Subject: Number Eighty-Four in the Series--Republic F-84F Thunderstreak (8 of 13)

From: [email-masked]
Date: 22 Jul 93 16:16:59 GMT

>From [email-masked]

A swept-wing version of the F-84 had been planned late in 1949 in order 
to bring the performance of the Thunderjet up to the level of that of 
the F-86 Sabre.  However, it was hoped that the swept wing version 
would retain or even improve the ground attack capabilities of the 
Thunderjet.  At this time, USAF funds for new aircraft development 
were rather limited, and it was thought that by using some 60 percent 
of existing Thunderjet tooling and a standard F-84E fuselage, a 
high-performance aircraft could be produced at minimal cost.  

The swept-wing version of the Thunderjet was initially designated 
XF-96A because of its extensive design changes.  The USAF sanctioned 
construction of a single prototype.  The last aircraft on the F-84E 
contract (49-2430) was selected for the conversion.  The fuselage of 
the XF-96A was essentially that of the F-84E, including the pilot's 
rearward-sliding canopy and the air brake underneath the fuselage.  
The tail was swept back and an entirely new wing, swept back at an 
angle of 38.5 degrees was used.  The new wing had an area of 325 
square feet and a span of 36 feet 5 inches.  The wing had its maximum 
thickness at 45 percent chord, although the chord-wise thickness ratio 
was only nine percent.  The swept wing had an anhedral (negative 
dihedral) of 3.5 degrees.  The engine was an Allison J35-A-25 of 5200 
lb.st.  

The construction of XF-96A 49-2430 took 167 days.  It was then 
dismantled and flown from Farmingdale via cargo aircraft out to Muroc.  
It was reassembled there and took off on its maiden flight on June 3, 
1950, piloted by Republic's Director of Flight Otto P.  Haas.  
Performance included a maximum speed of 693 mph at sea level (Mach 
0.93), and a range of 1716 miles at a cruising speed of 514 mph.  
Maximum fuel load was 1253 Imp. gall internally and externally, and 
the empty and maximum loaded weights were 12,150 pounds and 23,350 
pounds respectively.  Although the low-altitude speed was impressive, 
performance fell off rather badly with altitude.  Service ceiling was 
only 38,300 feet and it took 14.8 minutes to reach an altitude of 
35,000 feet.  It was felt that the performance improvement over the 
F-84E was only marginal at best, and the project proceeded with only 
low priority.  

Were it not for the Korean War, the XF-96A project probably would have 
been cancelled.  As it turned out, the onset of the Korean War freed 
up some USAF funds for continued development and a letter contract for 
F-96A production was received in July of 1950.  On August 9, 1950, the 
designation was changed to XF-84F, and the name Thunderstreak was 
chosen.  It was anticipated that the first production Thunderstreaks 
would be available in the autumn of 1951.  

Even though the low-level performance of the XF-84F was good, the USAF 
felt that more power was badly needed to improve a relatively sluggish 
takeoff, climb, and high-altitude performance.  For this purpose, the 
British-designed Armstrong-Siddeley Sapphire axial-flow turbojet of 
7200 lb.st. was selected, and arrangements were made to have the 
Sapphire engine produced under license in the USA by Curtiss-Wright as 
the J65.  

The Sapphire engine was considerably larger than the J35, which 
required that the fuselage of the XF-84F be extensively redesigned in 
order to accommodate it.  The depth of the fuselage was increased by 
seven inches, and the nose intake was enlarged to an elliptical shape.  
The first prototype XF-84F (49-2430) was reengined with an imported 
Sapphire, and flew for the first time with this engine on February 14, 
1951.  

Two pre-production YF-84F aircraft (51-1344 and 51-1345) with Sapphire 
engines were built by Republic in 1951.  The second example (51-1345) 
was completed with wing root air intakes, leaving the nose with a 
solid cover.  The wing root intakes resulted in thrust losses as 
compared to the nose intake version, and were not adopted for 
production fighters.  

