Array ( [0] => {{Short description|Process by which an object moves, through an atmosphere or beyond it}} [1] => {{Other uses}} [2] => [[File:Juvenile pelecanus occidentalis in flight.jpg|thumb|[[Bird flight|Natural flight]] by a [[brown pelican]]]] [3] => [[File:Royal Jordanian Airlines Boeing 787-8 (JY-BAA) arrives London Heathrow 11Apr2015 arp.jpg|thumb|Human-engineered flight: a [[Royal Jordanian Airlines]] [[Boeing 787]]]] [4] => '''Flight''' or '''flying''' is the process by which an [[object (physics)|object]] [[motion (physics)|moves]] through a [[space]] without contacting any [[planetary surface]], either within an [[atmosphere]] (i.e. air flight or [[aviation]]) or through the [[vacuum]] of [[outer space]] (i.e. [[spaceflight]]). This can be achieved by generating [[lift (force)|aerodynamic lift]] associated with [[gliding flight|gliding]] or [[air propulsion|propulsive thrust]], [[aerostat]]ically using [[buoyancy]], or by [[ballistics|ballistic]] movement. [5] => [6] => Many things can fly, from [[Flying and gliding animals|animal aviator]]s such as [[bird]]s, [[bat]]s and [[insect]]s, to natural gliders/parachuters such as [[patagium|patagial]] animals, [[anemochorous]] [[seed]]s and [[ballistospore]]s, to human inventions like [[aircraft]] ([[airplane]]s, [[helicopter]]s, [[airship]]s, [[balloon]]s, etc.) and [[rocket]]s which may propel [[spacecraft]] and [[spaceplane]]s. [7] => [8] => The engineering aspects of flight are the purview of [[aerospace engineering]] which is subdivided into [[aeronautics]], the study of vehicles that travel through the atmosphere, and [[astronautics]], the study of vehicles that travel through space, and [[ballistics]], the study of the flight of projectiles. [9] => [10] => ==Types of flight== [11] => ===Buoyant flight=== [12] => {{main article|Aerostat}} [13] => [[File:Goodyear-blimp.jpg|thumb|An airship flies because the upward force, from air displacement, is equal to or greater than the force of gravity]] [14] => Humans have managed to construct lighter-than-air vehicles that raise off the ground and fly, due to their [[buoyancy]] in the air. [15] => [16] => 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 [[balloon (aircraft)|free balloons]], [[airship]]s, and [[moored balloon]]s. An aerostat's main structural component is its [[wikt:envelope|envelope]], a lightweight [[skin]] that encloses a volume of [[lifting gas]]Walker 2000, p. 541. Quote: the gas-bag of a balloon or airship.Coulson-Thomas 1976, p. 281. Quote: fabric enclosing gas-bags of airship. to provide [[buoyancy]], to which other components are attached. [17] => [18] => Aerostats are so named because they use "aerostatic" lift, a [[buoyant]] force that does not require lateral movement through the surrounding air mass to effect a lifting force. By contrast, [[Aircraft#Heavier-than-air – aerodynes|aerodynes]] primarily use [[aerodynamic]] [[lift (force)|lift]], which requires the lateral movement of at least some part of the [[aircraft]] through the surrounding air mass. [19] => [20] => ===Aerodynamic flight=== [21] => [22] => ====Unpowered flight versus powered flight==== [23] => {{main article| Unpowered flight}} [24] => Some things that fly do not generate propulsive thrust through the air, for example, the [[flying squirrel]]. This is termed [[gliding (flight)|gliding]]. Some other things can exploit rising air to climb such as [[Bird of prey|raptors]] (when gliding) and [[glider (sailplane)|man-made sailplane gliders]]. This is termed [[Lift (soaring)|soaring]]. However most other birds and all [[powered aircraft]] need a source of [[propulsion]] to climb. This is termed powered flight. [25] => [26] => ====Animal flight==== [27] => [[File:Female mallard flight - natures pics.jpg|thumb|Female [[mallard]] duck]] [28] => [[File:Tau Emerald inflight edit.jpg|thumb|Tau emerald [[dragonfly]]]] [29] => [[File:Kea in Flight MC.jpg|thumb|[[Kea]]]] [30] => {{Main article|Flying and gliding animals}} [31] => [32] => The only groups of [[Flying and gliding animals|living things that use powered flight]] are [[bird]]s, [[insect]]s, and [[bat]]s, while many groups have evolved gliding. The extinct [[pterosaur]]s, an [[Order (biology)|order]] of reptiles contemporaneous with the [[dinosaur]]s, were also very successful flying animals, and there were apparently some flying dinosaurs (see [[Flying and gliding animals#Non-avian dinosaurs]]). Each of these groups' [[wing]]s [[Convergent evolution|evolved independently]], with insects the first animal group to evolve flight.