A swept wing is a wing angled either backward or occasionally forward from its root rather than perpendicular to the fuselage.
125-592: The Fairey Delta 2 or FD2 (internal designation Type V within Fairey) is a British supersonic research aircraft that was produced by the Fairey Aviation Company in response to a specification from the Ministry of Supply for a specialised aircraft for conducting investigations into flight and control at transonic and supersonic speeds. Features included a delta wing and a drooped nose . On 6 October 1954,
250-497: A North American F-100 Super Sabre . However, Fairey found the Ministry of Supply unsupportive, having adopted the prevailing belief being that manned military aircraft would soon be replaced by guided missiles . Fairey had great difficulty in obtaining permission for the attempt. Twiss stated that the situation was "curiously inverted" from expectations, having expected that government agencies would have been enthusiastically pressing for
375-496: A drooped nose was fitted; the nose section, including the cockpit, could be drooped 10° using a hydraulically-actuated mechanism, in a similar manner to that which was used later on Concorde. The Delta 2 has a relatively small cockpit for the pilot which left little room for the installation of additional equipment. The Delta was the first British aircraft to fly using all-powered controls. These controls, designed and produced by Fairey, were fully duplicated. The flight control system
500-548: A 'compromise', being less slender and lacking the additional fuel capacity that the maximal option provided for. In early September 1960, it was agreed that the "maximal" conversion would proceed; on 5 September of that year, WG774 was flown to Bristol's Filton facility. Following a period of detailed design work, the re-manufacturing process commenced in April 1961. Considerable cost-cutting measures and management strategies, such as PERT , were adopted by BAC in order to not overrun on
625-487: A British aircraft manufacturer, had become interested in delta wing technology and proceeded to submit multiple submissions based on the delta wing concept to the Ministry of Supply . The Ministry, being interested in these proposals, issued orders for models to test the envisioned delta wing, the first of which being built in 1947; testing was performed by the Royal Aircraft Establishment (RAE). The program
750-535: A collaborative effort to produce a delta wing aircraft capable of reaching Mach 2 to meet the German demand for fighter aircraft. The proposal would have seen Dassault produce the wings, Fairey manufacture the fuselage, and Rolls-Royce provide the engine, which was intended to be a Rolls-Royce Spey engine with reheat; Belgium also played a role in the programme. However, the American lobby proved to be too strong, in part due to
875-574: A detachment of Dassault engineers closely observed these trials, learning a great deal about delta wing aircraft from the FD2. Dassault went on to produce the MD.550 Mystère-Delta design, which Wood notes "bore a striking resemblance" to the FD2; the MD.550 design would proceed to be manufactured as the successful Dassault Mirage III fighter. Wood credits the Delta 2 as having served to confirm Dassault's theories and supporting
1000-514: A few differences in terms of equipment and instrumentation. In addition to the two flying aircraft, a single static test airframe was also completed. On 6 October 1954, WG774 , the first FD2 to be completed, conducted its maiden flight , flown by Fairey test pilot Peter Twiss . According to aviation author Derek Wood, the Delta 2 "proved to be an exceptional aeroplane from the outset". On 17 November 1954, WG774 suffered an engine flameout on its 14th flight when internal pressure build-up collapsed
1125-471: A highly swept twin-engine aircraft; however, the Ministry lacked enthusiasm for the twin-engine configuration, largely due to an existing rival project underway to produce a twin-engine supersonic aircraft – this would become the English Electric Lightning . In February 1949, it was suggested that Fairey examine the prospects for a single-engine transonic aircraft as an alternative; by the end of
1250-587: A lack of available information on wing and intake design, and the declaring of Fairey Gannet as a 'super-priority' by the British government, which had necessitated delays. In September 1952, technical drawings of the Fairey Delta 2 were issued and the development proper commenced. From the project's beginning, Fairey designed the parameters of the FD2 to intentionally exceed that which was necessary only to achieving Mach 1 . In addition to seeking very high performance,
1375-424: A lengthened undercarriage to mimic Concorde's attitude on the ground. It first flew on 1 May 1964. The sole 221 was used for varied flight testing from 1964 until 1973, after which it was placed on public display. The Fairey Delta 2 has a mid-wing tailless delta monoplane. It was powered by a single Rolls-Royce Avon RA.14R turbojet engine with reheat . The engine was fed by air intakes which were blended into
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#17328446529191500-509: A local indentation of the fuselage above and below the wing root. This proved to not be very effective. During the development of the Douglas DC-8 airliner, uncambered airfoils were used in the wing root area to combat the unsweeping. Swept wings on supersonic aircraft usually lie within the cone-shaped shock wave produced at the nose of the aircraft so they will "see" subsonic airflow and work as subsonic wings. The angle needed to lie behind
1625-468: A margin. The achievement had also made the Fairey Delta 2 the first jet aircraft to exceed 1,000 mph (1,600 km/h) in level flight. News of the new airspeed record quickly spread and had a prompt impact upon the international aeronautics industry, typical reactions being shock and near-disbelief. According to Wood, consequences included in-depth studies of the FD2 airframe by the United States and
1750-462: A means of creating positive longitudinal static stability . For a low-speed aircraft, swept wings may be used to resolve problems with the center of gravity , to move the wing spar into a more convenient location, or to improve the sideways view from the pilot's position. By 1905, Dunne had already built a model glider with swept wings followed by the powered Dunne D.5 , and by 1913 he had constructed successful powered variants that were able to cross
1875-464: A minimal conversion with a sub-optimal wing but no other major changes, or a "maximal" conversion with a larger six foot extension to the fuselage and a much taller landing gear more typical of the type expected on the Concorde. Both would also be equipped with a new Elliott Brothers stabilization system, and have the engine intakes moved under the wing. The minimal conversion was considered to be more of
