Gull wing

The gull wing was first implemented on a glider, specifically the Weltensegler, which performed its maiden flight in 1921. Its wings, which were externally braced, featured swept-back wingtips with negative incidence relative to the remainder of the main-plane.Simons, Martin. Sailplanes 1920-1945 2nd revised edition. EQIP Werbung und Verlag G.m.b.H.. Königswinter. 2006. {{ISBN|3-9806773-4-6}} The Weltensegler also used a unique control system, consisting of a various pulleys and springs connected to a single control stick for the pilot, which warped the wing-tips as directed by the pilot. This unorthodox method relied upon the incidence changing with the increase and release of tension, and was also expected to confer increased stability in pitch and roll by automatic changes in wing-tip incidence; however, it gave no direct control over the wing-tips. The flying career of the Weltensegler was very brief, it being destroyed during the 1921 Rhön gliding competition after the wing failed during a sharp spiralling dive at excessive speed, resulting in the death of Willy Leusch, the Weltensegler's company test pilot.Hoff, Wilhelm. “Technical memorandum No. 100, Rhön Soaring Flight Competition, 1921”. National Advisory Committee for Aeronautics. Washington D.C.. June 1922.

Following the Weltensegler's tragic loss, the gull wing was avoided by the majority of aircraft designers for almost a whole decade. During 1930, Alexander Lippisch's record-breaking Fafnir represented a high-profile comeback for the gull wing, which contributed to its resurgence shortly thereafter. Fafnir featured a laterally stabilising dihedral, an uncommon feature for gliders of the era, which spanned roughly 40 percent of the inner wing span.{{cite book |title=Sailplanes 1920-1945 |last=Simons |first=Martin |edition=2nd revised |year=2006 |publisher= EQIP Werbung & Verlag GmbH |location=Königswinter |isbn=3-9806773-4-6 |pages=65–70}} Lippisch had chosen to adopt this configuration for its increased wingtip clearance, as well as the ill-founded belief that it would improve its stability during turns; however, studies have shown that normal gull wing configurations result in significantly less severe and more easily recoverable stalls. Inverted gull wings exhibit the opposite stall behaviour, but both normal and inverted gull wings impede lift-to-drag ratio and climb performance.{{Cite web |title=Flight Testing and Response Characteristics of a Variable Gull-Wing Morphing Aircraft |url=http://dnc.tamu.edu/projects/flowcontrol/Morphing/public_html/papers/florida3.pdf |publisher=University of Florida |access-date=28 April 2012 |last=Abdulrahim |first=Mujahid |author2=Lind, Rick |pages=5–8 |archive-date=5 October 2013 |archive-url=https://web.archive.org/web/20131005001610/http://dnc.tamu.edu/projects/flowcontrol/Morphing/public_html/papers/florida3.pdf |url-status=dead }}

The performance demonstrated by Fafnir, such as a {{convert|220|km|mi|abbr=on}} flight between the Wasserkuppe and Magdeburg in late August 1930 that established a new world record, quickly encouraged numerous aircraft designers to perform their own investigations into the gull wing.{{cite book |title=Segelflug im Wettbewerb der Völker|last= Zuerl |first= Hubert |year=1941|publisher=E. S. Mittler & Sohn |location= Berlin|page=203 }} Accordingly, numerous other gliders, as well as other platforms, would soon feature broadly similar wing configurations as well. Having become a trend of the glider industry during the 1930s, the gull wing remained a staple feature amongst high-performance sailplanes through to the 1950s.{{Citation needed|date=November 2020}}

;Notable gull wing sailplanes:

• Bowlus Senior Albatross
• DFS Habicht
• DFS Kranich
• DFS Reiher
• Göppingen Gö 3 Minimoa
• Lawrence Tech IV "Yankee Doodle"
• Lippisch Fafnir
• Ross RS-1 Zanonia
• Schweyer Rhönsperber
• Slingsby Kite
• Weltensegler
• Ikarus Košava

File:Beriev Be-12 Gelenzhik 2Sept2004.jpg seaplane with gull wing profile]]