{{cite journal|doi=10.1146/annurev-environ-012420-050035|doi-access=free|title=The State of the World's Insects|year=2020|last1=Eggleton|first1=Paul|journal=Annual Review of Environment and Resources|volume=45|pages=61–82}} The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; those of insects are hypothesized to be highly modified versions of structures that form gills in most other groups of [[arthropod]]s.Averof, Michalis. [http://www.nature.com/nature/journal/v385/n6617/abs/385627a0.html "Evolutionary origin of insect wings from ancestral gills."] ''Nature'', Volume 385, Issue 385, February 1997, pp. 627–630. [33] => [34] => [[Bat]]s are the only [[mammal]]s capable of sustaining level flight (see ''[[bat flight]]'').''World Book Student.'' Chicago: World Book. Retrieved: April 29, 2011. However, there are several [[Flying squirrel|gliding mammals]] which are able to glide from tree to tree using fleshy membranes between their limbs; some can travel hundreds of meters in this way with very little loss in height. [[Flying frog]]s use greatly enlarged webbed feet for a similar purpose, and there are [[Draco blanfordii|flying lizards]] which fold out their mobile ribs into a pair of flat gliding surfaces. [[Chrysopelea|"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. [35] => [36] => [[Flying fish]] can glide using enlarged wing-like fins, and have been observed soaring for hundreds of meters. 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 flying fish was 45 seconds.[http://news.bbc.co.uk/1/hi/sci/tech/7410421.stm "BBC article and video of flying fish."] ''BBC'', May 20, 2008. Retrieved: May 20, 2008. [37] => [38] => Most [[bird]]s fly (''see [[bird flight]]''), with some exceptions. The largest birds, the [[ostrich]] and the [[emu]], are earthbound [[flightless bird]]s, as were the now-extinct [[dodo]]s and the [[Phorusrhacids]], which were the dominant predators of [[South America]] in the [[Cenozoic]] era. The non-flying [[penguin]]s have wings adapted for use under water and use the same wing movements for swimming that most other birds use for flight.{{citation needed|date=April 2011}} Most small flightless birds are native to small islands, and lead a lifestyle where flight would offer little advantage. [39] => [40] => Among living animals that fly, the [[wandering albatross]] has the greatest wingspan, up to {{convert|3.5|m|ft|abbr=off|sp=us}}; the [[great bustard]] has the greatest weight, topping at {{convert|21|kg|lb|abbr=off}}.[http://www.trumpeterswansociety.org/id.htm "Swan Identification."] {{webarchive|url=https://web.archive.org/web/20061031082245/http://www.trumpeterswansociety.org/id.htm |date=2006-10-31 }} ''The Trumpeter Swan Society.'' Retrieved: January 3, 2012. [41] => [42] => Most species of [[insect]]s can fly as adults. [[Insect flight]] makes use of either of two basic aerodynamic models: creating a leading edge vortex, found in most insects, and using [[clap and fling]], found in very small insects such as [[thrips]].{{cite journal |url=http://www.physics.emory.edu/~weeks/lab/papers/jwang-arf05.pdf |last=Wang|first= Z. Jane |author-link=Z. Jane Wang|title=Dissecting Insect Flight |doi=10.1146/annurev.fluid.36.050802.121940 |year=2005 |bibcode=2005AnRFM..37..183W |journal=Annual Review of Fluid Mechanics |volume=37 |issue=1 |pages=183–210 }}{{cite journal | url=http://www.cs.washington.edu/homes/diorio/MURI2003/Publications/sane_review.pdf | title=The aerodynamics of insect flight | author=Sane, Sanjay P. | journal=The Journal of Experimental Biology | year=2003 | volume=206 | pages=4191–4208 | doi=10.1242/jeb.00663 | pmid=14581590 | issue=23| s2cid=17453426 | doi-access=free }} [43] => [44] => Many species of [[spider]]s, [[spider mite]]s and [[lepidoptera]] use a technique called [[Ballooning (spider)|ballooning]] to ride [[air current]]s such as [[thermal]]s, by exposing their [[Spider silk|gossamer threads]] which gets lifted by wind and [[Atmosphere|atmospheric]] [[electric field]]s. [45] => [46] => ====Mechanical==== [47] => {{main article|Aviation}} [48] => [49] => [[File:Flight.rob.arp.750pix.jpg|thumb|Mechanical flight: A [[Robinson R22]] Beta [[helicopter]]]] [50] => '''Mechanical flight''' is the use of a [[machine]] to fly. These machines include [[aircraft]] such as [[airplane]]s, [[glider aircraft|gliders]], [[helicopter]]s, [[autogyro]]s, [[airship]]s, [[balloon (aircraft)|balloons]], [[ornithopter]]s as well as [[spacecraft]]. [[glider aircraft|Gliders]] are capable of unpowered flight. Another form of mechanical flight is para-sailing, where a parachute-like object is pulled by a boat. In an airplane, lift is created by the wings; the shape of the wings of the airplane are designed specially for the type of flight desired. There are different types of wings: tempered, semi-tempered, sweptback, rectangular and elliptical. An aircraft wing is sometimes called an [[airfoil]], which is a device that creates lift when air flows across it. [51] => [52] => =====Supersonic===== [53] => {{main article|Supersonic speed}} [54] => Supersonic flight is flight faster than the [[speed of sound]]. Supersonic flight is associated with the formation of [[shock wave]]s that form a [[sonic boom]] that can be heard from the ground,Bern, Peter. [http://news.bbc.co.uk/1/hi/talking_point/3207470.stm "Concorde: You asked a pilot."] ''BBC'', October 23, 2003. and is frequently startling. This shockwave takes quite a lot of energy to create and this makes supersonic flight generally less efficient than subsonic flight at about 85% of the speed of sound. [55] => [56] => =====Hypersonic===== [57] => {{main article|Hypersonic speed}} [58] => Hypersonic flight is very high speed flight where the heat generated by the compression of the air due to the motion through