In 1944, Alexander Kartveli, designer of the legendary Republic P-47 Thunderbolt fighter, began working on a jet-powered successor. Kartveli’s tubby-looking “Jug” proved a tough, hard-hitting ground attack plane and a fast, far-flying escort fighter in World War II. Unable to cram a turbojet in the Thunderbolt airframe, the Georgian engineer drafted a clean-sheet design dubbed the XP-84 Thunderjet with a J-35 turbojet spanning the fuselage from the intake in the nose to the tailpipe, with fuel stored in wingtip tanks.
Though a prototype briefly set a national speed record in 1946, early model Thunderjets (re-designated F-84s) required excessive maintenance and proved unstable due to weak wing spars for the thick wings and shaky wingtip fuel tanks. The Pentagon nearly canceled the jet prematurely when Republic finally introduced the F-84D model addressing the most glaring flaws by introducing sturdier wing spars, revised fuel tanks, a functioning ejection seat and a more powerful J-35A-17 engine.
Like the P-47, the Thunderjet was a “heavy”-feeling plane with high takeoff and landing speeds. It required longer mile-long runways and was less maneuverable than the Air Force’s earlier F-80 Shooting Star jet fighter. However, the F-84 was faster at 610 miles per hour, had a greater range of 800 miles, and was a hard-hitting and stable gun platform: in addition to its six extra-fast-firing M3 .50 caliber, it could lug thirty-two five-inch high-velocity rockets or two tons of bombs. Once the early models’ flaws were corrected, the Thunderjet also proved highly maintainable, its guts designed for easy access to mechanics.
However, Karteveli’s design used traditional straight rather than swept wings, which delay the formation of shockwaves when approaching supersonic speeds. This left the Thunderjet slower and less agile than the near-contemporary swept-wing F-86 Sabre and the Soviet MiG-15, which could attain speeds of around 680 miles per hour
Six months into the Korean War in December 1950, F-84Es of the 27th Fighter Escort Wing were dispatched to Taegu Air Base in South Korea to escort four-engine B-29 strategic bombers on raids targeting the Chinese border with North Korea. The F-84E model was lengthened fifteen inches to carry additional fuel and incorporated a radar-assisted gunsight
Thunderjets first encountered MiGs on January 21, 1952, when eight F-84s raiding Chongchan bridge were bounced by two flights of MiG-15s which shot an F-84 down. A MiG was claimed in return, but Soviet records reveal no corresponding losses. Two days later, F-84s and B-29s launched a massive raid targeting the airfield at Pyongyang. The MiGs, which excelled at high altitudes, were forced to dogfight strafing Thunderjets on the deck; three Communist jets were shot down and two more crippled.
However, thereafter the faster MiG-15s mostly engaged F-84s at high altitudes while escorting B-29s, repeatedly breaking through screens of up to fifty to 100 Thunderjets to ravage the B-29s they were escorting.
Henceforth, the UN forces in Korea switched heavy bombers to less-accurate night raids. F-86s focused on the MiG threat, while F-84s were relegated to ground attack missions, their tremendous firepower unleashed to strike frontline troops, blast rear-area depots, artillery batteries and convoys, cover helicopter search-and-rescue operations, and bombard key infrastructure targets. Over the course of the war, Thunderjets flew 86,000 missions and dropped 61,000 tons of bombs and napalm canisters—by one tally, accounting for 60 percent of ground targets destroyed by the U.S. Air Force during the war. The F-84’s robustness proved an asset, allowing it to survive punishing hits from heavy communist flak.
In June 1952, eighty-four Thunderjets obliterated 90 percent of the Sui-ho Dam complex, knocking out electricity throughout all of North Korea for two weeks. However, the raid, intended to pressure North Korean peace negotiators, backfired—inspiring anti-war opposition in the British parliament while conversely causing hawks in the U.S. to complain that the raid should have taken place sooner.
