured to provide negative lift. It may be a fixed horizontal stabilizer with a movable elevator or a stabilator that rotates on a shaft to change the angle of incidence.
- The vertical stabilizer is a small vertical wing that is usually attached to the rear of the fuselage but some aircraft have two vertical stabilizers attached to the horizontal stabilizer or boom structures. A rudder is attached to the vertical stabilizer.

Mobile parts

- Ailerons are located in the wing of the aircraft. They always act at the same time, but in inverse directions, so that the airplane can be turned along its longitudinal axis. This movement is called roll. Because roll changes the direction of lift of the wings it is the primary method of changing the direction of travel.
- Rudder is located on the vertical stabilizer and controls movement around the vertical axis called yaw.
- The elevators are located on the horizontal stabilizer to control the rotation around the lateral axis called pitch. The elevator and horizontal stabilizer may be combined into a stabilator.
- The landing gear that allows the airplane to take off and land. They retract during flight to reduce drag. (these are often fixed parts on smaller aircraft) Some aircraft are equipped with special landing gear, such as pontoons or skis to allow them to land on various surfaces.
- The Flaps which change the profile of the wing of the airplane, helping in the lift and the control of the speed of the aircraft in air, both in operations of low speed - especially important in the operations of landing and take-off.
- In the case of a propeller airplane: the propeller(s) Other common parts of aircraft include trim tabs, air brakes, spoilers, winglets and canards. Unconventional aircraft have been built in a variety of forms. For example: lifting body, canard, V-tail and flying wing.

Flight (lift)

An airplane flies due to the aerodynamic reactions that happen when air passes at high speed over the wing. When air passes over the wing, it is forced to pass underneath or over top of it. The length of the wing is larger on the top portion, so according to laws of aerodynamics, the air flow becomes faster, to compensate the larger distance to be travelled. This significantly diminishes the pressure of air on the wing; the difference of pressure under and over the wings creates the necessary lift for flight. Also they obey, on a smaller scale, the laws of inertia as formulated by Isaac Newton: a force acting in one given direction tends to be balanced by another force with same intensity, and of opposing direction. As the wings of the airplanes tend to make curve for low, a air flow is created in this direction and, as consequence, the airplane receives a push from same force in the opposing direction. Airplanes need a high speed so that the difference of the pressure of air under and over the wing is enough for lifting the aircraft. To reach these high speeds, an airplane needs to cover a certain distance on the ground, before reaching the speed needed for take-off. For larger and heavier aircraft it will generally require a longer runway to reach the necessary speed for the take-off, given the larger amount of energy needed.

Types of fixed-wing aircraft

Propeller aircraft

Isaac Newton Propeller airplanes make use of combustion engines, that in turn, turn a propeller, that creates the necessary force for the movement of the aircraft. They are relatively quiet, but they fly at lower speeds, and have lower load capacity compared to similar sized jet powered aircraft. However, they are significantly cheaper and much more economic than jets, and is the generally the best option for people who need to use an airplane in a smaller company to transport a few passengers and/or small amounts of cargo. They are also the aircraft of choice for pilots who wish to own their own aircraft.

Jet aircraft

combustion Jet airplanes make use of turbines for the creation of the necessary force for the movement of the aircraft. Jet airplanes generally have turbine engines that are much more powerful than their propeller driven cousins. As consequence, they have greater weight capacity and faster flight speeds than propeller driven aircraft. One drawback, however is the great amount of sound created for a turbine; this makes jet airplanes a source of noise pollution. They also require much larger amounts of maintenance compared to their propeller driven cousins. Huge widebodies ("wide bodies"), such as the Airbus A340 and Boeing 777, can carry hundreds of passengers and several tons of cargo, and are able to travel for distances of up to 13 thousand kilometers - a little more than one quarter of the circumference of the Earth. Jet airplanes possess high cruising speeds (700 to 900 km/h) and relatively high speeds for take-off and landing (150 to 250 km/h). Due to the high speeds needed for takeoff and landing, the jet airplane makes great use of flaps for the control of lift and speed, and has engine reversers (to direct the airflow frontward) on most engines for slowing down the aircraft upon landing to supplement the brakes.