The original production schedule for the Thunderstreak that was 
prepared in August of 1950 called for the first deliveries to be made 
by the autumn of 1951.  The production F-84Fs were to use heavy press 
forgings in the construction of the wing structure.  However, the only 
forge press in the country suitable for the job was tied up in the 
B-47 program.  A mechanical breakdown in the press caused further 
delays.  To make matters worse, serious delays were encountered in the 
production of the J65 license-built Sapphire engines.  In July of 
1951, Republic was forced to admit to the USAF that the original 
schedule could not be met.  

In order to get the F-84F program back on track, it was decided to 
redesign the wings so that they could be manufactured with existing 
tools and facilities.  Although this would cure the press forgings 
problem, this redesign would add many months to the delivery schedule.  
In order to fill in the production gap until the F-84F could be 
available, the USAF decided to have Republic built the straight-winged 
F-84G as a stop-gap measure.  The delays in the Thunderstreak program 
were in fact so time-consuming that the F-84G actually became the most 
widely-produced F-84 version produced, some 3025 examples being built 
before the last one rolled off the production lines on July 27, 1953.  

The first production F-84F-1-RE (51-1346) was finally ready for its 
first flight in the late fall of 1952.  It took off on its maiden 
flight on November 22, 1952.  The production F-84F differed in several 
important respects from the earlier service test models.  The cockpit 
canopy had previously been a sliding bubble type similar to that 
fitted to "straight-wing" F-84s.  The cockpit canopy was now of a 
hinged arm, upward-swinging type that raised the part of the enclosure 
upward above the pilot before it swung backwards.  For normal exits, 
the canopy was pushed upward, but for emergencies the canopy could be 
completely released from the aircraft to permit pilot ejection.  This 
canopy was stronger, easier to install, and better sealed than the 
sliding version.  

The production F-84F also introduced a raised "turtle deck" aft of the 
cockpit, which replaced the rear fuselage deck of the previous 
bubble-canopied versions.  

Service-test Thunderstreak models had a single speed brake on the 
belly of the fuselage, similiar to that of the Thunderjet.  The 
production Thunderstreak replaced this with two perforated panels on 
the fuselage sides just aft of the wing trailing edge.  These brakes 
could be opened at any speed up to the maximum dive speed without 
large trim changes or excessive buffeting.  

Leading edge wing slats were added to improve airflow characteristics.  
Control tabs were removed from the ailerons in favor of an 
irreversible power-boosted control system.  

Production of the Thunderstreak at Farmingdale was supplemented by 
subcontractors such as Kaiser Metal Products of Bristol, Pennsylvania 
which built the rear fuselage, Servel of Evansville, Indiana which 
built wings, and Goodyear Aircraft which built the cockpit windshield, 
canopy, and rear fuselage turtle deck.  

A second source of Thunderstreak production was established in 1952 
when a contract was given to General Motors to build Thunderstreaks in 
a plant at Kansas City.  This plant had been used by North American 
Aviation during World War II to build B-25 Mitchells.  General 
Motors-built Thunderstreaks were known as F-84F-GK (rather than RE), 
and could be distinguished from Republic-built Thunderstreaks only by 
their serial numbers.  

Ten examples of the F-84F-1-RE were built.  They were powered with the 
early US-built Wright J65-W-1 turbojet.  

The F-84F-5-RE had the 7330 lb.st.  J65-W-3 or the equivalent 
Buick-built J65-B-3.  The deliveries of this version began in the 
latter part of 1953.  

The first F-84F-25-RE (51-1621) appeared at the end of 1953.  It 
introduced an "all-flying" horizontal tailplane, in which the entire 
horizontal tail moved as a unit.  The earlier F-84Fs suffered from a 
high-g stall pitch-up tendency which was often severe enough to tear 
the wings off the aircraft.  This could make for a real bad day :-).  
The all-flying tail provided more positive control which helped to 
alleviate this problem, although the F-84F continued to operate under 
maneuverability restrictions throughout much of its service life.  

