Information AboutF-84 Thunderjet |
| CATEGORIES ABOUT F-84 THUNDERJET | |
| jet aircraft | |
| korean war aircraft | |
| u.s. fighter aircraft 1940-1949 | |
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]] The Republic Aviation F-84 Thunderjet was an American -built Turbojet fighter-bomber aircraft introduced in the 1940s and widely used in the Korean War . The F-84 was the first new American aircraft to enter production after World War II and it was the first single-seat fighter in United States Air Force to carry a Nuclear Bomb . This article also covers the Swept Wing variants '''Thunderstreak''' and '''Thunderflash''' as well as the '''Thunderscreech''' Turboprop prototype. DEVELOPMENT In 1944 , the Republic Aviation's chief designer Alexander Kartveli began working on a Turbojet -powered replacement for the P-47 Thunderbolt piston-engined fighter. The initial attempts to redesign the P-47 to accommodate a jet engine proved futile due to the large cross-section of the early Centrifugal Compressor turbojets. Instead, Kartveli and his team designed a brand-new aircraft with a streamlined fuselage largely occupied by an Axial Compressor turbojet engine and fuel stored in rather thick unswept wings. In November 1944, United States Army Air Forces ordered three prototypes of the new XP-84. The name '''Thunderjet''' was chosen to continue the Republic Aviation tradition started with the P-47 while emphasizing the new method of propulsion. Even before the aircraft took to the air, USAAF expanded its order to 25 service test '''YP-84''' and 75 production '''P-84A''' (later modified to 15 YP-84 and 85 P-84A). The first prototype XP-84 was transferred to Muroc Army Air Field (present-day Edwards Air Force Base ) where it flew for the first time on 28 February 1946 with Major William A. Lien at the controls. It was soon joined by the second prototype, both aircraft flying with General Electric (later Allison) J35-GE-7 engines producing 3,745 lbf (16.66 kN) of thrust. On 7 September 1946 , XP-84 set a new national speed record of 607.2 mph (977.6 km/h) -- a bit slower than the world record 612.2 mph (985.7 km/h) held by the British Gloster Meteor . The fifteen YP-84 delivered to Patterson Field (present-day Wright-Patterson Air Force Base ) for service tests differed from XP-84 in having an upgraded J35-A-13 engine and carrying six 0.50 in (12.7 mm) Browning M2 Machine Gun s in the nose. To meet USAAF demands, the aircraft were fitted with wingtip fuel tanks holding 226 US gal (870 L) each and faster-firing Browning M3 machine guns. The impact of wingtip tanks on aircraft handling was not thoroughly studied which proved problematic later. With these improvements, an even more powerful J35-A-15 engine, and an Ejection Seat , the aircraft entered production as P-84B. The P-84A was never built. After creation of USAF by the National Security Act Of 1947 , the "Pursuit" designation was replaced with "Fighter" and P-84 became '''F-84.''' Almost 8,000 F-84 were produced and they served in the United States Air Force and in the Air Force s of other nations which were allied to the US at that time. OPERATIONAL HISTORY The first F-84B began entering service in November 1947 with 14th Fighter Group . The implementation of the new fighter was far from smooth. The airplane promptly established a repuation as a "mechanic's nightmare" because of difficult maintenance. Then, numerous accidents involving the improved F-84C forced the USAF to ground all aircraft. The investigation found that wingtip fuel tanks caused warping of the wings and loss of control during high-speed high-G maneuvers. The problem was corrected with structural reinforcement of the wings and small triangular fins added to the wingtip tanks. A number of F-84s were built in the Arctic configuration with thicker aluminum skin and jet engine modified to run on 100- Octane gasoline. These aircraft actually had 15 mph (24 km/h) faster top speed due to stronger skin and the gasoline-burning engines were less capricious although the range fell by about 10%. Typical of most early jets, the Thunderjet's takeoff performance was far from stellar. In hot Korean summers with a full combat load, the aircraft routinely required 10,000 ft (3,050 m) for takeoff even with the help of RATO bottles (two or four of these were carried, each producing 1,000 lbf (4.45 kN) of thrust for 14 seconds). All but the very first aircraft had their visibility obscured by the thick smoke from the rockets. Early F-84s had to be pulled off the ground at 160 mph (260 km/h) with the control stick in the full rear position. Landings happened at a similar speed (for comparison, the P-51 Mustang landed at approximately 120 mph (190 km/h)). Despite the "hot" landing speeds, the Thunderjet was easy to fly on instruments and crosswinds did not present much of a problem. Thanks to the thick straight wing, the Thunderjet, which was otherwise blessed with good aerodynamics, rapidly reached its Mach 0.82 limitation at full throttle and low altitude. The aircraft had sufficient power to fly faster but exceeding the Mach limit at low altitudes resulted in a violent pitch-up and structural failure causing the wings to fall off. Above 15,000 ft (4,600 m), the F-84 could be flown faster but at the expense of severe buffeting. Fortunately, the airspeed was sufficiently easy control to make safe dive bombing from 10,000 ft (3,000 m) possible. This performance