Super sonic aircraft

Earth Super sonic airplanes, such as military fighters and bombers, the Concorde and others, make use of special turbines (often utilizing afterburners), that generate the huge amounts of power for flight faster than the speed of the sound. Moreover, the design of the supersonic airplane has substantial differences from the design of sub-sonic airplanes, in order to make the transition to supersonic flight smoother and to make supersonic flight more efficient. Flight at super-sonic speed creates much more sound pollution than flight at sub-sonic speeds, due to the phenomena of sonic booms. This limits super-sonic flights to areas of minimal population density or open ocean. When they approach an area of heavier population density, super-sonic airplanes are obliged to fly at sub-sonic speed. Due to the high costs, limited areas of use and low demand there are no longer any super-sonic aircraft in use by any major airline, and the last Concorde flight was November 26, 2003. It appears that supersonic aircraft will remain in use almost exclusively by militaries around the world for the foreseeable future.

Rocket-powered aircraft

sonic booms sonic booms Experimental rocket powered aircraft were developed by the Germans as early as World War II, although they were never mass produced by any power during that war. The first fixed wing aircraft to break the sound barrier was the rocket powered Bell X-1. The later North American X-15 was another important rocket plane, that broke many speed and altitude records and laid much of the groundwork for later aircraft and spacecraft design. Rocket airplanes are not in common usage today, although rocket-assisted takeoffs are somewhat common for military aircraft. SpaceShipOne is the most famous current rocket airplane that is the testbed for developing a commercial sub-orbital passenger service.

Ramjet aircraft

SpaceShipOne SpaceShipOne Ramjet (and the Scramjet variant) aircraft are mostly in the experimental stage. The D-21 Tagboard was an unmanned Mach 3+ reconnaissance drone that was put into production in 1969 for spying, but due to the poor level of success and the development of better spy satellites, it was cancelled in 1971. The SR-71's Pratt & Whitney J58 engines act as ramjets at high-speeds (Mach 3.2). The last SR-71 flight was in October 1999. The Boeing X-43 is an experimental scramjet with a world speed record for a jet-powered aircraft - Mach 9.6, or nearly 7,000 mph. The X-43A set the record on Nov. 16, 2004.