The F-84F-50-RE appeared in March of 1955.  It had the more powerful 
J65-W-7 (or J65-B-7), rated at 7800 lb.st.  Airframe limitations 
prevented any improvements in low-altitude speed, but the added power 
increased the initial climb rate and the combat ceiling.  

The F-84F-75-RE was the last version of the Thunderstreak to be built 
at Farmingdale.  It introduced a new fairing under the fuselage for 
the braking parachute.  This feature was later retrofitted to earlier 
models.  

The last Thunderstreak rolled off the production lines at Farmingdale 
in August of 1957.  A total of 2112 examples had been built.  An 
additional 599 had been built by General Motors.  

The USAF had the F-84F in service with twelve Wings by June of 1955.  
Six of them were attached to the Tactical Air Command (TAC) and six to 
the Strategic Air Command (SAC).  

The F-84Fs serving with the TAC were equipped for the delivery of 
nuclear weapons.  The nuclear bomb-toting Thunderstreaks were equipped 
with the Low Altitude Bombing System (LABS).  When using the LABS to 
deliver a nuclear bomb, the strategy was for the F-84F to come racing 
toward the target at tree-top level.  When nearing the target, the 
F-84F was to make a half loop upward, release its bomb, and then 
escape the nuclear blast with a rapid high-speed Immelmann to head 
back where it came from.  Fortunately, the Thunderstreak was never 
called upon to carry out such missions in real combat.  

The Thunderstreak-equipped USAF wings attached to the Strategic Air 
Command served as fighter escorts for B-29, B-50, and B-36 long-range 
strategic bombers.  As these bombers were replaced by jets, SAC 
relinquished its F-84Fs and turned them over to the Tactical Air 
Command.  By mid-1957, all the USAF Thunderstreaks had been shifted 
over to the TAC.  

The Thunderstreak was flown by the following Fighter Bomber Groups of 
the USAF: 

   20th Fighter Bomber Group 
   31st Fighter Bomber Group 
   407th Fighter Bomber Group (515th, 516th, 517th Squadrons) 
   366th Fighter Bomber Group (389th, 390th, 391st Squadrons) 
   81st Fighter Bomber Group (78th, 91st, 92nd Squadrons) 
   15th Fighter Bomber Group (45th, 46th, 47th Squadrons) 
   21st Fighter Bomber Group (416th Squadron) 

The pilots of the TAC and SAC found the F-84F to be a rather difficult 
plane to fly.  Its loaded weight of 20,000 pounds and its landing 
speed of 155 mph made it a rather "hot" ship for pilots who were more 
familiar to lighter and slower-landing machines, and it took a bit of 
getting used to.  In addition, the handling properties of the F-84F 
were somewhat tricky, and certain maneuvers were deemed too dangerous 
to perform except in extreme emergencies.  Nevertheless, the F-84F 
achieved a reputation for being of extremely robust construction and 
of high reliability, and it offered a relatively smooth ride through 
turbulent low-level air.  

Gradually, the F-84F was replaced in front-line service by the North 
American F-100 Super Sabre.  Numerous F-84Fs were turned over to Air 
National Guard units as they were withdrawn from USAF units.  However, 
the Berlin Crisis of 1961 saw the recall of numerous F-84Fs to active 
duty--the 141st Tactical Fighter Squadron from McGuire AFB, the 163rd 
TFS from Fort Wayne, Indiana, and the 166th TFS from Columbus, Ohio 
were Air National Guard units that were deployed to Europe in response 
to the crisis.  The F-84F remained with TAC until the mid 1960s, when 
they were replaced by McDonnell F-4C Phantoms.  The F-84Fs with the 
Air National Guard were finally phased out in the late 1960s.  The 
last F-84F left ANG service in 1971.  

The F-84F was supplied in large numbers to NATO air forces.  In fact, 
out of the 2711 Thunderstreaks built, 1301 were transferred to Europe 
for service with the air forces of allied nations.  

