The Boeing Model 200 Monomail was an American mail plane of the early 1930s.
86-477: The aircraft marked a departure from the traditional biplane configuration for a transport aircraft, instead featuring a single, low set, all metal cantilever wing. Retractable landing gear and a streamlined fuselage added to the aerodynamic efficiency of the aircraft. A single example was constructed for evaluation by both Boeing and the US Army (under the designation Y1C-18 ) but no mass production ensued, and
172-411: 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
258-592: A World War I scout like the Fokker D.VII , one bay is usually enough. But for larger wings carrying greater payloads, several bays may be used. The two-seat Curtiss JN-4 Jenny is a two-bay biplane, while large heavy types were often multi-bay biplanes or triplanes – the earliest examples of the German Albatros B.I , and all production examples of the DFW B.I two-seater unarmed observation biplanes of 1914 were two of
344-426: A biplane has 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 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
430-617: A compromise between the high drag of a fully cross-braced structure and the high weight of a fully cantilevered wing. They are common on high-wing types such as the Cessna 152 and almost universal on parasol-winged types such as the Consolidated PBY Catalina . Less commonly, some low-winged monoplanes like the Piper Pawnee have had lift struts mounted above the wing, acting in compression in flight and in tension on
516-624: A documented jet-kill, as one Lockheed F-94 Starfire was lost while slowing down to 161 km/h (100 mph) – below its stall speed – during an intercept in order to engage the low flying Po-2. Later biplane trainers 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
602-513: A faster and more comfortable successor to the Dragon. 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
688-420: A lot of heavy reinforcement. Making the structure deeper allows it to be much lighter and stiffer. To reduce weight and air resistance, the structure may be made hollow, with bracing connecting the main parts of the airframe. For example, a high-wing monoplane may be given a diagonal lifting strut running from the bottom of the fuselage to a position far out towards the wingtip. This increases the effective depth of
774-432: 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. 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
860-507: A minimum of struts; however, it was relatively easy to damage the thin metal skin and required careful handling by ground crews. 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. 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
946-482: A single jury strut connecting the main strut to an intermediate point on the wing. A braced monoplane with 'V' struts such as the Fleet Canuck may have a complicated assembly of jury struts. Bracing, both internal and external, was extensively used in early aircraft to support the lightweight airframes demanded by the low engine powers and slow flying speeds then available. From the first Wright flyer of 1903,
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#17327869076221032-473: A somewhat unusual sesquiplane arrangement, possessing a more substantial lower wing with two spars that eliminated the flutter problems encountered by single-spar sesquiplanes. The stacking of wing planes was suggested by Sir George Cayley in 1843. Hiram Maxim adopted the idea for his steam-powered test rig, which lifted off but was held down by safety rails, in 1894. Otto Lilienthal designed and flew two different biplane hang gliders in 1895, though he
1118-408: 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. Where an aircraft has a wing running clear above the main fuselage,
1204-402: A typical biplane was significantly affecting performance, while the heavier but sleeker strut-braced parasol monoplane was becoming practicable. For a period this type of monoplane became the design of choice. Although the strut-braced high-wing monoplane was outpaced during the 1930s by the true cantilever monoplane, it has remained in use throughout the postwar era, in roles where light weight
1290-492: 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 monoplane wing. Improved structural techniques, better materials and higher speeds made
1376-411: 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 1½ Strutter has a W shape cabane, however as it does not connect
1462-604: Is a bracing component stiff enough to resist these forces whether they place it under compression or tension. A wire is a bracing component able only to resist tension, going slack under compression, and consequently is nearly always used in conjunction with struts. A square frame made of solid bars is not rigid but tends to bend at the corners. Bracing it with an extra diagonal bar would be heavy. A wire would be much lighter but would stop it collapsing only one way. To hold it rigid, two cross-bracing wires are needed. This method of cross-bracing can be seen clearly on early biplanes, where
1548-560: Is better known for his monoplanes. By 1896 a group of young men in the United States, led by Octave Chanute , were flying hang gliders 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. Throughout the pioneer years, both biplanes and monoplanes were common, but by
1634-643: Is more important than high speed or long range. These include light cabin aircraft where downward visibility is also important, and small transports. Braced high-aspect-ratio wings were used by French Hurel-Dubois (now part of Safran ) with the Hurel-Dubois HD.10 demonstrator in 1948, and then the HD.31 /32/34 airliners, still used by the French Institut Geographique National until the early 1980s. A turbojet-powered HD.45
1720-624: Is much more common. 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
1806-536: 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. 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,
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#17327869076221892-703: 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. Although most ultralights are monoplanes,
1978-617: The Lite Flyer Biplane, the Sherwood Ranger , and the Murphy Renegade . 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
