View source for Biplane

{{short description|Airplane wing configuration with two vertically stacked main flying surfaces}}
{{distinguish|Tandem wing}}
{{For|biplanes in mathematics|Block design#Biplanes}}
[[File:Sopwith Camel - Season Premiere Airshow 2018 (42058141172).jpg|thumb|[[First World War]] [[Sopwith Camel]] biplane]]

A '''biplane''' is a [[fixed-wing aircraft]] with two main [[wing]]s stacked one above the other. The first powered, controlled [[aeroplane]] to fly, the [[Wright Flyer]], used a biplane wing arrangement, as did many aircraft in the early years of [[aviation]]. While a biplane wing structure has a structural advantage over a [[monoplane]], it produces more [[drag (aerodynamics)|drag]] than a monoplane wing. Improved structural techniques, better materials and higher speeds made the biplane configuration obsolete for most purposes by the late 1930s.

Biplanes offer several advantages over conventional [[cantilever]] monoplane designs: they permit lighter wing structures, low wing loading and smaller span for a given wing area. However, interference between the airflow over each wing increases drag substantially, and biplanes generally need extensive bracing, which causes additional drag.

Biplanes are distinguished from [[tandem wing]] arrangements, where the wings are placed forward and aft, instead of above and below.

The term is also occasionally used in [[biology]], to describe the [[wing]]s of some [[Flying and gliding animals|flying animals]].

==Characteristics==
[[File:Hang Glider 1920s.jpg|thumb|1920s biplane hang glider]]
In a biplane aircraft, two wings are placed one above the other. Each provides part of the lift, although they are not able to produce twice as much lift as a single wing of similar size and shape because the upper and the lower are working on nearly the same portion of the atmosphere and thus interfere with each other's behaviour. In a biplane configuration with no stagger from the upper wing to the lower wing, the [[lift coefficient]] is reduced by 10 to 15 percent compared to that of a monoplane using the same airfoil and [[aspect ratio (wing)|aspect ratio]].<ref name=Norton>F. H. Norton, The effect of staggering a biplane, NACA TN-70, Table, 1 p.3 1921</ref>
[[File:Gloster Gladiator 1.jpg|thumb|The [[Gloster Gladiator]], a [[World War II]] [[Fighter aircraft|fighter]] biplane]]

The lower wing is usually attached to the [[fuselage]], while the upper wing is raised above the fuselage with an arrangement of [[cabane strut]]s, although other arrangements have been used. Either or both of the main wings can support [[aileron]]s, while flaps are more usually positioned on the lower wing. Bracing is nearly always added between the upper and lower wings, in the form of [[interplane strut]]s positioned symmetrically on either side of the fuselage and bracing wires to keep the structure from flexing, where the wings are not themselves [[cantilever]] structures.

=== Advantages and disadvantages ===
[[File:Antonov an2 ha-mkf arp.jpg|thumb|Soviet [[Antonov An-2]] biplane from the 1940s]]
The primary advantage of the biplane over a [[monoplane]] is its ability to combine greater stiffness with lower weight. Stiffness requires structural depth and where early monoplanes had to have this provided with external bracing, the biplane naturally has a deep structure and is therefore easier to make both light and strong. Rigging wires on non-cantilevered monoplanes are at a much sharper angle, thus providing less tension to ensure stiffness of the outer wing. On a biplane, since the angles are closer to the ideal of being in direct line with the forces being opposed, the overall structure can then be made stiffer. Because of the reduced stiffness, wire braced monoplanes often had multiple sets of flying and landing wires where a biplane could easily be built with one bay, with one set of landing and flying wires. The extra drag from the wires was not enough to offset the aerodynamic disadvantages from having two airfoils interfering with each other however. Strut braced monoplanes were tried but none of them were successful, not least due to the drag from the number of struts used.{{facts|date=August 2021}}

The structural forces acting on the spars of a biplane wing tend to be lower as they are divided between four spars rather than two, so the wing can use less material to obtain the same overall strength and is therefore lighter. A given area of wing also tends to be shorter, reducing bending moments on the spars, which then allow them to be more lightly built as well.<ref>Berriman, 1913, p.26</ref> The biplane does however need extra struts to maintain the gap between the wings, which add both weight and drag.

