Introduction: The F-84 Thunderjet
The F-84 Thudnerjet was built by Republic Aircraft Company. It was one of the early jet fighter-bombers, first flying 28 February 1946. The United States Army AirForce (USAAF) sent a request for a “day fighter” in 1944 and Republic Aviation responded.
Although the Thunderjet entered the service in 1947, it failed to perform any of the required aspects of it’s intended mission. This was due to an engine and structural problems.
In 1948, the USAAF considered canceling the F-84 Thunderjet program. Now with the their “backs against the wall,” Republic came forth in 1949 with the F-84D model which kept the program alive.
The model “evolution” continued with the F-84G in 1951 In 1954, the swept wing F84F Thunderstreak along with the RF-84F Thunderflash, a recon aircraft.
The F-84 was the primary ground strike aircraft during the Korean War, destroying 60% of the assigned targets and flying 86,408 sorties. Although no match for the Soviet MiG 15, the Thunderjet did score 8 victories over the MiGs.
The Thunderjet was the StrategicAir command (SAC) primary aircraft from 1948 through 1957. The F-84 was the first production jet fighter to have in-flight refueling capabilities. It could carry the Mark 7 nuclear bomb.
The designation of F-84 could be a little confusing with the various models but to clarify the F-84A-F84E and F84Gmodels were straight winged and called the Thudnerjet. Models F-84F was sweptwing and called Thunderstreak. The RF-84F was also swept wing and called the Thunderflash. There was an experimental model XF-84H, a straight wing turboprop called the Thunderscreech.
The numeral designation of F-84 was retained as the difference of the swept and straight wing was a few parts difference. There were 7,524 of all models and variants produced.
Design
On 11 September 1944, the USAAF released and General Operational Requirement for a day fighter with a top speed of 600 mph and a range of 705 miles. Its armament would be six .50 cl or 4 .60cal machine guns and had to use the General Electric TG-180 axial turbojet which entered production as the Allison J-35.
On 11 November 1944, USAAF sent an order to Republic Aviation for 3 prototypes os the new XP-84 (P==pursuit, the designation F=fighter came later from the new United States Air Force- USAF). The on 04 January 1945, while the P-84 was still in the stage of prototype construction, USAAF increase their order to 15 YXP-84A and 5 P-84B production aircraft.
Meanwhile, wind tunnel testing was being conducted by the National Advisory Committee for Aeronautics on the YP-84A revealed horizontal instability and stabilizer skin buckling at high speeds.
This preliminary testing resulted in the XP-84 prototype which was limited to a gross weight of13,400 lbs and a more powerful engine the J35-GE-15 with a thrust of 4,000 lbs. The first flight of the P-84 was on 28 February 1946 at now-day Edwards Air Force Base in California.
The 15 YP-84s were delivered to now-day Wright-Patterson Air Force Base for further testing. They have an upgraded J35-A-15 engine, 6 .50 cal machine guns (4 in the nose and .one in each wing root)and provision for wing tip 225 gal fuel tanks for each wing. The new wingtip concept for the F-84 had not been thoroughly tested by the time the first production F-84s rolled out of the factory in 1947. This would produce aircraft control problems in the time to come.
Operational History
The F-84B became operational in December of 1947. Due to structural failures in the next few months, the entire fleet was grounded on 24 May 1948. In spite of reskinning the wings, new engine, and several other improvements, the F-84B and F-84C were taken out of service by 1952.
The F-84D had several improvements such as thicker wing skin, winterized fuel systems capable of using JP-4 type fuel and a new engine; J35-A-17D. This still wasn’t good enough as the F-84D was phased out of service also in 1952.
Finally, the F-84E became the first effective Thunderjet of the series having the J35-A-17 engine, wing reinforcement, a 12-inch fuselage extension ahead of the wing and a 3-inch extension aft of the wing. to enlarge the cockpit, improved radar, and gunsight along with 230-gallon pylon fuel tanks to increase the range of the F-84 to 1,000 miles.
The next F-84 Thunderjet model was the F-84G which was another straight wing Thunderjet. This model had the capability of in-flight refueling with an in-flight receptacle in the left wing, an autopilot, ILS system, and a new J35-A-29 engine. The “G” model came out in 1951 and lasted until the mid-60’s.
The F-84 was used in Korea during that war. Much like most of those jet fighters of that time, take-off required a long runway especially in the warm summers in Korea. The rotation speed (when the stick was pulled back for liftoff) was 160 mph and landing/approach speeds were similar.
In comparison, today’s passenger liners land at approximately 135 mph. The fighter flew very well on instruments and was not prone to cross-wind problems
Pilots had some amusing nicknames for the F-84: “The Lead Sled”, “The Iron Crowbar”, “The Hog”, “The World’s Fastest Tricycle”, and “Ground Loving Whore”. The pilots also believed (tongue in cheek) that a ground sniffer device was installed to alert the pilot that the dirt at the end of the runway could be “smelt” and would allow the aircraft to become airborne.
It had an airspeed restriction of .82 Mach due to structural problems above that speed. However, the aircraft speed could be controlled very easy allowing safe dive bombing approaches at 10,000 feet.
The top speed limitation proved to be a detriment in combat with the MiG15 as there were only eight recorded MiG kills during the war. The Thuderjet’s mission initially at the beginning of the war was to escort the B-29 bomber, but that was given over to the F-86 Sabrejet.
The F-84 found it’s perfect role as that of a ground attack aircraft. It flew 86,408 sorites dropping 55,586 tons of bombs destroying 60% of all ground targets in the war.
Where you can see the Thunderjet
45-59494 at the Discovery Park of America, Union City, Tennessee
45-59504 at Cradle of Aviation Museum Garden City, New York
45-59556 at Planes of Fame Museum Chino, California
47-1433 at Pima Air and Space Museum Tucson, Arizona
47-1498 at EAA Adventure Museum Oshkosh, Wisconsin
49-2285 at Texas Military Forces Austin, Texas
50-1143 at National Museum of the United States Air Force Wright-Patterson, Ohio
This is Just a Partial List of the Republic F-84Thunderjet on Display. Check With Your Local Air Museum for More Information.
Tech Specs for the F- 84G Thunderjet
Wingspan: 36 ft 5 in
Length: 38ft 1 in
Height: 12 ft 7 in
Weight: 11,470 lbs (empty)
Max Speed: 622 mph; Mach 0.82
Ceiling: 40,500 ft
Range: 1,00mi (combat); 2,000 mi (ferry) (with external tanks)
Engine: 1/Allison J35-A-29 Turbojet
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