View source for Wingtip device

{{Short description|Aircraft component fixed to the end of the wings to improve performance}}
{{distinguish|wing fence}}
{{Use mdy dates|date=March 2021}}
{{Use American English|date=March 2021}}
[[File:Airbus A350-941 F-WWCF MSN002 blended winglet ILA Berlin 2016 08.jpg|thumb|The [[Airbus A350]] wingtip device]]
[[File:737-NG winglet effect (simplified).svg|thumb|Line drawing of [[wingtip vortices]] behind a conventional wingtip (on the left) and a blended winglet (on the right)]]

'''Wingtip devices''' are intended to improve the efficiency of [[fixed-wing aircraft]] by reducing [[drag (physics)|drag]].<ref name="bca_aero_17_wingtip_devices">{{cite magazine |url= http://www.boeing.com/commercial/aeromagazine/aero_17/winglets.pdf |title= Blended winglets for improved airplane performance |author= Robert Faye, Robert Laprete, Michael Winter |magazine= Aero magazine |number= 17 |publisher= Boeing |date= January 2002 }}</ref> Although there are several types of [[wing tip]] devices which function in different manners, their intended effect is always to reduce an aircraft's drag. Such devices reduce drag by increasing the height of the lifting system, without greatly increasing the [[wingspan]]. Extending the span would reduce [[lift-induced drag]], but would increase [[parasitic drag]] and would require boosting the strength and weight of the wing. At some point, there is no net benefit from further increased span. There may also be operational considerations that limit the allowable wingspan (e.g. available width at [[Gate (airport)|airport gates]]).

== Physics ==

When a conventional [[wing]] generates lift, it also experiences [[lift-induced drag]]. Higher pressure air under the wing flows to the lower pressure surface on top at the wingtip, which results in a vortex caused by the forward motion of the aircraft. [[Erich Trefftz|Trefftz]]-plane theory shows that increasing the height of the lifting system will decrease induced drag. A vertical fin or winglet will reduce induced drag if it is placed anywhere along the wing off-center of the aircraft, but it is most effective when it is placed at the wingtip.<ref name="McLean Boeing" />

== Benefits ==

By reducing drag, wingtip devices increase [[fuel efficiency]] and aircraft [[Range (aircraft)|range]]. [[Aircraft performance]] is increased, allowing reduced takeoff field length due to better climb performance, and increased cruise altitude and cruise speed. Takeoff noise is also reduced.<ref name="McLean Boeing" /> In [[glider (sailplane)|glider]]s, reduced induced drag results in a higher cross-country speed, again increasing range.<ref name="bca_aero_17_wingtip_devices" /> Wingtip devices can also enhance safety for following aircraft, by reducing the strength of [[wingtip vortices]].

[[U.S. Air Force]] studies indicate that a given improvement in fuel efficiency correlates directly with the causal increase in the aircraft's lift-to-drag ratio.<ref>{{cite book |url= https://download.nap.edu/cart/download.cgi?record_id=11839 |title= Assessment of Wingtip Modifications to Increase the Fuel Efficiency of Air Force Aircraft |publisher= National Academies Press |date= 2007 |page= 33 |isbn= 978-0-309-38382-0 |author= Committee on Assessment of Aircraft Winglets for Large Aircraft Fuel Efficiency |work= Air Force Studies Board – Division on Engineering and Physical Sciences }}{{dead link|date=March 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

The average commercial jet sees a 4-6 percent increase in fuel efficiency and as much as a 6% decrease in in-flight noise from the use of winglets. Actual fuel savings and the related carbon output can vary significantly by plane, route and flight conditions.<ref>{{Cite web |title=The impact of winglets on fuel consumption and aircraft emissions |url=https://www.cirium.com/thoughtcloud/impact-winglets-on-fuel-consumption-and-aircraft-emissions/ |access-date=2022-08-02 |website=Cirium }}</ref>

== Early history ==

===Wing end-plates===
[[File:Blohm Voss Ha 137 side view.jpg|thumb|right|The [[Hamburger Flugzeugbau Ha 137|Ha 137]] prototype aircraft, fitted with vertical wing extensions, c.1935–1937]]
The initial concept dates back to 1897, when English engineer [[Frederick W. Lanchester]] patented wing end-plates as a method for controlling wingtip vortices.<ref name="nasa_c2r">{{cite book |chapter-url= https://history.nasa.gov/monograph29.pdf |title= Concept to Reality: Contributions of the Langley Research Center to US Civil Aircraft of the 1990s |chapter= Winglets |page= 35 |author= Joseph R. Chambers |publisher= [[NASA Langley Research Center]] |date= 2003 |isbn= 1493656783}}</ref> In the United States, Scottish-born engineer [[William E. Somerville]] patented the first functional winglets in 1910. Somerville installed the devices on his early biplane and monoplane designs.<ref>{{cite web |url= http://www.ilavhalloffame.org/members_10.htm |title= 2010 Inductees |publisher= Illinois Aviation Hall Of Fame |at= William E. "Billie" Somerville 1869–1950 }}</ref> [[Vincent Burnelli]] received US Patent no: 1,774,474 for his "Airfoil Control Means" on August 26, 1930.<ref>{{cite patent |country= US |number= 1774474  |title= Airfoil control means |pubdate= 26 Aug 1930 |fdate= 27 July 1929 |inventor= Vincent J Burnelli }}</ref>

Simple flat end-plates did not cause a reduction in drag, because the increase in profile drag was greater than the decrease in induced drag.<ref name="McLean Boeing">{{cite journal |last1=McLean |first1=Doug |title=Wingtip Devices: What They Do and How They Do It |journal=2005 Performance and Flight Operations Engineering Conference |date=2005 |page=Article 4 |url=https://mentourpilot.com/wp-content/uploads/2020/10/Wingtip_Devices-Doug-McLean-Boeing-flight-safety-conference-2005.pdf |access-date=18 March 2025 |publisher=Boeing}}</ref>

