A biplane is a fixed-wing aircraft with two main wings 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 than a similar unbraced or cantilever monoplane wing. Improved structural techniques, better materials and the quest for greater speed 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.
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. For example, in a wing of aspect ratio 6, and a wing separation distance of one chord length, the biplane configuration will only produce about 20 percent more lift than a single wing of the same planform.
In the biplane configuration, the lower wing is usually attached to the fuselage, while the upper wing is raised above the fuselage with an arrangement of cabane struts, although other arrangements have been used. Either or both of the main wings can support ailerons, 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 wires (tension members) and/or slender interplane struts positioned symmetrically on either side of the fuselage.
The primary advantage of the biplane over a monoplane is to combine great stiffness with light weight. Stiffness requires structural depth and, where early monoplanes had to have this added with complicated extra bracing, the box kite or biplane naturally has a deep structure and is therefore easier to make both light and strong. A braced monoplane wing must support itself fully, while the two wings of a biplane help to stiffen each other. The biplane is therefore inherently stiffer than the monoplane. Also, the structural forces in the spars of a biplane wing tend to be lower, so the wing can use less material to obtain the same overall strength and is therefore much lighter. A disadvantage of the biplane was the need for extra struts to space the wings apart, although the bracing required by early monoplanes reduced this disadvantage.
The low power supplied by the engines available in the first years of aviation meant that aeroplanes could only fly slowly. This required an even lower stalling speed, which in turn required a low wing loading, combining both large wing area with light weight. A biplane wing of a given span and chord has twice the area of a monoplane the same size and so can fly more slowly, or for a given flight speed can lift more weight. Alternatively, a biplane wing of the same area as a monoplane has lower span and chord, reducing the structural forces and allowing it to be lighter.
Biplanes suffer aerodynamic interference between the two planes. 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. Given the low speed and power of early aircraft, the drag penalty of the wires and struts and the mutual interference of airflows were relatively minor and acceptable factors. As engine power rose after World War One, the thick-winged cantilever monoplane became practicable and, with its inherently lower drag and higher speed, from around 1918 it began to replace the biplane in most fields of aviation.
The smaller biplane wing also allows greater maneuverability. During World War One, this further enhanced the dominance of the biplane and, despite the need for speed, military aircraft were among the last to abandon the biplane form. Specialist sports aerobatic biplanes are still occasionally made.
Biplanes were originally designed with the wings positioned directly one above the other. Moving the upper wing forward relative to the lower one is called positive stagger or, more often, simply stagger. It can help increase lift and reduce drag by reducing the aerodynamic interference effects between the two wings. Many biplanes have such staggered wings. A common example from the 1930s is the layout found for the Waco Standard Cabin series.
It is also possible to place the lower wing's leading edge ahead of the upper wing, giving negative stagger. This is usually done in a given design for practical engineering reasons. Examples of negative stagger include the Sopwith Dolphin and Beechcraft Staggerwing. However, positive (forward) stagger is more common because it improves both downward visibility and ease of cockpit access for open cockpit biplanes.
The space enclosed by a set of interplane struts is called a bay (much as 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.
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. The Sopwith 1 1⁄2 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.
Large transport and bombing biplanes often needed still more bays to provide sufficient strength. These are sometimes 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.
The sesquiplane is a common variation on the biplane where one wing (usually the lower) has not more than half the surface area of the other. The name means "one-and-a-half wings." The arrangement may reduce interference drag between the wings whilst retaining the biplane's structural advantage. The 1920s Pander E is an example of an aircraft with a lower wing of exactly half the span and nearly one quarter (23%) of the area of the upper one. Some designs keep the upper and lower spans nearly equal whilst reducing the lower chord, of which the best known examples are probably the Nieuport military aircraft—from the Nieuport 10 through to the Nieuport 27, all designed by Gustave Delage during the Great War. The later Waco Custom Cabin series proved to be a popular example in general aviation. Another notable sesquiplane was the German Junkers J.I armored ground attack aircraft which was the first all-metal combat aircraft to be mass-produced and enter service.
Although most 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 the man who became known as "Father Goose", Bill Lishman.
The biplane configuration was developed from the box kite, invented by the Australian Lawrence Hargrave. By 1896 Octave Chanute was flying biplane hang gliders and concluded that the externally braced biplane offered better prospects for powered flight than the monoplane. The Wright Flyer biplane of 1903 became the first successful powered aeroplane.