2000-477: A pair of proposed fighter aircraft equipped with swept wings from Hawker Aircraft and Supermarine , the Hawker Hunter and Supermarine Swift respectively, and successfully pressed for orders to be placed 'off the drawing board' in 1950. On 7 September 1953, the sole Hunter Mk 3 (the modified first prototype, WB 188 ) flown by Neville Duke broke the world air speed record for jet-powered aircraft, attaining
2125-406: A pilot and radar operator/navigation, seated in a side-by-side configuration. The fuselage was area ruled while large rectangular variable air intakes were adopted. As specified, the fighter was tentatively armed with wingtip-mounted de Havilland Red Top air-to-air missiles. Further design revisions saw the single Gyron engine being replaced by a pair of RB.122 engines instead and the adoption of
2250-411: A record-breaking flight as a means to bolster national prestige. According to Wood, Fairey was confronted by a combination of scepticism and apathy from Her Majesty's Civil Service , to the extent that it appeared that the government were opposing the endeavor. The Ministry of Supply sought to avoid any association with a speed record bid while Rolls-Royce , the FD2's engine manufacturer, also dismissed
2375-579: A record-breaking speed of Mach 1.06 (700 miles per hour (1,100 km/h; 610 kn)). The news of a successful straight-wing supersonic aircraft surprised many aeronautical experts on both sides of the Atlantic, as it was increasingly believed that a swept-wing design not only highly beneficial but also necessary to break the sound barrier. During the final years of the Second World War, aircraft designer Sir Geoffrey de Havilland commenced development on
2500-453: A reflex curve at the trailing edge. This results in a much weaker shock wave towards the rear of the upper wing surface and a corresponding increase in critical mach number. Shock waves require energy to form. This energy is taken out of the aircraft, which has to supply extra thrust to make up for this energy loss. Thus the shocks are seen as a form of drag . Since the shocks form when the local air velocity reaches supersonic speeds, there
2625-420: A swept wing as it travels through the air. The airflow over a swept wing encounters the wing at an angle. That angle can be broken down into two vectors, one perpendicular to the wing, and one parallel to the wing. The flow parallel to the wing has no effect on it, and since the perpendicular vector is shorter (meaning slower) than the actual airflow, it consequently exerts less pressure on the wing. In other words,
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#17328446529192750-534: A swept wing the wing panels on the Douglas DC-1 outboard of the nacelles also had slight sweepback for similar reasons. 2. to provide longitudinal stability for tailless aircraft, e.g. Messerschmitt Me 163 Kometuu . 3. most commonly to increase Mach-number capability by delaying to a higher speed the effects of compressibility (abrupt changes in the density of the airflow), e.g. combat aircraft, airliners and business jets. Other reasons include: 1. enabling
2875-507: A two-seat fighter equipped with radar and missiles with suitable performance to achieve an altitude of 60,000 feet (18,000 m) and Mach 2 within six minutes of taking off; while the company thought that their design would be fully capable of meeting the specified requirements, it was believed that the complete weapon system would not be fully developed until 1962. Thus, Fairey proposed that a simpler interim aircraft, if selected, could be available by 1960 or potentially earlier. In addition to
3000-412: A wing carry-through box position to achieve a desired cabin size, e.g. HFB 320 Hansa Jet . 2. providing static aeroelastic relief which reduces bending moments under high g-loadings and may allow a lighter wing structure. For a wing of given span, sweeping it increases the length of the spars running along it from root to tip. This tends to increase weight and reduce stiffness. If the fore-aft chord of
3125-434: A wing is generated by the airflow over it from front to rear. With increasing span-wise flow the boundary layers on the surface of the wing have longer to travel, and so are thicker and more susceptible to transition to turbulence or flow separation, also the effective aspect ratio of the wing is less and so air "leaks" around the wing tips reducing their effectiveness. The spanwise flow on swept wings produces airflow that moves
3250-534: A world speed record. On 12 April 1948, a D.H.108 did set a world's speed record at 973.65 km/h (605 mph), it subsequently became the first jet aircraft to exceed the speed of sound. Around this same timeframe, the Air Ministry introduced a program of experimental aircraft to examine the effects of swept wings, as well as the delta wing configuration. Furthermore, the Royal Air Force (RAF) identified
3375-410: Is a certain " critical mach " speed where sonic flow first appears on the wing. There is a following point called the drag divergence mach number where the effect of the drag from the shocks becomes noticeable. This is normally when the shocks start generating over the wing, which on most aircraft is the largest continually curved surface, and therefore the largest contributor to this effect. Sweeping
3500-564: Is an aircraft intended for testing new aerospace technologies and design concepts. The term research aircraft or testbed aircraft , by contrast, generally denotes aircraft modified to perform scientific studies, such as weather research or geophysical surveying, similar to a research vessel . The term "experimental aircraft" also has specific legal meaning in Australia, the United States and some other countries; usually used to refer to aircraft flown with an experimental certificate . In
3625-507: Is normally used to mean "swept back", but variants include forward sweep , variable sweep wings and oblique wings in which one side sweeps forward and the other back. The delta wing is also aerodynamically a form of swept wing. There are three main reasons for sweeping a wing: 1. to arrange the center of gravity of the aircraft and the aerodynamic center of the wing to coincide more closely for longitudinal balance, e.g. Messerschmitt Me 163 Komet and Messerschmitt Me 262 . Although not
3750-429: Is placed in an airstream at an angle of yaw – i.e., it is swept back. Now, even if the local speed of the air on the upper surface of the wing becomes supersonic, a shock wave cannot form there because it would have to be a sweptback shock – swept at the same angle as the wing – i.e., it would be an oblique shock. Such an oblique shock cannot form until the velocity component normal to it becomes supersonic." To visualize