Nonetheless, in 1953, F-84s were hammering dams at Toksan and Chasan—causing huge floods that swamped bridges, railway lines and roads, and badly damaged crops. By then, the final F-84G model had arrived in theater, bringing with it an uprated J-35 engine and revolutionary new in-flight refueling capability. F-84s could connect their wingtip tanks to a probe trailed by a KB-29 tanker, allowing them to fly missions over Korea from bases in Japan.
Of 335 F-84Ds, Es and Gs lost to all causes during the Korean War, at least 135 were destroyed by flak. U.S. records claim a further 18 were shot down by MiGs, while Soviet and Chinese fliers claimed 65. A side-by-side comparison of loss records (broken down here) suggests a number closer to twenty-five F-84s lost in aerial combat (including a “maneuver kill,” two crashes due to battle-damage and one incident of mutual mid-air collision) in exchange for seven to eight MiGs.
But F-84s and MiG-15s continued to battle on other fronts of the Cold War. On March 10, 1953, a MiG-15 encountered a two-ship F-84 patrol apparently straying into Czech airspace near Merklin. Czech pilot Jaroslav Šrámek told an interviewer:
They banked sharply and flew off at full throttle. But because the MIG 15s were better the F-84s we were able to turn easily and manoeuvre into a position where I could fire a warning shot. The warning shot hit his backup tank on the right-hand side. Fuel started escaping from it. He tried to escape to the south. In view of the fact that I was higher than him I was able to catch him easily and my second round disabled him. After firing the shot I saw flames coming from his craft so I stopped and headed home.”
Pilot Warren Brown ejected, and his crashed jet was found ten miles into the German side of the border.
The Republic of China Air Force received 246 F-84Gs which clashed repeatedly with their communist counterparts over the Taiwan Strait. In a series four 4-on-4 engagements in 1955 and 1956, ROCAF Thunderjets claimed five MiG-15 for no loss, though two Thunderjets were shot down in smaller-scale dogfights, and a third was lost to flak. However, on July 29, 1958, newer, ultra-maneuverable MiG-17s bounced four F-84s and shot down two over Nan’ao island, helping trigger the Second Taiwan Strait Crisis.
Of three-thousand F-84Gs built, Washington transferred over 200 each to Belgium, Denmark, France, Greece, Italy, Norway and even Communist Yugoslavia as part of the MDAP military assistance program. Particularly prolific operators included France (335) and Turkey (489), while Iran, the Netherlands and Thailand received smaller numbers.
F-84Gs became the first fighter operated by the Air Force’s Thunderbirds aerobatics in 1953. Thunderjets stationed in Europe, meanwhile, became the first single-engine aircraft modified to deliver a nuclear weapon—the 1,680-pound Mark 7 nuclear bomber with an adjustable yield as high as 61 kilotons. To avoid getting caught in the apocalyptic blast, the Thunderjet employed a Low Altitude Bombing System to semi-accurately “toss” their nuclear payload while climbing, then bank sharply to the side as the deadly warhead arced away.
The sturdy and steady F-84 also served as a platform to test new concepts—most importantly pioneering aerial refueling of jet fighters. But some of the ideas didn’t exactly pan out. An attempt to modify the F-84 to be towed behinds the B-29s it was meant to escort (and this extend range by saving fuel) ended in a deadly collision. F-84s were also tested with rocket-boosters so that they could perform “zero-length” takeoffs from truck trailers should a nuclear war destroy all the airfields.
By 1954, the superior swept-wing F-84F Thunderstreak model entered service, largely replacing the Thunderjet and also spawning the RF-84F Thunderflash photo-reconnaissance model, with intakes in the wing roots instead of the nose. Powered by a more powerful but finicky J65 turbojet, the Thunderstreak could attain speeds just shy of 700 miles per hour.
By the late 1950s, the Air Force began retiring all models of the F-84 in favor of the supersonic F-100 Super Sabre and F-105 Thunderchief, though F-84s served in Air National Guard units until 1970 and Portuguese Thunderjets saw action in a colonial war in Angola until 1974. The last Thunderflash was finally retired by the Greek Air Force in 1991—a long career for a tough jet that had seemed outdated nearly as soon as it entered service.
Sébastien Roblin holds a master’s degree in conflict resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.