2064-560: The Model 200 and the Model 221 were eventually modified for transcontinental service as the Model 221A , with slight fuselage stretches to give both a cabin for eight passengers. These aircraft were flown on United Air Lines ' Cheyenne -Chicago route. The advanced design of the Monomail was hampered by the lack of suitable engine and propeller technology. By the time variable-pitch propellers and more powerful engines were available,
2150-556: 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. The Saro Windhover was a sesquiplane with the upper wing smaller than the lower, which was a much rarer configuration than the reverse. The Pfalz D.III also featured
2236-874: The Westland IV or the undercarriage as on the Scottish Aviation Twin Pioneer . Lift struts remain common on small (2/4-seat) high-wing light aircraft in the ultralight and light-sport categories. Larger examples include the Short 360 36-passenger aircraft and the de Havilland Twin Otter 19-seater. A lift strut can be so long and thin that it bends too easily. Jury struts are small subsidiary struts used to stiffen it. They prevent problems such as resonant vibration and buckling under compressive loads. Jury struts come in many configurations. On monoplanes with one main strut, there may be just
2322-600: The Westland Lysander used extruded I section beams of light alloy, onto which were screwed a fore and aft pair of duralumin fairings. Later aircraft have had streamlined struts formed directly from shaped metal, like the extruded light alloy struts of the Auster AOP.9 , or from composites, for example the carbon fibre lift struts of the Remos GX eLITE . Designers have adopted different methods of improving
2408-497: The de Havilland Tiger Moth , 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 . However, positive (forward) stagger
2494-514: 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. 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
2580-528: 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 . 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
2666-515: 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. Anti-drag wires prevent
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2752-577: 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, using straightforward design to could carry six passengers on busy routes, such as London-Paris services. During early August 1934, one such aircraft, named Trail of
2838-609: 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. 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. Sesquiplane types, which were biplanes with abbreviated lower wings such as
2924-562: The advent of more powerful engines in 1909, but bracing remained essential for any practical design, even on monoplanes up until World War I when they became unpopular and braced biplanes reigned supreme. From 1911, the British researcher Harris Booth working at the National Physics Laboratory and the engineer Richard Fairey , then working for J.W. Dunne 's Blair Atholl Aeroplane Syndicate, began to develop and apply
3010-523: The aerodynamics of the strut-wing and strut-body connections, using similar approaches to those used in interplane struts. Sometimes the streamlining is tapered away close to the wing, as on the Farman F.190; other designs have an extended, faired foot, for example the Skyeton K-10 Swift . Lift struts are sometimes combined with other functions, for example helping to support the engines as on
3096-465: The aircraft eventually joined Boeing's fleet on the San Francisco - Chicago air mail route from July 1931. A second version was developed as the Model 221 , with a fuselage stretched by 8 inches (20 cm) that sacrificed some of its cargo capacity to carry six passengers in an enclosed cabin; the single pilot, however, sat in an open cockpit . This version first flew on 18 August 1930. Both
3182-408: The airflow. N-struts replace the incidence wires by a third strut running diagonally from the top of one strut to the bottom of the other in a pair. V-struts converge from separate attachment points on upper wing to a single point on the lower wing. They are often used for the sesquiplane wing, in which the lower wing has a considerably smaller chord than the upper wing. I-struts replaces
3268-488: The airframe both light and strong, the bracing is fitted externally. This was common in early aircraft due to the limited engine power available and the need for light weight in order to fly at all. As engine powers rose steadily through the 1920s and 30s, much heavier airframes became practicable, and most designers abandoned external bracing in order to allow for increased speed. Nearly all biplane aircraft have their upper and lower planes connected by interplane struts, with
3354-581: The basic loads imposed by lift and gravity, bracing wires must also carry powerful inertial loads generated during manoeuvres, such as the increased load on the landing wires at the moment of touchdown. Bracing wires must be carefully rigged to maintain the correct length and tension. In flight the wires tend to stretch under load, and on landing some may become slack. Regular rigging checks are required and any necessary adjustments made before every flight. Rigging adjustments may also be used to set and maintain wing dihedral and angle of incidence , usually with
3440-483: 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
3526-464: The cabane is replaced by a single thick, streamlined pylon. On a high-wing aircraft, a lift strut connects an outboard point on the wing with a point lower on the fuselage to form a rigid triangular structure. While in flight the strut acts in tension to carry wing lift to the fuselage and hold the wing level, while when back on the ground it acts in compression to hold the wing up. For aircraft of moderate engine power and speed, lift struts represent
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3612-608: 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 engines . 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
3698-707: The design had been surpassed by multi-engined aircraft, including Boeing's own 247 . However, many advancements of the Monomail were incorporated into the designs of the most advanced bomber and fighter aircraft of the early 1930s, the Boeing B-9 and the Model 248 (later developed into the P-26 Peashooter of the USAAC), respectively. General characteristics Performance Aircraft of comparable role, configuration, and era Biplane A biplane