History

The dream of flight goes back, for Man, to the days of pre-history. Many legends, beliefs and myths of antiquity involve flight, such as the legend of Icarus. Leonardo of the Vinci, among others visionary inventors, drew an airplane, in the 15th century. With the first flight made by man (Francois Pilatre de Rozier and Francois d'Arlandes) in an aircraft lighter than air, a balloon, the biggest challenge became to create other craft, capable of controlled flight. Years of research by many eager people who dreamed of flight produced very slow, but continuous, progress. On August 28 of 1883, John J. Montgomery became the first person to make a controlled flight in a glider. Other aviators who had made similar flights at that time were Otto Lilienthal, Percy Pilcher and Octave Chanute. Sir George Cayley, the inventor of the science of aerodynamics, was building and flying models of fixed wing aircraft as early as 1803, and he built a successful passenger-carrying glider in 1853, but it is known the first practical self-powered aeroplanes were designed and constructed by Clément Ader. On October 9, 1890, Ader attempted to fly the Éole, which succeeded in taking off and flying a distance of approximately 50 meters before witnesses. In August 1892 the Avion II flew for a distance of 200 metres, and on October 14, 1897, Avion III flew a distance of more than 300 metres. On August 28, 1903 in Hanover, the German Karl Jatho made his first flight. The Wright Brothers made their first successful test flights in December 17, 1903 and by 1904 Flyer III was capable of fully-controllable stable flight for substantial periods. Strictly, its wings were not completely fixed, as it depended for stability on a flexing mechanism named wing warping. This was soon superseded by the competitive development of ailerons, attached to an otherwise rigid wing. In some countries today, particularly Brazil, Santos-Dumont is considered to be the "Father of Aviation", because of the official and of public character of the 14-bis flight and/or technical points such as the plane's integral landing gear and its ability to take off on open ground. The 14 Bis, was the first to take off, fly, and land without the use of catapults, high winds, or other external assistance. Most Brazilians, and many other admirers of Alberto Santos-Dumont consider him, instead of the Wright Brothers, to be the true inventor of the airplane, although the very concept of the invention of the first flying machine has substantial ambiguity. Wars in Europe, in particular, the First World War, served as initial tests for the use of the airplane as a weapon. First seen by generals and commanders as a "toy", the airplane proved to be a machine of war capable of causing serious casualties to enemy lines. In the first war, great aces appeared, of which the greatest was the German Red Baron. On the side of the allies, the ace with the biggest amount of downed aircraft was René Fonck, of France. After the First World War, airplanes gained innumerable technological advances. Charles Lindbergh became the first person to cross the Atlantic Ocean in solo flight nonstop, on May 20, 1927. The first commercial flights took place between the United States and Canada, in 1919. The turbine or the jet engine was in development in the 1930's, military jet airplanes began operating in the 1940's. Airplanes played a primary role in the Second World War, having a presence, either major or minor, in all the known major battles of the war, especially in the Attack on Pearl Harbor, the battles of the Pacific and D-Day. They were also an essential part of several of the new military strategies of the time period, such as the German Blitzkrieg or the American and Japanese Aircraft carriers. In October of 1947, Chuck Yeager, in the Bell X-1, was the first person to exceed the speed of sound. The Boeing X-43 is an experimental scramjet with a world speed record for a jet-powered aircraft - Mach 9.6, or nearly 7,000 mph. Airplanes, in a civil military role, continued to feed and supply Berlin in 1948, when access to railroads and roads to the city, completely surrounded by Eastern Germany, were blocked, by order of the Soviet Union. The first commercial jet, the Havilland Comet, was introduced in 1952, and the first successful commercial jet, the Boeing 707, is still in use 50 years later. Boeing 707 would develop into the later in Boeing 737. The Boeing 727 was another widely used passenger airplane, and the Boeing 747, was the biggest commercial airplane in the world up to 2005, when it was surpassed by the Airbus A380.

Designing and constructing an airplane

Small airplanes, for one or two passengers, can be designed and constructed at home, by aviators who possess sufficient knowledge in the areas of engineering, physics and aerodynamics. Other aviators with less knowledge make their airplanes using complete kits, with pre-manufactured parts, and assemble the aircraft themselves. Airplanes produced in this way, however, are a small minority. Given its complexity, most airplanes are constructed by companies with the objective of producing them in quantity for customers. The design and of planning process, including safety tests can last up to 4 years, for small turboprops, and up to 12 years in airplanes with the capacity of the A380. In this process, the objectives and design specifications of the aircraft are established. In the beginning the construction company uses a great number of drawings and equations, simulations, wind tunnel tests and experience to predict the behavior of the aircraft. Generally computers are used by companies to draw, plan and do initial simulations of the airplane. Small models and mockups of all or certain parts of the airplane are, then, tested in wind tunnels, to verify the aerodynamics of the aircraft. When the airplane has made it through this process, the company constructs a limited number of these airplanes, for testing as a whole in the ground. Special attention is given to the engines (or turbines) and to the wings. After passing the above-designated process, the construction company has a governing agency of aviation make a first flight. When the behavior of the aircraft does not present suspicion of imperfections, the flight-tests continue until the airplane has fulfilled all the necessary requirements. Then, the governing public agency of aviation of the country authorizes the company to begin production en masse of the aircraft. In the United States, this agency is Federal Aviation Administration (FAA), and in the European Union, Joint Aviation Authorities (JAA). These two are the agency of regulation of most important aircraft of the world. In Canada, the prescribed the public agency in charge and authorizing the mass production of aircraft is the Department of Transport. In the case of the international trade of airplanes, a license of the public agency of aviation or transports of the country where the aircraft is also to be used is necessary. For example, aircraft from Airbus need to be certified by the FAA to be flown in the United States and vice versa, aircraft of Boeing need to be approved by the JAA to be flown in the European Union.

