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98-470: F9F may refer to: Grumman F9F Panther jet fighter (straight wing) Grumman F9F Cougar jet fighter (swept wing development of the Panther) [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change

196-405: A Panther (serial 0453/3-A-119) landed on Independencia as part of trials, the first jet to land on an Argentine aircraft carrier; it was not then catapult-launched, but off-loaded by crane when the ship returned to port. Argentine Navy F9F-2 Panthers were engaged in combat during the 1963 Argentine Navy Revolt . Several rebel-controlled aircraft flew bombing and strafing runs against a column of

294-614: A competing two-seat aircraft powered by four Westinghouse J30 turbojets , had been selected. On 11 April 1946, the Navy's Bureau of Aeronautics (BuAer) issued a development contract to Grumman to produce a pair of G-75 prototypes, which were given the Navy designation XF9F-1 , in case development of the Skyknight encountered severe problems. Shortly thereafter, Grumman recognised that the G-75 did not have much potential for either performance or growth;

392-418: 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 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

490-509: 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

588-462: 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

686-477: 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

784-579: 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

882-420: 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,

980-434: 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

1078-419: 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 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

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1176-576: 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 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

1274-534: 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

1372-601: Is a wing angled either backward or occasionally forward from its root rather than perpendicular to the fuselage. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds 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

1470-485: 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 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

1568-494: 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 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

1666-429: 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

1764-452: Is the largest continually curved surface, and therefore the largest contributor to this effect. Sweeping 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

1862-483: 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

1960-683: 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

2058-455: 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

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2156-555: The Korean War . It was the widest used Navy jet fighter of the conflict, cumulatively flying 78,000 sorties. F9F-2s, F9F-3s and F9F-5s, as rugged attack aircraft, were able to sustain operations despite being frequently opposed by intense anti-aircraft fire. The pilots also appreciated the air conditioned cockpit, which made for a welcome change from the humid environment of piston-powered aircraft. On 3 July 1950, Lieutenant, junior grade Leonard H. Plog, of VF-51 , flying an F9F-3 scored

2254-809: The MiG-15 . An immediately available stop-gap in the shape of the Gloster Meteor F.8 was operated by the RAAF in Korea from July 1951. (After its less-than-satisfactory performance against MiGs, the Meteor was replaced from 1954 by the CAC Sabre – an Australian-built, up-engined variant of the F-86. ) The Panther was the primary jet fighter and ground-attack aircraft of both the US Navy and USMC during

2352-668: The Rolls-Royce RB.44 Tay . The other engine that had been tested was the Allison J33-A-16. The armament was a quartet of 20mm guns, the Navy having already switched to this caliber (as opposed to the USAAF/USAF which continued to use .50 caliber M2/M3 guns). In addition, the Panther was soon armed with underwing air-to-ground rockets and up to 2,000 lb (910 kg) of bombs. From 1946, interest in developing an aircraft that harnessed

2450-520: 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

2548-418: 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

2646-444: 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" 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

2744-412: 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

2842-405: 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

2940-463: The Army 8th Tank Regiment which was advancing on the rebelling Punta Indio Naval Air Base . The attack destroyed several M4 Sherman tanks while one F9F Panther was shot down. The Argentine Panthers were involved in the general mobilization during the 1965 border clash between Argentina and Chile , but no combat occurred. The type was removed from service during 1969 due to a lack of available spare parts,

3038-647: The F9F extensively during the Korean War. While Australia was interested in the Panther during the late 1940s, the nation ultimately opted for the Gloster Meteor F.8 and the CAC Sabre instead. The aircraft's only export customer was Argentina , where it became the first jet aircraft to be operated by the Argentine Naval Aviation . It was operated mainly from land, as the catapults of the aircraft carrier ARA Independencia lacked sufficient power to readily launch

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3136-473: The F9F. Several Panthers participated in the 1963 Argentine Navy Revolt , firing upon Argentine Army forces sent to quell the revolt. During 1969, it was withdrawn from Argentine service due to a lack of spare parts. Grumman would develop the F9F design in response to U.S. Navy interest, producing the swept wing Grumman F-9 Cougar . The origins of the Panther can be traced back to development studies performed by Grumman into jet-powered fighter aircraft near

3234-560: The Fighting Lady starring Van Johnson , Walter Pidgeon and Keenan Wynn . Stock footage of an F9F piloted by George Chamberlain Duncan crashing into the fantail of the USS Midway (CV-41) during a 1951 test flight appears in several Hollywood films. Related development Aircraft of comparable role, configuration, and era Related lists Swept wing A swept wing

3332-580: The Navy specified the imported Rolls-Royce Nene turbojet, which was also more powerful, at 5,000 lb (2,300 kg) of thrust. Production aircraft were to also be powered by the Nene, built under license by Pratt & Whitney as the J42. Since there was insufficient space within the wings and fuselage to provide sufficient fuel for the thirsty jet engine, the design team opted to add permanently mounted wingtip fuel tanks , which had incidental advantage of improving

