Biplane
Overview
 
A biplane is a fixed-wing aircraft
Fixed-wing aircraft
A fixed-wing aircraft is an aircraft capable of flight using wings that generate lift due to the vehicle's forward airspeed. Fixed-wing aircraft are distinct from rotary-wing aircraft in which wings rotate about a fixed mast and ornithopters in which lift is generated by flapping wings.A powered...

 with two superimposed main wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

s. The Wright brothers'
Wright brothers
The Wright brothers, Orville and Wilbur , were two Americans credited with inventing and building the world's first successful airplane and making the first controlled, powered and sustained heavier-than-air human flight, on December 17, 1903...

 Wright Flyer
Wright Flyer
The Wright Flyer was the first powered aircraft, designed and built by the Wright brothers. They flew it four times on December 17, 1903 near the Kill Devil Hills, about four miles south of Kitty Hawk, North Carolina, U.S.The U.S...

 used a biplane design, as did most aircraft in the early years of aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...

. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...

 wing. Improved structural techniques and materials and the quest for greater speed made the biplane configuration obsolete for most purposes by the late 1930s.

The term is also occasionally used in biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, to describe the wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

s of some flying animals
Flying and gliding animals
A number of animals have evolved aerial locomotion, either by powered flight or by gliding. Flying and gliding animals have evolved separately many times, without any single ancestor. Flight has evolved at least four times, in the insects, pterosaurs, birds, and bats. Gliding has evolved on many...

.
In a biplane aircraft, two wings are placed one above the other.
Encyclopedia
A biplane is a fixed-wing aircraft
Fixed-wing aircraft
A fixed-wing aircraft is an aircraft capable of flight using wings that generate lift due to the vehicle's forward airspeed. Fixed-wing aircraft are distinct from rotary-wing aircraft in which wings rotate about a fixed mast and ornithopters in which lift is generated by flapping wings.A powered...

 with two superimposed main wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

s. The Wright brothers'
Wright brothers
The Wright brothers, Orville and Wilbur , were two Americans credited with inventing and building the world's first successful airplane and making the first controlled, powered and sustained heavier-than-air human flight, on December 17, 1903...

 Wright Flyer
Wright Flyer
The Wright Flyer was the first powered aircraft, designed and built by the Wright brothers. They flew it four times on December 17, 1903 near the Kill Devil Hills, about four miles south of Kitty Hawk, North Carolina, U.S.The U.S...

 used a biplane design, as did most aircraft in the early years of aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...

. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...

 wing. Improved structural techniques and materials and the quest for greater speed made the biplane configuration obsolete for most purposes by the late 1930s.

The term is also occasionally used in biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, to describe the wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

s of some flying animals
Flying and gliding animals
A number of animals have evolved aerial locomotion, either by powered flight or by gliding. Flying and gliding animals have evolved separately many times, without any single ancestor. Flight has evolved at least four times, in the insects, pterosaurs, birds, and bats. Gliding has evolved on many...

.

Overview

In a biplane aircraft, two wings are placed one above the other. Both provide part of the lift, although they are not able to produce twice as much lift as a single wing of similar size and shape
Planform
In aviation, a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing. Of all the myriad planforms used, they can typically be grouped into those used for low-speed flight, found on general aviation aircraft, and those used for high-speed flight, found on many military...

 because the upper and the lower are working on nearly the same portion of the atmosphere. For example, in a wing of aspect ratio
Aspect ratio (wing)
In aerodynamics, the aspect ratio of a wing is essentially the ratio of its length to its breadth . A high aspect ratio indicates long, narrow wings, whereas a low aspect ratio indicates short, stubby wings....

 6, and a wing separation distance of one chord
Chord (aircraft)
In aeronautics, chord refers to the imaginary straight line joining the trailing edge and the center of curvature of the leading edge of the cross-section of an airfoil...

 length, the biplane configuration can 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
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...