limitation proved troublesome against Soviet Mikoyan-Gurevich MiG-15 s in Korea. Slower than the MiG, the F-84 was also unable to turn tightly with instantaneous-turn 3 G load followed by rapid loss of airspeed. One F-84E pilot credited with two MiG kills achieved his second victory by intentionally flying his aircraft into pitch-up. The MiGs chasing him were unable to follow the violent maneuver and one crashed into the ground. Luckily for the pilot, the aircraft did not disintegrate but the airframe did suffer heavy warping. Largely unloved for its poor air combat performance, the F-84 nonetheless was a stable gun platform and the computing gunsight aided in accurate gunnery and bombing. Pilots praised the aircraft for Republic's legendary ruggedness. Thunderstreak/Thunderflash In 1949, Republic created a Swept Wing version of the F-84 hoping to bring performance to the F-86 level. The last production F-84E was fitted with a swept tail, a new wing with 38.5° of leading edge sweep and 3.5° of Anhedral , and a J35-A-25 engine. The aircraft, designated XF-96A flew on 3 June 1950 with Otto P. Haas at the controls. Although the airplane was capable of 693 mph (1,115 km/h), the performance gain over F-84E was considered rather minor. Nonetheless, it was ordered into production in July 1950 as '''F-84F Thunderstreak.''' In the meantime, USAF arranged for the British Armstrong-Siddeley Sapphire turbojet to be built in the United States as Wright J65 in the hopes that the more powerful engine would improve high-altitude performace. To accommodate the larger engine, '''YF-84F''' with British-built Sapphires as well as production F-84F with J65 had a vertically stretched fuselage with the air intake attaining an oval cross-section. Production delays with the F-84F forced USAF to order a number of straight-wing F-84G as an interim measure. When the first production F-84F finally flew on 22 November 1952 , it differed from the service test aircraft in having a different canopy which opened up and back instead of the sliding to the rear as well as airbrakes on the sides of the fuselage instead of the bottom of the aircraft. Since early aircraft suffered from accelerated stall pitch-up, F-84F-25-RE introduced an all-moving tailplane. The second YF-84F prototype was completed with wing-root air intakes which were not adopted for the fighter due to loss of thrust. However, this arrangement permitted placement of cameras in the nose and the design was adopted for the RF-84F Thunderflash reconnaissance version. The first YRF-84F was completed in February 1952. The aircraft retained an armament of four machine guns and could carry up to six cameras in the nose. Several modified Thunderflashes were used in the FICON Project . The Thunderstreak suffered from the same dismal takeoff performance as the straight-wing Thunderjets in spite of having a more powerful engine. In reality, almost 700 lbf (3.11 kN) or 10% of total thrust was lost because the J65 was installed at an angle and its exhaust had a prominent kink. On a hot day, 7,500 ft (2,285 m) of runway could be required for takeoff roll. A typical takeoff speed was 185 mph (300 km/h). Like the Thunderjet, the Thunderstreak excelled at cruise and had straightforward and predictable handling within its performance envelope. Like its predecessor, it also suffered from accelerated stall pitch-up and potential resulting separation of wings from the airplane. In addition, spins in the F-84F were practically unrecoverable and ejection was the only recourse below 10,000 ft (3,000 m). With the appearance of F-105 Thunderchief , the Thunderstreak became known as the Thud's Mother. Korean War The Thunderjet had a distinguished record during the Korean War . The first F-84E entered combat with 27th Fighter Escort Group on 7 December 1950 . The aircraft were initially tasked with escorting the B-29 Superfortress bombers. The first Thunderjet air-to-air victory was scored on 21 January 1951 at the cost of two F-84s. The F-84 was a generation behind the swept-wing Soviet Mikoyan-Gurevich MiG-15 and outmatched, especially when the MiGs were flown by Soviet pilots, and the escort duties were soon relegated to the F-86 Sabre . Like its famous predecessor, the P-47, the F-84 switched to the low-level interdiction role at which it excelled. The aircraft flew a total of 86,408 missions and dropped 111,171,000 lb (50,427 tons) of bombs and 12,258,000 lb (5,560 tons) of Napalm . USAF claimed that F-84 were responsible for 60% of all ground targets destroyed in the war. The F-84 pilots were credited with 8 MiG-15 kills at a loss of 64 aircraft in air combat. An additional 122 aircraft were lost to ground fire. During the war, F-84 became the first USAF fighter to utilize Aerial Refueling in combat. The F-84 was the first aircraft flown by the USAF Thunderbirds . The Thunderjet was eventually replaced by the F-100 Super Sabre and F-101 Voodoo and was relegated to duty in the Air National Guard . The last F-84F retired from ANG in 1971 . The last operational aeroplanes of the F-84 family were 3 Hellenic Air Force RF-84F's that retired in 1991 . VARIANTS
OPERATORS Belgium , France , Denmark , Germany , Greece , Iran , Italy , Netherlands , Norway , Portugal , Taiwan , Thailand , Turkey , United States (Air Force), Yugoslavia . SPECIFICATIONS (F-84G THUNDERJET)
SPECIFICATIONS (F-84F THUNDERSTREAK)
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