===Hoerner wing tips===
[[File:Heinkel He 162 CASM 2012 5 (cropped).jpg|thumb|[[Heinkel He 162A]] with ''Lippisch-Ohren'' wingtip devices]]

Following the end of World War II, Dr. [[Sighard F. Hoerner]] was a pioneer researcher in the field, having written a technical paper published in 1952<ref name="Aerodynamic Shape of the Wing Tips">{{cite journal|url= http://apps.dtic.mil/dtic/tr/fulltext/u2/a800374.pdf |title= Aerodynamic Shape of the Wing Tips |at= Technical Report No. 5752 |author= Hoerner, Dr. Sighard |journal= USAF Technical Reports |date= 1952 |publisher= Engineering Division, Air Materiel Command; Wright-Patterson Air Force Base, Dayton, Ohio; United States Air Force archive |archive-url= https://web.archive.org/web/20130316153354/http://www.dtic.mil/dtic/tr/fulltext/u2/a800374.pdf |url-status= live |archive-date= 2013-03-16 }}</ref> that called for drooped wingtips whose pointed rear tips focused the resulting wingtip vortex away from the upper wing surface. Drooped wingtips are often called "Hoerner tips" in his honor. Gliders and light aircraft have made use of Hoerner tips for many years.<ref name="History of Met-Co-Aire">{{cite web|last=Sakrison|first=David|date=2004|title=A German aerodynamicist, a California character, and a corkscrew|url=http://www.metcoaire.com/technical/tech_mcastory.shtml|url-status=live|archive-url=https://web.archive.org/web/20160322110205/http://www.metcoaire.com/technical/tech_mcastory.shtml|archive-date=March 22, 2016|publisher=Met-Co-Aire}}</ref><ref name="Aerodynamic Shape of the Wing Tips"/>

The earliest-known implementation of a Hoerner-style downward-angled "wingtip device" on a jet aircraft was during World War II.  This was the so-called "Lippisch-Ohren" (Lippisch-ears), allegedly attributed to the [[Messerschmitt Me 163]]'s designer [[Alexander Lippisch]], and first added to the M3 and M4 third and fourth prototypes of the [[Heinkel He 162]]A ''Spatz'' jet [[light fighter]] for evaluation.  This addition was done in order to counteract the [[dutch roll]] characteristic present in the original He 162 design, related to its wings having a marked [[Dihedral (aeronautics)|dihedral angle]].  This became a standard feature of the approximately 320 completed He 162A jet fighters built, with hundreds more He 162A airframes going unfinished by [[V-E Day]].<ref>{{cite book|last1=Creek|first1=J. Richard|url=http://www.scribd.com/doc/111359285/Aircraft-Profile-No-203-The-Heinkel-He-162|title=The Heinkel He 162 (Aircraft in Profile number 203)|last2=Conway|first2=William|date=1972|publisher=Profile Publications Ltd|location=Leatherhead, Surrey UK|pages=5|access-date=June 18, 2014|orig-year=1967|archive-date=August 19, 2013|archive-url=https://web.archive.org/web/20130819080135/http://www.scribd.com/doc/111359285/Aircraft-Profile-No-203-The-Heinkel-He-162|url-status=dead}}</ref>

== Winglets ==
{{Redirect|Winglet|the personal transporter by Toyota|Toyota Winglet}}
[[File:Winglet with attached tufts of an KC-135A.jpg|thumb|Winglet on [[KC-135 Stratotanker]] with attached [[Tuft (aeronautics)|tufts]] showing airflow during [[NASA]] tests in 1979–1980]]
[[File:NASA GulfstreamV in wind tunnel.jpg|thumb|[[Gulfstream V]] model winglet [[Aeroelasticity|flutter]] tests at [[NASA]] [[Langley Research Center|Langley]] [[Subsonic and transonic wind tunnel|transonic wind tunnel]]]]

The term "winglet" was previously used to describe an additional lifting surface on an aircraft, like a short section between wheels on fixed undercarriage. [[Richard T. Whitcomb|Richard Whitcomb's]] research in the 1970s at [[NASA]] first used winglet with its modern meaning referring to near-vertical extension of the [[wing tip]]s.<ref name="NASA innovation">{{cite book |title= NASA Innovation in Aeronautics: Select Technologies That Have Shaped Modern Aviation |publisher= [[National Aeronautics and Space Administration]] |author= Bargsten, Clayton J. |author2= Gibson, Malcolm T. |pages= 11–22 |url= https://www.hq.nasa.gov/office/aero/ebooks/downloads/nasa_innovation_in_aeronautics.pdf |date= August 2011 |access-date= November 1, 2017 |archive-date= September 21, 2021 |archive-url= https://web.archive.org/web/20210921060507/https://www.hq.nasa.gov/office/aero/ebooks/downloads/nasa_innovation_in_aeronautics.pdf |url-status= dead }}</ref>

Another potential benefit of winglets is that they reduce the intensity of [[wake vortices]].<ref>{{Citation |author= Richard T. Witcomb |title= A design approach and selected wind-tunnel results at high subsonic speeds for wing-tip mounted winglets |publisher= NASA |date= 1976 |url= https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760019075.pdf}}</ref> Those trail behind the plane and pose a hazard to other aircraft.<ref>{{Citation |title= London City Airport Wake Turbulence Study |publisher= Halcrow Group Limited |date= December 2010 |chapter-url= https://www.londoncityairport.com/content/pdf/LCY%20Wake%20Turbulence%20Study.pdf |chapter= Chapter 2 |url-status= bot: unknown |archive-url= https://web.archive.org/web/20171001213207/https://www.londoncityairport.com/content/pdf/LCY%20Wake%20Turbulence%20Study.pdf |archive-date= 2017-10-01 }}</ref> Minimum spacing requirements between aircraft operations at airports are largely dictated by these factors. Aircraft are [[Aircraft weight class|classified by weight]] (e.g. "Light", "Heavy", etc.) because the vortex strength grows with the aircraft [[lift coefficient]], and thus, the associated turbulence is greatest at low speed and high weight, which produced a high [[angle of attack]].{{Citation needed|date=September 2012}}