Industrialized production

There are relatively few companies that produce airplanes on a large scale. However, the production of an airplane for one company is a process that actually involves dozens, or even hundreds, of other companies and plants, that produce the parts that go into the aircraft. For example, one company can be responsible for the production of the landing gear, while another one is responsible for the radar. The production of such parts is not limited to the same city or country; in the case of large aircraft manufacturing companies, such parts can come from all over of the world. After being manufactured, the parts are sent to the main plant of the aircraft company, where the production line is located. The different parts are assembled with the others, eventually, producing the aircraft. In the case of large airplanes, lines of production are dedicated to the assembly of certain parts of the aircraft can exist, especially the wings and the fuselage. When complete, an airplane goes through a set of rigorous inspection, to search for imperfections and defects, and after being approved by the inspectors, the airplane is tested by a pilot, in a flight test, in order to assure that the controls of the aircraft are in working properly. With this final test, the airplane is ready to receive the "final touchups" (internal configuration, painting, etc), and is then ready to be sent to the customer.

Safety

Statistics show that the risk of an air accident is very small. You are more likely to have an accident going to the airport in your car than have one during your flight. Why then do many people have such a fear of flying? Perhaps it is because the risk of death in an aircraft accident, if you are in one, is extremely high. Furthermore, car crashes rarely feature outside local news whereas air crashes are reported internationally, making the risk seem greater. The majority of aircraft accidents occur due to human error, that is, an error of the pilot(s) or control tower. After human error, mechanical failure is the biggest cause of air accidents, which sometimes also can involve a human component (ie: negligence of the airline in carrying out proper maintenance). Adverse weather is the third largest cause of accidents. Icing of wings, downbursts and low visibility are often major contributors to weather related crashes.

North American English

North American English is a collective term to describe the varieties of the English language that are spoken in the United States and Canada. Because of the considerable similarities in pronunciation, vocabulary and accent between American English and Canadian English, the two spoken languages are sometimes grouped together under a single category, as distinguished from the varieties of English that are spoken in the United Kingdom, Australia, or New Zealand and the Hiberno-English used in Ireland. Despite the Canadian spellings being closer to Commonwealth English (which is spoken in e.g. Australia, the British Isles and India) the collective term "North American English" is sometimes also used to designate the written language of the two countries. Many terms in North American English are used almost exclusively in the two countries alone, such as "diaper", "gasoline", and "elevator". Though many English speakers from outside North America regard these words as distinctive "Americanisms", they are just as pervasive in Canada. Differences between American and Canadian English are somewhat more apparent in the written form, where Canadians retain much, though not all, of the standard British orthography. There are a considerable number of different accents within the regions of both the United States and Canada, originally deriving from the accents prevalent in different English and Scottish regions and corresponding to settlement patterns of these peoples in the colonies. These were developed and built upon as new waves of immigration, and migration across the North American continent, brought new accents and dialects to new areas, and as these ways of speaking merged and assimilated with the population. It is claimed that despite the centuries of linguistic changes there is still a close resemblance between the English East Anglia accents which would have been used by the Pilgrim Fathers and modern Northeastern United States accents. Similarly, the accents of Newfoundland is similar to Scots while Appalachian dialect retains Scots Irish features. Commonwealth English is sometimes used to collectively describe Australian English, British English, Canadian English, Caribbean English, and New Zealand English due to their historical Commonwealth connections and similarity of spelling.
- Category:English dialects