First to get Thunderstreaks was France.  The Armee de l'Air received 
its first Thunderstreaks in 1955.  They equipped the the 1st, 3rd, 
4th, 6th, and 11 th Escadres.  It was in French service that the 
Thunderstreak saw its only actual combat.  This was during the Suez 
incident of October of 1956.  On October 23, 1956, 36 French 
Thunderstreaks from the 1st Escadre flew to the Israeli base at Lyddia 
and at the same time F-84Fs from the 3rd Escadre moved to Akrotiri on 
Cyprus.  The French Thunderstreaks at Lydda supported the Israeli 
forces that invaded Sinai on October 29.  Cyprus-based units began 
direct attacks on Egyptian airfields on November 1.  Twenty Egyptian 
Ilyushin Il-28 bombers were destroyed on the ground and one Il-28 was 
shot down by these Lydda-based units.  These operations were concluded 
on November 6, and only one F-84F was lost.  The French F-84Fs were 
replaced by Mirage IIIE in the mid 1960s.  

Belgium's Force Aerienne Belge began receiving F-84Fs in August of 
1955.  They replaced the F-84G Thunderjets of the 2nd and 10th Fighter 
Bomber wings.  Most of the Belgian F-84Fs were replaced by F-104G 
Starfighters during the early 1960s.  

The six tactical fighter bomber squadrons of Holland's Koninklijke 
Nederlandse Luchtmacht (Nos.  311 through 316) standardized on the 
F-84F in 1956.  They were replaced by F-104G Starfighters during the 
early 1960s.  

The Aeronautica Militare Italiano equipped three Air Brigades 
(Aerobrigata 5a, 51, and 51a) with F-84Fs in 1956.  

The newly-revived West German Luftwaffe received large numbers of 
F-84Fs.  The Thunderstreak was in fact the first combat aircraft to be 
operated by the new Luftwaffe after the end of World War II.  On June 
20, 1958, the first German fighter-bomber wing, Jabo G.31, became 
operational.  Four more, Jabo G.32, 34, and 35, were soon added.  Some 
450 Thunderstreaks served with the Luftwaffe during the late 1950s and 
early 1960s.  The Thunderstreak was eventually replaced in Luftwaffe 
service by the European-built F-104G Starfighter.  

Some of the ex-German, Belgian, and Dutch Thunderstreaks were 
transferred to Greece and Turkey.  It seems that every time a combat 
aircraft is transferred to Greece, one must also be transferred to 
Turkey, and vice versa. :-).  Some of these Thunderstreaks remained 
operational into the late 1970s until they were finally replaced by 
Northrop F-5s.  F-84Fs were employed by Turkey in the fighting over 
Cyprus during the 1970s, but I have no record of Greek and Turkish 
Thunderstreaks ever facing each other in combat.  

Specification of the F-84F-25-RE: One Wright J65-W-3 turbojet rated at 
7220 lb.st.  Maximum speed (clean), 695 mph at sea level (Mach 0.91), 
658 mph at 20,000 feet (Mach 0.94) The F-84F is redlined at Mach 1.18 
in a dive.  Tactical radial (clean): 450 miles at 36,000 feet.  Combat 
radius with two 230 US gallon drop tanks is 790 miles.  Ferry range 
with four 230 US gallon drop tanks is 2140 miles.  Initial climb rate 
(clean): 8200 feet per minute.  Service ceiling: 46,000 feet.  
Weights: 14,014 pounds empty, 19,340 pounds combat weight (clean), 
normal loaded 26,000 pounds, and 28,000 pounds maximum takeoff.  
Dimensions: wingspan 33 feet 7 1/4 inches, length 43 feet 4 3/4 
inches, height 14 feet 4 3/4 inches, wing area 325 square feet.  