Winglets and wingtip fences also increase efficiency by reducing vortex interference with laminar airflow near the tips of the wing,<ref>{{cite book |title= Jar Professional Pilot Studies |pages= 2–11 |author= Phil Croucher |date= 2005 |isbn= 978-0-9681928-2-5 |publisher= Electrocution}}</ref> by 'moving' the confluence of low-pressure (over wing) and high-pressure (under wing) air away from the surface of the wing. Wingtip vortices create turbulence, originating at the leading edge of the wingtip and propagating backwards and inboard. This turbulence 'delaminates' the airflow over a small triangular section of the outboard wing, which destroys lift in that area. The fence/winglet drives the area where the vortex forms upward away from the wing surface, since the center of the resulting vortex is now at the tip of the winglet.{{Citation needed|date=September 2012}}

The [[Fuel economy in aircraft|fuel economy]] improvement from winglets increases with the mission length.<ref>{{cite magazine |url= http://www.boeing.com/commercial/aeromagazine/articles/qtr_03_09/pdfs/AERO_Q309.pdf |title= Blended Winglets Improve Performance |author= William Freitag, Terry Schulze |publisher= Boeing |magazine= Aero quarterly |date= Summer 2009 |pages= 9–12}}</ref>  Blended winglets allow a steeper angle of attack reducing [[takeoff]] distance.<ref>{{cite web |url= http://www.facc.com/content/download/4916/41556/file/Winglets%20Production.pdf |title= Winglets allow for steeper climbs |publisher= FACC AG |access-date= 2019-01-06 |archive-url= https://web.archive.org/web/20171107025237/http://www.facc.com/content/download/4916/41556/file/Winglets%20Production.pdf |archive-date= 2017-11-07 |url-status= dead }}</ref>

=== Early development ===
[[File:D-ALCF (14410530949).jpg|thumb|Winglet of [[McDonnell Douglas MD-11]]F]]
[[Richard T. Whitcomb]], an engineer at [[NASA]]'s [[Langley Research Center]], further developed Hoerner's concept in response to the sharp increase in the cost of fuel after the [[1973 oil crisis]]. With careful aeronautical design he showed that, for a given bending moment, a near-vertical winglet offers a greater drag reduction compared to a horizontal span extension.<ref name="McLean Understanding">{{cite book |last1=McLean |first1=Doug |title=Understanding aerodynamics : arguing from the real physics |date=2013 |publisher=Wiley-Blackwell |location=Chichester |isbn=978-1119967514 |page=422}}</ref> Whitcomb was the first to realize a net benefit in drag reduction by careful design to keep profile drag to a minimum.<ref name="McLean Boeing" />

Whitcomb's designs were flight-tested in 1979–80 by a joint NASA/Air Force team, using a [[KC-135 Stratotanker]] based at the [[Dryden Flight Research Center]].<ref name="nasa_c2r" /> A [[Lockheed L-1011]] and [[McDonnell Douglas DC-10]] were also used for testing, and the latter design was directly implemented by McDonnell Douglas on the derivative [[MD-11]], which was rolled out in 1990.<ref name="nasa_c2r" />

In May 1983, a high school student at [[Bowie High School (Maryland)|Bowie High School in Maryland]] won a grand prize at the 34th [[International Science and Engineering Fair]] in [[Albuquerque, New Mexico]] for the result of his research on wingtip devices to reduce drag.<ref>{{cite news |last1=Wynter |first1=Leon |title=Bowie Youth Sweeps Science 'World Series' |url=https://www.washingtonpost.com/archive/politics/1983/05/18/bowie-youth-sweeps-science-world-series/d620ac97-0aa7-4508-9da3-16c10f5277e4/ |newspaper=[[Washington Post]] |date=May 18, 1983}}</ref>{{importance inline|date=April 2021}} The same month, he filed a U.S. patent for "wingtip airfoils", published in 1986.<ref>patent {{patent|US|4595160}}</ref>{{importance inline|date=April 2021}}

===Implementations===

[[File:Learjet 28-29.jpg|thumb|A [[Learjet 28/29]], the first commercial aircraft with winglets]]

Learjet exhibited the prototype [[Learjet 28]] at the 1977 [[National Business Aviation Association]] convention. It employed the first winglets ever used on a production aircraft, either civilian or military. Learjet developed the winglet design without NASA assistance. Although the Model 28 was intended to be a prototype experimental aircraft, performance was such that it resulted in a production commitment from Learjet. Flight tests showed that the winglets increased range by about 6.5 percent and improved directional stability. Learjet's application of winglets to production aircraft continued with newer models including the [[Learjet 55]], [[Learjet 31|31]], [[Learjet 60|60]], [[Learjet 45|45]], and [[Learjet 40]].

[[Gulfstream Aerospace]] explored winglets in the late 1970s and incorporated winglets in the [[Gulfstream III]], [[Gulfstream IV]] and [[Gulfstream V]]. The Gulfstream V [[range (aircraft)|range]] of {{cvt|6500|nmi|km}} allows nonstop routes such as New York–Tokyo, it holds over 70 world and national flight records.<ref name="nasa_c2r"/>
The Rutan combined winglets-vertical stabilizer appeared on his [[Beechcraft Starship]] business aircraft design that first flew in 1986.

