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THE 456th FIGHTER INTERCEPTOR SQUADRON |
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THE PROTECTORS OF S. A. C. |
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The Republic P-84 / F-84 "Thunderjet" |
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1 The F-84E /G 2 3 More About THE F-84F 4 5 The Thunderbirds & The F-84G 6 7 YRF-84F FICOM 8 9 10
BY JOE BAUGER
The Republic Thunderjet / Thunderstreak / Thunderflash family of jet-powered fighter-bombers and reconnaissance planes was one of the most important of postwar combat aircraft, and equipped many allied and NATO air forces until the advent of supersonic aircraft.
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The series had its origin in a 1944 company-financed design study for a jet-powered replacement for the famed P-47 Thunderbolt. At first, Alexander Kartveli and his team at the Republic Aircraft Corporation considered a straightforward jet adaptation of the P-47 airframe, but soon decided that such a design was impractical and began over again from scratch. They settled on a cantilever low-wing monoplane with straight, laminar-flow wings and cantilevered horizontal tail-planes mounted halfway up the vertical tail. A large airbrake was to be installed in the belly of the aircraft, just underneath the cockpit. The engine selected was the General Electric TG-180 (J35) turbojet. This engine had an axial flow, which offered less fuel consumption than that of the centrifugal-flow engines of earlier jet fighters such as the Lockheed P-80 Shooting Star. The smaller diameter of the axial-flow engine had the additional advantage in that it allowed the use of a more streamlined, low drag fuselage. The intake for the jet engine was to be mounted in the nose. The pressurized cockpit was to have a teardrop canopy and was to be equipped with an ejector seat.
Since range as well as high speed was an important consideration, it was necessary to forego a thin profile wing in favor of an airfoil section that was thick enough to carry fuel tanks and landing gear. The critical Mach number of this wing was considerably lower than that of the fuselage, and was the primary limiter of performance on early P-84 models.
The USAAF liked what they saw, and ordered three prototypes and 400 production examples in March of 1945. The designation P-84 was chosen. However, with the coming of victory in the Pacific, all existing military aircraft orders were suspended pending a review of postwar needs. Most outstanding orders were cancelled in their entirety, but on January 15, 1946 the USAAF confirmed its order for 15 YP-84A service test aircraft and 85 production P-84Bs.
The first XP-84 (serial number 45-59475) was completed in December of 1945, and was powered by a 3750 lb.st. General Electric J35-GE-7 turbojet. It was partially disassembled and flown from the factory at Farmingdale, New York to Muroc AFB in California aboard the Boeing XC-97 transport. The XP-84 took off on its maiden flight on February 28, 1946, piloted by Major William A. Lien. It was the first new American fighter to have its maiden flight after the end of World War II.
In tests, the XP-84 achieved a maximum speed of 592 mph at sea level. Normal range was 1300 miles, and an altitude of 35,000 feet could be attained in 13 minutes. Weights were 9080 pounds empty, 13,400 pounds gross, and 16,200 pounds maximum.
The second XP-84 flew in August 1946. On September 7, 1946, this XP-84 set a new American speed record of 611 mph. However, that very same day, the record was snatched away by the Gloster Meteor, which reached 616 mph.
The RepublicYP-84A "Thunderjet"
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The YP-84A was the designation given to 15 pre-series Thunderjets. They were all delivered to the USAF by April of 1947. They were powered by the Allison J35-A-15 engine of 3750 lb. st. in place of the General Electric J35-GE-7 (the production of the J35 having been turned over to Allison). Armament consisted of six 0.50-in. machine guns, four in the upper front fuselage and two in the wings. The YP-84As were turned over to crews assigned to Muroc and to the Wright-Patterson bases for tests and pilot familiarization.
Serials of YP-84A
45-59482/59484 Republic YP-84A-1-RE Thunderjet 45-59485/59491 Republic YP-84A-5-RE Thunderjet 45-59492/59496 Republic YP-84A-10-RE Thunderjet.
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The Republic P-84 / F-84B "Thunderjet" |
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The P-84B was the first production version of the Thunderjet. An initial contract approved in January 1946 had called for 15 pre-production YP-84As and 85 production P-84Bs.
