Republic F-84F Thunderstreak

F-84F Thunderstreak
RF-84F Thunderflash
USAF F-84F Thunderstreak
Role Fighter-bomber
Reconnaissance aircraft
National origin United States
Manufacturer Republic Aviation
First flight June 3, 1950
Introduction May 12, 1954
Retired 1972 (US ANG)
1991 (Greece)
Primary users United States Air Force
German Air Force
Italian Air Force
Belgian Air Force
Number built 3,428
Developed from Republic F-84 Thunderjet
Variants Republic XF-84H Thunderscreech

The Republic F-84F Thunderstreak was an American swept-wing turbojet-powered fighter-bomber. The RF-84F Thunderflash was a photo reconnaissance version.

The design was originally intended to be a relatively simple upgrade to the F-84 Thunderjet to make it more competitive with the F-86 Sabre, differing largely in the use of a swept-wing and tail. Given the small number of changes, it was assigned the next model letter in the F-84 series, F. The prototypes demonstrated a number of performance and handling issues, which resulted in marginal improvement over the previous versions. Production was repeatedly delayed and another run of the straight-wing Thunderjets were completed as the G models.

Looking for a clear performance edge compared to the G models, the engine was upgraded to the much more powerful British Armstrong Siddeley Sapphire built in the United States as the Wright J65. The larger engine required the fuselage to be stretched into an oval shape and the air intake to be modified. With these and other changes, the design was finally ready to enter production, but only a fraction of the original production systems could be used and the aircraft was effectively a new design. It finally entered service in November 1954, by which time the Sabre had also undergone many upgrades and the Thunderstreak was relegated to the fighter-bomber role. Its time as a front-line design was brief, it began to be moved to secondary roles as early as 1958.

F-84Fs were then offered to NATO member countries and other allies, who took them up in large numbers. Operators included the Belgian Air Force, Royal Danish Air Force, French Air Force, West German Air Force, Greek Air Force, Italian Air Force, Royal Netherlands Air Force, Royal Norwegian Air Force, Republic of China Air Force, Turkish Air Force, and for a brief period using ex-French examples, the Israeli Air Force.

Development

In 1948, a swept wing version of the F-84 was created with the hope of bringing performance to the level of the F-86. The last production F-84E was fitted with a swept tail, a new wing with 38.5 degrees of leading edge sweep and 3.5 degrees of anhedral, and a J35-A-25 engine producing 5,300 pound-force (23.58 kN) of thrust. The aircraft was designated XF-96A. It flew on 3 June 1950 with Oscar P. Haas at the controls. Although the airplane was capable of 602 knots (693 mph, 1,115 km/h), the performance gain over the F-84E was considered minor. Nonetheless, it was ordered into production in July 1950 as the F-84F Thunderstreak. The F-84 designation was retained because the fighter was expected to be a low-cost improvement of the straight-wing Thunderjet with over 55 percent commonality in tooling.

YF-84F and YRF-84F prototypes in 1952. Note the early style wing root jet intakes, which were eventually only retained on the RF-84F, due to the need to fit cameras in the nose. The standard F-84F reverted to the original nose intake due to a loss of thrust from the wing root intakes.

In the meantime, the USAF, hoping for improved high-altitude performance from a more powerful engine, arranged for the British Armstrong Siddeley Sapphire turbojet engine to be built in the United States as the Wright J65. To accommodate the larger engine, YF-84Fs with a British-built Sapphire as well as production F-84Fs with the J65 had a vertically stretched fuselage, with the air intake attaining an oval cross-section. Production delays with the F-84F forced the USAF to order a number of straight-wing F-84Gs as an interim measure.