Piston engine

: reciprocating engine

Turbine

:For the developers of Massively Multiplayer Online Role Playing Games, see Turbine Inc.. Turbine Inc. Turbine Inc. A turbine is a rotary engine that extracts energy from a fluid flow. Claude Burdin coined the term from the Latin turbinis, or vortex, during an 1828 engineering competition. The simplest turbines have one moving part, a rotor-blade assembly. Moving fluid acts on the blades to spin them and impart energy to the rotor. Some modern turbines are among the most powerful machines ever made. Early turbine examples are windmills and water wheels. A turbine operating in reverse is called a compressor or Turbopump. Gas, steam, and water turbines usually have a casing around the blades that focuses and controls the fluid. The casing and blades may have variable geometry that allow efficient operation for a range of fluid flow conditions.

Theory of operation

A working fluid contains potential energy (pressure head) and kinetic energy (velocity head). The fluid may be compressible or non-compressible. Several physical principles are employed by turbines to collect this energy; kinetic energy Impulse turbines change the direction of flow of a high velocity fluid jet. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. There is no pressure change of the fluid in the turbine rotor blades. Pressure head is changed to velocity head by accelerating the fluid with a nozzle, prior to hitting the turbine blades. Pelton wheels and de Laval turbines use this concept. Impulse turbines do not require a pressure casement around the runner, since the fluid jet is prepared by a nozzle prior to hitting the turbine. Newton's second law describes the transfer of energy for impulse turbines. Reaction turbines develop torque by reacting to the fluid's pressure or weight. The pressure of the fluid changes as it passes through the turbine rotor blades. A pressure casement is needed to contain the working fluid as it acts on the turbine runner, or the turbine must be fully immersed in the fluid flow (wind turbines). The casing contains and directs the working fluid, and for water turbines, maintains suction imparted by the draft tube. Francis turbines and most steam turbines use this concept. For compressible working fluids, multiple turbine stages may by used to efficiently harness the expanding gas. Newton's third law describes the transfer of energy for reaction turbines. Velocity triangles are used to calculate the basic performance of a turbine stage. Gas exits the turbine nozzle guide vanes at absolute velocity Va1. The rotor rotates at velocity U. Relative to the rotor, the velocity of the gas as it impinges on the rotor entrance is Vr1. The gas is turned by the rotor and exits, relative to the rotor, at velocity Vr2. However, in absolute terms the rotor exit velocity is Va2. The velocity triangles are constructed using these various velocity vectors. Velocity triangles can be constucted at any section through the blading (e.g. hub , tip, etc), but are usually shown at the mean radius. Mean performance for the stage can be calculated from the velocity triangles at this radius as follows:

\delta\,H = U\cdot \delta\,Vw/g

where:

g =

acceleration of gravity

\delta\,H =

enthalpy drop across stage

\delta\,Vw =

delta whirl velocity Turbine designs will use both these concepts to varying degrees whenever possible. Wind turbines use a foil to generate lift from the moving fluid and impart it to the rotor (this is a form of reaction), they also gain some energy from the impulse of the wind, by deflecting it at an angle. Crossflow turbines are designed as an impulse machine, with a nozzle, but in low head applications maintain some efficiency through reaction, like a traditional water wheel. Classical turbine design methods were developed in the mid 19th century. Vector analysis related the fluid flow with turbine shape and rotation. Graphical calculation methods were used at first. Formulas for the basic dimensions of turbine parts are well documented, and a highly efficient machine can be reliably designed for any fluid flow condition. Some of the calculations are empirical 'rule of thumb' formulae, and others are based on classical mechanics. As with most engineering calculations, simplifying assumptions were made. Modern turbine design carries the calculations further. Computational fluid dynamics dispenses with many of the simplifying assumptions used to derive classical formulas, and computer software facilitates optimization. These tools have led to steady improvements in turbine design over the last forty years. The primary numerical classification of a turbine is its specific speed. This number describes the speed of the turbine at its maximum efficiency with respect to the power and flow rate. The specific speed is derived to be independent of turbine size. Given the fluid flow conditions and the desired shaft output speed, the specific speed can be calculated and an appropriate turbine design selected. The specific speed, along with some fundamental formulas can be used to reliably scale an existing design of known performance to a new size with corresponding performance. Off-design performance is normally displayed as a turbine map or characteristic.