The engine of the P-84B was a 4000 lb. st. Allison J35-A-15C, the same as that of the YP-84A. The P-84B differed from the YP-84A service test aircraft in having an ejector seat for the pilot. It had a radio compass, and new M-3 machine guns to replace the six M-2 guns.
New orders in June of 1947 added 141 more P-84Bs to the contracts. These covered production blocks 21 and beyond. In these aircraft, the machine gun armament was supplemented by retractable launchers for eight 5-inch rockets mounted underneath the wings outboard of the landing gear.
Delivery of the P-84B began in the summer of 1947 to the 14th Fighter Group at Dow Field. The last P-84B was delivered in February of 1948.
The designation of the P-84B was changed to F-84B on June 11, 1948.
80 obsolete F-84Bs were transferred to the US Navy during the 1950s, where they were used as target drones. These aircraft were re-designated F-84KX, and were given the BuAer numbers 142269/142348.
Two F-84Bs (46-641 and 46-661) were used in experiments in which they were attached to the wingtips of a modified EB-29A. It was hoped that this would help to increase the range of jet escort fighters, enabling them to be towed by bombers into the combat area and released when needed. However, this three-plane combination crashed during a test flight on April 24, 1953, and the project was abandoned shortly thereafter as being much too dangerous for aircrews.
Specification of the P-84B:
One Allison J35-A-15C, 4000 lb.st. Performance: Maximum speed 587 mph at 4000 feet. Initial climb rate 5200 feet per minute. Service ceiling 40,750 feet. Range 1282 miles. Weights were 9583 pounds empty, 16,475 pounds gross, 19,689 pounds maximum takeoff. Dimensions were wingspan 36 feet 5 inches, length 37 feet 5 inches, height 12 feet 10 inches, wing area 260 square feet. Armament consisted of six 0.50-inch machine guns, four in the fuselage and two in the wing roots.
Serials of the P-84B:
45-59497 Republic P-84B-2-RE Thunderjet 45-59498/59531 Republic P-84B-3-RE Thunderjet 45-59532/59556 Republic P-84B-11-RE Thunderjet 45-59557/59581 Republic P-84B-16-RE Thunderjet 46-533/567 Republic P-84B-21-RE Thunderjet 46-568/602 Republic P-84B-26-RE Thunderjet 46-603/637 Republic P-84B-31-RE Thunderjet 46-638/673 Republic P-84B-36-RE Thunderjet
The Republic P-84 /F-84C "Thunderjet"
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The next production version of the Thunderjet was the P-84C. It was quite similar to the P-84B, but differed in having a 4000 lb.st. Allison J35-A-13C in place of the similarly-rated -15C. The A-13C was found to be more serviceable than the A-15C engine. In addition, a new electrical system was fitted, and a simplified fuel system was provided.
191 P-84Cs were ordered in June of 1947. Delivery of the P-84C began in the spring of 1948, and the first P-84C entered service with the 20th Fighter Group at Shaw AFB.
The designation was changed to F-84C on June 11, 1948.
Specification of the P-84C:
One Allison J35-A-13C, 4000 lb.st. Maximum speed: 587 mph at 4000 feet. Initial climb rate 4180 feet per minute. Service ceiling 40,600 feet. Range 1274 miles. Weights were 9662 pounds empty, 16,584 pounds gross, 19,798 pounds maximum takeoff. Dimensions were wingspan 36 feet 5 inches, length 37 feet 5 inches, height 12 feet 10 inches, wing area 260 square feet.
Serials of the P-84C:
47-1412/1461 Republic P-84C-2-RE Thunderjet 47-1462/1511 Republic P-84C-6-RE Thunderjet 47-1512/1561 Republic P-84C-11-RE Thunderjet 47-1562/1602 Republic P-84C-16-RE Thunderjet
The Republic F-84E "Thunderjet"
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The next production version of the Thunderjet was the F-84E. By this time, the P-designation had been changed to F. The F-84E had the same engine as did the P-84D--the Allison J35-A-17D, rated at 5000 pounds of thrust. However, there were quite a few changes added to the fuselage. The F-84E had a Sperry APG-30 radar ranging gun-sight, improved wingtip tanks for combat use, and a 12-inch extension to the fuselage to provide more space for the pilot in the cockpit. Retractable jet assisted take-off (JATO) racks were added to the underside of the rear fuselage, raising the maximum takeoff weight to 22,460 pounds. Internal fuel capacity was increased from 416 US gallons to 452 US gallons. Two 230-gallon tanks could be carried at the wingtips, bringing the total fuel capacity to 912 gallons and giving a range of 1485 miles. In addition, the fuel system was modified to allow a 230-US gallon tank to be carried under each inner wing shackle, enabling a ferry range of 1950 miles to be attained.