Production quickly ran into problems. Although tooling commonality with the Thunderjet was supposed to be 55 percent, in reality only fifteen percent of tools could be reused. To make matters worse, the F-84F utilized press-forged wing spars and ribs. At the time, only three presses in the United States could manufacture these, and priority was given to the Boeing B-47 Stratojet bomber over the F-84. The YJ65-W-1 engine was considered obsolete and the improved J65-W-3 did not become available until 1954. When the first production F-84F finally flew on 22 November 1952, it differed from the service test aircraft. It had a different canopy which opened up and back instead of sliding to the rear (a unique design, the canopy was mounted on a pair of hydraulic rams and a pivoted lever arm that allowed it to lift up and backwards while remaining almost level with the fuselage, instead of the more common simple hinged canopy), as well as airbrakes on the sides of the fuselage instead of the bottom of the aircraft. The aircraft was considered not ready for operational deployment due to control and stability problems. The first 275 aircraft, equipped with conventional stabilizer-elevator tailplanes, suffered from accelerated stall pitch-up and poor turning ability at combat speeds. Beginning with Block 25, the problem was improved upon by the introduction of a hydraulically powered one-piece stabilator. A number of aircraft were also retrofitted with spoilers for improved high-speed control. As a result, the F-84F was not declared operational until 12 May 1954.

Thunderflash

RF-84F Thunderflash, the reconnaissance version of the F-84F. Note the unique articulation of the canopy, which is mounted on a pair of hydraulic rams and a lever arm, allowing it to automatically pivot up and backwards behind the cockpit.

The second YF-84F prototype was completed with wing-root air intakes. These 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 fifteen cameras. Innovations included computerized controls which adjusted camera settings for light, speed, and altitude, a periscope to give the pilot better visualization of the target, and a voice recorder to let the pilot narrate his observations. Being largely identical to the F-84F, the Thunderflash suffered from the same production delays and engine problems, delaying operational service until March 1954. The aircraft was retired from active duty in 1957, only to be reactivated in 1961, and finally retired from the ANG in 1972.

Several modified Thunderflashes were used in the FICON project.

Design

Instrument panel in the F-84F cockpit

The Thunderstreak suffered from the same poor takeoff performance as the straight-wing Thunderjet despite having a more powerful engine. In reality, almost 700 pounds-force (3.11 kN) or ten percent of total thrust was lost because the J65 was installed at an angle and its jet pipe was not perfectly straight (in addition to the usual thrust losses from the long jet pipe). On a hot day, 7,500 feet (2,285 m) of runway were required for takeoff roll. A typical takeoff speed was 160 knots (185 mph, 300 km/h). Like the Thunderjet, the Thunderstreak excelled at cruise and had predictable handling characteristics 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 feet (3,000 m).

Operational history

An Ohio Air National Guard F-84F in the late 1960s
F-84F Thunderstreaks flown by USAF Thunderbirds
F-84F

Project Run In completed operational tests in November 1954 and found the aircraft to be to USAF satisfaction and considerably better than the F-84G. However, ongoing engine failures resulted in the entire fleet being grounded in early 1955. Also, the J65 engine continued to suffer from flameouts when flying through heavy rain or snow. As the result of the problems, the active duty phaseout began almost as soon as the F-84F entered service in 1954, and was completed by 1958. Increased tensions in Germany associated with construction of the Berlin Wall in 1961 resulted in reactivation of the F-84F fleet. In 1962, the fleet was grounded due to the corrosion of control rods. A total of 1,800 man hours were expended to bring each aircraft to full operational capacity. Stress corrosion eventually forced the retirement of ANG F-84Fs in 1971.

On 9 March 1955, Lt. Col. Robert R. Scott, in a F-84F Thunderstreak, set a three-hour, 44-minute and 53-second record for the 2,446 miles (3,936 km) flight from Los Angeles to New York.

With the appearance of the Republic F-105 Thunderchief, which used wing-root mounted air intakes of a similar design to those fitted on the RF-84F, the photorecon variant Thunderflash became known as the Thud's Mother. The earlier F-84A had been nicknamed the "Hog" and the F-84F "Super Hog," the F-105 becoming the "Ultra Hog".