The low power supplied by the engines available in the first years of aviation limited aeroplanes to fairly low speeds. This required an even lower [[Stall (fluid dynamics)|stalling]] speed, which in turn required a low [[wing loading]], combining both large wing area with light weight. Obtaining a large enough wing area without the wings being long, and thus dangerously flexible was more readily accomplished with a biplane.{{facts|date=August 2021}}

The smaller biplane wing allows greater [[Aerobatics|maneuverability]]. Following World War I, this helped extend the era of the biplane and, despite the performance disadvantages, most [[fighter aircraft]] were biplanes as late as the mid-1930s. Specialist sports [[aerobatics|aerobatic]] biplanes are still made in small numbers.<ref>{{cite news |last1=Reisch |first1=Felipe |title=Biplanes Are Back, Bigger and Bolder Than Ever |url=https://robbreport.com/motors/aviation/biplanes-modern-classic-style-1235651674/ |access-date=3 September 2025 |work=Robb Report |date=12 June 2024}}</ref>

Biplanes suffer aerodynamic interference between the two planes when the high pressure air under the top wing and the low pressure air above the lower wing cancel each other out.{{dubious|date=August 2021}} This means that a biplane does not in practice obtain twice the lift of the similarly-sized monoplane. The farther apart the wings are spaced the less the interference, but the spacing struts must be longer, and the gap must be extremely large to reduce it appreciably.

As engine power and speeds rose late in [[World War I]], thick cantilever wings with inherently lower drag and higher wing loading became practical, which in turn made monoplanes more attractive as it helped solve the structural problems associated with monoplanes, but offered little improvement for biplanes.{{facts|date=August 2021}}

=== Stagger ===
[[File:Fleet 16B (C-FPFF).jpg|thumb|Wing stagger on a [[Fleet Finch]] primary trainer]]
The default design for a biplane has the wings positioned directly one above the other. Moving the upper wing forward relative to the lower one is called [[Stagger (aviation)|positive stagger]] or, more often, simply stagger. It can increase lift and reduce drag by reducing the aerodynamic interference effects between the two wings by a small degree, but more often was used to improve access to the cockpit. Many biplanes have staggered wings. Common examples include the [[de Havilland Tiger Moth]], [[Bücker Bü 131|Bücker Bü 131 Jungmann]] and [[Travel Air 2000]].

Alternatively, the lower wing can instead be moved ahead of the upper wing, giving negative stagger, and similar benefits. This is usually done in a given design for structural reasons, or to improve visibility. Examples of negative stagger include the [[Sopwith Dolphin]], [[Breguet 14]] and [[Beechcraft Staggerwing]].<ref name="Sport Aviation">{{cite journal |journal=Sport Aviation |date=January 1961 |title=The Beechcraft Biplanes}}</ref><ref name="Cooksley p34">Cooksley 1991, p. 34.</ref> However, positive (forward) stagger is much more common.

=== Bays ===
The space enclosed by a set of [[interplane strut]]s is called a ''bay'' (much as [[Bay (architecture)|the architectural form]] is used), hence a biplane or [[triplane]] with one set of such struts connecting the wings on each side of the aircraft is a ''single-bay biplane''. This provided sufficient strength for smaller aircraft such as the [[First World War]]-era [[Fokker D.VII]] fighter and the [[Second World War]] [[de Havilland Tiger Moth]] basic trainer.<ref name = "jackson 3 4">Jackson 1966, pp. 3–4.</ref>

The larger two-seat [[Curtiss JN-4]] Jenny is a ''two bay biplane'', the extra bay being necessary as overlong bays are prone to flexing and can fail. The [[SPAD S.XIII]] fighter, while appearing to be a two bay biplane, has only one bay, but has the midpoints of the rigging braced with additional struts; however, these are not structurally contiguous from top to bottom wing.<ref name="profile p6-7">Andrews 1965, pp. 6–7.</ref> The [[Sopwith 1½ Strutter]] has a W shape cabane, however as it does not connect the wings to each other, it does not add to the number of bays.<ref name="bomber-40">Lake 2002, p. 40.</ref>