Throughout the pioneer years, both biplanes and monoplanes were common, but by the outbreak of the First World War biplanes had gained favour due to a number of monoplane structural failures that resulted in the RFC's "Monoplane Ban" when all monoplanes in military service were grounded, while the French also withdrew most monoplanes from combat roles and relegated them to training. During the period from 1914 to 1925 most new aircraft were biplanes although by 1918, the Germans were experimenting with a new generation of monoplanes such as the Junkers D.I and Fokker D.VIII that might have ended the biplane's advantages earlier had the war not ended when it had, and the French already had the Morane-Saulnier AI strut braced parasol monoplane in service. Sesquiplane types, which were biplanes with abbreviated lower wings such as the French Nieuport 17 and German Albatros D.III, offered slightly lower drag than a conventional biplane while being stronger than a monoplane.
As the available engine-power and speed increased, the drag penalty of external bracing limited aircraft performance. In order to fly faster, it would be necessary to do away with the external bracing to create an aerodynamically clean wing. Early cantilever designs were too weak or too heavy. The 1917 Fokker V.4 prototype (identified by some as the V.3) was a cantilever triplane but suffered excessive flexing of the wings, while the all-metal Junkers J 1 cantilever monoplane of 1915 was overweight and had a poor rate of climb from its use of electrical steel sheet for its construction.
By the 1930s biplanes had reached their performance limits, and monoplanes had become predominant, particularly in continental Europe where monoplanes had been 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 use but they were clearly uncompetitive, and most were used in specialist roles, such as training or shipboard operation, until shortly after the end of the war. The British Gloster Gladiator and the Italian Fiat CR.42 biplane fighters were both still operational after 1939. The German Heinkel He 50 and the Soviet Polikarpov Po-2 were both used in the night ground attack role until late in the war; the latter was even used by the Korean People's Air Force in the Korean War for night bombing. The British Fleet Air Arm flew Fairey Swordfish torpedo bombers from its aircraft carriers in the anti-submarine warfare role until the end of the war because they could operate from the decks of small escort carriers. The Swordfish was especially well suited to its role and outlived its intended replacement.
Later biplane trainers included the de Havilland Tiger Moth in the RAF, RCAF and others, the Stampe SV.4 in the French and Belgian Air Forces, the Boeing Stearman in the USAAF and the Naval Aircraft Factory N3N with the US Navy. In later civilian use, the Stearman became particularly associated with stunt flying such as wing-walking.
Modern biplane designs still exist in specialist niche roles such as aerobatics and agricultural aircraft with the competition aerobatics role and format for such a biplane well-defined in the mid-1930s by the Udet U 12 Flamingo. 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 engines of comparatively low power; 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 and the aforementioned An-2 (in the form of the An-3) are available in upgraded versions with turboprop engines.
The two most produced biplane designs are the 1913 British Avro 504 (11,303 built) and the 1928 Soviet Polikarpov Po-2 (over 20,000 built), and coincidentally with the Po-2 being the direct replacement for the Soviet copies of the Avro 504.
It has been suggested the feathered dinosaur Microraptor glided, and perhaps even flew, on four wings, which were held in a biplane-like arrangement. This was made possible by the presence of flight feathers on both the forelimbs and hindlimbs of Microraptor, and it has been suggested the earliest flying ancestors of birds may have possessed this morphology, with the monoplane arrangement of modern birds evolving later.
Blackburn Aircraft Limited was a British aircraft manufacturer that concentrated mainly on naval and maritime aircraft during the first part of the 20th century.Bracing (aeronautics)
In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in compression or tension as the need arises, and/or wires, which act only in tension.
In general, bracing allows a stronger, lighter structure than one which is unbraced, but external bracing in particular adds drag which slows down the aircraft and raises considerably more design issues than internal bracing. Another disadvantage of bracing wires is that they require routine checking and adjustment, or rigging, even when located internally.
During the early years of aviation, bracing was a universal feature of all forms of aeroplane, including the monoplanes and biplanes which were then equally common. Today, bracing in the form of lift struts is still used for some light commercial designs where a high wing and light weight are more important than ultimate performance.Curtiss JN-4
The Curtiss JN-4 "Jenny" was one of a series of "JN" biplanes built by the Curtiss Aeroplane Company of Hammondsport, New York, later the Curtiss Aeroplane and Motor Company. Although the Curtiss JN series was originally produced as a training aircraft for the U.S. Army, the "Jenny" (the common nickname derived from "JN-4", with an open-topped four appearing as a Y) continued after World War I as a civil aircraft, as it became the "backbone of American postwar [civil] aviation." Thousands of surplus Jennys were sold at bargain prices to private owners in the years after the war and became central to the barnstorming era that helped awaken the U.S. to civil aviation through much of the 1920s.Curtiss Model D
The 1911 Curtiss Model D (or frequently, "Curtiss Pusher") was an early United States pusher aircraft with the engine and propeller behind the pilot's seat. It was among the very first aircraft in the world to be built in any quantity — all of which were produced by Curtiss during an era of trial-and-error development and equally important parallel technical development in internal combustion engine technologies.