3875-447: Is rare and the wing must be unusually rigid. There are two sweep angles of importance, one at the leading edge for supersonic aircraft and the other 25% of the way back from the leading edge for subsonic and transonic aircraft. Leading edge sweep is important because the leading edge has to be behind the mach cone to reduce wave drag. The quarter chord (25%) line is used because subsonic lift due to angle of attack acts there and, up until
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4000-483: The Sabre dance in reference to the number of North American F-100 Super Sabres that crashed on landing as a result. Reducing pitch-up to an acceptable level has been done in different ways such as the addition of a fin known as a wing fence on the upper surface of the wing to redirect the flow to a streamwise direction. The MiG-15 was one example of an aircraft fitted with wing fences. Another closely related design
4125-537: The ER.103/C , was also proposed, upon which the wings would have been scaled up by 50 per cent, with no radical aerodynamic alterations made. Combat equipment would have been provisioned, including a Ferranti -built aircraft interception radar 1495 and de Havilland Firestreak air-to-air missiles . Fairey claimed that the ER.103/C would be capable of attaining Mach 2.26 at an altitude of 55,000 feet (17,000 m). "If it were not for
4250-683: The English Channel . The Dunne D.5 was exceptionally aerodynamically stable for the time, and the D.8 was sold to the Royal Flying Corps ; it was also manufactured under licence by Starling Burgess to the United States Navy amongst other customers. Dunne's work ceased with the onset of war in 1914, but afterwards the idea was taken up by G. T. R. Hill in England who designed a series of gliders and aircraft to Dunne's guidelines, notably
4375-454: The Hawker Hunter and Gloster Javelin , there was an appetite for even more promising entirely new aircraft. Following on from the Delta 1, the Ministry of Supply requested that Fairey conduct a further model programme for the purpose of transonic investigations. However, Fairey did not find this proposal attractive, believing that a piloted aircraft would be mandatory if the project was to produce any worthwhile data. Fairey commenced work on
4500-455: The Junkers Ju 287 or HFB 320 Hansa Jet . However, larger sweep suitable for high-speed aircraft, like fighters, was generally impossible until the introduction of fly by wire systems that could react quickly enough to damp out these instabilities. The Grumman X-29 was an experimental technology demonstration project designed to test the forward swept wing for enhanced maneuverability during
4625-613: The Minister of Defence , announced the effective termination of nearly all fighter aircraft development for the RAF, instantly removing the F.155 requirement. A final attempt was made to progress a Delta 2 derivative into production came during the late 1950s for the new German Air Force of West Germany . Running against a competing American bid with the Lockheed F-104G Starfighter , Fairey joined forces with Rolls-Royce and Dassault in
4750-520: The Red Dean missile, alongside refinements such as intake improvements and increased internal fuel capacity. Fairey stated that the aircraft was suited to interceptor duties at various altitudes, strike and aerial reconnaissance missions were also mooted. On 1 April 1957, Fairey were informed by officials within the Ministry of Supply that their proposals were the favourite to meet Operational Requirement F.155. However, on 4 April 1957, Duncan Sandys ,
4875-456: The United States , this also includes most homebuilt aircraft , many of which are based on conventional designs and hence are experimental only in name because of certain restrictions in operation. This aircraft-related article is a stub . You can help Misplaced Pages by expanding it . Swept wing Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds
5000-570: The Westland-Hill Pterodactyl series. However, Dunne's theories met with little acceptance amongst the leading aircraft designers and aviation companies at the time. The idea of using swept wings to reduce high-speed drag was developed in Germany in the 1930s. At a Volta Conference meeting in 1935 in Italy, Adolf Busemann suggested the use of swept wings for supersonic flight. He noted that
5125-418: The de Havilland Comet , which would become the world's first jet airliner. An early design consideration was whether to apply the new swept-wing configuration. Thus, an experimental aircraft to explore the technology, the de Havilland DH 108 , was developed by the firm in 1944, headed by project engineer John Carver Meadows Frost with a team of 8–10 draughtsmen and engineers. The DH 108 primarily consisted of
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5250-566: The supersonic booms were received. Tests of the Delta 2's low-level supersonic flight capability were disrupted due to the perceived heightened risk posed by supersonic booms being produced during lower altitude flight; as such, the Ministry of Supply refused to allow this testing to be performed over the UK. Despite this refusal, Fairey was able to base the Delta 2 temporarily in France and later in Norway so that
5375-412: The 1930s and 1940s, but the breakthrough mathematical definition of sweep theory is generally credited to NACA 's Robert T. Jones in 1945. Sweep theory builds on other wing lift theories. Lifting line theory describes lift generated by a straight wing (a wing in which the leading edge is perpendicular to the airflow). Weissinger theory describes the distribution of lift for a swept wing, but does not have
5500-405: The 1980s. The Sukhoi Su-47 Berkut is another notable demonstrator aircraft implementing this technology to achieve high levels of agility. To date, no highly swept-forward design has entered production. The first successful aeroplanes adhered to the basic design of rectangular wings at right angles to the body of the machine. Such a layout is inherently unstable; if the weight distribution of
5625-416: The Delta 2 made its maiden flight , flown by Fairey test pilot Peter Twiss ; two aircraft would be produced. The Delta 2 was the final aircraft to be produced by Fairey as an independent manufacturer. The Fairey Delta 2 was the first jet aircraft to exceed 1,000 miles per hour (1,600 km/h) in level flight. On 10 March 1956, it set a new world speed record of 1,132 mph (1,822 km/h), exceeding
5750-625: The Delta 2's wing one of the thinnest known at that time. The internal space housed both the main undercarriage and a total of four fuel tanks without any bulges or fairings in the wing, while four spars provided for significant structural strength. The sizable horn-balanced ailerons and inboard elevators gave the Delta 2 a high level of manoeuvrability. Data from The Illustrated Encyclopedia of Aircraft General characteristics Performance Related development Aircraft of comparable role, configuration, and era Related lists Research aircraft An experimental aircraft