Large transport and [[Bomber|bombing]] biplanes often needed still more bays to provide sufficient strength. These are often referred to as ''multi-bay biplanes''. A small number of biplanes, such as the [[Zeppelin-Lindau D.I]] have no interplane struts and are referred to as being ''strutless''.<ref name=G0>Grosz 1998, p. 0.</ref>
<gallery>
File:Zeppelin-Lindau (Do) D.I.jpg|[[Zeppelin-Lindau D.I]] strutless biplane
File:Nieuport 23 C.1 (colour).jpg|[[Nieuport 23]] single-bay sesquiplane
File:SPAD S.XIII Front.jpg|[[SPAD S.XIII]] single-bay biplane with auxiliary struts
File:Fearless Freddie, stuntman cph.3b18313.jpg|[[Curtiss JN-4]] two-bay biplane
File:Handley Page V-1500.jpg|[[Handley Page V/1500]] four-bay or multi-bay biplane
</gallery>

=== Rigging ===
{{main|Bracing (aeronautics)#Rigging}}
Because most biplanes do not have [[cantilever]] structures, they require rigging wires to maintain their rigidity. Early aircraft used simple wire (either braided or plain), however during the First World War, the British [[Royal Aircraft Factory]] developed airfoil section wire named RAFwire in an effort to both increase the strength and reduce the drag. 
Four types of wires are used in the biplane wing structure. Drag wires inside the wings prevent the wings from being folded back against the fuselage, running inside a wing bay from the forward inboard corner to the rear outboard corner.<ref name=GunstonP210>Gunston, 2004, p.210</ref> Anti-drag wires prevent the wings from moving forward when the aircraft stops and run the opposite direction to the drag wires.<ref name=GunstonP51>Gunston, 2004, p.51</ref> Both of these are usually hidden within the wings, and if the structure is sufficiently stiff otherwise, may be omitted in some designs. Indeed many early aircraft relied on the fabric covering of the wing to provide this rigidity, until higher speeds and forces made this inadequate. 
Externally, lift wires prevent the wings from folding up, and run from the underside of the outer wing to the lower wing root.<ref name=GunstonP382>Gunston, 2004, p.382</ref> Conversely, landing wires prevent the wings from sagging, and resist the forces when an aircraft is landing, and run from the upper wing centre section to outboard on the lower wings.<ref name=GunstonP375>Gunston, 2004, p.375</ref> Additional drag and anti-drag wires may be used to brace the cabane struts which connect the fuselage to the wings, and interplane struts, which connect the upper and lower wings together.

===Sesquiplane===  <!-- linked from other pages-->
[[File:Early Nieuport 17 climbing (cropped).jpg|thumb|The lower wing of the [[Nieuport 17]] has smaller chord, but similar span, than the upper wing]]
The ''sesquiplane'' is a type of biplane where one wing (usually the lower) is significantly smaller than the other.<ref name=Wraff74>Wragg 1974, p. 54.</ref><ref name=Gunston>Gunston 2009, p. 606.</ref> The word, from Latin, means "one-and-a-half wings". The arrangement can reduce [[Drag (physics)#Aerodynamics|drag]] and weight while retaining the biplane's structural advantages. The lower wing may have a significantly shorter span, or a reduced [[chord (aircraft)|chord]].<ref name=Wraff74/>

Examples include the series of [[Nieuport]] military aircraft—from the [[Nieuport 10]] through to the [[Nieuport 27]] which formed the backbone of the Allied air forces between 1915 and 1917.<ref>Chassard 2018, p. 1.</ref> The performance of the Nieuport sesquiplanes was so impressive that the {{lang|de|[[Idflieg]]}} (the German Inspectorate of flying troops) requested their aircraft manufacturers to produce copies, an effort which was aided by several captured aircraft and detailed drawings; one of the most famed copies was the [[Siemens-Schuckert D.I]].<ref>Andrews 1966, pp. 3, 7.</ref> The [[Albatros D.III]] and [[Albatros D.V|D.V]], which had also copied the general layout from Nieuport, similarly provided the backbone of the German forces during the First World War.<ref name = "And 78"/> The Albatros sesquiplanes were widely acclaimed by their aircrews for their maneuverability and high rate of climb.<ref name="VanWyngarden 2007, p. 19">VanWyngarden 2007, p. 19.</ref>

