Republic F-84 Thunderjet (2024)

History of the Republic F-84 Thunderjet

The Republic F-84 Thunderjet emerged as a post-war American design and played a key role in the early Cold War. This nimble little system provided many allies with a nuclear deterrent against Soviet invasion and played a major role in a ground attack in the upcoming Korean War. The F-84 came in three main forms - the basic original F-84 Thunderjet, an improved swept-wing derivative in the F-84 Thunderstreak, and a dedicated scout bird in the F-84 Thunderflash.

Throughout its operation, the Thunderjet series has earned salacious nicknames such as "Wild Boar", "World's Fastest Tricycle", "Crowbar" and "Lead Sled" for its long takeoff run.

Origins

The design of the Thunderjet dates back to the last years of World War II. In 1944, Republican chief designer Alexander Kartveli had already begun work on replacing the company's other product, the fabled P-47 Thunderbolt. Thunderbolts gained a reputation during the war for their versatility and effectiveness against air and ground targets.

The Thunderbolt, nicknamed the "jug" for its rugged appearance (requiring additional piping at the bottom of the fuselage), was a piston-powered single-seat fighter that proved to be a blessing from God for the Allies. This puts Republic Air firmly in the pantheon of classic American warbirds.

Starting with the structure of the P-47, Kartveli attempted to configure Thunderbolt to accommodate centrifugal turbojets. Despite being a bolt test, the Thunderbolt's hull simply couldn't accommodate the wide cross-section of a centrifugal supercharger engine.

Therefore, an entirely new fighter design was adopted, in which the engine consisted of a turbojet driven by an axial compressor. Although the axial compressor engine is a more complex alternative, widely used to power various jet aircraft due to its high efficiency and smaller cross-section, it has also proven to be very complex and expensive.

In September 1944, the USAAF (United States Army Air Force) had developed specifications for upgrading its battle groups. The specification calls for the fighter jet to be powered by a General Electric TG-180 (Allison J35) axial-flow turbojet engine with a top speed of 600 mph and a range of 705 miles (combat radius).

Weapons should be 6x. 50 caliber heavy machine guns or 4 x 15.2mm heavy machine guns. The USAF took note of the Republic's promising model AP-23 jet engine and awarded the Republic a noncompetitive contract in November 1944 to designate three prototypes as XP-84 "Thunder Jets".

The choice of Thunderjet as the aircraft's official name is notable here, as the aircraft will continue the Republic's "Thunder" product line that began with the P-47, while denoting the way the new jet-powered aircraft will be propulsion.

Such is the potential of the Republic product, and the USAF has made no secret of their interest, resulting in an expanded contract for 25 YP-84A evaluation models and another 75 P-84B production models. This is an interesting commission as no XP-84 system has flown so far. Regardless, the U.S. Air Force saw the Republic design as a more capable and capable replacement for the Lockheed P-80 Meteor jet fighter, which was eventually introduced in 1945.

Both Republic and Lockheed designs played a role in the Korean War (the latter was renamed the F-80 Meteor).

Early Disadvantages

During the development of the XP-84, wind tunnel test results imposed some weight constraints on the Republic design, culminating in the XP-84A prototype. Early turbojets were largely in relatively weak condition, forcing designers to pay close attention to the weight constraints of their engineering feats. This proved critical to the XP-84's success, so the XP-84A is now equipped with more powerful General Electric J35-GE-15 series turbojets with up to 4,000 lbf of thrust.

The XP-84's maiden flight finally took place on February 28, 1946. The XF-84 prototype quickly rose to national fame, hitting 607.2 mph, making it the fastest American-built aircraft to date. This top speed is just 5 mph shy of the world record (612.2 mph) set by the Gloucester Meteor in the UK.

The prototype was followed by a batch of 15 YP-84A models with slightly upgraded engines of the same type and full armament and wingtip fuel tanks.

USAF becomes USAF

The year 1947 brought about a major and historic change in the structure of America's defense. The United States Air Force has now branched off into its own Air Force, appropriately called the United States Air Force (USAF). As a result, many aspects of the pre-war modus operandi have also changed, including the use of the "P" for the "Pursuit" aircraft. This fell out of favor, and was replaced by the "F" naming system for "fighter".

Because of this, systems like the Lockheed P-80 Meteor and Northrop P-61 Black Widow became the F-80 Meteor and F-61 Black Widow during the Korean War. Deliveries of today's F-84 Thunderjet began in December 1947 when the first F-84B entered service with the 14th Fighter Group in Bangor, Maine.

As the Thunderjet with the wingtip fuel tanks underwent little wind tunnel or evaluation testing, it was quickly determined that the F-84B model had some structural flaws, so much so that the entire production line was discontinued on May 24, 1948. A similar F-84C joined in with poor results, with both variants deemed unsuitable for their required mission roles. The subsequent release of the F-84D featured structural revisions and improvements to the inherent design issues of the B and C models.

With the arrival of the D model, the future of the F-84 Thunderjet was largely spared from total failure. The Thunderjet was later refined in the final F-84G production model that began in 1951 and saw quantified totals throughout its service life.

Tour

Externally, the F-84 series has a typical 1950s design. The system is often photographed in a silver metallic finish and can come in both straight and swept shapes. The hull is tubular in nature, with a solid center section and tapered fore and aft sections. The nose is dominated by circular air intakes (covered on the RF-84) that power a single engine occupying the middle and rear of the design. Pilot positions include forward placement, sitting above the air intakes and under a glass canopy with a lightweight front frame.