5875-457: The Gyron engine of earlier proposals, the proposed fighter was to be equipped with a pair of de Havilland Spectre rocket engines that were mounted in fairings on the rear fuselage. The high-test peroxide (HTP) fuel for the rocket engines was stored in tanks held in underwing fairings and within the wing's leading edge , separate from the turbojet engine's fuel storage. It featured a two-man crew,
6000-449: The RAE and Fairey began discussions about converting one of the Delta 2 prototypes to support the ogee wing. Fairey proposed stretching the fuselage a further three feet to better match the long planform, with the wing extending out onto the drooping nose. However, calculations showed that this extension was not great enough to counter the forward moving centre of pressure (CoP) that resulted from
6125-462: The RAE known as the ogee or ogival delta design. This design aimed to improve both supersonic wave drag with high leading-edge sweep and low thickness/chord ratio at the root, and low-speed lift through flow separation at the leading edge which creates a rolled up vortex on top of the wing. The added suction under the vortex increases lift by an amount known as vortex lift. The wing root chord should be as long as possible, and highly swept where it meets
6250-687: The actual aircraft speed is, this becomes a problem during slow-flight phases, such as takeoff and landing. There have been various ways of addressing the problem, including the variable-incidence wing design on the Vought F-8 Crusader , and swing wings on aircraft such as the F-14 , F-111 , and the Panavia Tornado . The term "swept wing" is normally used to mean "swept back", but other swept variants include forward sweep , variable sweep wings and oblique wings in which one side sweeps forward and
6375-434: The air does have time to react, and is pushed spanwise by the angled leading edge, towards the wing tip. At the wing root, by the fuselage, this has little noticeable effect, but as one moves towards the wingtip the airflow is pushed spanwise not only by the leading edge, but the spanwise moving air beside it. At the tip the airflow is moving along the wing instead of over it, a problem known as spanwise flow . The lift from
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#17328446529196500-421: The air would be added to the previously perpendicular airflow, resulting in an airflow over the wing at an angle to the leading edge. This angle results in airflow traveling a greater distance from leading edge to trailing edge, and thus the air pressure is distributed over a greater distance (and consequently lessened at any particular point on the surface). This scenario is identical to the airflow experienced by
6625-414: The aircraft changes even slightly, the wing will want to rotate so its front moves up (weight moving rearward) or down (forward) and this rotation will change the development of lift and cause it to move further in that direction. To make an aircraft stable, the normal solution is to place the weight at one end and offset this with an opposite downward force at the other - this leads to the classic layout with
6750-512: The aircraft reached transonic speeds during this first flight. Following the final contractor check flight on 14 April 1956, WG777 was formally accepted, upon which it was assigned to the RAE's high-speed research programme, conducting measurement, stability and handling research. In September 1956, both aircraft performed flight displays at the Farnborough Airshow in Hampshire . The Delta 2
6875-405: The aircraft to participate in further research was first mooted in that same year as well. In its original configuration, the Delta 2 performed flight tests, interspersed with periods of storage, up until mid-1966. During August 1955, the Delta 2 flew at supersonic speed without using its reheat since the testing schedule did not yet require its use at that time. According to Wood, many members of
7000-422: The aircraft to reach speeds closer to Mach 1. One limiting factor in swept wing design is the so-called "middle effect". If a swept wing is continuous - an oblique swept wing - the pressure isobars will be swept at a continuous angle from tip to tip. However, if the left and right halves are swept back equally, as is common practice, the pressure isobars on the left wing in theory will meet the pressure isobars of
7125-418: The airspeed over the wing was dominated by the normal component of the airflow, not the freestream velocity, so by setting the wing at an angle the forward velocity at which the shock waves would form would be higher (the same had been noted by Max Munk in 1924, although not in the context of high-speed flight). Albert Betz immediately suggested the same effect would be equally useful in the transonic. After
7250-413: The angle of attack at the tip, thus reducing the bending moment on the wing, as well as somewhat reducing the chance of tip stall. However, the same effect on forward-swept wings produces a wash-in effect that increases the angle of attack promoting tip stall. Small amounts of sweep do not cause serious problems, and had been used on a variety of aircraft to move the spar into a convenient location, as on
7375-472: The attempt, claiming that the air intakes were unsuitable for speeds around Mach 1.5, and that the Avon engine would disintegrate at such speeds, despite an absence of any practical data to support this assertion. In spite of this opposition, Fairey sought to continue, and were given permission to proceed. The Ministry provided no financial support, having opted instead to loan the aircraft itself to Fairey and to charge
7500-401: The basic concept of simple sweep theory, consider a straight, non-swept wing of infinite length, which meets the airflow at a perpendicular angle. The resulting air pressure distribution is equivalent to the length of the wing's chord (the distance from the leading edge to the trailing edge). If we were to begin to slide the wing sideways ( spanwise ), the sideways motion of the wing relative to
7625-412: The capability to include chordwise pressure distribution. There are other methods that do describe chordwise distributions, but they have other limitations. Jones' sweep theory provides a simple, comprehensive analysis of swept wing performance. An explanation of how the swept wing works was offered by Robert T. Jones : "Assume a wing is a cylinder of uniform airfoil cross-section, chord and thickness and
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#17328446529197750-533: The clumsy way in which you tackle things in Britain, you could have made the Mirage yourself." Marcel Dassault , founder of Dassault Aviation According to Fairey's projections, the ER.103/B could have been ready to fly within eighteen months of having received an order, while the ER.103/C could reach the same readiness within 30 months. In particular, Fairey pursued Operational Requirement F.155 , which called for
