Glider (aircraft): Difference between revisions

{{More footnotes needed|date=November 2009}}

[[File:Dg800.jpg|thumb|300px|Single-seat high performance fiberglass [[Glaser-Dirks DG-808]] [[Glider (sailplane)|glider]] over the [[Lac de Serre Ponçon]] in the [[French Alps]]]]

[[File:Habicht (468040905).jpg|thumb|300px|Aerobatic glider with tip smoke, pictured on July 2, 2005, in [[Lappeenranta]], [[Finland]]]]

A '''glider''' is a [[fixed-wing aircraft]] that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and whose [[gliding flight|free flight]] does not depend on an engine.<ref>[http://www.faa.gov/library/manuals/aircraft/glider_handbook/media/faa-h-8083-13.pdf FAA Glider handbook] {{webarchive|url=https://web.archive.org/web/20090206073836/http://www.faa.gov/library/manuals/aircraft/glider_handbook/media/faa-h-8083-13.pdf |date=2009-02-06 }}</ref> Most gliders do not have an engine, although [[motor-glider]]s have small engines for extending their flight when necessary by sustaining the altitude (normally a sailplane relies on rising air to maintain altitude) with some being powerful enough to take off by [[Motor glider|self-launch]].

There isare a wide variety of types differing in the construction of their wings, aerodynamic efficiency, location of the pilot, controls and intended purpose. Most exploit [[lift (soaring)|meteorological phenomena]] to maintain or gain height. Gliders are principally used for the [[air sport]]s of [[gliding]], [[hang gliding]] and [[paragliding]]. However some [[spacecraft]] have been designed to descend as gliders and in the past [[military glider]]s have been used in warfare. Some simple and familiar types of glider are toys such as [[paper plane]]s and [[balsa wood]] gliders.

''Glider'' is the [[agent noun]] form of the verb ''to glide''. It derives from Middle English ''gliden'', which in turn derived from Old English ''glīdan''. The oldest meaning of glide may have denoted a precipitous running or jumping, as opposed to a smooth motion. Scholars are uncertain as to its original derivation, with possible connections to "slide", and "light" having been advanced..<ref>Liberman, Anatoly. [http://userpage.fu-berlin.de/~alvismal/7etym.pdf "An Addendum to “Ten Scandinavian and North English Etymologies”"] {{Webarchive|url=https://web.archive.org/web/20160303195306/http://userpage.fu-berlin.de/~alvismal/7etym.pdf |date=2016-03-03 }}, from ''alvíssmál'' 7. 1997. 101–4101–104.</ref>

Early pre-modern accounts of flight are in most cases difficult to verify and it is unclear whether each craft was a glider, kite or parachute and to what degree they were truly controllable. Often the event is only recorded a long time after it allegedly took place. A 17th-century account reports an attempt at flight by the 9th-century poet [[Abbas Ibn Firnas]] near [[CordobaCórdoba, Spain]] which ended in heavy back injuries.<ref>[[Lynn Townsend White, Jr.]] (Spring, 1961) "Eilmer of Malmesbury, an Eleventh Century Aviator: A Case Study of Technological Innovation, Its Context and Tradition", ''Technology and Culture'' '''2''' (2), pp. 97–111 [100–101].</ref> The monk [[Eilmer of Malmesbury]] is reported by [[William of Malmesbury]] (c. 1080–1143{{Circa|1080|1143}}), a fellow monk and historian, to have flown off the roof of his [[Malmesbury Abbey|Abbey in Malmesbury]], [[England]], sometime between 1000 and 1010 AD, gliding about {{convert|200|m|yd}} before crashing and breaking his legs.<ref>White, L., Jr., ''Eilmer of Malmesbury, an Eleventh Century Aviator''. Medieval Religion and Technology. Los Angeles: University of California Press, 1978, Chapter 4.</ref> According to these reports, both used a set of (feathery) wings, and both blamed their crash on the lack of a tail.<ref>[[Lynn Townsend White, Jr.]] (Spring, 1961). "Eilmer of Malmesbury, an Eleventh Century Aviator: A Case Study of Technological Innovation, Its Context and Tradition", ''Technology and Culture'' '''2''' (2), pp. 97–111 [98 & 101].</ref> [[Hezârfen Ahmed Çelebi]] is alleged to have flown a glider with eagle-like wings over the [[Bosphorus]] strait from the [[Galata Tower]] to [[Üsküdar]] district in [[Istanbul]] around 1630–1632.<ref>[http://www.cmistanbulbogazici.com/who-is-hezarfen-ahmet-celebi/ Who is Hezarfen Ahmet Çelebi?] {{webarchive|url=https://web.archive.org/web/20160121173615/http://www.cmistanbulbogazici.com/who-is-hezarfen-ahmet-celebi/ |date=2016-01-21 }}</ref><ref>[http://www.privatetour.net/hezarfen-ahmet-celebi-the-first-man-to-fly Hezârfen Ahmed Çelebi "The First Man to Fly"] {{webarchive|url=https://web.archive.org/web/20160121173616/http://www.privatetour.net/hezarfen-ahmet-celebi-the-first-man-to-fly |date=2016-01-21 }}</ref><ref>Çelebi, Evliya (2003). Seyahatname. Istanbul: Yapı Kredi Kültür Sanat Yayıncılık, p. 318.</ref>

