Editing Flight (section)

== Types of flight ==

=== Buoyant flight ===
{{Main|Aerostat}}
[[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]]
Humans have managed to construct lighter-than-air vehicles that raise off the ground and fly, due to their [[buoyancy]] in the air.

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]]<ref>Walker 2000, p. 541. Quote: the gas-bag of a balloon or airship.</ref><ref>Coulson-Thomas 1976, p. 281. Quote: fabric enclosing gas-bags of airship.</ref> to provide [[buoyancy]], to which other components are attached.

Aerostats are so named because they use "aerostatic" lift, a [[buoyant]] force that does not require 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.

=== Aerodynamic flight ===

==== Unpowered flight versus powered flight ====
{{Main|Unpowered flight}}
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.

==== Animal flight ====
{{Main|Flying and gliding animals}}
[[File:Female mallard flight - natures pics.jpg|thumb|Female [[mallard]] duck]]
[[File:Tau Emerald inflight edit.jpg|thumb|Tau emerald [[dragonfly]]]]
[[File:Kea in Flight MC.jpg|thumb|[[Kea]]]]

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,<ref name="averof"/> and there were apparently some [[flying dinosaur]]s. Each of these groups' [[wing]]s [[Convergent evolution|evolved independently]], with insects the first animal group to evolve flight.<ref>{{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}}</ref> The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; insect wings are hypothesized to be highly modified versions of structures that form gills in most other groups of [[arthropod]]s.<ref name="averof">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.</ref>

[[Bat]]s are the only [[mammal]]s capable of sustaining level flight (see ''[[bat flight]]'').<ref>''World Book Student.'' Chicago: World Book. Retrieved: April 29, 2011.</ref> 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.

[[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.<ref name=aa>[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.</ref>

[[Bird flight|Most birds can fly]], 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.

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}}.<ref>[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.</ref>

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]].<ref>{{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 }}</ref><ref>{{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 | bibcode=2003JExpB.206.4191S }}</ref>

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.

==== Mechanical ====<!-- This section is linked from [[Anthony Fokker]] -->
{{Main|Aviation}}
[[File:Flight.rob.arp.750pix.jpg|thumb|Mechanical flight: A [[Robinson R22]] Beta [[helicopter]]]]

'''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.

===== Supersonic =====
{{Main|Supersonic speed}}
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,<ref>Bern, Peter. [http://news.bbc.co.uk/1/hi/talking_point/3207470.stm "Concorde: You asked a pilot."] ''BBC'', October 23, 2003.</ref> and is frequently startling. The creation of this shockwave requires a significant amount of energy; because of this, supersonic flight is generally less efficient than subsonic flight at about 85% of the speed of sound.

===== Hypersonic =====
{{Main|Hypersonic speed}}
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]].
[[File:ISS after STS-117 in June 2007.jpg|thumb|The [[International Space Station]] in Earth [[orbit]]]]

=== Ballistic ===
{{Main|Ballistics}}

==== Atmospheric ====
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.

==== Spaceflight ====
{{Main|Spaceflight}}
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.

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.

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.<ref>{{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}}</ref> 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.

==== Solid-state propulsion ====
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.<ref>{{cite news<!--|authors=Haofeng Xu, Yiou He, Kieran L. Strobel, Christopher K. Gilmore, Sean P. Kelley, Cooper C. Hennick, Thomas Sebastian, Mark R. Woolston, David J. Perreault & Steven R. H. Barrett-->|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}}</ref><ref>{{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 }}</ref>