the air causes chemical changes to the air. Hypersonic flight is achieved primarily by reentering spacecraft such as the [[Space Shuttle]] and [[Soyuz spacecraft|Soyuz]]. [59] => [[File:ISS after STS-117 in June 2007.jpg|thumb|The [[International Space Station]] in Earth [[orbit]]]] [60] => [61] => ===Ballistic=== [62] => {{main article|Ballistics}} [63] => [64] => ====Atmospheric==== [65] => Some things generate little or no lift and move only or mostly under the action of momentum, gravity, air drag and in some cases thrust. This is termed ''ballistic flight''. Examples include [[ball]]s, [[archery|arrows]], [[bullet]]s, [[firework]]s etc. [66] => [67] => ====Spaceflight==== [68] => {{main article|Spaceflight}} [69] => Essentially an extreme form of ballistic flight, spaceflight is the use of [[space technology]] to achieve the flight of [[spacecraft]] into and through [[outer space]]. Examples include [[ballistic missile]]s, [[orbital spaceflight]], etc. [70] => [71] => Spaceflight is used in [[space exploration]], and also in commercial activities like [[space tourism]] and [[telecommunications satellite|satellite telecommunications]]. Additional non-commercial uses of spaceflight include [[Space observatory|space observatories]], [[reconnaissance satellite]]s and other [[Earth observation satellite]]s. [72] => [73] => A spaceflight typically begins with a [[rocket launch]], which provides the initial thrust to overcome the force of [[gravity]] and propels the spacecraft from the surface of the Earth.{{Cite book| url=https://books.google.com/books?id=kjVGAAAAYAAJ&q=A+spaceflight+typically+begins+with+a+rocket+launch,+which+provides+the+initial+thrust+to+overcome+the+force+of+gravity | title=Astronautics: A Historical Perspective of Mankind's Efforts to Conquer the Cosmos | last=Spitzmiller | first=Ted | date=2007 | page=467 | publisher=Apogee Books | isbn=9781894959667 | language=en}} Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called [[astrodynamics]]. Some spacecraft remain in space indefinitely, some disintegrate during [[atmospheric reentry]], and others reach a planetary or lunar surface for landing or impact. [74] => [75] => ====Solid-state propulsion==== [76] => In 2018, researchers at [[Massachusetts Institute of Technology]] (MIT) managed to fly an aeroplane with no moving parts, powered by an "[[ion]]ic wind" also known as electroaerodynamic thrust.{{cite news|author=Haofeng Xu|display-authors=etal|title=Flight of an aeroplane with solid-state propulsion|publisher=Nature|year=2018|volume=563|pages=532–535|doi=10.1038/s41586-018-0707-9}}{{cite web |author=Jennifer Chu |url=http://news.mit.edu/2018/first-ionic-wind-plane-no-moving-parts-1121 |title=MIT engineers fly first-ever plane with no moving parts |website=MIT News |date=21 November 2018 }} [77] => [78] => ==History== [79] => Many human cultures have built devices that fly, from the earliest projectiles such as stones and spears,[http://www.tmth.edu.gr/en/aet/1/14.html "Archytas of Tar entum."] {{webarchive |url=https://web.archive.org/web/20081226181400/http://www.tmth.edu.gr/en/aet/1/14.html |date=December 26, 2008 }} ''Technology Museum of Thessaloniki, Macedonia, Greece/'' Retrieved: May 6, 2012.[http://automata.co.uk/History%20page.htm "Ancient history."] {{Webarchive|url=https://web.archive.org/web/20021205014113/http://www.automata.co.uk/History%20page.htm |date=2002-12-05 }} ''Automata.'' Retrieved:May 6, 2012. the [80] => [[boomerang]] in [[Australia]], the hot air [[Kongming lantern]], and [[kite]]s. [81] => [82] => ===Aviation=== [83] => {{main article|History of aviation}} [84] => [[George Cayley]] studied flight scientifically in the first half of the 19th century,{{cite web [85] => | title = Sir George Cayley [86] => | url = http://www.flyingmachines.org/cayl.html [87] => | publisher = Flyingmachines.org [88] => | access-date = 27 August 2019 [89] => | quote = Sir George Cayley is one of the most important people in the history of aeronautics. Many consider him the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight.}}{{cite web [90] => | title = The Pioneers: Aviation and Airmodelling [91] => | url = http://www.ctie.monash.edu.au/hargrave/cayley.html [92] => | access-date =26 July 2009 [93] => | quote = Sir George Cayley, is sometimes called the 'Father of Aviation'. A pioneer in his field, he is credited with the first major breakthrough in heavier-than-air flight. He was the first to identify the four aerodynamic forces of flight – weight, lift, drag, and thrust – and their relationship and also the first to build a successful human-carrying glider.