7875-511: The cone increases with increasing speed, at Mach 1.3 the angle is about 45 degrees, at Mach 2.0 it is 60 degrees. The angle of the Mach cone formed off the body of the aircraft will be at about sin μ = 1/M (μ is the sweep angle of the Mach cone) When a swept wing travels at high speed, the airflow has little time to react and simply flows over the wing almost straight from front to back. At lower speeds
8000-413: The design adopted a general configuration and structure that would be readily adapted to future military requirements, so that it could potentially become a fighter aircraft. In total, a pair of flight-capable aircraft were produced: Serial numbers WG774 and WG777 . WG777 , the second to be manufactured, was very similar to WG774 except the underwing flap system was not incorporated. There were also
8125-547: The design team lacked experience with high speed projects. As a remedy to this, in October 1951, Sir Robert Lickley of Hawker Aircraft was promptly recruited as Fairey's new Chief Engineer and became a major force behind the programme. Data that had been obtained from the earlier model work also proved to have been highly valuable to the Fairy Delta 2 programme. Early development work on the FD2 would be hindered by two major factors,
8250-532: The designing and development of the Mirage III. Once the manufacturer's testing was completed, both aircraft were formally handed over to the RAE. In addition to providing the institution with useful information on the characteristics of the 60°-swept delta wing, from 1958 onwards, the FD2 aircraft participated in various research projects and flying trials, including an investigation into the performance of ejector-type propulsive nozzles . The substantial rebuilding of
8375-410: The development team recognised that the FD2 possessed huge speed potential, beyond any other British-built aircraft in existence of that time. During early flight testing, Twiss came to realise that the Delta 2 would be capable of speeds above 1,000 miles per hour (1,600 km/h) and proposed that it be flown on with the aim of breaking the current air speed record, which had then been held since 1955 by
8500-417: The early and mid 1950s, the Royal Air Force (RAF) had developed an intense desire to advance the performance of their aircraft; in particular, the service sought new fighter aircraft that would be capable of routinely flying at very high speeds and high altitudes as a long-term replacement for its existing inventory of roughly 700 first-generation jet fighters . At the time, there was a perception that Britain
8625-412: The effects of compressibility in transonic and supersonic aircraft because of the reduced pressures. This allows the mach number of an aircraft to be higher than that actually experienced by the wing. There is also a negative aspect to sweep theory. The lift produced by a wing is directly related to the speed of the air over the wing. Since the airflow speed experienced by a swept wing is lower than what
8750-460: The engine in front and the control surfaces at the end of a long boom with the wing in the middle. This layout has long been known to be inefficient. The downward force of the control surfaces needs further lift from the wing to offset. The amount of force can be decreased by increasing the length of the boom, but this leads to more skin friction and weight of the boom itself. This problem led to many experiments with different layouts that eliminates
8875-521: The extended planform, and there were also concerns that the over-wing engine intakes would swallow the vortex above the wing. During 1960, further development activity was disrupted by the purchase of Fairey by Westland Aircraft , who assigned further work on the conversion project to Hunting Aircraft . Accordingly, in July 1960, the programme moved to Bristol and was now a part of the larger British Aircraft Corporation (BAC). Bristol suggested two ways forward,
9000-535: The fastest aircraft of the era were only approaching 400 km/h (249 mph).The presentation was largely of academic interest, and soon forgotten. Even notable attendees including Theodore von Kármán and Eastman Jacobs did not recall the presentation 10 years later when it was re-introduced to them. Hubert Ludwieg of the High-Speed Aerodynamics Branch at the AVA Göttingen in 1939 conducted
9125-489: The final day available, the first run also failed; the second and last run that day became the only chance left before the attempt would end. On 10 March 1956, the Fairey Delta 2 broke the World Air Speed Record , raising it to 1,132 mph (1,811 km/h) or Mach 1.73. This achievement exceeded the prior recorded airspeed record by 310 mph, or 37 per cent; never before had the record ever been raised by such
9250-404: The firm for its use of RAE assets. Fairey also had to finance its own insurance. Regardless, Fairey chose to continue with the record attempt. In order to reduce the risk of another competitor beating them to it, preparations had to be carried out in a short space of time and in great secrecy. The development and deployment of equipment suitable for the accurate measurement of flight at such speeds
9375-616: The first wind tunnel tests to investigate Busemann's theory. Two wings, one with no sweep, and one with 45 degrees of sweep were tested at Mach numbers of 0.7 and 0.9 in the 11 x 13 cm wind tunnel. The results of these tests confirmed the drag reduction offered by swept wings at transonic speeds. The results of the tests were communicated to Albert Betz who then passed them on to Willy Messerschmitt in December 1939. The tests were expanded in 1940 to include wings with 15, 30 and -45 degrees of sweep and Mach numbers as high as 1.21. With
9500-452: The fixed-price contract it had been issued for the work; some engineers were allegedly frustrated by this as apparent means of further improvement were dismissed. On 7 July 1961, the newly christened BAC 221 was completed. Various problems were encountered during the conversion. The newly lengthened landing gear required more hydraulic fluid, which required a larger reservoir to hold it, a higher capacity pump to move it quickly enough through
9625-501: The forward fuselage. Continued studies of this basic concept led to the ogee layout and it eventually became apparent that a series of full-scale flight tests would be necessary for its validation. Low-speed testing of the concept was already being provided by the Handley Page HP.115 . Although high-speed performance appeared to be predictable, a dedicated testbed aircraft was desired, especially for drag measurements. As early as 1958,