Overall, from this position, he has a good all-round vision. The dashboard follows the traditional design, with a flat and relatively uncluttered layout for the dials and gauges. Future systems like the G Model contain enough new instruments. The joystick remains in the middle, while the throttle stick is on the left.

Avionics (F-84G) consists of an A-1CM or A-4 targeting system connected to an APG-30 or MK-18 ranging radar.

As mentioned above, earlier Thunderjet models had a traditional straight-wing mid-mounted layout. These are attached under the fuselage, just behind the co*ckpit. Each wing contains a main landing gear system that retracts into the fuselage. The nose landing gear is mounted at the very end of the forward fuselage - a distinctly identifying feature of the aircraft - and retracts at the rear of the design, giving the aircraft a distinct "nose-up" appearance when stationary.

The air brake is prone to the center of the bottom of the fuselage. The rear wing is conventional, with a single circular vertical rear wing and two horizontal planes.

Weapons

The F-84 family of weapons consisted of a simple set of 6 x 12.7mm M3 Browning machine guns (removed in RF-84). Four of these are mounted in the upper forward fuselage (just above the air intake), while the remaining two are located at the root of the wing, a gun on one wing (the RF-84 uses air intakes instead of weapons in this location) . In addition, the F-84 is also licensed to use other munitions such as 24 x 5 inch rockets, bombs and even Mark 7 nukes.

External ammunition capacity is limited to 4,450 pounder guns.

Variant - "straight wing"

The F-84 family was broken down into straight-wing and swept-wing variants, the F-84 was launched with the P-84B (F-84B) mated to the J35-A-15 engine. In the end, 226 examples of this model were produced. Two F-84Bs were modified for the "Tip-Tow Program" to demonstrate the effectiveness of the Thunderjet as a "Parasite" fighter, codenamed EF-84B.

The Parasite fighter project originated in World War II and basically revolved around the idea of ??bombers carrying their own fighters for defense and releasing said fighters to intercept enemy aircraft when the time came. Specifically, these F-84Bs will be installed on the wingtips of a modified Boeing B-29 Superfortress (designated EB-29A) multi-engine bomber.

The F-84C variant came online later for the much-improved J35-A-13 family of turbojets. Not only are these engines more reliable, improvements in fuel also increase the aircraft's utility. Additionally, modifications to the electrical and hydraulic systems help make this model a more powerful platform than its production predecessor.

A total of 191 copies were made.

The F-84D has some structural improvements when equipped with the J35-A-17 series turbojets. Other improvements include the finned fuel tank on the wingtip and the relocation of the Pitot tube pressure gauge from the vertical tail to the intake splitter.

In the end, 154 examples of this model were delivered.

The F-84E was a post-Korean War model that used a similar J35-A-17D engine in an elongated fuselage, allowing for a larger co*ckpit and Sperry AN/APG-30 radar sights. Additionally, "wet wings" were installed to add more fuel, thereby increasing the aircraft's range. As a result, fuel ports were added under the rear of the fuselage, many of which were later fitted with canopies from modified F-84G models.

An impressive 843 system was produced. At least two F-84E models were used as modified testbeds for in-flight refueling, and these models were designated EF-84Es.

The F-84G was the first Thunder jet approved to carry a nuclear payload. The aircraft was of the fighter-bomber type, making it the first nuclear-capable single-seat fighter. The G model was equipped with an autopilot, J35-A-29 series turbojets, LABS, and a redesigned canopy that was later added to the existing F-84E model. In-flight refueling is standard on this model and can be accomplished via conventional refueling probes along the port side of the aircraft and via tapers connected directly to the wingtip tanks. Nearly 1,000 examples of the model (no doubt due to its nuclear capabilities) were shipped to Europe to serve NATO forces stationed there.

A total of 3,025 G models were produced. The Model G is simply considered a fast-launching interceptor in the EF-84G, powered by the MGM-1 Matador cruise missile launcher.

The last straight-wing Thunderjets as target UAVs modified by the US Navy. At least 80 F-84B variants were used under the F-84KX designation.

Variant - "Swept Wing"

The F-84F "Thunderstreak" established the family of swept-wing fighter-bombers for the Thunderjet family. These differed not only in improvements and refinements of the previous system, but also included the eventual use of swept wings and a Wright J65 turbojet - the latter an axial flow system manufactured under the Curtiss-Wright banner under license from British company Armstrong - Siddeley . The J65 was essentially an evolution of the Sapphire engine that powered other American designs throughout its life cycle. The production version of the F-84F evolved from the short-lived designation YF-96A, which in one instance became the XF-84F. Subsequently, two XF-84F prototypes were fully modified with enlarged airframes, equipped with Wright J65 series engines, and flew on June 3, 1950. At least 2,711 of the models were eventually produced, of which 2,112 were under the Republic flag and 599 were built by General Motors.

Deliveries began in 1954, mostly to Tactical Air Command (TAC).

Thunderstreak spawns Thunderflash

The F-84F spawned a family of converted reconnaissance platforms with the RF-84F "Thunderflash". While somewhat similar to the swept-wing F-Types they represent, these planes have side-mounted triangular air intakes at the root of the wings, while making room in the nose for camera equipment. Additionally, these F-84s featured the use of a capped nose assembly.

Production totaled 715 vehicles, of which 386 were produced by U.S. allies.

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