During [[interwar period]], the sesquiplane configuration continued to be popular, with numerous types such as the [[Nieuport-Delage NiD 42]]/[[Nieuport-Delage NiD 52|52]]/[[Nieuport-Delage NiD 62|62]] series, [[Fokker C.V]]d & e, and [[Potez 25]], all serving across a large number of air forces. In the general aviation sector, aircraft such as the [[Waco Custom Cabin series]] proved to be relatively popular.<ref>[http://registry.faa.gov/aircraftinquiry/acftinqSQL.asp?striptxt=&mfrtxt=Waco FAA Registry Search for Waco] {{webarchive|url=https://web.archive.org/web/20120217034911/http://registry.faa.gov/aircraftinquiry/acftinqSQL.asp?striptxt=&mfrtxt=Waco |date=17 February 2012 }} accessed 12 June 2009.</ref> The [[Saro Windhover]] was a sesquiplane with the upper wing smaller than the lower, which was a much rarer configuration than the reverse.<ref name="London">{{harvnb|London|1988|pp=125–130|id=London1988}}</ref> The [[Pfalz D.III]] also featured a somewhat unusual sesquiplane arrangement, possessing a more substantial lower wing with two spars that eliminated the flutter problems encountered by single-spar sesquiplanes.<ref name = "And 78">Andrews 1966, pp. 7–8.</ref>

==History==
[[File:LilienthalDoppeldecker 1895-10-19.jpg|thumb|Otto Lilienthal flying his [[Lilienthal Large Biplane|Large Biplane]] in Lichterfelde (near Berlin) on October 19, 1895]]
[[File:Anvers Aviation Meeting in 1909. Rougier flying a Voisin biplane with a Gnôme Oméga engine.jpg|thumb|1909 Voisin biplane, with "curtains" connecting the upper and lower wings]]
[[File:Fiat CR42 ‘MM5701 - 95-13’ (16974203557).jpg|thumb|Late 1930s [[Fiat CR.42 Falco]] with [[Warren truss]] interplane struts which reduced the work needed in rigging a biplane]]
[[File:Hillson Bi-mono 3view.svg|thumb|[[Hillson Bi-mono]] with slip-wing. The aircraft could take off as a biplane, [[Jettison (aviation)|jettison]] the upper, disposable wing, and continue flying as a monoplane. A single example was built, which successfully demonstrated jettisoning of the slip wing in flight]]
The stacking of wing planes was suggested by [[Sir George Cayley]] in 1843.<ref>J. A. D. Ackroyd; "Sir George Cayley: The Invention of the Aeroplane near Scarborough at the Time of Trafalgar", Journal of Aeronautical History, Paper No. 2011/6, 2011.</ref> [[Hiram Maxim]] adopted the idea for his steam-powered test rig, which lifted off but was held down by safety rails, in 1894.<ref>Wragg 1974, p. 206.</ref> [[Otto Lilienthal]] designed and flew two different biplane [[hang glider]]s in 1895,<ref>Schwipps, Werner. ''Die Flugzeuge von Otto Lilienthal.  Technik - Dokumentation - Rekonstruktion. (The airplanes of Otto Lilienthal. Technique - Documentation - Reconstruction)''. Otto-Lilienthal-Museum Anklam, 2016. {{ISBN|978-3-941681-88-0}}
</ref> though he is better known for his monoplanes.<ref name=Wright>[http://www.lilienthal-museum.de/olma/ewright.htm "From Lilienthal to the Wrights."] ''Otto Lilienthal Museum.''  Retrieved: 8 January 2012.</ref> By 1896 a group of young men in the United States, led by [[Octave Chanute]], were flying [[hang glider]]s including biplanes and concluded that the externally braced biplane offered better prospects for powered flight than the monoplane. In 1903, the ''[[Wright Flyer]]'' biplane became the first successful powered aeroplane.<ref name=NewarkDailyAdvocate_19031228>{{cite news |title=Machine That Flies / What the Wright Brothers' Invention Has Accomplished |url=https://newspaperarchive.com/newark-advocate-dec-28-1903-p-7/ |work=The Newark Daily Advocate |date=28 December 1903 |location=Newark, Ohio, U.S. |page=7}}</ref>