3784-511: The early years of aviation, bracing was a universal feature of all forms of aeroplanes, 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. Bracing works by creating a triangulated truss structure which resists bending or twisting. By comparison, an unbraced cantilever structure bends easily unless it carries
3870-549: 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. According to aviation author Gianni Cattaneo,
3956-464: The engineering analysis of individual bays in a biplane, to calculate the structural forces and use the minimal amount of material in each bay to achieve maximum strength. Analytical techniques such as this led to lighter and stronger aircraft and became widely adopted. At the same time, the amount of bracing could be progressively reduced. At low speeds a thin wire causes very little drag and early flying machines were sometimes called "bird cages" due to
4042-451: The fuselage was no more than a braced framework and even fore-aft diagonal bracing was used to hold the wings at right angles to it. Some very early aircraft used struts made from bamboo . Most designs employed streamlined struts made either from spruce or ash wood, selected for its strength and light weight. Metal struts were also used, and both wood and metal continue in use today. The need for fore-aft wing bracing disappeared with
4128-416: The fuselage. This could be used both to provide some protection to the pilot if the craft overturned on the ground, and also for the attachment of landing wires which ran out in a slightly inclined vee to fore and aft points near the wing tips. In parasol wing monoplanes the wing passes above the fuselage and is joined to the fuselage by cabane struts, similarly to the upper wing of a biplane. On some types
4214-543: The ground. Sometimes each wing has just a single lift strut, as on the Cessna 152, but they often come in pairs, sometimes parallel as on the Catalina, sometimes splayed or as V-form pairs (e.g. Auster Autocrat ) joined to the fuselage at a single point. Many more complicated arrangements have been used, often with two primary lift struts augmented by auxiliary interconnections known as jury struts between each other or to
4300-400: The help of a clinometer and plumb-bob . Individual wires are fitted with turnbuckles or threaded-end fittings so that they can be readily adjusted. Once set, the adjuster is locked in place. Internal bracing was most significant during the early days of aeronautics when airframes were literally frames, at best covered in doped fabric, which had no strength of its own. Wire cross-bracing
4386-438: The hind limbs could not have opened out sideways but in flight would have hung below and slightly behind the fore limbs. Interplane strut 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 struts , which act in compression or tension as
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#17327869076224472-520: 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. The default design for
4558-639: 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 . Other biplane ultralights include the Belgian-designed Aviasud Mistral , the German FK12 Comet (1997–),
4644-412: 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 interplane struts 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. The primary advantage of the biplane over
4730-411: The mid-1930s. Specialist sports aerobatic biplanes are still made in small numbers. 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. 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
4816-573: The most famed copies was the Siemens-Schuckert D.I . 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. The Albatros sesquiplanes were widely acclaimed by their aircrews for their maneuverability and high rate of climb. During interwar period , the sesquiplane configuration continued to be popular, with numerous types such as
4902-434: 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
4988-609: 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. 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 bases. The Po-2 is also the only biplane to be credited with
5074-477: The number of wires present. However, as speeds rise the wire must be made thinner to avoid drag while the forces it carries increase. The steady increase in engine power allowed an equally steady increase in weight, necessitating less bracing. Special bracing wires with flat or aerofoil sections were also developed in attempts to further reduce drag. The German professor Hugo Junkers was seriously interested in doing away with drag-inducing struts and rigging around
5160-486: The outbreak of the First World War biplanes had gained favour after several monoplane structural failures 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. Figures such as aviation author Bruce observed that there was an apparent prejudice held even against newly-designed monoplanes, such as
5246-406: 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
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#17327869076225332-657: 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. 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. Both the German Heinkel He 50 and the Soviet Polikarpov Po-2 were used with relative success in
5418-487: The same forces of lift and gravity. Many later monoplanes, beginning in 1915 , have used cantilever wings with their lift bracing within the wing to avoid the drag penalties of external wires and struts . In many early wire-braced monoplanes , e.g. the Blériot XI and Fokker Eindecker (both wing warping designs), dorsal and sometimes ventral strut systems or cabanes were placed either above, or above and below
5504-499: 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. 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
5590-502: 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 . 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
5676-728: 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. 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
5762-474: The start of World War I, and by mid-1915 his firm had designed the Junkers J 1 all-metal "technology demonstrator" monoplane, possessing no external bracing for its thick-airfoil cantilever wing design, which could fly at just over 160 km/h with an inline-six piston engine of just 120 horsepower. By the end of World War I, engine powers and airspeeds had risen enough that the drag caused by bracing wires on
