Biplane

First World War Sopwith Camel

biplane

A biplane is a

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 wings of some flying animals.

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

The lower wing is usually attached to the

structures.

Advantages and disadvantages

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.^{[citation needed]}

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.^[2] 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 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.^{[citation needed]}

The smaller biplane wing allows greater 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 aerobatic biplanes are still made in small numbers.^{[citation needed]}

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 – discuss]} 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.^{[citation needed]}

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

.

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

However, positive (forward) stagger is much more common.

Bays

The space enclosed by a set of

The larger two-seat

Large transport and 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.^[8]

• 
  Zeppelin-Lindau D.I strutless biplane
• 
  Nieuport 23

  single-bay sesquiplane
• 
  SPAD S.XIII single-bay biplane with auxiliary struts
• 
  Curtiss JN-4

  two-bay biplane
• 
  Handley Page V/1500 four-bay or multi-bay biplane

Because most biplanes do not have

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.^[9] Anti-drag wires prevent the wings from moving forward when the aircraft stops and run the opposite direction to the drag wires.^[10] 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.^[11] 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.^[12] 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.

The sesquiplane is a type of biplane where one wing (usually the lower) is significantly smaller than the other.

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.^[15] The performance of the Nieuport sesquiplanes was so impressive that the 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.^[16] The Albatros D.III and D.V, which had also copied the general layout from Nieuport, similarly provided the backbone of the German forces during the First World War.^[17] The Albatros sesquiplanes were widely acclaimed by their aircrews for their maneuverability and high rate of climb.^[18]

During interwar period, the sesquiplane configuration continued to be popular, with numerous types such as the Nieuport-Delage NiD 42/52/62 series, Fokker C.Vd & 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.^[19] The Saro Windhover was a sesquiplane with the upper wing smaller than the lower, which was a much rarer configuration than the reverse.^[20] 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.^[17]

The stacking of wing planes was suggested by

Throughout the pioneer years, both biplanes and monoplanes were common, but by the outbreak of the

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

, 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, using straightforward design to could carry six passengers on busy routes, such as London-Paris services.^[31] 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.^[32][33] Despite its relative success, British production of the Dragon was quickly ended when 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.^[34]

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 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.^[35] 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.^[8]

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

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 carriers. Its low stall speed and inherently tough design made it ideal for operations even in the often severe mid-Atlantic weather conditions.^[40] By the end of the conflict, the Swordfish held the distinction of having caused the destruction of a greater tonnage of Axis shipping than any other Allied aircraft.^[41]

Both the German

Later biplane

wing-walking

, and with crop dusting, where its compactness worked well at low levels, where it had to dodge obstacles.

Modern biplane designs still exist in specialist roles such as

dominated aerobatics for many years after World War II and is still in production.

The vast majority of biplane designs have been fitted with

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.

Although most

Other biplane ultralights include the Belgian-designed Aviasud Mistral, the German FK12 Comet (1997–), the Lite Flyer Biplane,^[46][47] the Sherwood Ranger, and the Murphy Renegade.

The

See also

• History of aviation
• Multiplane (aeronautics)
• Wing configuration

Bibliography

• Andrews, C.F. Profile No 17: The SPAD XIII C.1. Leatherhead, Surrey, UK: Profile Publications, 1965.
• Andrews, C. F. (1966). The Nieuport 17. Aircraft in Profile no. 49. Leatherhead, Surrey: Profile Publications.
• 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.
• Chatterjee S, Templin RJ (30 January 2007). "Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui". Proceedings of the National Academy of Sciences of the United States of America. 104 (5): 1576–80.
  PMID 17242354
  .
• Chassard, Marc (2018). Nieuport 17 Analyse détaillée des premières series (in French). France: FAREWO (French Aviation Research Work).
• Coggins, Edward V. (2000). Wings That Stay on. Turner.
  ISBN 978-1681621760
  .
• Cooksley, Peter. Sopwith Fighters in Action (Aircraft No. 110). Carrollton, Texas: Squadron/Signal Publications, 1991.
  ISBN 0-89747-256-X
  .
• Dommasch, Daniel O.; Sherby, Sydney S.; Connolly, Thomas F. (1961). Airplane Aerodynamics (3rd ed.). Pitman Publishing.
  ASIN B003YKT5YK
  .
• Dorr, Robert F. B-29 Superfortress units of the Korean War. Botley, Oxford, UK: Osprey Publishing, 2003.
  ISBN 1-84176-654-2
  .
• Grosz, Peter (1998). Dornier D.I Windsock Mini datafile # 12. Hertfordshire, UK: Albatros Publications.
  ISBN 9780948414923
  .
• Gunston, Bill (2009). Cambridge Aerospace dictionary (2nd ed.). Cambridge, UK: Cambridge University Press. p. 606.
  ISBN 978-0-521-19165-4
  .
• Gunston, Bill (2004). The Cambridge Aerospace Dictionary Cambridge. Cambridge University Press. p. 34.
  ISBN 978-0521841405
  .
• 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. 84–85.
• Lewis, Peter (1971). British Racing and Record-Breaking Aircraft. London: Putnam.
  ISBN 0-370-00067-6
  .
• London, Peter (1988). Saunders and Saro Aircraft since 1917. London: Putnam & Company Ltd. pp. 125–130.
  ISBN 0-85177-814-3
  .
• Moss, Peter W. (1966). The de Havilland Rapide: Profile Publications Number 144. Leatherhead, Surrey, UK: Profile Publications.
• "Report on the Junker Armoured Two-Seater Biplane, Type J.1." Flight, 18 March 1920.
• Riding, Richard (June 1980). "The Black Dragons".
  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
  .
• Wragg, David W. (1974). Flight before flying. Osprey Publishing.
  ISBN 978-0850451658
  .
• Wragg, David. Swordfish: The Story of the Taranto Raid. London: Weidenfeld and Nicolson, 2003.
  ISBN 0-297-84667-1
  .

External links

Wikimedia Commons has media related to Biplanes.

• Historical Collection of Biplane Pictures
• Jacqui Hayes: Bird wings evolved from biplane dinosaurs Archived 2007-01-27 at the
  Cosmos
• Spicerweb.org, Octave Chanute biplane hang glider