}}{{cite web [94] => |title = U.S. Centennial of Flight Commission – Sir George Cayley [95] => |url = http://www.centennialofflight.gov/essay/Prehistory/Cayley/PH2.htm [96] => |access-date = 10 September 2008 [97] => |quote = Sir George Cayley, born in 1773, is sometimes called the Father of Aviation. A pioneer in his field, Cayley literally has two great spurts of aeronautical creativity, separated by years during which he did little with the subject. He was the first to identify the four aerodynamic forces of flight – weight, lift, drag, and thrust and their relationship. He was also the first to build a successful human-carrying glider. Cayley described many of the concepts and elements of the modern aeroplane and was the first to understand and explain in engineering terms the concepts of lift and thrust. [98] => |url-status = dead [99] => |archive-url = https://web.archive.org/web/20080920052758/http://centennialofflight.gov/essay/Prehistory/Cayley/PH2.htm [100] => |archive-date = 20 September 2008 [101] => }} and in the second half of the 19th century [[Otto Lilienthal]] made over 200 gliding flights and was also one of the first to understand flight scientifically. His work was replicated and extended by the [[Wright brothers]] who made gliding flights and finally the first controlled and extended, manned powered flights.[http://www.shapell.org/btl.aspx?2972360 "Orville Wright's Personal Letters on Aviation."] {{Webarchive|url=https://web.archive.org/web/20120611224943/http://www.shapell.org/btl.aspx?2972360 |date=2012-06-11 }} ''Shapell Manuscript Foundation'', (Chicago), 2012. [102] => [103] => ===Spaceflight=== [104] => {{main article|History of spaceflight}} [105] => Spaceflight, particularly [[human spaceflight]] became a reality in the 20th century following theoretical and practical breakthroughs by [[Konstantin Tsiolkovsky]] and [[Robert H. Goddard]]. The [[Sputnik 1|first orbital spaceflight]] was in 1957,{{Cite web|url=https://history.nasa.gov/sputnik/sputorig.html|title = Sputnik and the Origins of the Space Age}} and [[Yuri Gagarin]] was carried aboard the first crewed orbital spaceflight in 1961.[http://www.nasa.gov/mission_pages/shuttle/sts1/gagarin_anniversary.html "Gagarin anniversary."] {{Webarchive|url=https://web.archive.org/web/20130405064118/http://www.nasa.gov/mission_pages/shuttle/sts1/gagarin_anniversary.html |date=2013-04-05 }} ''NASA''. Retrieved: May 6, 2012. [106] => [107] => ==Physics== [108] => [[File:Luftschiff small.jpg|thumb|Lighter-than-air [[airship]]s are able to fly without any major input of energy]] [109] => {{main article|Aerodynamics}} [110] => [111] => There are different approaches to flight. If an object has a lower [[density]] than air, then it is [[buoyancy|buoyant]] and is able to [[aerostat|float in the air]] without expending energy. A [[heavier than air]] craft, known as an [[Aircraft#Heavier than air .80.93 aerodynes|aerodyne]], includes flighted animals and insects, [[fixed-wing aircraft]] and [[rotorcraft]]. Because the craft is heavier than air, it must generate [[lift (force)|lift]] to overcome its [[weight]]. The wind resistance caused by the craft moving through the air is called [[drag (physics)|drag]] and is overcome by [[Air propulsion|propulsive thrust]] except in the case of [[gliding (flight)|gliding]]. [112] => [113] => Some vehicles also use thrust in the place of lift; for example [[rocket]]s and [[Harrier jump jet]]s. [114] => [115] => ===Forces=== [116] => [[File:Forces2.gif|thumb|Main forces acting on a heavier-than-air aircraft]] [117] => {{main article|Aerodynamics}} [118] => [119] => Forces relevant to flight are[http://www.grc.nasa.gov/WWW/K-12/airplane/forces.html "Four forces on an aeroplane."] ''NASA.'' Retrieved: January 3, 2012. [120] => * [[Air propulsion|Propulsive thrust]] (except in gliders) [121] => * [[Lift (force)|Lift]], created by the reaction to an airflow [122] => * [[Drag (physics)|Drag]], created by aerodynamic [[friction]] [123] => * [[Weight]], created by gravity [124] => * [[Buoyancy]], for lighter than air flight [125] => [126] => These forces must be balanced for stable flight to occur. [127] => [128] => ====Thrust==== [129] => {{main|Thrust}} [130] => [[File:aeroforces.svg|thumb|Forces on an [[aerofoil]] cross section]] [131] => [132] => A [[fixed-wing aircraft]] generates forward thrust when air is pushed in the direction opposite to flight. This can be done in several ways including by the spinning blades of a [[Propeller (aircraft)|propeller]], or a rotating [[Mechanical fan|fan]] pushing air out from the back of a [[jet engine]], or by ejecting hot gases from a [[rocket engine]].{{cite web| url = http://www.grc.nasa.gov/WWW/k-12/airplane/newton3.html| url-status = dead| archive-url = https://web.archive.org/web/19991128055408/http://www.grc.nasa.gov/WWW/K-12/airplane/newton3.html| archive-date = 1999-11-28| title = Newtons Third Law}} The forward thrust is proportional to the [[mass]] of the airstream multiplied by the difference in [[velocity]] of the airstream. Reverse thrust can be generated to aid braking after landing by reversing the pitch of variable-pitch propeller blades, or using a [[Thrust reversal|thrust reverser]] on a jet engine. [[Rotary wing aircraft]] and [[thrust vectoring]] [[V/STOL]] aircraft use engine thrust to support the weight of the aircraft, and vector sum of this thrust fore and aft to control forward speed. [133] => [134] => ====Lift==== [135] => {{main article|Lift (force)}} [136] => [[File:Airfoil lift and drag.svg|thumb|right|300px|Lift is defined as the component of the [[aerodynamic force]] that is perpendicular to the flow direction, and drag is the component that is parallel to the flow direction]] [137] => In the context of an [[fluid flow|air flow]] relative to a flying body, the '''lift''' force is the [[Vector (geometric)#Vector components|component]] of the [[aerodynamic force]] that is [[perpendicular]] to the flow direction.