Winglets are also applied to other business aircraft, reducing take-off distance to operate from smaller airports, and allowing higher cruise altitudes. Along winglets on new designs, aftermarket vendors developed retrofits. Winglet Technology, LLC of [[Wichita, Kansas]] should have tested its elliptical winglets designed to increase [[payload-range]] on [[hot and high]] departures to retrofit the [[Citation X]].<ref>{{cite news |work= Aero news network |url= http://www.aero-news.net/index.cfm?ContentBlockID=7c28af6c-9576-41d4-97df-88d10885156c |title= Winglets Coming For Citation X Bizjets |date= March 13, 2007}}</ref>

Conventional winglets were fitted to Rutan's [[Rutan Voyager]], the first aircraft to circumnavigate the world without refueling in 1986. The aircraft's wingtips were damaged, however, when they dragged along the runway during takeoff, removing about {{convert|1|ft|cm|sigfig=1}} from each wingtip, so the flight was made without benefit of winglets.<ref>{{cite web|url=http://www.centennialofflight.net/essay/Explorers_Record_Setters_and_Daredevils/rutan/EX32.htm |title=Dick Rutan, Jeana Yeager, and the Flight of the Voyager |publisher= U.S. Centennial of Flight Commission}}</ref>

==== Wingtip fence ====
[[File:EC-JZY CDG-BCN (7173062326).jpg|thumb|Wingtip fences are featured on most Airbus legacy models.]]
A wingtip fence refers to the winglets including surfaces extending both above and below the wingtip, as described in Whitcomb's early research.<ref name="NASA innovation" /> Both surfaces are shorter than or equivalent to a winglet possessing similar aerodynamic benefits. The [[Airbus A310-300]] was the first airliner with wingtip fences in 1985.<ref>{{cite web |url= http://www.airbus.com/en/corporate/innovation/ |work= Corporate information – Innovation & technology |publisher= Airbus |title= From the A300 to the A380: Pioneering leadership |url-status= bot: unknown |archive-url= https://web.archive.org/web/20090421092103/http://www.airbus.com/en/corporate/innovation/ |archive-date= 2009-04-21 }}</ref> Other Airbus models followed with the [[Airbus A300-600|A300-600]], the [[A320ceo]], and the [[Airbus A380|A380]]. Other Airbus models including the [[Airbus A320 Enhanced]], [[A320neo]], [[Airbus A350|A350]] and [[A330neo]] have blended winglets rather than wingtip fences. The [[Antonov An-158]] uses wingtip fences.

==== Canted winglets ====
[[Boeing]] announced a new version of the [[Boeing 747|747]], the [[747-400]], in 1985, with an extended range and capacity, using a combination of winglets and increased span to carry the additional load. The winglets increased the 747-400's range by 3.5% over the 747-300, which is otherwise aerodynamically identical but has no winglets. The 747-400D variant lacks the wingtip extensions and winglets included on other 747-400s since winglets would provide minimal benefits on short-haul routes while adding extra weight and cost, although the -400D may be converted to the long-range version if needed.<ref name="bca_aero_17_wingtip_devices"/> Winglets are preferred for Boeing derivative designs based on existing platforms, because they allow maximum re-use of existing components. Newer designs are favoring increased span, other wingtip devices or a combination of both, whenever possible.{{citation needed|date=November 2017}}

The [[Ilyushin Il-96]] was the first Russian and modern jet to feature winglets in 1988. The [[Bombardier CRJ-100]]/200 was the first regional airliner to feature winglets in 1992. The [[Airbus A340|A340]]/[[Airbus A330|A330]] followed with canted winglets in 1993/1994. The [[Tupolev Tu-204]] was the first [[narrowbody]] aircraft to feature winglets in 1994. The [[Airbus A220]] (née CSeries), from 2016, has canted winglets. 

==== Blended winglets ====
A blended winglet is attached to the wing with a smooth curve instead of a sharp angle and is intended to reduce [[interference drag]] at the wing/winglet junction. A sharp interior angle in this region can interact with the [[boundary layer]] flow causing a drag inducing vortex, negating some of the benefit of the winglet. [[Seattle]]-based [[Aviation Partners]] develops blended winglets as retrofits for the [[Gulfstream II]], [[Hawker 800]] and the [[Falcon 2000]].

<gallery mode="packed" heights="140px">
File:Winglet and nav light arp.jpg|[[Boeing 747-400]] canted winglet
File:Lufthansa winglet (14511808755).jpg|[[A320 family|Airbus A320]] sharklet (blended winglet)
File:Delta Air Lines 767-400ER @LHR.jpg|[[Boeing 767#767-400ER|Boeing 767-400ER]] with raked wingtips
File:Wing.slat.600pix.jpg|[[Airbus A310-300]] wingtip fence
</gallery>