In what is probably one of the very few air-to-air engagements involving the F-84F, two Turkish Air Force F-84F Thunderstreaks shot down two Iraqi Il-28 Beagle bombers that crossed the Turkish border by mistake during a bombing operation against Iraqi Kurdish insurgents. This engagement took place on 16 August 1962.

The F-84F was retired from active service with the USAF in 1964, and replaced by the North American F-100 Super Sabre. The RF-84F was replaced by the RF-101 Voodoo in USAF units, and relegated to duty in the Air National Guard. The last F-84F Thunderflash retired from the ANG in 1971. Three Hellenic Air Force RF-84Fs that were retired in 1991 were the last operational F-84s.

Variants

An Italian F-84F
The Republic XF-84H Thunderscreech prototype
One of the YF-84J prototypes
YF-84F
Two swept-wing prototypes of the F-84F, initially designated YF-96.
F-84F Thunderstreak
Swept wing version with Wright J65 engine. Tactical Air Command aircraft were equipped with Low-Altitude Bombing System (LABS) for delivering nuclear bombs. 2,711 built, 1,301 went to NATO under Mutual Defense Assistance Program (MDAP).
GRF-84F
25 RF-84Fs were converted to be carried, and launched from the bomb bay of a GRB-36F bomber as part of the FICON project. The aircraft were later redesignated RF-84K.
RF-84F Thunderflash
Reconnaissance version of the F-84F with intakes relocated to the wing-roots, 715 built.
RF-84K Thunderflash (FICON)
RF-84F with a retractable probe for hookup with carrier GRB-36Ds and tailplanes with marked anhedral, 25 redesignated from RF-84F.
XF-84H
Two F-84Fs were converted into experimental aircraft. Each was fitted with an Allison XT40-A-1 turboprop engine of 5,850 shaft horsepower (4,365 kW) driving a supersonic propeller. Ground crews dubbed the XF-84H the Thunderscreech due to its extreme noise output.
YF-84J
Two F-84Fs were converted into YF-84J prototypes with enlarged nose intakes and a deepened fuselages for the General Electric J73 engine; the YF-84J reached Mach 1.09 in level flight on 7 April 1954. The project was cancelled due to the excessive cost of converting existent F-84Fs.

Operators

Royal Netherlands Air Force F-84F
Republic RF-84F Thunderflash at Militärhistorisches Museum Flugplatz Berlin-Gatow, Berlin, Germany; note the distinctive Republic-type wing root intakes that led to the RF-84F being called "Thud's Mother", due to the use of similar intakes on the later Republic F-105 Thunderchief
A Michigan Air National Guard RF-84F
 Belgium
 Denmark
 France
 Germany
 Greece
 Israel
 Italy
  • Italian Air Force - operated 194 Republic F-84F Thunderstreak and 78 RF-84F Thunderflash from 1956 until 1974
 Netherlands
 Norway
 Taiwan (Republic of China)
 Turkey
 United States

Aircraft on display

Belgian Air Force Thunderstreaks

Belgium

F-84F Thunderstreak
RF-84F Thunderflash

Denmark

RF-84F

France

F-84F

Germany

F-84F Thunderstreak
  • tactical number BF-106 – Luftwaffenmuseum Gatow - Militärhistorisches Museum Flugplatz Berlin-Gatow
  • tactical number DD-313 – Luftwaffenmuseum Gatow - Militärhistorisches Museum Flugplatz Berlin-Gatow
  • tactical number DE 254 (s.n.51-1702) – Flugausstellung Peter Junior, Hermeskeil
  • tactical number BF 105 (s.n.52-6778) – Flugausstellung Peter Junior, Hermeskeil
RF-84F Thunderflash
  • tactical number EB-344 – Luftwaffenmuseum Gatow - Militärhistorisches Museum der Bundeswehr
  • tactical number EA 241 (s.n.52-7663) – Flugausstellung Peter Junior, Hermeskeil