[http://www.lerc.nasa.gov/WWW/K-12/aerosim/Manual/fsim0020.htm "Definition of lift."] {{webarchive|url=https://web.archive.org/web/20090203074439/http://www.lerc.nasa.gov/WWW/K-12/aerosim/Manual/fsim0020.htm |date=2009-02-03 }} ''NASA.'' Retrieved: May 6, 2012. Aerodynamic lift results when the wing causes the surrounding air to be deflected - the air then causes a force on the wing in the opposite direction, in accordance with [[Newton's third law of motion]]. [138] => [139] => Lift is commonly associated with the [[wing]] of an [[Fixed-wing aircraft|aircraft]], although lift is also generated by [[Helicopter rotor|rotors]] on [[rotorcraft]] (which are effectively rotating wings, performing the same function without requiring that the aircraft move forward through the air). While common meanings of the word "[[wikt:lift#English|lift]]" suggest that lift opposes gravity, aerodynamic lift can be in any direction. When an aircraft is [[cruise (flight)|cruising]] for example, lift does oppose gravity, but lift occurs at an angle when climbing, descending or banking. On high-speed cars, the lift force is directed downwards (called "down-force") to keep the car stable on the road. [140] => [141] => ====Drag==== [142] => {{main article|Drag (physics)}} [143] => For a solid object moving through a fluid, the drag is the component of the [[Net force|net]] [[Aerodynamic force|aerodynamic]] or [[hydrodynamics|hydrodynamic]] [[force]] acting opposite to the direction of the movement.French 1970, p. 210.[http://www.ucmp.berkeley.edu/vertebrates/flight/physics.html "Basic flight physics."] ''Berkeley University.'' Retrieved: May 6, 2012.[http://www.grc.nasa.gov/WWW/k-12/airplane/drag1.html "What is Drag?"] {{Webarchive|url=https://web.archive.org/web/20100524003905/http://www.grc.nasa.gov/WWW/K-12/airplane/drag1.html |date=2010-05-24 }} ''NASA.'' Retrieved: May 6, 2012.[http://lorien.ncl.ac.uk/ming/particle/cpe124p2.html "Motions of particles through fluids."] {{webarchive|url=https://web.archive.org/web/20120425070933/http://lorien.ncl.ac.uk/ming/particle/cpe124p2.html |date=2012-04-25 }} ''lorien.ncl.ac.'' Retrieved: May 6, 2012. Therefore, drag opposes the motion of the object, and in a powered vehicle it must be overcome by [[thrust]]. The process which creates lift also causes some drag. [144] => [145] => ====Lift-to-drag ratio==== [146] => [[File:Drag curves for aircraft in flight.svg|thumb|Speed and drag relationships for a typical aircraft]] [147] => {{main article|Lift-to-drag ratio}} [148] => Aerodynamic lift is created by the motion of an aerodynamic object (wing) through the air, which due to its shape and angle deflects the air. For sustained straight and level flight, lift must be equal and opposite to weight. In general, long narrow wings are able deflect a large amount of air at a slow speed, whereas smaller wings need a higher forward speed to deflect an equivalent amount of air and thus generate an equivalent amount of lift. Large cargo aircraft tend to use longer wings with higher angles of attack, whereas supersonic aircraft tend to have short wings and rely heavily on high forward speed to generate lift. [149] => [150] => However, this lift (deflection) process inevitably causes a retarding force called drag. Because lift and drag are both aerodynamic forces, the ratio of lift to drag is an indication of the aerodynamic efficiency of the airplane. The lift to drag ratio is the L/D ratio, pronounced "L over D ratio." An airplane has a high L/D ratio if it produces a large amount of lift or a small amount of drag. The lift/drag ratio is determined by dividing the lift coefficient by the drag coefficient, CL/CD.The Beginner's Guide to Aeronautics - NASA Glenn Research Center https://www.grc.nasa.gov/www/k-12/airplane/ldrat.html [151] => [152] => The lift coefficient Cl is equal to the lift L divided by the (density r times half the velocity V squared times the wing area A). [Cl = L / (A * .5 * r * V^2)] The lift coefficient is also affected by the compressibility of the air, which is much greater at higher speeds, so velocity V is not a linear function. Compressibility is also affected by the shape of the aircraft surfaces. [153] => The Beginner's Guide to Aeronautics - NASA Glenn Research Center https://www.grc.nasa.gov/www/k-12/airplane/liftco.html [154] => [155] => The drag coefficient Cd is equal to the drag D divided by the (density r times half the velocity V squared times the reference area A). [Cd = D / (A * .5 * r * V^2)] [156] => The Beginner's Guide to Aeronautics - NASA Glenn Research Center https://www.grc.nasa.gov/www/k-12/airplane/dragco.html [157] => [158] => Lift-to-drag ratios for practical aircraft vary from about 4:1 for vehicles and birds with relatively short wings, up to 60:1 or more for vehicles with very long wings, such as gliders. A greater angle of attack relative to the forward movement also increases the extent