3430-475: The Panther for four years, beginning in 1951. The Panther was the Blue Angels' first jet. Some Panthers continued to serve in small numbers into the 1960s. From September 1962, surviving operational Panthers were designated F-9 within the new combined US tri-service designation system. The only foreign buyer of the Panther was the Argentine Naval Aviation , which purchased 28 ex-USN F9F-2B aircraft during 1957;

3528-630: The Yalu River. Two more MiG-15s were downed on 18 November 1950. On 18 November 1952, the American aircraft carrier USS  Oriskany and three other carriers were operating in the Sea of Japan conducting air strikes against the North Korean city of Hoeryong . The group launched four F9F's for a combat patrol near the North Korean border with China. The group's leader suffered mechanical problems and returned to

3626-687: 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

3724-434: 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

3822-481: 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 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

3920-421: 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

4018-591: The aircraft after it was brought down by a wire strung across a valley in 1951. Future astronaut John Glenn and Boston Red Sox all-star baseball player Ted Williams also flew the F9F as Marine Corps pilots. During 1956, the Panther was withdrawn from frontline combat service, having been displaced by new fighter aircraft, including its swept-wing Cougar derivative. However, the type remained active in secondary roles, such as for training and with U.S. Naval Air Reserve and U.S. Marine Air Reserve units, until 1958. The Navy's Blue Angels flight demonstration team used

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4116-414: 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

4214-422: The aircraft, like the wings and empennage , this allows 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

4312-418: 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

4410-413: 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

4508-401: 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

4606-412: 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

4704-539: The carrier together with his wingman. Lt Royce Williams of VF-781 , flying off USS  Oriskany and his wingman continued on the mission. They then identified seven Soviet Naval Aviation Migs heading towards the task force from the Russian mainland. The naval commanders therefore ordered the two F9Fs to position themselves between the Migs and the carrier group. During this maneuver, four Soviet MiG-15s opened fire, despite

4802-460: The carriers, Williams was out of ammo, but still had one Mig on his tail. The re-appearance of his wingman on the Mig's tail then scared this one off. By that time Williams's plane was so damaged that he could not turn sideways anymore. Oriskany was therefore aligned with the plane, so he could land. After landing, his Panther was found to have 263 hits by cannon shells or fragments and was beyond repair. It

4900-590: The company had already undertaken work on a completely different single-engine day fighter, the G-79 . In a bureaucratic maneuver, BuAer opted not to cancel the G-75 contract, but instead changed the wording to include three prototypes of the entirely different G-79. It was this design that became the Panther. At that time, the few American engines that were available for use, such as the Allison J33 and Westinghouse J34 , were not considered to be sufficiently reliable; thus,

4998-511: 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

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5096-475: The danger posed by these systems increased over time as more capable AA apparatus was supplied to the North Korean force. Panthers also routinely undertook aerial reconnaissance missions over Korea. Starting in 1952, the Panther began to be supplemented by the newer Cougar derivative in the theatre. Future astronaut Neil Armstrong flew the F9F extensively during the Korean conflict, although he ejected from one of

5194-459: The detachable rear section of the aircraft unintentionally came off; remedial changes were made to avoid any future repetition. During May 1949, carrier suitability trails commenced. In September 1949, the F9F was cleared for flight from aircraft carriers. During the development phase, Grumman decided to change the Panther's engine, selecting the Pratt & Whitney J48 -P-2, a license built version of

5292-412: 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

5390-487: The end of World War II . The company was keen to capitalise on the emergence of the first practical jet engines by integrating them into a new aircraft design. This design, which was internally designated G-75 , was submitted to a United States Navy competition that sought a jet-powered night fighter to equip its aircraft carriers with. However, on 3 April 1946, it was announced that the Douglas F3D Skyknight ,

5488-460: 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

5586-419: 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 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

5684-502: The fact that the countries were not at war. Williams opened fire on the tail Mig, which dropped out of formation, and was followed down by Williams' wingman. What followed was a 35-minute dogfight between Williams and six MiG-15s. The Mig 15 was a more capable plane, but Williams nevertheless succeeded in shooting down three more. He ascribed this to both sides doing as they were trained, but the Soviet pilots making mistakes. While heading back to

5782-535: 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

5880-553: The fighter's rate of roll . The wings featured another innovation in the form of leading edge flaps that generated additional lift while landing; speed brakes were also present on the underside of the fuselage. On 21 November 1947, the prototype Panther conducted its maiden flight , piloted by test pilot Corky Meyer. It was followed by the second prototype only five days later. Initial issues with directional and longitudinal stability were encountered, but were quickly rectified. During one early land-based arresting gear test,

