Republic F-84 Thunderjet

https://en.wikipedia.org/wiki/Republic_F-84_Thunderjet

The Republic F-84 Thunderjet was an American turbojet fighter-bomber aircraft.
Originating as a 1944 United States Army Air Forces (USAAF) proposal for a "day
fighter", the F-84 first flew in 1946. Although it entered service in 1947, the
Thunderjet was plagued by so many structural and engine problems that a 1948
U.S. Air Force review declared it unable to execute any aspect of its intended
mission and considered canceling the program. The aircraft was not considered
fully operational until the 1949 F-84D model and the design matured only with
the definitive F-84G introduced in 1951. In 1954, the straight-wing Thunderjet
was joined by the swept-wing F-84F Thunderstreak fighter and RF-84F Thunderflash
photo reconnaissance aircraft.

The Thunderjet became the USAF's primary strike aircraft during the Korean War,
flying 86,408 sorties and destroying 60% of all ground targets in the war as
well as eight Soviet-built MiG fighters. Over half of the 7,524 F-84s produced
served with NATO nations, and it was the first aircraft to fly with the U.S. Air
Force Thunderbirds demonstration team. The USAF Strategic Air Command had F-84
Thunderjets in service from 1948 through 1957.

The F-84 was the first production fighter aircraft to utilize inflight refueling
and the first fighter capable of carrying a nuclear weapon, the Mark 7 nuclear
bomb. Modified F-84s were used in several unusual projects, including the FICON
and Tom-Tom dockings to the B-29 Superfortress and B-36 bomber motherships, and
the experimental XF-84H Thunderscreech turboprop.

The F-84 nomenclature can be somewhat confusing. The straight-wing F-84A to
F-84E and F-84G models were called the Thunderjet. The F-84F Thunderstreak and
RF-84F Thunderflash were different airplanes with swept wings. The XF-84H
Thunderscreech (not its official name) was an experimental turboprop version of
the F-84F. The F-84F swept wing version was intended to be a small variation of
the normal Thunderjet with only a few different parts, so it kept the basic F-84
number. Production delays on the F-84F resulted in another order of the
straight-wing version; this was the F-84G.

Role
Fighter-bomber

Manufacturer
Republic Aviation

First flight
28 February 1946

Introduction
November 1947

Primary user
United States Air Force

Number built
7,524

Unit cost

US$237,247 (F-84G)
US$769,330 (F-84F)


Variants
Republic F-84F Thunderstreak
Republic XF-84H Thunderscreech
Republic XF-91 Thunderceptor

The first effective and fully capable Thunderjet was the F-84E model which
entered service in 1949. The aircraft featured the J35-A-17 engine, further wing
reinforcement, a 12 in (305 mm) fuselage extension in front of the wings and 3
in (76 mm) extension aft of the wings to enlarge the cockpit and the avionics
bay, an A-1C gunsight with APG-30 radar, and provision for an additional pair of
230 gal (870 L) fuel tanks to be carried on underwing pylons. The latter
increased the combat radius from 850 to 1,000 miles (740 to 870 nmi; 1,370 to
1,610 km).

One improvement to the original F-84 design was rocket racks that folded flush
with the wing after the 5-inch HVAR rockets were fired, which reduced drag over
the older fixed mounting racks. This innovation was adopted by other U.S. jet
fighter-bombers.

Despite the improvements, the in-service rates for the F-84E remained poor with
less than half of the aircraft operational at any given time. This was primarily
due to a severe shortage of spares for the Allison engines. The expectation was
that F-84Es would fly 25 hours per month, accumulating 100 hours between engine
overhauls. The actual flight hours for Korean War and NATO deployments rapidly
outpaced the supply and Allison's ability to manufacture new engines. The F-84E
was withdrawn from USAF service in 1956, lingering with ANG units until 1959.

The definitive straight-wing F-84 was the F-84G which entered service in 1951.
The aircraft introduced a refueling boom receptacle in the left wing, autopilot,
Instrument Landing System, J35-A-29 engine with 5,560 lbf (24.73 kN) of thrust,
a distinctive framed canopy (also retrofitted to earlier types), and the ability
to carry a single Mark 7 nuclear bomb. The F-84G was retired from USAF in the
mid-1960s.