of deflection, and thus generates extra lift. However a greater angle of attack also generates extra drag. [159] => [160] => Lift/drag ratio also determines the glide ratio and gliding range. Since the glide ratio is based only on the relationship of the aerodynamics forces acting on the aircraft, aircraft weight will not affect it. The only effect weight has is to vary the time that the aircraft will glide for – a heavier aircraft gliding at a higher airspeed will arrive at the same touchdown point in a shorter time.The Beginner's Guide to Aeronautics - NASA Glenn Research Center [161] => https://www.grc.nasa.gov/www/k-12/airplane/ldrat.html [162] => [163] => ====Buoyancy==== [164] => {{main article|Buoyancy}} [165] => Air pressure acting up against an object in air is greater than the pressure above pushing down. The buoyancy, in both cases, is equal to the weight of fluid displaced - [[Archimedes' principle]] holds for air just as it does for water. [166] => [167] => A cubic meter of air at ordinary [[atmospheric pressure]] and room temperature has a mass of about 1.2 kilograms, so its weight is about 12 [[Newton (unit)|newtons]]. Therefore, any 1-cubic-meter object in air is buoyed up with a force of 12 newtons. If the mass of the 1-cubic-meter object is greater than 1.2 kilograms (so that its weight is greater than 12 newtons), it falls to the ground when released. If an object of this size has a mass less than 1.2 kilograms, it rises in the air. Any object that has a mass that is less than the mass of an equal volume of air will rise in air - in other words, any object less dense than air will rise. [168] => [169] => ====Thrust to weight ratio==== [170] => {{main article|Thrust-to-weight ratio}} [171] => '''Thrust-to-weight ratio''' is, as its name suggests, the ratio of instantaneous [[thrust]] to [[weight]] (where weight means weight at the [[Earth]]'s standard acceleration g_0).Sutton and Biblarz 2000, p. 442. Quote: "thrust-to-weight ratio F/W0 is a dimensionless parameter that is identical to the acceleration of the rocket propulsion system (expressed in multiples of g0) if it could fly by itself in a gravity free vacuum." It is a dimensionless parameter characteristic of [[rocket]]s and other jet engines and of vehicles propelled by such engines (typically space [[launch vehicle]]s and jet [[aircraft]]). [172] => [173] => If the [[thrust-to-weight ratio]] is greater than the local gravity strength (expressed in ''g''s), then flight can occur without any forward motion or any aerodynamic lift being required. [174] => [175] => If the thrust-to-weight ratio times the lift-to-drag ratio is greater than local gravity then [[takeoff]] using aerodynamic lift is possible. [176] => [177] => ===Flight dynamics=== [178] => [[File:Aileron pitch.gif|thumb|[[Aircraft principal axes|Pitch]]]] [179] => [[File:Aileron yaw.gif|thumb|[[Yaw (rotation)|Yaw]]]] [180] => [[File:Aileron roll.gif|thumb|[[Aerobatic maneuver|Roll]]]] [181] => [[File:dihedral.airliner.arp.750pix.jpg|thumb|The upward tilt of the wings and tailplane of an aircraft, as seen on this [[Boeing 737]], is called dihedral angle]]{{main article|Flight dynamics}} [182] => '''Flight dynamics''' is the science of [[aircraft|air]] and [[spacecraft|space]] vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three [[dimensions]] about the vehicle's [[center of mass]], known as ''pitch'', ''roll'' and ''yaw'' (See [[Tait-Bryan rotations]] for an explanation). [183] => [184] => The control of these dimensions can involve a [[horizontal stabilizer]] (i.e. "a tail"), [[ailerons]] and other movable aerodynamic devices which control angular stability i.e. flight attitude (which in turn affects [[altitude]], [[Aircraft heading|heading]]). Wings are often angled slightly upwards- they have "positive [[Dihedral (aircraft)|dihedral angle]]" which gives inherent roll stabilization. [185] => [186] => ===Energy efficiency=== [187] => {{main article|propulsive efficiency}} [188] => To create thrust so as to be able to gain height, and to push through the air to overcome the drag associated with lift all takes energy. Different objects and creatures capable of flight vary in the efficiency of their muscles, motors and how well this translates into forward thrust. [189] => [190] => Propulsive efficiency determines how much energy vehicles generate from a unit of fuel.[http://www.hq.nasa.gov/pao/History/SP-468/ch10-3.htm ch10-3 "History."] ''NASA.'' Retrieved: May 6, 2012.Honicke et al. 1968 {{Page needed|date=May 2012}} [191] => [192] => ===Range=== [193] => {{main article|range (aircraft)}} [194] => The range that powered flight articles can achieve is ultimately limited by their drag, as well as how much energy they can store on board and how efficiently they can turn that energy into propulsion.