5848-510: The two components are often connected by cabane struts running up from the top of the fuselage or crew cabin to the wing centre section. Such a wing is usually also braced elsewhere, with the cabane struts forming part of the overall bracing scheme. Because cabane struts often carry engine thrust to the upper wing to overcome its drag, the loads along each diagonal between fore and aft struts are unequal and they are often formed as N-struts. They may also have cross-braced torsion wires to help stop
5934-400: 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. The word, from Latin, means "one-and-a-half wings". The arrangement can reduce drag and weight while retaining the biplane's structural advantages. The lower wing may have a significantly shorter span, or a reduced chord . Examples include
6020-467: The upper wing running across above the fuselage and connected to it by shorter cabane struts. These struts divide the wings into bays which are braced by diagonal wires. The flying wires run upwards and outwards from the lower wing, while the landing wires run downwards and outwards from the upper wing. The resulting combination of struts and wires is a rigid box girder -like structure independent of its fuselage mountings. Interplane struts hold apart
6106-417: The usual pair of struts by a single, thicker streamlined strut with its ends extended fore and aft along the wing. The span of a wing between two sets of interplane or cabane struts is called a bay . Wings are described by the number of bays on each side. For example, a biplane with cabane struts and one set of interplane struts on each side of the aircraft is a single-bay biplane. For a small type such as
6192-490: The very few single-engined, three-bay biplanes used during World War I . Some biplane wings are braced with struts leaned sideways with the bays forming a zigzag Warren truss . Examples include the Ansaldo SVA series of single-engined high-speed reconnaissance biplanes of World War I, and the early World War II-era Fiat CR.42 Falco . Other variations have also been used. The SPAD S.XIII fighter, while appearing to be
6278-481: The wing or the fuselage. Each pair of the inverted V struts of the Pawnee, for example, is assisted by a pair of vertical support struts. From early times these lift struts have been streamlined , often by enclosing metal load bearing members in shaped casings. The Farman F.190 , for example, had its high wings joined to the lower fuselage by parallel duralumin tubes enclosed in streamlined spruce fairings and
6364-422: The wing root to the height of the fuselage, making it much stiffer for little increase in weight. Typically, the ends of bracing struts are joined to the main internal structural components such as a wing spar or a fuselage bulkhead, and bracing wires are attached close by. Bracing may be used to resist all the various forces which occur in an airframe, including lift, weight, drag and twisting or torsion. A strut
6450-405: The wing twisting. A few biplane designs, like the British 1917 Bristol Fighter two-seat fighter/escort, had its fuselage clear of the lower wing as well as the upper one, using ventral cabane struts to accomplish such a design feature. Early monoplanes relied entirely on external wire bracing, either directly to the fuselage or to kingposts above it and undercarriage struts below to resist
6536-498: The wings and interplane struts form a rectangle which is cross-braced by wires. Another way of arranging a rigid structure is to make the cross pieces solid enough to act in compression and then to connect their ends with an outer diamond acting in tension. This method was once common on monoplanes, where the wing and a central cabane or a pylon form the cross members while wire bracing forms the outer diamond. Most commonly found on biplane and other multiplane aircraft, wire bracing
6622-419: 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
6708-434: The wings from folding up, and run from the underside of the outer wing to the lower wing root. 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. 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
6794-421: The wings from moving forward when the aircraft stops and run the opposite direction to the drag wires. 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
6880-418: The wings of a biplane or multiplane, also helping to maintain the correct angle of incidence for the connected wing panels. Parallel struts : The most common configuration is for two struts to be placed in parallel, one behind the other. These struts will usually be braced by "incidence wires" running diagonally between them. These wires resist twisting of the wing which would affect its angle of incidence to
6966-604: 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 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 . 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
7052-463: The wings up when they are not generating lift. (The wires connecting a basket or gondola to a balloon are also called flying wires.) Thinner incidence wires are sometimes run diagonally between fore and aft interplane struts to stop the wing twisting and changing its angle of incidence to the fuselage. In some pioneer aircraft, wing bracing wires were also run diagonally fore and aft to prevent distortion under side loads such as when turning. Besides
7138-415: Was also common on early monoplanes . Unlike struts, bracing wires always act in tension. The thickness and profile of a wire affect the drag it causes, especially at higher speeds. Wires may be made of multi-stranded cable, a single strand of piano wire , or aerofoil sectioned steel. Bracing wires primarily divide into flying wires which hold the wings down when flying and landing wires which hold
7224-421: Was extensively used to stiffen such airframes, both in the fabric-covered wings and in the fuselage, which was often left bare. Routine rigging of the wires was needed to maintain structural stiffness against bending and torsion. A particular problem for internal wires is access in the cramped interior of the fuselage. Often, providing sufficient internal bracing would make a design too heavy, so in order to make
7310-423: 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. 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
7396-777: 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. Modern biplane designs still exist in specialist roles such as aerobatics and agricultural aircraft with
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