9750-442: The freestream conditions around the rest of the aircraft, and as the flow enters an adverse pressure gradient in the aft section of the wing, a discontinuity emerges in the form of a shock wave as the air is forced to rapidly slow and return to ambient pressure. At the point where the density drops, the local speed of sound correspondingly drops and a shock wave can form. This is why in conventional wings, shock waves form first after
9875-422: The further development of the Delta 2. The first of these was another experimental aircraft, designated as the ER.103/B , which would have paired the wings of the FD2 with a revised fuselage, which had a greater span and length. The ER.103/B was to have been powered by either a de Havilland Gyron or Rolls-Royce RB.122 and would have accommodated underwing fuel tanks for extended endurance. A combat fighter model,
10000-409: The fuselage collector tank, closing off the fuel supply to the engine, while heading away from the airfield at 30,000 ft (9,100 m), 30 mi (50 km) after taking off from RAF Boscombe Down. Twiss managed to glide to a dead-stick landing at high speed on the airfield. Only the nose gear had deployed, and the aircraft sustained damage that put it out of action for eight months. Twiss, who
10125-645: The immediate post-war era, several nations were conducting research into high speed aircraft. In the United Kingdom, work commenced during 1943 on the Miles M.52 , a high-speed experimental aircraft equipped with a straight wing that was developed in conjunction with Frank Whittle 's Power Jets company, the Royal Aircraft Establishment (RAE) in Farnborough , and the National Physical Laboratory . The M.52
10250-530: The introduction of jets in the later half of the Second World War , the swept wing became increasingly applicable to optimally satisfying aerodynamic needs. The German jet-powered Messerschmitt Me 262 and rocket-powered Messerschmitt Me 163 suffered from compressibility effects that made both aircraft very difficult to control at high speeds. In addition, the speeds put them into the wave drag regime, and anything that could reduce this drag would increase
10375-494: The introduction of supercritical sections, the crest was usually close to the quarter chord. Typical sweep angles vary from 0 for a straight-wing aircraft, to 45 degrees or more for fighters and other high-speed designs. Shock waves can form on some parts of an aircraft moving at less than the speed of sound. Low-pressure regions around an aircraft cause the flow to accelerate, and at transonic speeds this local acceleration can exceed Mach 1. Localized supersonic flow must return to
10500-559: The major reshaping of military aircraft programs in France. Fairey itself was elated with the achievement, viewing it as a practical endorsement of their design, and fuelled the firm's ambitions to establish a family of supersonic fighters on its basis. The record stood until 12 December 1957, when it was beaten by a McDonnell JF-101A Voodoo of the United States Air Force. Fairey produced a number of proposals which would have involved
10625-399: The maximum Thickness/Chord and why all airliners designed for cruising in the transonic range (above M0.8) have supercritical wings that are flatter on top, resulting in minimized angular change of flow to upper surface air. The angular change to the air that is normally part of lift generation is decreased and this lift reduction is compensated for by deeper curved lower surfaces accompanied by
10750-420: The need for the downward force. One such wing geometry appeared before World War I , which led to early swept wing designs. In this layout, the wing is swept so that portions lie far in front and in back of the center of gravity (CoG), with the control surfaces behind it. The result is a weight distribution similar to the classic layout, but the offsetting control force is no longer a separate surface but part of
10875-459: The original FD2. The Delta 2 had often run low on fuel while still accelerating, thereby never reaching its full performance. The modifications for the 221 meant it was not capable of the same levels of performance; however, speeds of Mach 1.6 were attained during its test flights. In total, the BAC 221 featured a new wing, engine inlet configuration, a Rolls-Royce Avon RA.28, modified vertical stabilizer and
11000-433: The other back. The delta wing also incorporates the same advantages as part of its layout. Sweeping a wing forward has approximately the same effect as rearward in terms of drag reduction, but has other advantages in terms of low-speed handling where tip stall problems simply go away. In this case the low-speed air flows towards the fuselage, which acts as a very large wing fence. Additionally, wings are generally larger at
11125-421: The pairing of the front fuselage of the de Havilland Vampire to a swept wing and small vertical tail; it was the first British swept wing jet, unofficially known as the "Swallow". It first flew on 15 May 1946, a mere eight months after the project's go-ahead. Company test pilot and son of the builder, Geoffrey de Havilland Jr ., flew the first of three aircraft and found it extremely fast – fast enough to try for
11250-458: The performance of their aircraft, notably the notoriously short flight times measured in minutes. This resulted in a crash program to introduce new swept wing designs, both for fighters as well as bombers . The Blohm & Voss P 215 was designed to take full advantage of the swept wing's aerodynamic properties; however, an order for three prototypes was received only weeks before the war ended and no examples were ever built. The Focke-Wulf Ta 183
11375-415: The pilot would result in air "spilling" out of the intakes, which was a concern because it could flow above the wing and disrupt the vortex. Small lips were added to the intakes to help prevent this, but this proved to cause intake buzzing. Changes to the ducts, assisted by Rolls-Royce, addressed this issue. One major advantage of the new design was its larger fuel capacity, which has been a major problem for
11500-402: The presentation the host of the meeting, Arturo Crocco , jokingly sketched "Busemann's airplane of the future" on the back of a menu while they all dined. Crocco's sketch showed a classic 1950s fighter design, with swept wings and tail surfaces, although he also sketched a swept propeller powering it. At the time, however, there was no way to power an aircraft to these sorts of speeds, and even
11625-453: The previous official record by 310 mph (500 km/h). The Delta 2 held the absolute World Air Speed Record for over a year. It continued to be used for flight testing, and was allocated to the Royal Aircraft Establishment (RAE) in 1958. A testbed aircraft was required to verify design calculations and wind tunnel results for the Concorde " ogee delta " wing design so one of the aircraft