, while the upper wing is raised above the fuselage with an arrangement of cabane strut
Cabane strut
The cabane struts of a biplane aircraft support the upper wing over the fuselage and work in conjunction with other wing components such as spars and flying wires to transmit flight loads....

s, although other arrangements have been used. Almost all biplanes also have a third horizontal surface, the tailplane
Tailplane
A tailplane, also known as horizontal stabilizer , is a small lifting surface located on the tail behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed wing aircraft such as helicopters and gyroplanes...

, to control the pitch, or angle of attack
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...

 of the aircraft (although there have been a few exceptions). Either or both of the main wings can support flaps or aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...

s to assist lateral rotation and speed control; usually the ailerons are mounted on the upper wing, and flaps (if used) on the lower wing. Often there is bracing between the upper and lower wings, in the form of wires (tension member
Tension member
Tension members are structural elements that are subjected to axial tensile forces. They are usually used in different types of structures. Examples of tension members are: bracing for buildings and bridges, truss members, and cables in suspended roof systems....

s) and slender interplane strut
Interplane strut
An interplane strut is an aircraft airframe component designed to transmit lift and landing loads between wing panels on biplanes and other aircraft with multi-wing designs. They also maintain the correct angle of incidence for the connected wing panels and are often braced with wires...

s (compression members) positioned symmetrically on either side of the fuselage.

The space enclosed by a set of struts is called a bay, hence a biplane with one set of such struts on each side is said to be a single-bay biplane. Two bay biplanes (with one set of struts closer to the fuselage, and another closer to the wing tips) were also common during the biplane's heyday, and some larger biplanes had three or more bays, the Handley Page Hyderabad
Handley Page Hyderabad
|-See also:-Bibliography:* Barnes, C. H. Handley Page Aircraft Since 1907. London: Putnam & Company, Ltd., 1987. ISBN 0-85177-803-8.* Clayton, Donald C. Handley Page, an Aircraft Album. Shepperton, Surrey, UK: Ian Allan Ltd., 1969. ISBN 0-7110-0094-8....

 for example had three.

Variations on the biplane concept include the sesquiplane, where one wing (usually the lower) is significantly smaller than the other, either in span, chord, or both. Sometimes the lower wing is only large enough to support the bracing struts for the upper wing. The name means "one-and-a-half wings." This significantly reduces interference drag while retaining the structural advantages of a biplane. Probably the best known examples of sesquiplanes are the Nieuport
Nieuport
Nieuport, later Nieuport-Delage, was a French aeroplane company that primarily built racing aircraft before World War I and fighter aircraft during World War I and between the wars.-Beginnings:...

 single and two-seat military aircraft of World War I, from the Nieuport 10
Nieuport 10
|-See also:- External links :* *...

 of 1915 through to the Nieuport 27 of 1917, although it was a common layout throughout the 1920s and 30s, until superseded by improvements in structural design that made monoplane designs more practicable.

The tandem wing
Tandem wing
thumb|right|QAC Quickie Q2A tandem wing aircraft usually involves two full-sized wings, both of which are full airfoils. Sometimes an aircraft of this configuration can look like a variation on the biplane, but is in fact very different. The forward wing is often technically a canard, fitted with...

is an aircraft configuration with one wing or set of wings in front of the other (e.g. a wing in the nose and a wing in the tail). The unsuccessful Langley Aerodrome
Langley Aerodrome
The Langley Aerodrome was a pioneering but unsuccessful manned, powered flying machine designed at the close of the 19th century by Smithsonian Institution Secretary Samuel Langley. The U.S...

 was an early example of this layout. This is not usually considered a biplane, as the two wings do not overlap in plan view. Aerodynamic research by NASA found that it is necessary for the two wings to be different in either chord or span, otherwise longitudinal oscillation would occur. The tandem wing has not found much favor, in particular as it still suffers from higher tip vortex drag than an equivalent monoplane.