The gull wing design found its way into seaplanes by the early 1930s. As engine power increased, so did the need for large propellers that could effectively convert power to thrust. The gull wing allowed designers to ensure adequate propeller tip clearance over the water by placing the engines on the highest point of the wing. The alternative was placing the engine on a pylon. The first flying boat to utilize the gull wing configuration may have been the Short Knuckleduster, which first flew in 1933.Barnes and James 1989, p. 281. The Dornier Do 26, a high-speed airliner and transport platform, of which six aircraft were built, made its first flight during 1938.{{cite book |last=Schneider |first=Helmut (Dipl.Ing.) |title=Flugzeug-Typenbuch : Handbuch der Deutschen Luftfahrt- und Zubehör-Industrie 1939/40 |date=1939 |language=de |publisher=Gondrom |location=leipzig |isbn=3811206273 |edition=Facsimile reprint 1988 |page=36}} The configuration was also used on the US Navy's PBM Mariner and P5M Marlin maritime patrol aircraft.Bridgeman 1946, p. 245. The emergence of long range, land-based jets in the 1950s and the subsequent demise of the seaplane prevented widespread use of the gull wing, although it was still used in some post-war designs, like Beriev Be-12 Chaika (the name means 'gull' in Russian).{{cite book |title=Jane's All The World's Aircraft |year=1975–1976 |isbn=0-354-00521-9 |pages=488–489|last1=Taylor |first1=John W. R. |publisher=Macdonald and Jane's }}

Examples:

• Beriev Be-6
• Dornier Do 26
• Martin P5M Marlin
• Piaggio P.136
• Short Knuckleduster

File:PZL P.11c '39 - 2' (14338643326).jpgc, showing an idea of original Puławski's wing]]

During the late 1920s, the gull wing design found its way into landplanes. In 1928, the Polish aircraft designer Zygmunt Puławski developed the PZL P.1, an experimental fighter aircraft; a major innovation of the PZL P.1 was its relatively high-mounted gull wing.{{cite book |last1=Cynk |first1=Jerzy B. |title=Polish aircraft, 1893-1939 |date=1971 |publisher=Putnam |location=London |isbn=0-370-00085-4 |pages=[https://archive.org/details/polishaircraft1800cynk/page/123 123-128] |url-access=registration |url=https://archive.org/details/polishaircraft1800cynk/page/123 }} Seeking to protect his new wing arrangement, Puławski filed for an associated patent for this wing arrangement during the following year.{{cite web |url = http://pubserv.uprp.pl/PublicationServer/generuj_dokument.php?plik=PL_000000000013826_B1_PDF |title = Polish patent |date = 4 December 1929 }}{{Dead link|date=June 2024 |bot=InternetArchiveBot |fix-attempted=yes }} The arrangement devised by Puławski has been referred to as the "Puławski Wing" or the "Polish Wing". The PZL P.1 led to a production model, the PZL P.7, of which 149 were produced between 1932 and 1933.Morgała, Andrzej (2003): Samoloty wojskowe w Polsce 1924–1939. Warszawa: Bellona. {{ISBN|83-11-09319-9}}, pp. 48–54 (in Polish)

The gull wing was used to improve visibility in a high wing arrangement, because such wing could be thinnest by the fuselage, and in theory should limit pilot's view no more than A-pillars of a windscreen in a car body. It was used on multiple fighter aircraft, including the PZL P.11 and Soviet Polikarpov I-15. The PZL P.11 was a further improvement of the PZL P.7 that was in production throughout the early 1930s. It possessed various cutting-edge features for the era in addition to the high-mounted gull wing, such as its all-metal structure and its metal exterior; according to aviation author Jerzy Cynk, the P.11 was commonly considered to have been the most advanced fighter aircraft of its kind in the world upon its introduction. The P.11 served as Poland's primary fighter aircraft during the mid to late 1930s, participating in the Polish campaign of 1939 to resist an invasion by neighbouring Nazi Germany. As a consequence of the rapid aeronautical advances made during the late 1930s, the P.11 was outclassed by newer fighters such as the Messerschmitt Bf 109 at the onset of the conflict.{{cite book |last=Cynk |first=Jerzy B. |title=Polish Aircraft 1893-1939 |url=https://archive.org/details/polishaircraft1800cynk |url-access=registration |publisher=Putnam & Company Ltd. |location=London |year=1971 |edition=1st |pages=[https://archive.org/details/polishaircraft1800cynk/page/158 158–172] |isbn=0-370-00103-6}}