The first heavier-than-air (i.e. non-balloon) man-carrying aircraft that were based on published scientific principles were Sir [[George Cayley]]'s series of gliders which achieved brief wing-borne hops from around 1849. Thereafter gliders were built by pioneers such as [[Jean Marie Le Bris]], [[John J. Montgomery]], [[Otto Lilienthal]], [[Percy Pilcher]], [[Octave Chanute]] and [[Augustus Moore Herring]] to develop [[aviation]]. Lilienthal was the first to make repeated successful flights (eventually totaling over 2,000) and was the first to use rising air to prolong his flight. Using a Montgomery tandem-wing glider, [[Daniel J. Maloney|Daniel Maloney]] was the first to demonstrate high-altitude controlled flight using a balloon-launched glider launched from 4,000 feet in 1905.<ref>Harwood, Craig S. and Fogel, Gary B. ''Quest for Flight: John J. Montgomery and the Dawn of Aviation in the West,'', University of Oklahoma Press 2012.</ref>

In the inter-war years, [[glider (sailplane)|recreational gliding]] flourished in Germany under the auspices of [[Rhön-Rossitten Gesellschaft|Rhön-Rossitten]]. In the United States, the [[Schweizer brothers]] of Elmira, New York, manufactured sport sailplanes to meet the new demand. Sailplanes continued to evolve in the 1930s, and sport gliding has become the main application of gliders. As their performance improved, gliders began to be used to fly cross-country and now regularly fly hundreds or even over a thousand of kilometers in a day,<ref>{{cite web|url=https://www.fai.org/page/igc-1000km-badges|access-date=24 May 2019|title=FAI list of people with 1000km diplomas|date=5 October 2017|archive-date=8 May 2019|archive-url=https://web.archive.org/web/20190508043629/https://www.fai.org/page/igc-1000km-badges|url-status=live}}</ref> if the weather is suitable.

[[Military glider]]s were developed during [[World War II]] by a number of countries for landing troops. A glider – the [[Colditz Cock]] – was even built secretly by [[Prisoner of War|POWs]] as a potential escape method at [[Attempts to escape Oflag IV-C#The "Colditz Cock" glider|Oflag IV-C]] near the end of the war in 1944.

[[File:Lithuanian glider BrO-18 Boružė by Br.Oškinis, 1975.jpg|thumb|Smallest glider in the world -– BrO-18 "Boružė" ([[Coccinellidae|Ladybird]]), constructed in [[Lithuania]] in 1975]]

January 10, 1963 American [[Domina Jalbert]] filed a patent [httphttps://wwwpatents.google.com/patents?id=h81TAAAAEBAJpatent/US3131894 US Patent 3131894] on the [[Parafoil]] which had sectioned cells in an [[Airfoil|aerofoil]] shape; an open leading edge and a closed trailing edge, inflated by passage through the air – the ''ram-air'' design.<ref>{{Cite web |url=http://www.circlinghawk.com/history.html |title=History of Paragliding |access-date=2009-02-15 |archive-url=https://web.archive.org/web/20090913071154/http://www.circlinghawk.com/history.html |archive-date=2009-09-13 |url-status=dead }}</ref> The 'Sail Wing' was developed further for recovery of [[NASA]] space capsules by David Barish. Testing was done by using [[ridge lift]].<ref>{{Cite web |url=http://www.ushpa.aero/article.asp?id=29 |title=Pilot Profile: David Barish, the Probable Inventor of the Paraglider |access-date=2009-03-10 |archive-url=https://web.archive.org/web/20100608083256/http://www.ushpa.aero/article.asp?id=29 |archive-date=2010-06-08 |url-status=dead }}</ref> After tests on [[Hunter Mountain (New York)|Hunter Mountain]], [[New York (state)|New York]] in September 1965, he went on to promote "[[slope soaring]]" as a summer activity for [[ski resort]]s (apparently without great success).<ref>[http://www.flyaboveall.com/articles/davidbarish.htm David Barish, The Forgotten Father of Paragliding] {{webarchive|url=https://web.archive.org/web/20101029042939/http://www.flyaboveall.com/articles/davidbarish.htm |date=2010-10-29 }}</ref> NASA originated the term "paraglider" in the early 1960s, and ‘paragliding’ was first used in the early 1970s to describe foot-launching of gliding parachutes. Although their use is mainly recreational, unmanned paragliders have also been built for military applications e.g. [[Atair Insect]].