Advantages and disadvantages

Aircraft built with two main wings (or three in a triplane
Triplane
A triplane is a fixed-wing aircraft equipped with three vertically-stacked wing planes. Tailplanes and canard foreplanes are not normally included in this count, although they may occasionally be.-Design principles:...

) can usually lift up to 20 percent more than can a similarly sized monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...

 of similar wingspan
Wingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...

. Biplanes will therefore typically have a shorter wingspan than a similar monoplane, which tends to afford greater maneuverability
Aerobatics
Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in normal flight. Aerobatics are performed in airplanes and gliders for training, recreation, entertainment and sport...

. The struts and wire bracing of a typical biplane form a box girder
Box girder
A box or tubular girder is a girder that forms an enclosed tube with multiple walls, rather than an or H-beam. Originally constructed of riveted wrought iron, they are now found in rolled or welded steel, aluminium extrusions or pre-stressed concrete....

 that permits a light but very strong wing structure.

On the other hand there are many disadvantages to the configuration. Each wing negatively interferes with the aerodynamics of the other. For a given wing area the biplane produces more drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

 and less lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...

 than a monoplane.

Stagger

Many biplanes were designed with the wings positioned directly "one-above-the-other," as was first done with the Wright's 1903 Flyer I. Moving one wing forward relative to the other can help increase lift and reduce drag, though it may distort the box girder effect of the wing and reduce the structural benefits of the biplane layout. Many biplanes have been designed with the upper wing positioned with its leading edge ahead of the that of the lower wing, in a "positive stagger
Stagger (aviation)
In aviation stagger refers to the horizontal positioning of a biplane, triplane, or multiplane's wings in relation to one another.An aircraft is said to have positive stagger, or simply stagger, when the upper wing is positioned forward of the lower wing, such as the de Havilland Tiger Moth or...

" format. Less common have been biplanes with the lower wing's leading edge ahead of the upper wing, called "negative stagger". Examples of negative stagger include the Airco DH.5
Airco DH.5
-Bibliography:* Bruce, J.M. Warplanes of the First World War, Vol. 1. London: MacDonald, 1965, pp. 128–132.* Jackson, A.J. De Havilland Aircraft since 1915. London: Putnam, 1962....

, Sopwith Dolphin, and the Beechcraft Staggerwing
Beechcraft Staggerwing
The Beechcraft Model 17 Staggerwing is an American biplane with an atypical negative stagger , that first flew in 1932.-Development:...

.

Forward stagger was more common because it improves both downward visibility and ease of cockpit access for open cockpit biplanes.

History

Early designers considered both monoplane and biplane designs. However, the weakness of the materials and design techniques available required these designers to place great effort into making wings capable of withstanding the required loads. A biplane (having the characteristics of a box girder
Box girder
A box or tubular girder is a girder that forms an enclosed tube with multiple walls, rather than an or H-beam. Originally constructed of riveted wrought iron, they are now found in rolled or welded steel, aluminium extrusions or pre-stressed concrete....

) can be made lighter for a given strength requirement, and was therefore a more common choice.

Most successful early aircraft were biplanes, in spite of considerable early experimentation with monoplanes, triplane
Triplane
A triplane is a fixed-wing aircraft equipped with three vertically-stacked wing planes. Tailplanes and canard foreplanes are not normally included in this count, although they may occasionally be.-Design principles:...

s and even quadraplanes. During the period (~1914 to 1925) almost all aircraft were biplanes.

Early monoplanes and biplanes were often externally braced, having struts and/or bracing wires. These elements gave added strength without excess weight, but they did add unwanted aerodynamic drag.

The long-term answer to the problem was a cantilever
Cantilever
A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...

 monoplane wing – having sufficient stiffness to dispense with external bracing. Such wings were already being developed by several designers, including Hugo Junkers
Hugo Junkers
Hugo Junkers was an innovative German engineer, as his many patents in varied areas show...