11750-422: The problem. In addition to pitch-up there are other complications inherent in a swept-wing configuration. For any given length of wing, the actual span from tip-to-tip is shorter than the same wing that is not swept. There is a strong correlation between low-speed drag and aspect ratio , the span compared to chord, so a swept wing always has more drag at lower speeds. In addition, there is extra torque applied by
11875-403: The right wing on the centerline at a large angle. As the isobars cannot meet in such a fashion, they will tend to curve on each side as they near the centerline, so that the isobars cross the centerline at right angles to the centerline. This causes an "unsweeping" of the isobars in the wing root region. To combat this unsweeping, German aerodynamicist Dietrich Küchemann proposed and had tested
12000-431: The root anyway, which allows them to have better low-speed lift. However, this arrangement also has serious stability problems. The rearmost section of the wing will stall first causing a pitch-up moment pushing the aircraft further into stall similar to a swept back wing design. Thus swept-forward wings are unstable in a fashion similar to the low-speed problems of a conventional swept wing. However unlike swept back wings,
12125-402: The stagnation point on the leading edge of any individual wing segment further beneath the leading edge, increasing effective angle of attack of wing segments relative to its neighbouring forward segment. The result is that wing segments farther towards the rear operate at increasingly higher angles of attack promoting early stall of those segments. This promotes tip stall on back-swept wings, as
12250-462: The subsequently uncovered Lockheed bribery scandals that had influenced German decision makers, and the F-104G was selected instead. This was the end for the FD2 as a fighter concept; the concept never saw any use as a production aircraft; Wood summarised the state of affairs as "the harvest was left to France to gather". The Concorde design used a then-new type of delta wing that was being developed at
12375-540: The swept wing design used by most modern jet aircraft, as this design performs more effectively at transonic and supersonic speeds. In its advanced form, sweep theory led to the experimental oblique wing concept. Adolf Busemann introduced the concept of the swept wing and presented this in 1935 at the Fifth Volta Conference in Rome. Sweep theory in general was a subject of development and investigation throughout
12500-418: The system, and so on through the hydraulic system. Moving the intakes below the wing meant they were no longer in-line with the compressor face so the ducting to the engine was curved upwards giving a noticeable bulge on the wing upper surface. No attempt was made to fit variable intakes. At high throttle settings, considerable suction into the inlets was generated; in the event of a sudden down-throttle motion by
12625-453: The tests could be performed. The French government required the tests to be insured against damage claims; this demand had proved unacceptable with two British insurance companies quoting a premium of about £1,000 per flight; however, a French company insured them for £40. No claims were ever received in either France or Norway. On 15 February 1956, WG777 , the second Delta 2, performed its maiden flight from RAF Boscombe Down; piloted by Twiss,
12750-411: The tips are most rearward, while delaying tip stall for forward-swept wings, where the tips are forward. With both forward and back-swept wings, the rear of the wing will stall first creating a nose-up moment on the aircraft. If not corrected by the pilot the plane will pitch up, leading to more of the wing stalling and more pitch up in a divergent manner. This uncontrollable instability came to be known as
12875-450: The tips on a forward swept design will stall last, maintaining roll control. Forward-swept wings can also experience dangerous flexing effects compared to aft-swept wings that can negate the tip stall advantage if the wing is not sufficiently stiff. In aft-swept designs, when the airplane maneuvers at high load factor the wing loading and geometry twists the wing in such a way as to create washout (tip twists leading edge down). This reduces
13000-404: The tips to bend upwards in normal flight. Backwards sweep causes the tips to reduce their angle of attack as they bend, reducing their lift and limiting the effect. Forward sweep causes the tips to increase their angle of attack as they bend. This increases their lift causing further bending and hence yet more lift in a cycle which can cause a runaway structural failure. For this reason forward sweep
13125-472: The wing also remains the same, the distance between leading and trailing edges reduces, reducing its ability to resist twisting (torsion) forces. A swept wing of given span and chord must therefore be strengthened and will be heavier than the equivalent unswept wing. A swept wing typically angles backward from its root rather than forwards. Because wings are made as light as possible, they tend to flex under load. This aeroelasticity under aerodynamic load causes
13250-448: The wing experiences airflow that is slower - and at lower pressures - than the actual speed of the aircraft. One of the factors that must be taken into account when designing a high-speed wing is compressibility , which is the effect that acts upon a wing as it approaches and passes through the speed of sound . The significant negative effects of compressibility made it a prime issue with aeronautical engineers. Sweep theory helps mitigate
13375-402: The wing has the effect of reducing the curvature of the body as seen from the airflow, by the cosine of the angle of sweep. For instance, a wing with a 45 degree sweep will see a reduction in effective curvature to about 70% of its straight-wing value. This has the effect of increasing the critical Mach by 30%. When applied to large areas of the aircraft, like the wings and empennage , this allows
13500-421: The wing roots and featured an eyelid -type nozzle. Located just forward of the nozzle were petal -type air brakes . The Delta 2 has a cylindrical cross-section fuselage , which closely fitted the Avon engine, and smoothly flowed into a long tapered nose. A long nose would normally have obscured the pilot's forward vision during landing, take-off and movement on the ground; so, to provide adequate visibility
13625-469: The wing to the fuselage which has to be allowed for when establishing the transfer of wing-box loads to the fuselage. This results from the significant part of the wing lift which lies behind the attachment length where the wing meets the fuselage. Sweep theory is an aeronautical engineering description of the behavior of airflow over a wing when the wing's leading edge encounters the airflow at an oblique angle. The development of sweep theory resulted in