The first F-84E was ordered on December 29, 1948, and the first example (49-2022) flew on May 18, 1949. In all, 843 F-84Es were built.
The F-84E was the version that equipped most of the six USAF wings using Thunderjets when the Korean War began. It was first taken into combat on December 7, 1950 by the 27th Fighter Escort Group, which had reequipped from F-82E Twin Mustangs only a couple of months earlier.
The 27th's F-84Es were initially assigned to B-29 escort duties, in the course of which they were engaged in frequent combat with MiG-15s. The first F-84 MiG kill took place on January 21, 1951. However, the straight-winged F-84E was much too slow to match the swept-wing MiG-15, and MiGs were often able to slip through the escort screen and make successful attacks on B-29s. The total air-to-air score ended up as nine MiGs downed as opposed to 18 Thunderjets lost, which gave the Thunderjet a 2 to 1 inferiority against the MiG-15.
The task of dealing with the MiGs was left to the more capable F-86 Sabre, and the Thunderjets were transferred to ground attack duties, a task at which they excelled. The F-84 replaced the F-80 in the fighter-bomber role in the 49th, 58th, 116th, and 474th Wings. The F-84E and the later F-84G flew a total of 86,400 sorties and delivered 55,897 tons of bombs. 122 Thunderjets were lost to antiaircraft fire. Perhaps the two most spectacular Thunderjet operations of the Korean War were the attacks on the Toksan irrigation dam on May 13, 1953, and the raid on the Chusan irrigation dam three days later.
Specification of the F-84E:
One Allison J35-A-17, 5000 lb.st. Maximum speed: 613 mph at sea level Initial climb rate 6061 feet per minute. Service ceiling 43,220 feet. Normal range 1485 miles. Maximum range 1950 miles. Weights were 10,205 pounds empty, 14,724 pounds gross, 22,460 pounds maximum takeoff. Dimensions were wingspan 36 feet 5 inches, length 38 feet 7 inches, height 12 feet 10 inches, wing area 260 square feet. Offensive load included two 1000-pound bombs, or two 1200-lb 11.75-inch "Tiny Tim" rockets carried on the inboard under wing pylons. For short ranges, an array of 32 five-inch rockets could be carried underneath the wings.
F-84E-20-RE serial number 50-1143R is on display at the Wright Patterson Air Force Base Museum in Dayton, Ohio.
Serials of the F-84E:
49-2022 Republic F-84E Thunderjet 49-2023/2122 Republic F-84E-1-RE Thunderjet 49-2123/2222 Republic F-84E-5-RE Thunderjet 49-2223/2322 Republic F-84E-10-RE Thunderjet 49-2323/2429 Republic F-84E-15-RE Thunderjet 50-1111/1200 Republic F-84E-20-RE Thunderjet 50-1201/1230 Republic F-84E-25-RE Thunderjet 50-1813/1837 Republic F-84E-20-RE Thunderjet 51-477/606 Republic F-84E-25-RE Thunderjet 51-607/691 Republic F-84E-30-RE Thunderjet 51-9548/9622 Republic F-84E-30-RE ThunderjetSources:
The Republic F-84G "Thunderjet"
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In November of 1950, the Tactical Air Command began the development of a variant of the F-84 Thunderjet capable of carrying nuclear bombs in a tactical role. The variant developed for this role was the F-84G. It was viewed only as an interim type, being manufactured only until the swept-wing F-84F Thunderstreak could be introduced into service. However, because of delays in getting the F-84F into production, the F-84G continued in production until July 27, 1953, the last day of the Korean War. It actually became the most-widely manufactured version of the F/P-84 series, some 3025 examples being built.