5978-421: The final months of World War II to harness the recent innovation of the jet engine. Grumman designed a single-engined, straight-winged day fighter that was armed with four 20 mm (0.79 in) cannons and could also carry a wide assortment of air-to-ground munitions. Production aircraft were typically powered by a single Allison J33 or Pratt & Whitney J48 -P-2 turbojet engine. On 21 November 1947,

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6076-505: The first 10 arrived in 1958. Only 24 aircraft were put in service, as the remainder were used as spares. The first flight of an Argentine Panther was in December 1958, and the last aircraft entered into service during January 1961. The catapult on the then only Argentine carrier, ARA Independencia , was not powerful enough to launch the F9F, so the aircraft were land-based. However, in July 1963,

6174-460: The first US Navy air victory of the war by shooting down a propeller-powered Yak-9 . Despite their relatively low speed, Panther pilots also claimed seven Mikoyan-Gurevich MiG-15s , for the loss of two F9Fs. The first MiG-15 was downed on 9 November 1950, by Lieutenant Commander William (Bill) Amen of VF-111 flying an F9F-2B, during a UN Command attack on the Sinuiju bridges, near the mouth of

6272-565: 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

6370-715: 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

6468-509: The increasingly popular swept wing grew and, following concerns that the Panther was inferior to its MiG opponents over the skies of Korea, Grumman launched work on a conversion project, known as Design 93. This effort resulted in a swept-wing derivative, the F9F Cougar , which retained the Panther's designation number. Later stage development work on the Panther continued, being largely focused on engine improvements, expanding fuel capacity, and

6566-472: 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

6664-461: The left wing in theory will meet the pressure isobars of 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

6762-421: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=F9F&oldid=932820892 " Category : Letter–number combination disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages F9F Panther Development of the Panther commenced in

6860-420: 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

6958-433: 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

7056-421: 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

7154-458: 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

7252-430: The pilots lost were Captains Belyakov and Vandalov, and Lieutenants Pakhomkin and Tarshinov. As the conflict progressed, Panthers became primarily tasked with ground attack missions. Attacks upon hostile anti-aircraft equipment were commonly conducted. This was a risky mission type, with numerous Panthers being damaged or even lost to fire from the same ground batteries that they were seeking to neutralize. Furthermore,

7350-402: 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

7448-422: 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

7546-451: The prototype performed its maiden flight , powered by an imported Rolls-Royce Nene engine. During September 1949, the F9F was cleared for flight from aircraft carriers. The Panther was used extensively by the U.S. Navy and Marine Corps in the Korean War . On 3 July 1950, a F9F-3 recorded the first U.S. Navy air victory of the conflict, having shot down a propeller-powered Yak-9 . In the Korean theatre, Panther pilots cumulatively claimed

7644-431: 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,

7742-532: The service opted to replace them with Douglas A-4Q Skyhawks . The Argentine Navy also operated the F-9 Cougar trainer version. Data from United States Navy Aircraft since 1911 General characteristics Performance Armament The F9F Panther was featured in the 1954 Korean War film The Bridges at Toko-Ri starring William Holden , Grace Kelly , Mickey Rooney and Fredric March , and in Men of

7840-426: The shocks are seen as a form of drag . Since the shocks form when the local air velocity reaches supersonic speeds, there 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

7938-536: The shooting down of seven Mikoyan-Gurevich MiG-15s . During 1956, the type was withdrawn from front-line combat service, but remained in secondary roles, such as for training and with U.S. Naval Air Reserve and U.S. Marine Air Reserve units, until 1958. The Panther was also the first jet aircraft used by the Blue Angels aerobatics demonstration team, being flown in this capacity from 1949 through to late 1954. Future astronauts Neil Armstrong and John Glenn both flew

8036-403: 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 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

8134-402: 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

8232-540: 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

8330-411: 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

8428-450: 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

8526-467: 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 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

8624-826: The use of alternative munitions. In 1949, the Panther was considered by the Australian government, as a possible locally-built replacement for the Mustang Mk 23 and De Havilland Vampire then operated by the Royal Australian Air Force (RAAF). The other designs considered initially were an Australian design, the CAC CA-23 (an unconventional, twin-jet all-weather fighter ) and the Hawker P.1081 . By mid-1950, however, RAAF Mustangs were in action in Korea and seen as highly vulnerable to

8722-448: 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

8820-469: 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

8918-524: 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

9016-564: 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

9114-543: 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

9212-510: 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

9310-634: 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

9408-523: 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

9506-770: Was therefore pushed overboard. The engagement is little-known for two reasons. The US feared that publication of the incident could increase tensions with the Soviet Union. Another reason was the involvement of the US National Security Agency (NSA) – the existence of which was then top secret – in planning the mission; the MiGs were intercepted as a result of intelligence provided by the NSA. The four MiGs that were shot down were flown by Soviet Naval Aviation pilots: Russian sources confirmed Williams' claims, 40 years later, stating

9604-471: 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

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