It was also the aircraft type which made the first takeoff from the deck of a ship (flown by Eugene B. Ely off the deck of USS Birmingham on November 14, 1910, near Hampton Roads, Virginia) and made the first landing aboard a ship (USS Pennsylvania) on January 18, 1911, near San Francisco, California.
It was originally fitted with a foreplane for pitch control, but this was dispensed with when it was accidentally discovered to be unnecessary. The new version without the foreplane was known as the Headless Pusher. Like all Curtiss designs, the aircraft used ailerons instead, which first existed on a Curtiss-designed airframe as quadruple "wing-tip" ailerons on the 1908 June Bug to control rolling in flight, thus avoiding use of the Wright brothers' patented wing warping technology.Etrich Taube
The Etrich Taube, also known by the names of the various later manufacturers who build versions of the type, such as the Rumpler Taube, was a pre-World War I monoplane aircraft. It was the first military aeroplane to be mass-produced in Germany.
The Taube was very popular prior to the First World War, and it was also used by the air forces of Italy and Austria-Hungary. Even the Royal Flying Corps operated at least one Taube in 1912. On November 1, 1911, Giulio Gavotti, an Italian aviator, dropped the world's first aerial bomb from his Taube monoplane over the Ain Zara oasis in Libya. Once the war began, it quickly proved inadequate as a warplane and was soon replaced by other designs.Fokker FG-2
The Fokker FG-2 was built by Anthony Fokker for the 1922 Rhön gliding competition, after visiting the Wasserkuppe during the 1921 competition.Gloster Aircraft Company
The Gloster Aircraft Company was a British aircraft manufacturer from 1917 to 1963.
Founded as the Gloucestershire Aircraft Company Limited during the First World War, with the aircraft construction activities of H H Martyn & Co Ltd of Cheltenham, England it produced fighters during the war. It was renamed later as foreigners found 'Gloucestershire' difficult to pronounce. It later became part of the Hawker Siddeley group and the Gloster name disappeared in 1963.
Gloster designed and built several fighters that equipped the British Royal Air Force (RAF) during the interwar years including the Gladiator, the RAF's last biplane fighter. The company built most of the wartime production of Hawker Hurricanes and Hawker Typhoons for their parent company Hawker Siddeley while its design office was working on the first British jet aircraft, the E.28/39 experimental aircraft. This was followed by the Meteor, the RAF's first jet-powered fighter and the only Allied jet fighter to be put into service during Second World War.Grumman F3F
The Grumman F3F was the last American biplane fighter aircraft delivered to the United States Navy (indeed, the last biplane fighter delivered to any American military air arm), and served between the wars. Designed as an improvement on the single-seat F2F, it entered service in 1936. It was retired from front line squadrons at the end of 1941 before it could serve in World War II, and was first replaced by the Brewster F2A Buffalo. The F3F which inherited the Leroy Grumman-designed retractable main landing gear configuration first used on the Grumman FF served as the basis for a biplane design ultimately developed into the much more successful F4F Wildcat.List of aircraft (pre-1914)
This is a chronological list of pioneer aircraft built before 1914. Entries here may or may not be repeated in the main List of aircraft pages.List of aircraft of the Royal Air Force
Many aircraft types have served in the British Royal Air Force since its formation in April 1918 from the merger of the Royal Flying Corps and Royal Naval Air Service. This is a list of RAF aircraft, including all currently active and retired types listed in alphabetic order by their RAF type name. For just those aircraft currently in service, see List of active United Kingdom military aircraft. Aircraft operated with the Fleet Air Arm from 1924 until 1939 were operated by the Royal Air Force on behalf of the Navy and are included; those operated by the Royal Navy after it re-acquired control of the aircraft used to support its operations in 1939 are not, but all aircraft operated in conjunction with the Navy are listed at List of aircraft of the Fleet Air Arm. Army Air Corps aircraft are not included but can be found at List of aircraft of the Army Air Corps.