On February 18, 2000, blended winglets were announced as an option for the [[Boeing 737 Next Generation#737-800|Boeing 737-800]]; the first shipset was installed on 14 February 2001 and entered revenue service with [[Hapag-Lloyd Flug]] on 8 May 2001.<ref>{{cite web |url= http://boeing.com:80/commercial/737family/pf/pf_ng_milestones.html |archive-url= https://web.archive.org/web/20080429193504/http://boeing.com/commercial/737family/pf/pf_ng_milestones.html |url-status= dead |archive-date= 2008-04-29 |title= Next-Generation 737 Program Milestones |publisher= Boeing |access-date= 2019-02-05 }}</ref> The Aviation Partners/Boeing {{cvt|8|ft|m}} extensions decrease [[fuel economy in aircraft|fuel consumption]] by 4% for long-range flights and increase range by {{cvt|130 or 200|nmi|km}} for the 737-800 or the derivative [[Boeing Business Jet]] as standard.<ref name="bca_aero_17_wingtip_devices" /> Also offered for the [[737 Classic]], many operators have retrofitted their fleets with these for the fuel savings.{{citation needed|date=November 2018}} Aviation Partners Boeing also offers blended winglets for the [[Boeing 757|757]] and [[Boeing 767|767-300ER]].<ref>{{cite magazine |magazine= [[Aviation Week & Space Technology]] |date= February 23, 2009 |url= http://aviationweek.com/awin/american-airlines-set-debut-767-winglet-mod |title= American Airlines Set To Debut 767 Winglet Mod |author= Guy Norris |page= 39 |url-access= subscription}}</ref> In 2006 Airbus tested two candidate blended winglets, designed by Winglet Technology and Airbus for the [[Airbus A320 family]].<ref>{{cite news |url= http://www.boeing.com/news/frontiers/archive/2006/march/i_iw.html |at= Airbus to test new winglets for single-aisle jetliners |title= Industry Wrap |publisher= Boeing |work= Frontiers |volume= 4 |issue= 10 |date= March 2006}}</ref> In 2009 Airbus launched its "Sharklet" blended winglet, designed to enhance the [[payload-range]] of its [[A320 family]] and reduce fuel burn by up to 4% over longer sectors.<ref>{{cite press release |url= http://www.airbus.com/newsroom/press-releases/en/2013/07/american-airlines-takes-delivery-of-its-first-a320-family-aircraft.html |title= American Airlines takes delivery of its first A320 Family aircraft |publisher= Airbus |date= July 23, 2013 |access-date= November 1, 2017 |archive-date= November 7, 2017 |archive-url= https://web.archive.org/web/20171107005102/http://www.airbus.com/newsroom/press-releases/en/2013/07/american-airlines-takes-delivery-of-its-first-a320-family-aircraft.html |url-status= dead }}</ref> This corresponds to an annual CO<sub>2</sub> reduction of 700 tonnes per aircraft.<ref>{{cite press release |url= http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/korean-air-aerospace-to-manufacture-new-a320-family-sharklets/ |title= Korean Air Aerospace to manufacture and distribute Sharklets |publisher= Airbus |date= May 31, 2010 }}</ref> The A320s fitted with Sharklets were delivered beginning in 2012.<ref name="Airbus15Nov09">{{cite web |url =http://www.aircraft.airbus.com/presscentre/pressreleases/press-release-detail/detail/airbus-launches-sharklet-large-wingtip-devices-for-a320-family-with-commitment-from-air-new-zealan/ |title =Airbus launches "Sharklet" large wingtip devices for A320 Family with commitment from Air New Zealand |publisher =[[Airbus]] |date =15 November 2009 |url-status =dead |archive-url =https://web.archive.org/web/20171107021641/http://www.aircraft.airbus.com/presscentre/pressreleases/press-release-detail/detail/airbus-launches-sharklet-large-wingtip-devices-for-a320-family-with-commitment-from-air-new-zealan/ |archive-date =7 November 2017 }}</ref><ref name=":0">{{Cite web|last=Gardiner|first=Ginger|date=May 1, 2014|title=First A320neo features composite Korean Sharklets|url=https://www.compositesworld.com/articles/first-a320neo-in-final-assembly-features-composite-sharklets-made-in-korea|access-date=2020-09-09|website=CompositesWorld}}</ref> They are used on the [[A320neo]], the [[A330neo]] and the [[Airbus A350|A350]]. They are also offered as a retrofit option.<ref name=":0" /><ref>{{Cite web|title=Airbus Selects Korean Air Aerospace to manufacture Sharklet wingtips for the A330neo Family|url=https://www.airbus.com/newsroom/press-releases/en/2015/04/airbus-selects-korean-air-aerospace-to-manufacture-sharklet-wingtips-for-the-a330neo-family.html|archive-url=https://web.archive.org/web/20230126121852/https://www.airbus.com/newsroom/press-releases/en/2015/04/airbus-selects-korean-air-aerospace-to-manufacture-sharklet-wingtips-for-the-a330neo-family.html|url-status=dead|archive-date=January 26, 2023|access-date=2020-09-09|website=Airbus}}</ref>

==== Raked wingtip ====

Raked wingtips, where the tip has a greater [[wing sweep]] than the rest of the wing, are featured on some [[Boeing Commercial Airplanes]] to improve [[fuel efficiency]], takeoff and climb performance. Like winglets, they increase the effective [[wing aspect ratio]] and diminish [[wingtip vortices]], decreasing lift-induced drag. In testing by Boeing and NASA, they reduce drag by as much as 5.5%, compared to 3.5% to 4.5% for conventional winglets.<ref name="bca_aero_17_wingtip_devices" />  While an increase in span would be more effective than a same-length winglet, its [[bending moment]] is greater.  A {{cvt|3|ft|cm}} winglet gives the performance gain of a {{cvt|2|ft|cm}} span increase but has the bending force of a {{cvt|1|ft|cm}} span increase.<ref name="airspace">{{cite web |url= https://www.airspacemag.com/flight-today/how-things-work-winglets-2468375/ |title= How Things Work: Winglets |work= Air & Space Magazine |date= September 2001 |author= George C. Larson |publisher= Smithsonian}}</ref>
[[File:Anh-2-15222236062661656996940.jpg|thumb|The [[Boeing 787 Dreamliner]] is an example of raked wingtips utilization.]]
Raked wingtips offer several weight-reduction advantages relative to simply extending the conventional main [[wingspan]]. At high load-factor structural design conditions, the smaller [[Chord (aeronautics)|chords]] of the wingtip are subjected to less load, and they result in less induced loading on the outboard main wing. Additionally, the leading-edge [[Swept wing|sweep]] results in the [[Center of pressure (fluid mechanics)|center of pressure]] being located farther aft than for simple extensions of the span of conventional main wings. At high load factors, this relative aft location of the center of pressure causes the raked wingtip to be twisted more leading-edge down, reducing the bending moment on the inboard wing. However, the relative aft-movement of the center of pressure accentuates [[Aeroelasticity#Flutter|flutter]].<ref>{{Cite web|last=Herrick|first=Larry|date=June 12, 1998 |title=Blunt Leading-Edge Raked Wingtips|url=https://patentimages.storage.googleapis.com/71/cf/0d/66512395e96100/US6089502.pdf|access-date=2021-12-06|website=Google Patents}}</ref>

Raked wingtips are installed on the [[Boeing 767]]-400ER (first flight on October 9, 1999), all generations of [[Boeing 777]] (June 12, 1994) including the upcoming [[Boeing 777X|777X]], the 737-derived [[Boeing P-8 Poseidon]] (25 April 2009), all variants of the [[Boeing 787]] (December 15, 2009) (the cancelled [[Boeing 787#787-3|Boeing 787-3]] would have had a {{cvt|51.7|m|ft|order=flip}} wingspan to fit in [[ICAO#Aerodrome Reference Code|ICAO Aerodrome Reference Code]] D, as its wingspan was decreased by using blended winglets instead of raked wingtips <ref>{{cite web |url= http://www.aci-na.org/static/entransit/Gen.%20Rich%20Breuhaus.pdf |title= 787 Dreamliner: A New Airplane for a New World |author= Rich Breuhaus |date= 20 May 2008 |publisher= Boeing |work= ACI-NA Commissioners Conference |access-date= 2019-01-06 |archive-url= https://web.archive.org/web/20170307045010/http://www.aci-na.org/static/entransit/Gen.%20Rich%20Breuhaus.pdf |archive-date= 2017-03-07 |url-status= dead }}</ref>), and the [[Boeing 747-8]] (February 8, 2010). The Embraer [[E-jet E2]] and [[Embraer C-390 Millennium|C-390 Millennium]] wings also have raked wingtips.