Types of turbines

- Steam turbine
- Gas turbine engines are sometimes referred to as turbine engines. Such engines usually feature a compressor, combustor, nozzle, etc, in addition to one or more turbines.
- transonic turbine The gasflow in most turbines employed in gas turbine engines remains subsonic throughout the expansion process. In a so-called transonic turbine, the gasflow becomes supersonic as it exits the nozzle guide vanes, although the downstream velocities normally become subsonic. Transonic turbines operate at a higher pressure ratio than normal, but are usually less efficient.
- contra-rotating turbines Some efficiency advantage can usually be obtained if a downstream turbine rotates in the opposite direction to an upstream unit.
- statorless turbine Most turbines have a set of static (i.e. stationary) inlet guide vanes that direct the gasflow onto the rotating rotor blades. In a statorless turbine, the gasflow exiting an upstream rotor impinges onto a downstream rotor, without an intermediate set of nozzle guide vanes being encountered.
- Water turbine
- Wind turbine :Water and Wind turbines have a thermodynamic cycle that is part of weather.

Uses of turbines

Almost all electrical power on Earth is produced with a turbine of some type, the exceptions being solar panels and fuel cells. All jet engines rely on turbines to supply mechanical work from their fuel, as do all nuclear warships and power plants. Turbines are often part of a larger machine. A Gas turbine, for example, may refer to an internal combustion machine that contains a turbine, compressor, combustor, and alternator. Piston engines, especially for aircraft, can use a turbine powered by their exhaust to drive an intake compressor, a configuration known as a turbocharger (turbine supercharger) or colloquially as a "turbo". Turbines can have incredible power density (with respect to volume and weight). This is because of their ability to operate at very high speeds. The Space Shuttle fuel pump turbine, for example, is slightly larger than an automobile engine and produces 25,000 hp (19 MW).

External links

- [http://www.du.edu/~jcalvert/tech/fluids/turbine.htm Turbine introductory math]
- [http://www.power.alstom.com/home/equipment___systems/turbines/7385.EN.php?languageId=EN&dir=/home/equipment___systems/turbines/ ALSTOM Power]
- [http://www.siemenswestinghouse.com/en/gasturbinesitem/index.cfm Siemens Westinghouse] Category:Mechanical engineering Category:Turbines Category:Jet engines ja:タービン

Turboprop

A Turboprop (Turbo-propeller) or turboshaft engine is a type of gas turbine. It differs from a Turbojet in that the design is optimized to produce rotating shaft power to drive a propeller, instead of thrust from the exhaust gas. Basically, a turbojet consists of an intake, compressor, combustor, turbine and a propelling nozzle. Air drawn into the intake is compressed by the compressor. Fuel is burnt with the compressed air in the combustor. The hot combustion gases expand through the turbine, to provide power to the compressor. Further expansion of the gases occurs in the propelling nozzle; the high velocity jet produced providing forward thrust. In a turboprop much of the jet thrust is sacrificed in favor of shaftpower, which is obtained by extracting additional power (to that necessary to drive the compressor) from the turbine expansion process. Whilst the power turbine may be integral with the compressor turbine, most turboprops today feature a Free Power Turbine, on a separate coaxial shaft. This enables the propeller to rotate freely, independent of compressor speed. Owing to the additional expansion in the turbine system, the residual energy in the jet is fairly low

Aircraft

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Flight

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Autogyro

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See also

North American English

Piston engine

Turbine

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Types of turbines

Uses of turbines

External links

Turboprop