{{Cite web|url=http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node98.html|title = 13.3 Aircraft Range: The Breguet Range Equation}} [195] => [196] => For powered aircraft the useful energy is determined by their [[fuel fraction]]- what percentage of the takeoff weight is fuel, as well as the [[specific energy]] of the fuel used. [197] => [198] => ===Power-to-weight ratio=== [199] => {{main article|power-to-weight ratio}} [200] => All animals and devices capable of sustained flight need relatively high power-to-weight ratios to be able to generate enough lift and/or thrust to achieve take off. [201] => [202] => ==Takeoff and landing== [203] => {{main article|takeoff and landing}} [204] => Vehicles that can fly can have different ways to '''takeoff and land'''. Conventional aircraft accelerate along the ground until sufficient lift is generated for [[takeoff]], and reverse the process for [[landing]]. Some aircraft can take off at low speed; this is called a short takeoff. Some aircraft such as helicopters and [[Harrier jump jet]]s can take off and land vertically. Rockets also usually take off and land vertically, but some designs can land horizontally. [205] => [206] => ==Guidance, navigation and control== [207] => {{main article|Guidance, navigation and control}} [208] => [209] => ===Navigation=== [210] => [[Navigation]] is the systems necessary to calculate current position (e.g. [[compass]], [[GPS]], [[LORAN]], [[star tracker]], [[inertial measurement unit]], and [[altimeter]]). [211] => [212] => In aircraft, successful [[air navigation]] involves piloting an aircraft from place to place without getting lost, breaking the laws applying to aircraft, or endangering the safety of those on board or on the [[Earth|ground]]. [213] => [214] => The techniques used for navigation in the air will depend on whether the aircraft is flying under the [[visual flight rules]] (VFR) or the [[instrument flight rules]] (IFR). In the latter case, the [[aviator|pilot]] will navigate exclusively using [[flight instruments|instruments]] and [[radio navigation aid]]s such as beacons, or as directed under [[radar]] control by [[air traffic control]]. In the VFR case, a pilot will largely navigate using [[dead reckoning]] combined with visual observations (known as [[pilotage]]), with reference to appropriate maps. This may be supplemented using radio navigation aids. [215] => [216] => ===Guidance=== [217] => {{main article|Guidance system}} [218] => A '''guidance system''' is a device or group of devices used in the [[navigation]] of a [[ship]], [[aircraft]], [[missile]], [[rocket]], [[satellite]], or other moving object. Typically, guidance is responsible for the calculation of the vector (i.e., direction, velocity) toward an objective. [219] => [220] => ===Control=== [221] => [222] => {{main article|Flight control system}} [223] => A conventional fixed-wing '''aircraft flight control system''' consists of [[flight control surfaces]], the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight. [[Aircraft engine controls]] are also considered as flight controls as they change speed. [224] => [225] => ====Traffic==== [226] => In the case of aircraft, air traffic is controlled by [[air traffic control]] systems. [227] => [228] => [[Collision avoidance (spacecraft)|Collision avoidance]] is the process of controlling spacecraft to try to prevent collisions. [229] => [230] => ==Flight safety== [231] => {{main article|Aviation safety}} [232] => '''Air safety''' is a term encompassing the theory, investigation and categorization of [[Aviation accidents and incidents|flight failures]], and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of [[air travel]]. [233] => [234] => ==See also== [235] => {{Commons category|Flight}} [236] => * [[Aerodynamics]] [237] => * [[Levitation (physics)|levitation]] [238] => * [[Transvection (flying)]] [239] => [240] => ==References== [241] => ;Notes [242] => {{Reflist|33em}} [243] => ;Bibliography [244] => {{Refbegin}} [245] => * Coulson-Thomas, Colin. ''The Oxford Illustrated Dictionary.'' Oxford, UK: [[Oxford University Press]], 1976, First edition 1975, {{ISBN|978-0-19-861118-9}}. [246] => * French, A. P. ''Newtonian Mechanics'' (The M.I.T. Introductory Physics Series) (1st ed.). New York: [[W. W. Norton & Company]] Inc., 1970. [247] => * Honicke, K., R. Lindner, P. Anders, M. Krahl, H. Hadrich and K. Rohricht. ''Beschreibung der Konstruktion der Triebwerksanlagen.'' Berlin: Interflug, 1968. [248] => * Sutton, George P. Oscar Biblarz. ''Rocket Propulsion Elements.'' New York: [[Wiley-Interscience]], 2000 (7th edition). {{ISBN|978-0-471-32642-7}}. [249] => * Walker, Peter. ''[[Chambers Dictionary|Chambers Dictionary of Science and Technology]].'' Edinburgh: Chambers Harrap Publishers Ltd., 2000, First edition 1998. {{ISBN|978-0-550-14110-1}}. [250] => {{Refend}} [251] => [252] => ==External links== [253] => {{wiktionary|flight}} [254] => {{wikivoyage|Flights}} [255] => {{wikivoyage inline}} [256] => *{{Cite EB1911 |wstitle=Flight and Flying |volume=10 |pages=502–519 |first=James Bell |last=Pettigrew |short=1}} History and photographs of early aeroplanes etc. [257] => * [http://www.vega.org.uk/video/programme/84 'Birds in Flight and Aeroplanes' by Evolutionary Biologist and trained Engineer John Maynard-Smith] Freeview video provided by the Vega Science Trust. [258] => [259] => {{Authority control}} [260] => [261] => [[Category:Flight| ]] [262] => [[Category:Aerodynamics]] [263] => [[Category:Sky]] [] => )
good wiki