Starting in the early 1960s, the aircraft was deployed by the Força Aérea
Portuguesa (FAP) during the Portuguese Colonial War in Africa. By 1972, all four
operating F-84 aircraft were supplementing the FAP in Angola.

Flying the Thunderjet:

Typical of most early jets, the Thunderjet's takeoff performance left much to be
desired. In hot Korean summers with a full combat load, the aircraft routinely
required 10,000 ft (3,000 m) of runway for takeoff even with the help of RATO
bottles (two or four of these were carried, each producing 1,000 lbf (4.4 kN) of
thrust for 14 seconds). All but the lead aircraft had their visibility obscured
by the thick smoke from the rockets. Early F-84s had to be pulled off the ground
at 160 mph (140 kn, 260 km/h) with the control stick held all the way back.
Landings were made at a similar speed, for comparison the North American P-51
Mustang landed at approximately 120 mph (100 kn, 190 km/h). Despite the "hot"
landing speeds, the Thunderjet was easy to fly on instruments and crosswinds did
not present much of a problem.

Thanks to the thick straight wing the Thunderjet rapidly reached its Mach 0.82
limitation at full throttle and low altitude. The aircraft had sufficient power
to fly faster, but exceeding the Mach limit at low altitudes resulted in a viole
nt pitch-up and structural failure causing the wings to break off. Above 15,000
ft (4,600 m), the F-84 could be flown faster but at the expense of severe
buffeting. However, the airspeed was sufficiently easy to control to make safe
dive bombing from 10,000 ft (3,000 m) possible. The top speed limitation proved
troublesome against Soviet Mikoyan-Gurevich MiG-15s in Korea. Slower than the
MiG, the F-84 was also unable to turn tightly with a maximum instantaneous-turn
load of only 3 Gs followed by rapid loss of airspeed. One F-84E pilot credited
with two MiG kills achieved his second victory by intentionally flying his
aircraft into pitch-up. The MiGs chasing him were unable to follow the violent
maneuver and one crashed into the ground. Luckily for the F-84E pilot, the
aircraft did not disintegrate but the airframe did suffer heavy warping. The
F-84 was a stable gun platform and the computing gunsight aided in accurate
gunnery and bombing. Pilots praised the aircraft for Republic's legendary
ruggedness.

Pilots nicknamed the Thunderjet "The Lead Sled". It was also called "The Iron
Crowbar", "a hole sucking air", "The Hog" ("The Groundhog"), and "The World's
Fastest Tricycle", "Ground Loving Whore" as a testament to its long takeoff
rolls. F-84 lore stated that all aircraft were equipped with a "sniffer" device
that, upon passing V2, would look for the dirt at the end of the runway. As soon
as the device could smell the dirt, the controls would turn on and let the pilot
fly off the ground. In the same vein, it was suggested a bag of dirt should be
carried in the front landing gear well. Upon reaching V2, the pilot would dump
the dirt under the wheels, fooling the sniffer device.

Specifications (F-84G Thunderjet)

General characteristics
Crew: one
Length: 38 ft 1 in (11.60 m)
Wingspan: 36 ft 5 in (11.10 m)
Height: 12 ft 7 in (3.84 m)
Wing area: 260 ft² (24 m²)
Empty weight: 11,470 lb (5,200 kg)
Loaded weight: 18,080 lb (8,200 kg)
Max. takeoff weight: 23,340 lb (10,590 kg)
Powerplant: 1 × Allison J35-A-29 turbojet, 5,560 lbf (24.7 kN)

Performance
Maximum speed: 622 mph (540 kn, 1,000 km/h,Mach .81)
Cruise speed: 475 mph (413 kn, 770 km/h)
Range: 1,000 mi (870 nmi, 1,600 km) combat
Ferry range: 2,000 mi (1,700 nmi, 3,200 km) with external tanks
Service ceiling: 40,500 ft (12,350 m)
Rate of climb: 3,765 ft/min (19.1 m/s)
Wing loading: 70 lb/ft² (342 kg/m²)
Thrust/weight: 0.31 lbf/lb

Armament

6 × .50 in (12.7 mm) M3 Browning machine guns, 300 rpg
Up to 4,450 lb (2,020 kg) of rockets and bombs, including 1 × Mark 7 nuclear
bomb

Avionics

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




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