, whose work during 1915 resulted in the pioneering Junkers J 1
Junkers J 1
The Junkers J 1, nicknamed the Blechesel , was the world's first practical all-metal aircraft. Built early in World War I, when aircraft designers relied largely on fabric-covered wooden structures, the Junkers J 1 was a revolutionary development in aircraft design, being built and flown only 12...

, the world's first practical all-metal aircraft of any type. Cantilever monoplane wings were becoming the norm for most applications by the early nineteen thirties; the era of the biplane was almost over.
Several air forces continued to use biplanes for primary training up till WWII and even beyond: the de Havilland Tiger Moth
De Havilland Tiger Moth
The de Havilland DH 82 Tiger Moth is a 1930s biplane designed by Geoffrey de Havilland and was operated by the Royal Air Force and others as a primary trainer. The Tiger Moth remained in service with the RAF until replaced by the de Havilland Chipmunk in 1952, when many of the surplus aircraft...

 in the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

, Stampe SV.4
Stampe SV.4
-Bibliography:* Pacco, John. "Stampe & Vertongen SV-4B" Belgisch Leger/Armee Belge: Het Militair Vliegwezen/l'Aeronautique Militaire 1930-1940. Aartselaar, Belgium, 2003, pp. 85-86. ISBN 90-801136-6-2....

 in French and Belgian Air Forces, and the Boeing Stearman
Boeing Stearman
|-See also:-Bibliography:* Avis, Jim and Bowman, Martin. Stearman: A Pictorial History. Motorbooks, 1997. ISBN 0-76030-479-3.* Bowers, Peter M. Boeing Aircraft since 1916. London:Putnam, 1989. ISBN 0-85177-804-6....

 in the USAF.

Modern biplane designs now exist only in specialist niche roles and markets such as aerobatics
Aerobatics
Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in normal flight. Aerobatics are performed in airplanes and gliders for training, recreation, entertainment and sport...

 and agricultural aircraft
Agricultural aircraft
An agricultural aircraft is an aircraft that has been built or converted for agricultural use - usually aerial application of pesticides or fertilizer ; in these roles they are referred to as "crop dusters" or "top dressers"...

.

The vast majority of biplane designs have been fitted with reciprocating engine
Reciprocating engine
A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...

s of comparatively low power; exceptions include the Antonov An-3
Antonov An-3
|- See also :- References : - External links :*...

 and WSK-Mielec M-15 Belphegor
WSK-Mielec M-15 Belphegor
The Mielec M-15 was a jet agricultural aircraft, manufactured by PZL Mielec in Poland for the USSR agricultural aviation. It was the only jet biplane and only jet agricultural plane in the world...

, fitted with turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...

 and turbofan
Turbofan
The turbofan is a type of airbreathing jet engine that is widely used for aircraft propulsion. A turbofan combines two types of engines, the turbo portion which is a conventional gas turbine engine, and the fan, a propeller-like ducted fan...

 engines, respectively. Some older biplane designs, such as the Grumman Ag Cat
Grumman Ag Cat
-See also:-References:* Michell, Simon. Jane's Civil and Military Aircraft Upgrades 1994-95. Coulsdon, UK:Jane's Information Group, 1994. ISBN 0 7106 1208 7.-External links:*...

 and the aforementioned An-2 (in the form of the An-3) are available in upgraded versions with turboprop engines.

Famous biplanes include the Sopwith Camel
Sopwith Camel
The Sopwith Camel was a British First World War single-seat biplane fighter introduced on the Western Front in 1917. Manufactured by Sopwith Aviation Company, it had a short-coupled fuselage, heavy, powerful rotary engine, and concentrated fire from twin synchronized machine guns. Though difficult...

, Antonov An-2
Antonov An-2
The Antonov An-2 is a single-engine biplane utility/agricultural aircraft designed in the USSR in 1946...

, Beechcraft Staggerwing
Beechcraft Staggerwing
The Beechcraft Model 17 Staggerwing is an American biplane with an atypical negative stagger , that first flew in 1932.-Development:...