Flight

Flight is the ability of an object to move through the air, using aerodynamics to generate lift and overcome gravity. This concept has fascinated humans for centuries, leading to the invention of various flying devices such as kites, hot air balloons, and airplanes.

More about us

About

This concept has fascinated humans for centuries, leading to the invention of various flying devices such as kites, hot air balloons, and airplanes. The history of flight can be traced back to ancient civilizations, where mythological beings and gods were described as having the power to fly. However, it was not until the late 18th century that the first true human flight occurred, thanks to advancements in the understanding of aerodynamics and the invention of the hot air balloon. Over the years, flight technology has significantly evolved, with the development of heavier-than-air aircraft such as gliders and airplanes. The latter revolutionized the transportation industry, enabling people to traverse long distances much faster than ever before. Today, flight is an integral part of modern society, with millions of people traveling by air every day. Commercial aviation has become a vital industry, connecting people and goods across the globe. Furthermore, the concept of flight has also extended beyond Earth, with the advent of space exploration and human missions to outer space. Overall, the Wikipedia page on flight provides an in-depth exploration of the history, science, and various aspects related to this incredible human achievement.

Expert Team

Vivamus eget neque lacus. Pellentesque egauris ex.

Award winning agency

Lorem ipsum, dolor sit amet consectetur elitorceat .

10 Year Exp.

Pellen tesque eget, mauris lorem iupsum neque lacus.

You might be interested in

Aeronautics

Aeronautics is the science or art involved with the study, design, and manufacturing of air flight-capable machines, and the techniques of operating aircraft and rockets within the atmosphere.

Aircraft

An aircraft is a vehicle that is capable of flying through the Earth's atmosphere or beyond it.

Atmosphere

Atmosphere is a comprehensive Wikipedia page that provides a thorough overview of Earth's atmosphere.

Aviation

Aviation is a branch of technology that deals with the design, development, production, operation, and use of aircraft.

Bird

Birds are a group of warm-blooded vertebrates characterized by feathers, beaks, wings, and the ability to lay eggs.

Buoyancy

Buoyancy is a fundamental principle in physics, specifically in the study of fluid dynamics.

EARTH

Earth is the third planet from the Sun in our solar system and the only known celestial body to support life.

GPS

Global Positioning System (GPS) is a satellite-based navigation system that provides accurate location and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.

Gravity

Gravity is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward one another.

Mammal

The Wikipedia page for Mammal provides an overview of this diverse group of animals that includes humans, as well as cats, dogs, whales, and many others.

Navigation

Navigation refers to the process of directing or guiding oneself through a physical or digital environment in order to reach a particular destination or desired outcome.

Propulsion

Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid.

Satellite

A satellite is an object that orbits another object in space.

Ship

A ship is a large watercraft that is designed to navigate through the water, typically larger than a boat and capable of carrying cargo, passengers, or both.

SPACE

Space is the vast, seemingly boundless expanse that exists beyond Earth and extends throughout the universe.

Spacecraft

A spacecraft is a vehicle designed to travel in outer space.

Spaceflight

Spaceflight (or space flight) is an application of astronautics to fly objects, usually spacecraft, into or through outer space, either with or without humans on board.

Vacuum

A vacuum is a space devoid of matter, such as air or other gases.