Throughout the pioneer years, both biplanes and monoplanes were common, but by the outbreak of the [[First World War]] biplanes had gained favour after several monoplane structural failures resulted in the [[Royal Flying Corps|RFC's]] "Monoplane Ban" when all monoplanes in military service were grounded,<ref name = "bruce 3">Bruce 1967, p. 3.</ref> while the French also withdrew most monoplanes from combat roles and relegated them to training. Figures such as aviation author Bruce observed that there was an apparent prejudice held even against newly-designed monoplanes, such as the [[Bristol M.1]], that caused even those with relatively high performance attributes to be overlooked in favour of 'orthodox' biplanes, and there was an allegedly widespread belief held at that time that monoplane aircraft were inherently unsafe during combat.<ref name = "bruce 6">Bruce 1967, p. 6.</ref><ref>{{cite web |title=Bristol M1 Monoplane |url=https://www.baesystems.com/en/heritage/bristol-m1-monoplane |publisher=BAE Systems |access-date=30 August 2018}}</ref>

Between the years of 1914 and 1925, a clear majority of new aircraft introduced were biplanes; however, during the latter years of the First World War, the Germans had been experimenting with a new generation of monoplanes, such as the [[Fokker D.VIII]], that might have ended the biplane's advantages earlier had the conflict not ended when it had.<ref>Connors, John F., "''Fokker's Flying Razors''", Wings, Granada Hills, California, August 1974, Volume 4, Number 4, pages 45, 48.</ref> The French were also introducing the [[Morane-Saulnier AI]], a strut-braced [[parasol monoplane]], although the type was quickly relegated to the advanced trainer role following the resolution of structural issues.<ref name="Lamberton">Lamberton 1960, p. 84.</ref> [[Sesquiplane]] types, which were biplanes with abbreviated lower wings such as the French [[Nieuport 17]] and German [[Albatros D.III]], offered lower drag than a conventional biplane while being stronger than a monoplane.

During the [[Interwar period]], numerous biplane airliners were introduced. The British [[de Havilland Dragon]] was a particularly successful aircraft, a straightforward design which could carry six passengers on busy routes, such as London-Paris services.<ref>Jackson 1973, p. 122.</ref> During early August 1934, one such aircraft, named ''Trail of the Caribou'', performed the first non-stop flight between the Canadian mainland and Britain in 30 hours 55 minutes, although the intended target for this long distance flight had originally been [[Baghdad]], [[Iraq]].{{sfn|Riding|1980|p=289}}<ref name="racing p265">Lewis 1971, p. 265.</ref> Despite its relative success, British production of the Dragon was quickly ended in favour of the more powerful and elegant [[de Havilland Dragon Rapide]], which had been specifically designed to be a faster and more comfortable successor to the Dragon.<ref name = "moss 3">Moss 1966, p. 3.</ref>
 
As the available engine power and speed increased, the drag penalty of external bracing increasingly limited aircraft performance. To fly faster, it would be necessary to reduce external bracing to create an aerodynamically clean design; however, early cantilever designs were either too weak or too heavy. The 1917 [[Junkers J.I]] sesquiplane utilized [[wikt:corrugated|corrugated]] aluminum for all flying surfaces, with a minimum of struts; however, it was relatively easy to damage the thin metal skin and required careful handling by ground crews.<ref name="flight-18-03-1920-317">''Flight'' 18 March 1920, p. 317.</ref> The 1918 [[Zeppelin-Lindau D.I]] fighter was an all-metal stressed-skin [[monocoque]] fully cantilevered biplane, but its arrival had come too late to see combat use in the conflict.<ref name=G0/>