The F-84G differed from earlier Thunderjets in having a more powerful engine--the Allison J35-A-29, rated at 5600 pounds of thrust. The F-84G had provision for up to 4000 pounds of external stores. It had provision for in-flight boom refueling, with a refueling probe receptacle in the port wing. This was in contrast to the probe-and-drogue system which had been tested on some earlier F-84s. Because longer-duration missions were anticipated for the F-84G, an autopilot was fitted to provide some relief to the pilot. Perhaps the most distinctive feature of the F-84G was the introduction of a multi-framed, reinforced canopy which replaced the clear unframed canopy of earlier versions. However, the presence of a reinforced canopy on a Thunderjet was not always a reliable indicator of its being a G-model, since this type of canopy was fitted retroactively to many earlier F-84s.
The first F-84G was delivered in to the USAF in June of 1951. Most of them went to TAC and SAC units and served with stateside units and with units deployed in Europe, although a few did serve in Korea. The 49th Air Division with one wing (the 20th Fighter Bomber Wing) equipped with F-84Gs deployed to the UK in 1952. The F-84G also served with SAC in the long-range escort role. It began making long-range refueled flights in 1952.
In 1953, straight-winged Thunderjets were serving with 14 USAF wings. Those F-84Gs equipped for the delivery of nuclear weapons used the Low Altitude Bombing System (LABS) in which the aircraft would approach its target at low altitudes, pull up sharply, toss its nuclear bomb, then do an Immelmann and fly back in the opposite direction to escape the nuclear blast.
Some 3025 F-84G aircraft were constructed, bringing the grand total of all straight-wing Thunderjets built to 4455. 1936 of the G-models purchased by the USAF went directly to NATO allies and to other nations participating in the Mutual Defense Assistance Program (MDAP). Since they were purchased with MDAP funds, they carried USAF serial numbers although these foreign-operated Thunderjets never flew in US service. By 1953, straight-winged Thunderjets were serving with some 21 NATO fighter-bomber wings. F-84Gs served with the air forces of Belgium, Denmark, Norway, the Netherlands, France, Italy, Greece, Turkey, Portugal, and Taiwan. F-84Gs were also exported to "non-aligned" nations such as Yugoslavia, Iran, and Thailand. Since Yugoslavia was at that time run by a "Communist" government, the export of F-84Gs to Yugoslavia caused some political controversy in the USA.
The F-84G had been largely retired from SAC by 1956, but was still active with the TAC. By the late 1950s, they had largely been replaced in USAF service by swept-wing F-84F Thunderstreaks.
Specification of the F-84G:
One Allison J35-A-29, 5600 lb.st. Performance: Maximum speed: 622 mph at sea level. An altitude of 35,000 feet could be attained in 9.4 minutes. Service ceiling 40,500 feet. Maximum range 2000 miles. Weights were 10,205 pounds empty, 14,724 pounds gross, 22,46 pounds maximum takeoff. Dimensions were wingspan 36 feet 5 inches, length 38 feet 1 inches, height 12 feet 7 inches, wing area 260 square feet.
Serials of the F-84G:
51-692/996 Republic F-84G-1-RE Thunderjet 51-997/1066 Republic F-84G-5-RE Thunderjet 51-1067/1116 Republic F-84G-10-RE Thunderjet 51-1117/1226 Republic F-84G-15-RE Thunderjet 51-1227/1281 Republic F-84G-20-RE Thunderjet 51-1282/1343 Republic F-84G-25-RE Thunderjet 51-9548/9622 Republic F-84E-30-RE Thunderjet 51-9623/9707 Republic F-84G-2-RE Thunderjet 51-9708/9964 Republic F-84G-6-RE Thunderjet 51-9965/10304 Republic F-84G-11-RE Thunderjet 51-10305/10764 Republic F-84G-16-RE Thunderjet 51-10765/10974 Republic F-84G-21-RE Thunderjet 51-10975/11249 Republic F-84G-26-RE Thunderjet 51-16643/16751 Republic F-84G-26-RE Thunderjet 52-2893/3192 Republic F-84G-31-RE Thunderjet 52-3193/3242 Republic F-84G-25-RE Thunderjet 52-3243/3329 Republic F-84G-30-RE Thunderjet 52-8287/8486 Republic F-84G-31-RE ThunderjetSources;
- Fighters of the United States Air Force, Robert F. Dorr and David Donald, Temple Press Aerospace, 1990.
- The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.
- American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.
- United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
BY JOE BAUGER
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