, Boeing Stearman
Boeing Stearman
|-See also:-Bibliography:* Avis, Jim and Bowman, Martin. Stearman: A Pictorial History. Motorbooks, 1997. ISBN 0-76030-479-3.* Bowers, Peter M. Boeing Aircraft since 1916. London:Putnam, 1989. ISBN 0-85177-804-6....

, Bristol Bulldog
Bristol Bulldog
|-See also:-References:NotesBibliography* Andrews, C.F. The Bristol Bulldog . Leatherhead, Surrey, UK: Profile Publications Ltd., 1965.* Barnes, C.H. Bristol Aircraft Since 1910. London: Putnam, 1964....

, Curtiss JN-4
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...

, de Havilland Tiger Moth
De Havilland Tiger Moth
The de Havilland DH 82 Tiger Moth is a 1930s biplane designed by Geoffrey de Havilland and was operated by the Royal Air Force and others as a primary trainer. The Tiger Moth remained in service with the RAF until replaced by the de Havilland Chipmunk in 1952, when many of the surplus aircraft...

, Fairey Swordfish
Fairey Swordfish
The Fairey Swordfish was a torpedo bomber built by the Fairey Aviation Company and used by the Fleet Air Arm of the Royal Navy during the Second World War...

, Pitts Special
Pitts Special
The Pitts Special is a series of light aerobatic biplane designed by Curtis Pitts. It has accumulated many competition wins since its first flight in 1944...

 and the Wright Flyer
Wright Flyer
The Wright Flyer was the first powered aircraft, designed and built by the Wright brothers. They flew it four times on December 17, 1903 near the Kill Devil Hills, about four miles south of Kitty Hawk, North Carolina, U.S.The U.S...

. The Stearman is particularly associated with stunt flying with wing-walkers. Famous sesquiplanes include the Nieuport 17
Nieuport 17
|-Specifications :-See also:-Bibliography:* Bruce, Jack. "Those Classic Nieuports". Air Enthusiast Quarterly. Number Two, 1976. Bromley, UK:Pilot Press. pp. 137–153....

 and Albatros D.III
Albatros D.III
The Albatros D.III was a biplane fighter aircraft used by the Imperial German Army Air Service and the Austro-Hungarian Air Service during World War I. The D.III was flown by many top German aces, including Manfred von Richthofen, Ernst Udet, Erich Löwenhardt, Kurt Wolff, and Karl Emil Schäfer...

.

A few biplanes are still made today, typically for nostalgia or aerobatics. Examples include the Pitts Special
Pitts Special
The Pitts Special is a series of light aerobatic biplane designed by Curtis Pitts. It has accumulated many competition wins since its first flight in 1944...

 and the Waco
Waco F series
-External links:*...

.

Ultralight aircraft

Although most ultralights
Ultralight aviation
The term "ultralight aviation" refers to light-weight, 1- or 2-person airplanes., also called microlight aircraft in the UK, India and New Zealand...

 are monplanes the low speeds and simple construction involved have inspired a small number of biplane ultralights, such as Larry Mauro's Easy Riser. 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
Bill Lishman
Bill Lishman is a Canadian inventor, artist, and ultralight aircraft enthusiast.-Gliders and ultralights:Lishman started out by flying a motorized ultralight fixed-wing glider called the UFM Easy Riser, a bi-wing craft designed in California by Larry Mauro as a hang glider...

. Other biplane ultralights are the Belgian-designed Aviasud Mistral
Aviasud Mistral
-References:* Lambert, Mark . Jane's All The World's Aircraft 1993-94. Coulsdon, UK: Jane's Data Division, 1993. ISBN 0-7106-1066-1.* Taylor, John W.R. Jane's All The World's Aircraft 1988-89. Jane's Defence Data, 1988. ISBN 0-7106-0867-5....

, the German FK12 Comet, and the Lite Flyer Biplane.

In avian evolution

It has been suggested the feathered dinosaur Microraptor
Microraptor
Microraptor is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovered from Liaoning, China...

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.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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