By the 1930s, biplanes had reached their performance limits, and monoplanes become increasingly predominant, particularly in continental Europe where monoplanes had been increasingly common from the end of [[World War I]]. At the start of [[World War II]], several air forces still had biplane combat aircraft in front line service but they were no longer competitive, and most were used in niche roles, such as training or shipboard operation, until shortly after the end of the war. The British [[Gloster Gladiator]] biplane, the Italian [[Fiat CR.42 Falco]] and Soviet [[I-153]] sesquiplane fighters were all still operational after 1939.<ref name=Coggins>Coggins 2000, p. 20.</ref><ref>{{cite web| url = http://www.historyofwar.org/articles/weapons_polikarpov_I-153.html| title = Polikarpov I-153 Chaika (Seagull)}}</ref> According to aviation author Gianni Cattaneo, the CR.42 was able to achieve success in the defensive [[night fighter]] role against RAF bombers that were striking industrial targets throughout northern Italy.<ref>Gustavsson, Håkan. [http://surfcity.kund.dalnet.se/italy_francois.htm "''Tenente Colonnello'' Armando François: Biplane fighter aces Italy."] ''surfcity.kund.dalnet.se'', ''Håkans aviation page''. Retrieved: 22 July 2009.</ref><ref name = "catt 10">Cattaneo 1967, p. 10.</ref>

[[File:stearman.e75.g-bswc.longshot.arp.jpg|thumb|left|[[Boeing-Stearman Model 75]] PT-13D biplane trainer from the 30s and 40s]]
The British [[Fleet Air Arm]] operated the [[Fairey Swordfish]] [[torpedo bomber]] from its aircraft carriers, and used the type in the [[anti-submarine warfare]] role until the end of the conflict, largely due to their ability to operate from the relatively compact decks of [[escort carrier]]s. Its low stall speed and inherently tough design made it ideal for operations even in the often severe mid-Atlantic weather conditions.<ref name="wragg">Wragg 2003, p. 142.</ref> By the end of the conflict, the Swordfish held the distinction of having caused the destruction of a greater tonnage of [[Axis powers|Axis]] shipping than any other Allied aircraft.<ref name = "stott 21">Stott 1971, p. 21.</ref>

Both the German [[Heinkel He 50]] and the Soviet [[Polikarpov Po-2]] were used with relative success in the night [[ground attack]] role throughout the Second World War. In the case of the Po-2, production of the aircraft continued even after the end of the conflict, not ending until around 1952.<ref name=wveh>[http://www.wwiivehicles.com/ussr/aircraft/bomber/polikarpov-u-2-po-2.asp#p7TPMc1_4 "Soviet Polikarpov U-2 bomber, trainer; Polikarpov Po-2 bomber, trainer."] {{Webarchive|url=https://web.archive.org/web/20140703083246/http://www.wwiivehicles.com/ussr/aircraft/bomber/polikarpov-u-2-po-2.asp#p7TPMc1_4 |date=2014-07-03 }} ''wwiivehicles.com.'' Retrieved: 30 November 2012.</ref> A significant number of Po-2s were fielded by the [[Korean People's Air Force]] during the [[Korean War]], inflicting serious damage during night raids on [[United Nations Command (Korea)|United Nations]] bases.<ref>Dorr 2003, p. 50.</ref> The Po-2 is also the only biplane to be credited with a documented jet-kill, as one [[Lockheed F-94 Starfire]] was lost while slowing down to {{convert|161|kph|mph|0|abbr=on}} – below its stall speed – during an intercept in order to engage the low flying Po-2.<ref>Grier, Peter. "15 April 1953". ''Air Force Magazine'', Air Force Association, June 2011, p. 57.</ref>

Later biplane [[Trainer (aircraft)|trainer]]s included the [[de Havilland Tiger Moth]] in the [[Royal Air Force]] (RAF), [[Royal Canadian Air Force]] (RCAF) and others and the [[Stampe SV.4]], which saw service postwar in the French and Belgian Air Forces. The [[Stearman PT-13]] was widely used by the [[United States Army Air Force]] (USAAF) while the US Navy operated the [[Naval Aircraft Factory N3N]]. In later civilian use in the US, the Stearman became particularly associated with stunt flying such as [[wing-walking]], and with crop dusting, where its compactness worked well at low levels, where it had to dodge obstacles.

[[File:Flight Po-2 RA-1945g (4723729033).jpg|thumb|[[Polikarpov Po-2]], of which over 20,000 were built by the Soviet Union]]
Modern biplane designs still exist in specialist roles such as [[aerobatics]] and [[agricultural aircraft]] with the competition aerobatics role and format for such a biplane well-defined by the mid-1930s by the [[Udet U 12 Flamingo]] and [[Waco Taperwing]]. The [[Pitts Special]] dominated aerobatics for many years after World War II and is still in production.