[[File:Glider2010-overgunma.ogv|thumb|325px|(video) A glider sails over [[Gunma prefecture|Gunma]], [[Japan]].]]

Initially training was done by short 'hops' in [[primary glider]]s which are very basic aircraft with no [[Cockpit (aviation)|cockpit]] and minimal instruments.<ref name="Schweizer">Schweizer, Paul A: ''Wings Like Eagles, The Story of Soaring in the United States'', pages 14–22. Smithsonian Institution Press, 1988. {{ISBN|0-87474-828-3}}</ref> Since shortly after [[World War II]] training has always been done in two-seat dual control gliders, but high performance two-seaters are also used to share the workload and the enjoyment of long flights. Originally skids were used for landing, but the majority now land on wheels, often retractable. Some gliders, known as [[motor glider]]s, are designed for unpowered flight, but can deploy [[Reciprocating engine|piston]], [[rotary engine|rotary]], [[jet engine|jet]] or [[electric motor|electric engines]].<ref name="definition">{{Cite web |url=http://www.fai.org/component/phocadownload/category/?download=5849:section-3-2012 |title=Definition of gliders used for sporting purposes in FAI Sporting Code |access-date=2013-01-01 |archive-url=https://web.archive.org/web/20140106224126/http://www.fai.org/component/phocadownload/category/?download=5849:section-3-2012 |archive-date=2014-01-06 |url-status=dead }}</ref> Gliders are classified by the [[Fédération Aéronautique Internationale|FAI]] for competitions into [[Glider Competition Classes|glider competition classes]] mainly on the basis of span and flaps.

* In the original and still most common designs, Class 1, the pilot is suspended from the center of the flexible wing and controls the aircraft by shifting his/hertheir weight.

A paraglider is a free-flying, foot-launched aircraft. The pilot sits in a harness suspended below a fabric wing. Unlike a hang glider whose wings have frames, the form of a paraglider wing is formed by the pressure of air entering vents or cells in the front of the wing. This is known as a ram-air wing (similar to the smaller parachute design). The paraglider's light and simple design allows them to be packed and carried in large backpackbackpacks, and make them one of the simplest and economical modes of flight. Competition level wings can achieve glide ratios up to 1:10 and fly around speeds of {{convert|45|km/h|mph|abbr=on}}.

Like sailplanes and hang gliders, paragliders use rising air (thermals or ridge lift) to gain height. This process is the basis for most recreational flights and competitions, though aerobatics and 'spot landing competitions' also occur. Launching is often done by jogging down a slope, but winch launches behind a towing vehicle are also used. A [[Paramotor]] is a paraglider wing powered by a motor attached to the back of the pilot, and is also known as a [[Powered paragliding|powered paraglidersparaglider]]. A variation of this is the [[paraplane]], which has a motor mounted on a wheeled frame rather than the pilot's back.

A paper plane, paper aeroplane (UK), paper airplane (US), paper glider, paper dart or dart is a toy aircraft (usually a glider) made out of paper or paperboard; the practice of constructing paper planes is sometimes referred to as aerogami (Japanese: kamihikōki), after origami, the Japanese art of paper folding.<ref>{{cite web |title=Aerogami -– Event Description |url=https://www.pragyan.org/16/home/events/chill_pill/aerogami/ |website=Pragyan |access-date=21 March 2019 |archive-date=21 March 2019 |archive-url=https://web.archive.org/web/20190321063409/https://www.pragyan.org/16/home/events/chill_pill/aerogami/ |url-status=live }}</ref>

A [[glide bomb]] is a bomb with aerodynamic surfaces to allow a gliding flightpath rather than a ballistic one. This allows the bomber aircraft to stand off from the target and launch the bomb from a safe distance. Most types have a remote control system which enables the aircraft to direct the bomb accurately to the target. Glide bombs were developed in Germany from as early as 1915. In [[World War II]] they were most successful as anti-shipping weapons. Some air forces today are equipped with gliding devices that can remotely attack airbases with a [[cluster bomb]] warhead.