==== Split-tip ====

[[File:Boeing 737-8 MAX Belyakov.jpg|thumb|upright|737 MAX split-tip winglet]]
The [[McDonnell Douglas MD-11]] was the first aircraft with split-tip winglets in 1990.

For the [[737 Next Generation]], third-party vendor [[Aviation Partners]] has introduced a similar design to the 737 MAX wingtip device known as the split scimitar winglet,<ref>{{cite web | url=http://www.aviationpartnersboeing.com/products_737_800_3.php | title=737-800-3 | work=Aviation Partners Boeing }}</ref> with [[United Airlines]] as the launch customer.<ref>{{cite press release | url= http://newsroom.united.com/2013-07-17-United-Airlines-is-First-to-Install-Split-Scimitar-Winglets | title= United is first to install Split Scimitar winglets |publisher= United Airlines | date=July 17, 2013}}</ref>

The [[Boeing 737 MAX]] uses a new type of wingtip device.<ref>{{cite web |url=http://www.nycaviation.com/2012/05/boeing-says-radical-new-winglets-on-737-max-will-save-more-fuel/ |title=Boeing Says Radical New Winglets on 737 MAX Will Save More Fuel |author= Matt Molnar  |date=2 May 2012  |work=NYCAviation }}</ref>  Resembling a three-way hybrid of a winglet, wingtip fence, and raked wingtip, Boeing claims that this new design should deliver an additional 1.5% improvement in fuel economy over the 10-12% improvement already expected from the 737 MAX.

==== Gliders ====
[[File:Schempp-Hirth Ventus 2b glider being launched at Lasham Airfield in UK.jpg|thumb|[[Schempp-Hirth Ventus-2]] [[glider (sailplane)|glider]] with factory winglets [[Gliding#winchlaunch|winch-launching]]]]

In 1987, [[mechanical engineering|mechanical engineer]] [[Peter Masak]] called on aerodynamicist [[Mark D. Maughmer]], an associate professor of aerospace engineering at the [[Pennsylvania State University]], about designing winglets to improve performance on his {{convert|15|m|ft|adj=on|sp=us}} wingspan racing [[sailplane]]. Others had attempted to apply Whitcomb's winglets to gliders before, and they did improve climb performance, but this did not offset the parasitic drag penalty in high-speed cruise. Masak was convinced it was possible to overcome this hurdle.<ref>{{cite web |url= http://www.engr.psu.edu/newsevents/EPS/v16n3_2000summer/tip.htm |title= The tip of the iceberg |author= Curtis Chan |date= Summer 2000 |volume= 16 |issue= 3 |work= Engineering Penn State magazine |url-status= bot: unknown |archive-url= https://web.archive.org/web/20040611220212/http://www.engr.psu.edu/newsevents/EPS/v16n3_2000summer/tip.htm |archive-date= 2004-06-11 }}</ref> By trial and error, they ultimately developed successful winglet designs for [[gliding competitions]], using a new PSU–90–125 [[airfoil]], designed by Maughmer specifically for the winglet application. At the 1991 [[World Gliding Championships]] in [[Uvalde, Texas]], the trophy for the highest speed went to a winglet-equipped 15-meter class limited wingspan glider, exceeding the highest speed in the unlimited span [[Glider competition classes|Open Class]], an exceptional result.<ref>{{cite journal|last=Masak|first=Peter|date=April–May 1992|title=Winglet Design for Sailplanes|journal=Free Flight|volume=1992|issue=2|page=8|issn=0827-2557|url=http://www.postfrontal.com/PDF/Winglets_01.pdf}}</ref> Masak went on to win the 1993 U.S. 15 Meter Nationals gliding competition, using winglets on his prototype [[Masak Scimitar]].<ref>{{cite web |url= http://ridgesewing.com/mifflin/contests.htm |title= Past Mifflin Contests |publisher= Mifflin Soaring Association}}</ref>

[[File:PSU-90-125.PNG|thumb|PSU-90-125 winglet [[airfoil]] profile]]
The Masak winglets were originally retrofitted to production sailplanes, but within 10 years of their introduction, most high-performance gliders were equipped from the factory with winglets or other wingtip devices.<ref>{{cite web |url= http://www.mandhsoaring.com/Why%20Winglets/WL-Soaring.pdf |title= About Winglets |author= Mark D. Maughmer |work= [[Soaring Magazine]] |date= June 2002 |author-link= Mark D. Maughmer }}</ref> It took over a decade for winglets to first appear on a production airliner, the original application that was the focus of the NASA development. Yet, once the advantages of winglets were proven in competition, adoption was swift with gliders. The point difference between the winner and the runner-up in soaring competition is often less than one percent, so even a small improvement in efficiency is a significant competitive advantage. Many non-competition pilots fitted winglets for handling benefits such as increased [[roll (flight)|roll rate]] and roll authority and reduced tendency for wing tip [[stall (flight)|stall]]. The benefits are notable, because sailplane winglets must be removable to allow the glider to be stored in a [[Trailer (vehicle)|trailer]], so they are usually installed only at the pilot's preference.{{citation needed|date=May 2015}}

The [[Glaser-Dirks DG-300|Glaser-Dirks DG-303]], an early glider derivative design, incorporating winglets as factory standard equipment.