For aircraft operated before the merger of the RFC and RNAS in 1918:
Refer to List of aircraft of the Royal Flying Corps
Refer to List of aircraft of the Royal Naval Air Service.List of civil aircraft
List of civil aircraft is a list of articles on civilian aircraft with descriptions, which excludes aircraft operated by military organizations in civil markings, warbirds, warbirds used for racing, replica warbirds and research aircraft.List of military aircraft of Germany
This list of military aircraft of Germany includes prototype, pre-production, and operational types. No distinction is drawn here between different services until 1991.
In 1990, the various air arms of the former German Democratic Republic were absorbed by their counterparts in the Federal Republic of Germany. Some types that had been operated by the GDR were no longer in service by then, and these are so noted.List of most-produced aircraft
This is a list of the most-produced aircraft types whose numbers exceed or exceeded 5,000. Any and all types of aircraft qualify, including airplanes, airships, balloons, gliders (sailplanes), helicopters, etc.List of seaplanes and amphibious aircraft
The following is a list of seaplanes and amphibious aircraft, which includes floatplanes and flying boats, by country of origin.
Seaplanes are any aircraft that has the capability of landing on water while amphibious aircraft are equipped with wheels to alight on land, as well as being able to land on the water. Flying boats rely on the fuselage or hull for buoyancy, while floatplanes rely on external pontoons or floats. Some experimental aircraft used specially designed skis to skim across the water but did not always have a corresponding ability to float.
This list does not include ekranoplans, 'Wing-In-Ground-effect' (WIG), water-skimmers, wingships or similar vehicles reliant on ground effect.List of submarine-borne aircraft
This is a list of aircraft carried undersea and used from submarines (see Submarine aircraft carriers).
These were primarily used during the Second World War, also included for comparison are earlier developments of submarine carried aircraft from the First World War and the period between the World Wars.Monoplane
A monoplane is a fixed-wing aircraft with a single main wing plane, in contrast to a biplane or other multiplane, each of which has multiple planes.
A monoplane has inherently the highest efficiency and lowest drag of any wing configuration and is the simplest to build. However, during the early years of flight, these advantages were offset by its greater weight and lower manoeuvrability, making it relatively rare until the 1930s. Since then, the monoplane has been the most common form for a fixed-wing aircraft.Stagger (aeronautics)
In aviation, stagger is the relative horizontal fore-aft positioning of stacked wings in a biplane, triplane, or multiplane.
An aircraft is said to have positive stagger, or simply stagger, when the upper wing is positioned forward of the lower (bottom) wing, Examples include the de Havilland Tiger Moth or Stearman. Conversely, an aeroplane is said to have negative stagger in unusual cases where the upper wing is positioned behind the lower wing, as in the Sopwith Dolphin or Beech Model 17 Staggerwing. An aircraft with the wings positioned directly above each other is said to have unstaggered wings, as in the Sopwith Cuckoo or Vickers Vildebeest.Voisin 1907 biplane
The 1907 Voisin biplane (designated the Voisin II by the 1913 edition of Jane's All the World's Aircraft), was the first successful powered aircraft designed by aeronautical engineer and manufacturer Gabriel Voisin. It was used by the French aviator Henri Farman to make the first heavier-than-air flight lasting more than a minute in Europe, and also to make the first full circle.
The first examples of the aircraft were known by the name of their owners, for instance the Delagrange I, or the Henri Farman n°1. Farman made many modifications to his aircraft, and these were incorporated into later production aircraft built by Voisin. The type enjoyed widespread success, and around sixty were built.Wing configuration
The wing configuration of a fixed-wing aircraft (including both gliders and powered aeroplanes or airplanes) is its arrangement of lifting and related surfaces.
Aircraft designs are often classified by their wing configuration. For example, the Supermarine Spitfire is a conventional low wing cantilever monoplane of straight elliptical planform with moderate aspect ratio and slight dihedral.
Many variations have been tried. Sometimes the distinction between them is blurred, for example the wings of many modern combat aircraft may be described either as cropped compound deltas with (forwards or backwards) swept trailing edge, or as sharply tapered swept wings with large leading edge root extensions (or LERX). Some are therefore duplicated here under more than one heading. This is particularly so for variable geometry and combined (closed) wing types.
Most of the configurations described here have flown (if only very briefly) on full-size aircraft. A few significant theoretical designs are also noted.
Note on terminology: Most fixed-wing aircraft have left hand and right hand wings in a symmetrical arrangement. Strictly, such a pair of wings is called a wing plane or just plane. However, in certain situations it is common to refer to a plane as a wing, as in "a biplane has two wings", or to refer to the whole thing as a wing, as in "a biplane wing has two planes". Where the meaning is clear, this article follows common usage, only being more precise where needed to avoid real ambiguity or incorrectness.