13750-524: The wing, which would have existed anyway. This eliminates the need for separate structure, making the aircraft have less drag and require less total lift for the same level of performance. These layouts inspired several flying wing gliders and some powered aircraft during the interwar years. The first to achieve stability was British designer J. W. Dunne who was obsessed with achieving inherent stability in flight. He successfully employed swept wings in his tailless aircraft (which, crucially, used washout ) as
13875-519: The year, the company had produced their new project, out of which the Fairey Delta 2 (FD2) would directly originate. Accordingly, the Ministry issued Air Ministry Specification ER.103 for the project, ordering that a pair of prototype aircraft be produced. At the time, Fairey was mostly known for producing naval aircraft, such as the Fairey Swordfish biplane and the Fairey Firefly monoplane ;
14000-513: Was a challenge in itself. For this purpose, a variety of ground measurement cameras were set up at Chichester and at RNAS Ford , various ground markers were installed at specified locations, and radar tracking from RNAS Ford and RAF Sopley ; flights by Gloster Meteors and de Havilland Venoms for calibration purposes were also conducted by the RAF. Operational demands on both the pilot and ground crews were severe and many runs were attempted but failed to qualify on one technicality or another. On
14125-564: Was another swept wing fighter design, but was also not produced before the war's end. In the post-war era, Kurt Tank developed the Ta 183 into the IAe Pulqui II , but this proved unsuccessful. A prototype test aircraft, the Messerschmitt Me P.1101 , was built to research the tradeoffs of the design and develop general rules about what angle of sweep to use. When it was 80% complete, the P.1101
14250-488: Was captured by US forces and returned to the United States , where two additional copies with US-built engines carried on the research as the Bell X-5 . Germany's wartime experience with the swept wings and its high value for supersonic flight stood in strong contrast to the prevailing views of Allied experts of the era, who commonly espoused their belief in the impossibility of manned vehicles travelling at such speeds. During
14375-460: Was envisioned to be capable of achieving 1,000 miles per hour (1,600 km/h) in level flight, thus enabling the aircraft to potentially be the first to exceed the speed of sound in the world. In February 1946, the programme was abruptly discontinued for unclear reasons. It has since been widely recognised that the cancellation of the M.52 was a major setback in British progress in the field of supersonic design. Another, more successful, programme
14500-502: Was extensively rebuilt as the BAC 221 . On 1 May 1964, the modified aircraft performed its first flight. The FD2 was also used as the basis for Fairey's submissions to the Ministry for advanced all-weather interceptor designs, culminating in the proposed Fairey Delta 3 to meet the F.155 specification ; however, the FD3 never got past the drawing-board stage. During the late 1940s, Fairey Aviation ,
14625-448: Was first investigated in Germany as early as 1935 by Albert Betz and Adolph Busemann , finding application just before the end of the Second World War . It has the effect of delaying the shock waves and accompanying aerodynamic drag rise caused by fluid compressibility near the speed of sound , improving performance. Swept wings are therefore almost always used on jet aircraft designed to fly at these speeds. The term "swept wing"
14750-406: Was hydraulically operated and possessed no mechanical backup. Fairey had recently developed a new high-pressure hydraulic system and this was used in the design. The hydraulics provided no feedback or "feel" to the pilot's controls, so another system providing artificial feel was necessary. The wing features a 60° sweep of the leading edge and was very thin, at only 4% thickness-chord ratio , making
14875-492: Was shaken up by the experience but otherwise uninjured, received the Queen's Commendation for Valuable Service in the Air . One result of the crash was a temporary halt on the test programme, which did not resume until August 1955. During early flight tests, repeated supersonic test runs over southern Britain were conducted; as a result of these flights, a number of claims for damages against
15000-561: Was succeeded multiple times, including an investigation into potential VTOL operations, leading to further flight tests of the delta wing models to be conducted in Cardigan Bay , Wales and Woomera, Australia . In 1947, Air Ministry Specification E.10/47 was issued for a full-scale piloted delta wing aircraft, resulting in the Fairey Delta 1 , which conducted its maiden flight at RAF Boscombe Down on 12 March 1951. Meanwhile, throughout
15125-634: Was the US's Bell X-1 , which also was equipped with a straight wing. According to Miles Chief Aerodynamicist Dennis Bancroft, the Bell Aircraft company was given access to the drawings and research on the M.52. On 14 October 1947, the Bell X-1 performed the first manned supersonic flight, piloted by Captain Charles "Chuck" Yeager , having been drop launched from the bomb bay of a Boeing B-29 Superfortress and attained
15250-523: Was the addition of a dogtooth notch to the leading edge, used on the Avro Arrow interceptor. Other designs took a more radical approach, including the Republic XF-91 Thunderceptor 's wing that grew wider towards the tip to provide more lift at the tip. The Handley Page Victor was equipped with a crescent wing , with three values of sweep, about 48 degrees near the wing root where the wing
15375-471: Was thickest, a 38 degree transition length and 27 degrees for the remainder to the tip. Modern solutions to the problem no longer require "custom" designs such as these. The addition of leading-edge slats and large compound flaps to the wings has largely resolved the issue. On fighter designs, the addition of leading-edge extensions , which are typically included to achieve a high level of maneuverability, also serve to add lift during landing and reduce
15500-468: Was trailing behind in supersonic aircraft design, and there was pressure to correct this. Events such as the Korean War and rapid advances in the fields of supersonic aerodynamics, structures and aero engines by the British aircraft industry had the effect of increasing demand and the potential capabilities of new fighters. In addition to developing improved versions of existing and emerging fighters such as
15625-490: Was typically used to conduct a multitude of tests including aerodynamics characteristics, handling, and stability performance. Testing of the Delta 2 was carried out in France for some time, in part due to Fairey's good relations with Dassault Aviation of France and the French Air Force . In October and November 1956, a total of 47 low-level supersonic test flights were conducted from Cazaux Air Base , Bordeaux , France;
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