The vast majority of biplane designs have been fitted with [[reciprocating engine]]s. Exceptions include the [[Antonov An-3]] and [[WSK-Mielec M-15 Belphegor]], fitted with [[turboprop]] and [[turbofan]] engines respectively. Some older biplane designs, such as the [[Grumman Ag Cat]] are available in upgraded versions with turboprop engines.

The two most produced biplane designs were the 1913 British [[Avro 504]] of which 11,303 were built, and the 1928 Soviet [[Polikarpov Po-2]] of which over 20,000 were built, with the Po-2 being the direct replacement for the Soviet copy of the Avro 504. Both were widely used as trainers. The [[Antonov An-2]] was very successful too, with more than 18,000 built.

===Ultralight aircraft===
[[File:Mauro Solar Riser.jpg|thumb|[[Mauro Solar Riser]] electric-powered ultralight biplane]]
Although most [[Ultralight aviation|ultralights]] are monoplanes, the low speeds and simple construction involved have inspired a small number of biplane ultralights, such as Larry Mauro's ''[[Easy Riser]]'' (1975–). Mauro also made a version powered with solar cells driving an electric motor called the [[Solar Riser]]. Mauro's ''Easy Riser'' was used by "Father Goose", [[Bill Lishman]].<ref>{{cite web| url = http://www.ultralightnews.com/antulbg/easyriser_ultralight.htm| title = Larry Mauro and Bill Lishman}}</ref>

Other biplane ultralights include the Belgian-designed [[Aviasud Mistral]], the German [[B&F Fk12|FK12 Comet]] (1997–), the [[Lite Flyer]] Biplane,<ref>{{cite web| url = http://liteflite.tripod.com| title = Lite Flyer Biplane}}</ref><ref>{{cite web| url = http://www.pilotmix.com/index.php?pgid=11&lang=en&maxInfo=587| title = Pilotmix.com}}</ref> the [[Tiger Cub Developments Sherwood Ranger|Sherwood Ranger]], and the [[Murphy Renegade]].

==Avian evolution==
The [[feathered dinosaur]] ''[[Microraptor gui]]'' glided, and perhaps even flew, on four wings, which may have been configured in a staggered sesquiplane arrangement. This was made possible by the presence of flight feathers on both forelimbs and hindlimbs, with the feathers on the forelimbs opening to a greater span. It has been suggested that the hind limbs could not have opened out sideways but in flight would have hung below and slightly behind the fore limbs.<ref name=Chatterjee>Chatterjee, 2007, pp.1576–80</ref>

==See also==
* [[History of aviation]]
* [[Multiplane (aeronautics)]]
* [[Wing configuration]]