== Non-planar wingtip ==
[[File:Spiroid winglet.jpg|thumb|A Falcon 50 with a spiroid winglet]]

[[Aviation Partners]] developed and flight tested a [[Closed wing|closed-surface]] Spiroid winglet on a [[Dassault Falcon 50|Falcon 50]] in 2010.<ref>{{cite web |url= http://www.aviationpartners.com/aircraft-winglets/types-blended-winglets/ |title= Types of blended winglets |publisher= Aviation Partners}}</ref>

Non-planar wingtips are normally angled upwards in a polyhedral wing configuration, increasing the local [[dihedral (aircraft)|dihedral]] near the wing tip, with polyhedral wing designs themselves having been popular on [[Free flight (model aircraft)|free-flight]] model aircraft designs for decades. Non-planar wingtips provide the wake control benefit of winglets, with less parasitic drag penalty, if designed carefully. The non-planar wing tip is often swept back like a [[#Raked wingtip|raked wingtip]] and may also be combined with a [[#Winglet|winglet]]. A winglet is also a special case of a non-planar wingtip.{{citation needed|date=May 2015}}

Aircraft designers employed mostly planar wing designs with simple dihedral after World War II, prior to the introduction of winglets. With the wide acceptance of winglets in new sailplane designs of the 1990s, designers sought to further optimize the aerodynamic performance of their wingtip designs. Glider winglets were originally retrofitted directly to planar wings, with only a small, nearly right-angle, transition area. Once the performance of the winglet itself was optimized, attention was turned to the transition between the wing and winglet. A common application was tapering the transition area from the wing tip [[chord (aircraft)|chord]] to the winglet chord and raking the transition area back, to place the winglet in the optimal position. If the tapered portion was canted upward, the winglet height could also be reduced. Eventually, designers employed multiple non-planar sections, each canting up at a greater angle, dispensing with the winglets entirely.{{citation needed|date=May 2015}}

The [[Schempp-Hirth Discus-2]] and [[Schempp-Hirth Duo Discus]] use non-planar wingtips.

== Active wingtip device ==
[[File:Tamarack Aerospace - AV.N86LA.RAMP.102315.6.7x5.jpg|thumb|Tamarack Aerospace's active wingtip device]]
Tamarack Aerospace Group, a company founded in 2010 by aerospace structural engineer Nicholas Guida, has patented an Active Technology Load Alleviation System (ATLAS), a modified version of a wingtip device.<ref name=":1">{{Cite web|last=Gerzanics|first=Mike|date=October 23, 2019|title=ANALYSIS: ATLAS Citation separates winglet from 'blinglet'|url=https://www.flightglobal.com/analysis/analysis-atlas-citation-separates-winglet-from-blinglet/134703.article|access-date=2020-09-09|website=Flight Global}}</ref> The system uses Tamarack Active Camber Surfaces (TACS) to aerodynamically "switch off" the effects of the wingtip device when the aircraft is experiencing high-g events such as large gusts or severe pull-ups. TACS are movable panels, similar to [[Flap (aeronautics)|flaps]] or [[aileron]]s, on the trailing edge of the wing extension.<ref name=":1" /><ref name=":2">{{Cite patent|country=US|number=7900877B1|title=Active winglet|status=patent|pubdate=2011-03-08|gdate=2010-09-24|invent1=Guida|inventor1-first=Nicholas R.|url=https://patents.google.com/patent/US7900877B1/en}}</ref> The system is controlled by the aircraft's electrical system and a high-speed [[Servomotor|servo]] which is activated when the aircraft senses an oncoming stress event, essentially simulating an actuating wingtip. However, the wingtip itself is fixed and the TACS are the only moving part of the wingtip system. Tamarack first introduced ATLAS for the [[Cessna Citation family]] aircraft,<ref name=":1" /><ref name=":2" /> and it has been certified for use by the [[Federal Aviation Administration]] and [[European Union Aviation Safety Agency]].<ref>{{Cite web|last=Bergqvist|first=Pia|date=February 6, 2018|title=Tamarack Active Winglets Certified for Citation 525 Series|url=http://www.flyingmag.com/tamarack-active-winglets-certified-for-citation-525-series/|access-date=2020-09-09|website=Flying}}</ref><ref>{{Cite web|last=Finfrock|first=Rob|date=July 8, 2019|title=EASA Approves Tamarack Fixes To Lift Atlas Emergency AD|url=https://www.ainonline.com/aviation-news/business-aviation/2019-07-08/easa-approves-tamarack-fixes-lift-atlas-emergency-ad|access-date=2020-09-09|website=Aviation International News}}</ref>

== Actuating wingtip device ==
There has been research into actuating wingtip devices, including a filed patent application,<ref>
{{cite patent |country= EP |number= 1531126 |title= Wing tip device |pubdate= 2005-05-18 |invent1= Jan Irving |invent2= Robert Davies |assign1= Airbus}}</ref> though no aircraft currently uses this feature as described. The [[XB-70 Valkyrie]]'s wingtips were capable of drooping downward in flight, to facilitate [[Mach number|Mach 3]] flight using [[WaveRider|waveriding]].