Armament consisted of six 0.50-inch M-3 machine guns, four mounted in 
the nose and two mounted in the wing roots.  A radar-ranging A-4 
gunsight was provided.  A maximum of 6000 pounds of external ordinance 
could be carried, a typical load being two 2000-lb. bombs and eight 
5-inch HVARs or four 1000-pound bombs and 24 3-inch rockets.  Total 
internal fuel capacity was 475 Imp.gall., but two 191.5 Imp.gall.  
drop tanks are normally carried on the inner underwing racks, while 
for ferry purposes two 375 Imp.  gall or four 191.5 Imp.gall drop 
tanks could be carried to provide a range of 2140 miles.  

F-84F-40-RE serial number 52-6526 is on display at the Wright 
Patterson Air Force Base Museum in Dayton, Ohio.  

F-84F serial numbers: 

51-1344/1345 	Republic YF-84F-RE Thunderstreak 
51-1346/1355 	Republic F-84F-1-RE Thunderstreak 
51-1356/1380 	Republic F-84F-5-RE Thunderstreak 
51-1381/1430 	Republic F-84F-10-RE Thunderstreak 
51-1431/1510 	Republic F-84F-15-RE Thunderstreak 
51-1511/1620 	Republic F-84F-20-RE Thunderstreak 
51-1621/1709 	Republic F-84F-25-RE Thunderstreak 
51-1710/1760 	Republic F-84F-25-RE Thunderstreak 
51-1761/1827 	Republic F-84F-30-RE Thunderstreak 
51-9311/9320 	General Motors F-84F-1-GK Thunderstreak 
51-9321/9335 	General Motors F-84F-5-GK Thunderstreak 
51-9336/9356 	General Motors F-84F-10-GK Thunderstreak 
51-9357/9409 	General Motors F-84F-25-GK Thunderstreak 
51-9410/9454 	General Motors F-84F-30-GK Thunderstreak 
51-9455/9503 	General Motors F-84F-35-GK Thunderstreak 
51-9504/9547 	General Motors F-84F-40-GK Thunderstreak 
51-17061/17088 	Republic F-84F-35-RE Thunderstreak 
52-6355/6422 	Republic F-84F-30-RE Thunderstreak 
52-6423/6522 	Republic F-84F-35-RE Thunderstreak 
52-6523/6642 	Republic F-84F-40-RE Thunderstreak 
52-6643/6812 	Republic F-84F-45-RE Thunderstreak 
52-6813/6907 	Republic F-84F-50-RE Thunderstreak 
52-6908/7007 	Republic F-84F-55-RE Thunderstreak 
52-7008/7017 	Republic F-84F-56-RE Thunderstreak 
52-7018/7049 	Republic F-84F-35-RE Thunderstreak 
52-7050/7089 	Republic F-84F-40-RE Thunderstreak 
52-7090/7114 	Republic F-84F-45-RE Thunderstreak 
52-7115/7126 	Republic F-84F-46-RE Thunderstreak 
52-7127/7191 	Republic F-84F-51-RE Thunderstreak 
52-7192/7228 	Republic F-84F-56-RE Thunderstreak 
52-8767/8834 	General Motors F-84F-41-GK Thunderstreak 
52-8835/8982 	General Motors F-84F-46-GK Thunderstreak 
52-8983/9128 	General Motors F-84F-51-GK Thunderstreak 
52-10510/10538 	Republic F-84F-56-RE Thunderstreak 
53-6532/6715 	Republic F-84F-61-RE Thunderstreak 
53-6716/6835 	Republic F-84F-66-RE Thunderstreak 
53-6836/6955 	Republic F-84F-71-RE Thunderstreak 
53-6956/7075 	Republic F-84F-76-RE Thunderstreak 
53-7076/7230 	Republic F-84F-81-RE Thunderstreak 
53-7231/7520 	Cancelled contract for F-84F 

Sources:

  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.

  The Republic F-84F Thunderstreak, Ray Wagner, Profile Publications, 1966.

Joe Baugher		AT&T Bell Laboratories   	
2000 North Naperville Road      Naperville, Illinois 60566-7033