==References==
===Citations===
{{Reflist}}

===Bibliography===
{{refbegin}}
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* {{cite book |last=Andrews |first=C. F. |title=The Nieuport 17 |series=Aircraft in Profile no. 49 |publisher=Profile Publications |location=Leatherhead, Surrey |year=1966}}
* Berriman, A.E.; ''Aviation'', Methuen, 1913.
* Bruce, J.M. ''The Bristol M.1 (Aircraft in Profile no. 193)''. Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
* Cattaneo, Gianni. ''The Fiat CR.42 (Aircraft in Profile no. 170)''. Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
* {{cite journal |author=Chatterjee S, Templin RJ |title=Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui |journal=Proceedings of the National Academy of Sciences of the United States of America |date=30 January 2007 |volume=104 |issue=5 |pages=1576–80 |pmid=17242354 |doi = 10.1073/pnas.0609975104 |pmc=1780066 |bibcode = 2007PNAS..104.1576C |doi-access=free }}
* {{cite book |last=Chassard |first=Marc |title=Nieuport 17 Analyse détaillée des premières series |publisher=FAREWO (French Aviation Research Work) |location=France |language=fr |year=2018}}
* {{cite book |last=Coggins |first=Edward V.|title=Wings That Stay on |url=https://books.google.com/books?id=MG5wioBJyK0C&pg=PA20 |publisher=Turner |year=2000 |isbn=978-1681621760}}
* Cooksley, Peter. ''Sopwith Fighters in Action (Aircraft No. 110).'' Carrollton, Texas: Squadron/Signal Publications, 1991. {{ISBN|0-89747-256-X}}.
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* Dorr, Robert F. ''B-29 Superfortress units of the Korean War''. Botley, Oxford, UK: Osprey Publishing, 2003. {{ISBN|1-84176-654-2}}.
* {{cite book |last1=Grosz |first1=Peter |title=Dornier D.I Windsock Mini datafile # 12 |publisher=Albatros Publications |location=Hertfordshire, UK |year=1998 |isbn=9780948414923}}
* {{cite book |last=Gunston |first=Bill |title=Cambridge Aerospace dictionary |publisher=Cambridge University Press |location=Cambridge, UK |edition=2nd |year=2009 |isbn=978-0-521-19165-4 |page=606}}
* {{cite book |last=Gunston |first=Bill |title=The Cambridge Aerospace Dictionary Cambridge |publisher=Cambridge University Press |year=2004 |isbn=978-0521841405 |pages=34}}
* Jackson, A.J. '' The de Havilland Tiger Moth: Aircraft Profile No. 132''. Leatherhead, Surrey, UK: Profile Publications Ltd., 1966.
* Jackson, A.J. ''British Civil Aircraft since 1919: Volume II''. London:Putnam, Second edition 1973. {{ISBN|0-370-10010-7}}.
* Lake, Jon. ''The Great Book of Bombers: The World's Most Important Bombers from World War I to the Present Day''. St. Paul, Minnesota: MBI Publishing Company, 2002. {{ISBN|0-7603-1347-4}}.
* Lamberton, W.M. ''Fighter Aircraft of the 1914-1918 War.'' Herts, UK: Harleyford Publications Ltd., 1960, pp.&nbsp;84–85.
* {{cite book |last=Lewis |first=Peter |title=British Racing and Record-Breaking Aircraft |year=1971 |publisher=Putnam |location=London |isbn=0-370-00067-6}}
* {{cite book |last=London |first=Peter |title=Saunders and Saro Aircraft since 1917 |publisher=Putnam & Company Ltd. |location=London |year=1988 |pages=125–130 |isbn=0-85177-814-3}}
* {{cite book |last=Moss |first=Peter W. |title=The de Havilland Rapide: Profile Publications Number 144 |year=1966 |location=Leatherhead, Surrey, UK |publisher=Profile Publications }}
* [http://www.flightglobal.com/pdfarchive/view/1920/1920%20-%200315.html "Report on the Junker Armoured Two-Seater Biplane, Type J.1."] ''Flight'', 18 March 1920.
* {{cite magazine |last=Riding |first=Richard |title=The Black Dragons |magazine=[[Aeroplane Monthly]] |date=June 1980 |volume=8 |issue=6 |pages=284–290 |issn=0143-7240 }}
* Stott, Ian G. '' The Fairey Swordfish Mks. I-IV'' (Aircraft in Profile 212). Windsor, Berkshire, UK: Profile Publications, 1971. {{OCLC|53091961}}.
* VanWyngarden, Greg. ''Albatros Aces of World War I Part 2 (Aircraft of the Aces No. 77).'' Oxford: Osprey Publishing, 2007. {{ISBN|1-84603-179-6}}.
* {{cite book |last=Wragg |first=David W. |title=Flight before flying |publisher=Osprey Publishing |year=1974 |isbn=978-0850451658}}
* Wragg, David. ''Swordfish: The Story of the Taranto Raid.'' London: Weidenfeld and Nicolson, 2003.  {{ISBN|0-297-84667-1}}.
{{refend}}

==External links==
{{Commons category}}
* Historical Collection of [https://web.archive.org/web/20070116144905/http://www.old-picture.com/biplanes-index-001.htm Biplane Pictures]
* Jacqui Hayes: [http://www.cosmosmagazine.com/node/984 Bird wings evolved from biplane dinosaurs] {{Webarchive|url=https://web.archive.org/web/20070127002632/http://www.cosmosmagazine.com/node/984 |date=2007-01-27 }}, ''[[Cosmos (magazine)|Cosmos]]''
* [http://spicerweb.org/Chanute/Cha_index.aspx Spicerweb.org], Octave Chanute biplane hang glider

{{Authority control}}

[[Category:Aircraft wing design]]
[[Category:Wing configurations]]
[[Category:Biplanes|*]]