Examples:

• PZL P.1
• PZL P.6
• PZL P.7
• PZL P.8
• PZL P.11
• PZL P.24
• Henschel Hs 121
• Loire 46
• Polikarpov I-153

File:StukaRA.jpg German ground-attack aircraft of WWII]]

File:F4U-1 Corsair of VF-17 bouncing during landing aboard USS Bunker Hill (CV-17), in 1943.jpg landing on USS Bunker Hill]]

File:B7A-Ryusei torpedo.jpg carrying torpedo.]]

During the 1930s, a derivative of the standard design, known as the inverted gull wing, was developed. It was chiefly used on single engine military aircraft with increasingly powerful engines. Before contra-rotating propellers came into use, such powers required larger diameter propellers but clearance between the propeller tip and ground had to be maintained. Long landing gear legs are heavy, bulky, and weaker than their shorter counterparts. The Vought F4U Corsair, designed from the onset as a carrier-based fighter, not only had the largest propeller of any U.S. fighter, but was also expected to face rough landings aboard a pitching carrier deck. By adopting the inverted gull wing, the landing gear could be shorter and allowed to retract straight back (while twisting through 90º to place the mainwheels atop the lower gear strut ends), the latter factor improving internal wing space.Green 1973, p. 188. The anhedral of the wing's center-section also permitted the wing and fuselage to meet at the optimum angle for minimizing drag, without using wing root fairings or other measures.

Another reason for having an inverted gull wing is to permit clearance for a large external bomb load, as on the Junkers Ju 87 Stuka. The inverted gull wing has been described by aviation author Manfred Griehl as being the most distinctive feature of the Ju 87.Griehl 2001, pp. 38–39. These wings, which comprised conventional Junkers double-wing construction, reportedly gave the Ju 87 a considerable advantage over its contemporaries during take-off; relatively large lift forces were created through the aerofoil even when flown at a shallow angle, reducing take-off and landing runs. They also provided a high level of ground visibility to the pilot, as well as enabling the use of a shorter undercarriage.Erfurth 2004, pp. 48-49.

Examples:

• Aichi B7A
• Blohm & Voss Ha 137
• Junkers Ju 87 Stuka
• Vought F4U Corsair
• Mitsubishi A5M first prototype
• Yermolayev Yer-2

{{Reflist}}

{{Refbegin}}

• Barnes, Christopher H. and Derek N. James. Shorts Aircraft since 1900. London: Putnam, 1989. {{ISBN|0-85177-819-4}}.
• Bridgeman, Leonard. “The Martin Model 162 Mariner.” Jane's Fighting Aircraft of World War II. London: Studio, 1946. {{ISBN|1-85170-493-0}}.
• {{cite book|last=Erfurth|first=Helmut|title=Junkers Ju 87 |series=Black Cross |volume=V|location=Bonn|publisher=Bernard & Graefe Verlag|year=2004|isbn=1-85780-186-5}}
• Green, William. "Vought F4U-1, F4U-4 (FG-1 Corsair)". War Planes of the Second World War, Volume Four: Fighters. Garden City, New York: Doubleday & Company, 1973, pp. 188–194. {{ISBN|0-385-03259-5}}.
• {{cite book|last=Griehl|first=Manfred|title=Junker Ju 87 Stuka|location=London/Stuttgart|publisher=Airlife/Motorbuch|year=2001|isbn=1-84037-198-6}}

{{Refend}}

• [https://web.archive.org/web/20060617015834/http://scalesoaring.co.uk/Documentation/Documentation.html Scale Soaring UK Documentation Section]
• [http://www.airventuremuseum.org/collection/aircraft/Chance%20Vought%20F4U%20Corsair.asp Vought F4U Corsair design considerations]

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Category:Wing configurations

Category:Aircraft wing design