Greece

F-84F Thunderstreak
  • tactical number 26595 - Hellenic Air Force Museum (Μουσείο Πολεμικής Αεροπορίας)
  • tactical number 37050 - Larissa air base
RF-84F Thunderflash
  • tactical number 17-011 (s/n 51-17011 - ex-Luftwaffe) - Hellenic Air Force Museum (Μουσείο Πολεμικής Αεροπορίας)
F-84F Thunderstreak
  • tactical number unknown - Rentina Agrafon (Ρεντίνα Αγράφων)

Italy

F-84F
RF-84F Thunderflash
  • 52-7458 – Italian Air Force Museum, Vigna di Valle.
  • 52-7456 - private display of P.i.p. Lido, Via Roma Destra, 30016 Venice

Netherlands

F-84F
RF-84F
  • 51-11253 - TP-19, in storage at Nationaal Militair Museum, Soesterberg
  • 53-7644 - FR31, ex. Belgian Air Force. Now displayed as P-7 at Schaarsbergen.

Norway

RF-84F Thunderflash

Poland

F-84F

Russia

F-84F
  • ?-3033 (Ex-Belgium) – Technical Museum, Moscow

Turkey

F-84F
RF-84F
  • 51-1860 - Bursa Uludag University
  • 51-1901 – Istanbul Aviation Museum
  • 51-1917 – Istanbul Aviation Museum
  • 51-1924 – (ex-Dutch AF as P-24) TUAF Museum, Etimesgut

United Kingdom

F-84F

United States

XF-84F
F-84F
F-84F at the Barksdale Global Power Museum
F-84F at the National Museum of the United States Air Force; note the .50 (12.7 mm) caliber machine gun muzzle openings in the nose (4) and wing roots (2).
Republic F-84F Thunderstreak from the Evergreen Aviation & Space Museum
RF-84F Thunderflash

Accidents and incidents

Specifications (F-84F)

3-view line drawing of the Republic F-84F Thunderstreak
3-view line drawing of the Republic F-84F Thunderstreak
3-view line drawing of the Republic RF-84F Thunderflash
3-view line drawing of the Republic RF-84F Thunderflash

Data from Fighters of the United States Air Force, Combat Aircraft since 1945

General characteristics

  • Crew: 1
  • Length: 43 ft 4.75 in (13.23 m)
  • Wingspan: 33 ft 7.25 in (10.25 m)
  • Height: 14 ft 4.75 in (4.39 m)
  • Wing area: 325 sq ft (30 m2)
  • Empty weight: 13,830 lb (6,200 kg)
  • Max takeoff weight: 28,000 lb (12,701 kg)
  • Powerplant: 1 × Wright J65-W-3 turbojet, 7,220 lbf (32.1 kN) thrust

Performance

  • Maximum speed: 695 mph (1,119 km/h, 604 kn) at sea level
  • Range: 810 mi (1,304 km, 704 nmi) combat radius with two droptanks
  • Service ceiling: 46,000 ft (14,000 m)
  • Rate of climb: 8,200 ft/min (42 m/s)
  • Wing loading: 86 lb/sq ft (423 kg/m2)

Armament

Avionics

  • A-1CM or A-4 gunsight with APG-30 or MK-18 ranging radar

Communications Equipment

  • AN/ARC-33 or 34 command set radio
  • AN/APX-6 or 6A IFF set
  • AN/AR-6 radio compass
  • AN/APW-11 or 11A radar set
  • AN/APN-21 TACAN set

Notable appearances in media

Richard Bach, who later wrote the bestseller Jonathan Livingston Seagull, was an ANG F-84F pilot who was once activated for duty in Europe. His first book, Stranger to the Ground, described in detail what it was like to fly the Thunderstreak in the course of an operational flight at night from England to France in adverse weather.

F-84Fs were also used to represent North Korean MiG-15 fighters in the 1958 film version of James Salters' novel "The Hunters", because none of the Soviet fighters were available during the ongoing Cold War for filming. They were painted a flat gray with red star insignia.

See also

Related development

Aircraft of comparable role, configuration, and era


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