== Use on rotating blades ==

Wingtip devices are also used on rotating [[Propeller (aircraft)|propeller]], [[helicopter rotor]], and [[wind turbine]] blades to reduce drag, reduce diameter, reduce noise and/or improve efficiency. By reducing aircraft blade tip vortices interacting with the ground surface during [[taxiing]], [[takeoff]], and [[Hover (helicopter)|hover]], these devices can reduce damage from dirt and small stones picked up in the vortices.<ref name=HP>{{cite web |url= http://www.hartzellpropellers.com/product_support/support_faqs.htm |title= What is a Q-Tip propeller? What are its advantages? |work= Product Support: Frequently Asked Questions |publisher= [[Hartzell Propeller]] |quote= Aerodynamic improvements include a reduced diameter and decreased tip speeds. This results in quieter operation and reduced tip vortices. The 90° bend reduces the vortices that, on traditional blades, pick up debris that can contact the blades and cause nicks, gouges and scratches. |url-status= bot: unknown |archive-url= https://web.archive.org/web/20010318034156/http://www.hartzellpropellers.com/product_support/support_faqs.htm |archive-date= 2001-03-18 }}</ref>

<gallery mode="packed" heights="140px">
File:Merlin at RIAT 2009.JPG|[[AgustaWestland AW101]] Merlin showing [[BERP rotor]] with distinctive blade tip profile
File:Hercules.propeller.arp.jpg|[[C-130J Super Hercules]] showing [[scimitar propeller]]s with raked tips
File:WindTurbine Rotor Winglet.JPG|Detail view of the wingtip device on a wind turbine rotor-blade
File:Ceiling fan at Chicago O'Hare Airport.jpg|Ceiling fan with wingtip devices
</gallery>

=== Rotorcraft applications ===
[[File:ILA 2018, Schönefeld (1X7A5334).jpg|thumb|Wingtip device on a [[NHIndustries NH90]]]]
The main rotor blades of the [[AgustaWestland AW101]] (formerly the EH101) have a distinctive tip shape; pilots have found that this rotor design alters the downwash field and reduces [[Brownout (aviation)|brownout]] which limits visibility in dusty areas and leads to accidents.<ref name=NG>{{cite web|url=http://ngccommunity.nationalgeographic.com/ngcblogs/explorer/engineering/|first=Gareth|last=Harvey|title=Super Chopper : Life-Saving Features: No More Brown-Outs|publisher=National Geographic Channel|work=Engineering Archives|access-date=August 1, 2009|date=November 28, 2005|quote=To counteract this, the EH101's 'winged-tip' rotor blades create what its pilots call the "donut effect" – a circular window of clear air inside the dust storm that allows them to see the ground as they come in to land.|url-status=dead|archive-url=https://web.archive.org/web/20090721184318/http://ngccommunity.nationalgeographic.com/ngcblogs/explorer/engineering/|archive-date=July 21, 2009}}</ref>

=== Propeller applications ===
[[Hartzell Propeller]] developed their "Q-tip" propeller used on the [[Piper PA-42 Cheyenne]] and several other fixed-wing aircraft types by bending the blade tips back at a 90-degree angle to get the same [[thrust]] from a reduced diameter propeller disk; the reduced propeller tip speed reduces noise, according to the manufacturer.<ref name=HP/> Modern [[scimitar propeller]]s have increased [[sweepback]] at the tips, resembling a raked tip on an aircraft wing.

=== Other applications ===
Some [[ceiling fan]]s have wingtip devices. Fan manufacturer [[Big Ass Fans]] has claimed that their Isis fan, equipped with wingtip devices, has superior efficiency.<ref>{{cite news |author= Nino Machetti |url= http://earthtechling.com/2010/05/isis-ceiling-fan-claims-higher-energy-efficiency/ |title= Isis ceiling fan claims higher efficiency |date= May 10, 2010 |publisher= EarthTechling}}</ref> However, for certain high-volume, low-speed designs, wingtip devices may not improve efficiency.<ref name="macroair">{{cite news |author= Eddie Boyd |url= https://macroairfans.com/blog/winglets-help-hindrance-hvls-fan-performance/ |title= Winglets: Help or Hindrance to HVLS Fan Performance?|publisher= MacroAir |date= February 4, 2014}}</ref>
Another application of the same principle was introduced to the keel of the "America's Cup"- winning Australian yacht [[Australia II]] of 1982, designed by [[Ben Lexcen]].

==See also==
*[[Oswald efficiency number]]

== References ==
{{Reflist}}

== External links ==
{{Commons category|Wingtip devices (aircraft wings)}}
* {{cite web |url = http://www.soaridaho.com/Schreder/Technical/Winglets/Masak.htm |title= Winglet Design for Sailplanes |author = Peter Masak |year = 1991|author-link= Peter Masak }}
* {{cite web |url = http://www.mh-aerotools.de/airfoils/winglets.htm |title= A close Look at Winglets |author = Martin Hepperle |work = International Nurflügelmeeting des MFC Osnabrück |date= May 1993}}
* {{cite magazine |url = https://www.flightglobal.com/news/articles/winglet-benefits-17118/ |title = Winglet benefits |date= 1 May 1996 |magazine= Flight International |at= Winglets could bring operational benefits to the Boeing 747-200F }}
* {{cite press release |url= http://boeing.mediaroom.com/2003-10-16-New-Boeing-777-300ER-Bristles-with-Technology |publisher= Boeing |title= New Boeing 777-300ER Bristles with Technology |date= Oct 16, 2003 }}
* {{cite web |url= http://www.aerospaceweb.org/question/aerodynamics/q0148.shtml |title= Boeing 767 Raked Wingtips |author= Joe Yoon |date= 2 November 2003 |website = Aerospaceweb.org }}
* {{cite magazine |url = http://www.aviationpartnersboeing.com/pdf/news/at69winglets.pdf |title= Winglets: making their presence felt |magazine= Aircraft Technology Engineering & Maintenance |date= April–May 2004 }}
* {{cite web |url=https://mentourpilot.com/wp-content/uploads/2020/10/Wingtip_Devices-Doug-McLean-Boeing-flight-safety-conference-2005.pdf |title=Wingtip Devices: What They Do and How They Do It |author=Doug McLean |publisher=Boeing |date=2005 |work=Performance and Flight Operations Engineering Conference }}
* {{cite magazine |url = http://www.aviationpartnersboeing.com/pdf/news/109_FLTOPS_2.pdf |title= The benefits of winglets and performance enhancing kits |magazine= Aircraft Commerce |issue= 109 |date= December 2016 – January 2017 }}

{{Aircraft components}}

{{DEFAULTSORT:Wingtip Device}}
[[Category:Aircraft aerodynamics]]
[[Category:Aircraft configurations]]
[[Category:Aircraft wing components]]
[[Category:NASA spin-off technologies]]