The F-105B was the initial production version of the Thunderchief. It was powered by the new high-thrust Pratt & Whitney J75 turbojet, rated at 23,500 pounds of thrust with afterburning. The airframe was extensively revised to take full advantage of the new J75 turbojet, and had a fuselage that was reconfigured according to the Area Rule devised by Richard Whitcomb.
The RF-84F-style air intakes fitted to the YF-105A were replaced by a set of swept-forward air intakes that would take advantage of the increased engine power and would make a Mach 2 performance possible. A boundary layer fence was located in front of each intake next to the fuselage. There was a variable plug inside each duct which could be moved forwards or backwards under the control of a Bendix central air data computer to provide proper airflow to the engine as a function of Mach number. These ramps were fully retracted at low speeds, allowing maximum air ingestion, and at high speed they were fully extended to decrease air flow.
A set of auxiliary air inlets were provided that could be opened automatically whenever negative pressure existed in the ducts to provide needed airflow at low speeds. These air inlets could be opened only when the landing gear was extended, an interlock keeping the doors fully closed whenever the landing gear was retracted. Just in front of the engine compressor stage there were a set of bleed doors in the intake ducting that could dump any excess airflow which would tend to force the shock wave out of the duct throat.
In order to prevent vertical tail flutter (which had been a problem with both the earlier F-100A and with the YF-105A as well), the vertical tail and rudder on the F-105B were increased in both height and chord. A ram-air intake was fitted to the base of the vertical fin, capturing air for the cooling of the aft end of the aircraft. In addition, on F-105B production aircraft the small rear vision windows behind the canopy (a carryover from the F/RF-84F) were deleted.
The F-105B also introduced a four-petal, cloverleaf set of air brakes fitted around the jet engine exhaust orifice at the extreme rear of the aircraft. The four segments could be deployed in several different configurations, depending on the needs of the mission. They could be opened outward to a maximum angle of 90 degrees. During landing, only the two side segments could be deployed because the bottom segment had insufficient ground clearance and the top segment would block the brake ‘chute deployment.
Four YF-105B service test prototypes were built (serials were 54-100/103). They were powered by the YJ75-P-3 turbojet, rated at 16,470 lb.s.t. dry and 23,500 lb.s.t. with afterburning.
The first YF-105B (54-100) flew on May 26, 1956, piloted by Republic test pilot Lin Hendrix. It flew for one hour but was damaged on landing when the nose gear failed to extend. It was damaged beyond economical repair when it was dropped by the crane operator while it was being removed from the runway at Edwards AFB.
On June 19, 1956, the name Thunderchief was officially given to the F-105.
On January 30, 1957, the next YF-105B (54-101) took off on its first flight. It too ended up on its belly after yet another landing gear failure. The problem was traced to an interference between the main landing gear and auxiliary air intakes, and was fairly easily fixed.
Further schedule slippages and excessive costs generated numerous changes in USAF procurement planning. In March of 1956, the Air Force released funds for the acquisition of 65 F-105Bs and 17 RF-105Bs. The RF-105B was a photographic reconnaissance version of the F-105B fighter bomber and was designed to replace the RF-84F. In June, five two-seat F-105Cs were added to the program.
The maximum speed reached during tests was Mach 2.15, which was remarkable considering the weight of the plane. The tests proved generally satisfactory as far as aircraft performance was concerned. However, other key systems had reliability problems, including the General Electric MA-8 fire control system and its principal components (E-34 radar ranging set, E-50 gyroscopic sight, E-30 toss-bombing set, and nuclear weapon safing and arming system), the Bendix navigation computer, and the General Electric FC-25 autopilot. The complexities of the F-105’s subsystems compounded the contractor’s difficulties,
In January of 1957, GOR 49 was amended to call for the incorporation of the APN-105 all-weather navigation system.
The first production F-105B (54-104) took off on its maiden flight on May 14, 1957, Henry G. Beaird Jr. being at the controls. It was accepted by the Air Force on May 27, three years later than originally anticipated.
On November 22, 1957, GOR 49 was revised once again, and the inertial navigation system was deleted in favor of the projected AN/APN 105 system. Several requirements were added, e.g., a new cockpit instrument display, a tow target subsystem, and a TX-43 nuclear weapon capability.
The F-105B was equipped with the MA-8 fire control system, which consisted of an E-50 sighting system operating in conjunction with an E-34 radar ranging gunsight mounted in the extreme nose and an E-30 bomb toss computer.
The roomy fuselage had a capacious bomb bay in the belly. The bay was originally designed to carry a nuclear weapon, since the original role of the Thunderchief was tactical nuclear strike. Later, as the use of nuclear weapons in warfare became less likely, the internal weapons bay was redesigned so that it could carry an additional fuel tank or other types of conventional weaponry. Conventional weapons could also be carried on four underwing hardpoints and on one ventral hardpoint underneath the fuselage.
The fuel was carried in seven separate fuel tanks lined up along the upper rear fuselage behind the pilot. Total internal fuel capacity was 1160 US gallons, of which 25 gallons of useful fuel was actually located in the fuel lines. Two 450-gallon drop tanks could be carried under the inboard underwing pylons, and an additional 450 or 650-gallon drop tank could be carried on a hardpoint underneath the fuselage. In addition, the bomb bay could accommodate a 390 gallon fuel tank in place of the “special store”. Total fuel load (internal plus external) could be as high as 3100 US gallons.
A retractable probe-and-drogue type of midair refuelling probe was mounted on the left side of the fuselage nose just ahead of the pilot’s cockpit.
The public got its first view of the F-105B at a display at the Andrews AFB Open House on July 28, 1957, which celebrated the 50th anniversary of military aviation.
Production F-105Bs began to roll off the line at Farmingdale in 1958, and the Air Force officially accepted its first machine on May 27, 1958. The first unit to receive the F-105B was the 335th Tactical Fighter Squadron of the 4th Tactical Fighter Wing of the TAC. This outfit was first based at Eglin AFB, then later at Seymour Johnson AFB. The 335th began to work up with the F-105B in August 1958, and in January of 1959 the unit was declared operational with the type. Since various delays had precluded the completion of all the pre-operational tests, the 335th had to carry out some of these tests. However because of maintenance difficulties and production slippages the 335th did not become fully operational with the F-105B until 1960. There were significant problems with the autopilot, the central air data computer, and the MA-8 fire control system. In addition, there was an acute shortage of spare parts which kept many aircraft from flying. In early 1960, all the F-105Bs flying with the 335th had to be grounded for various regions, including a lack of spare parts. Nevertheless, the F-105B did manage to complete its first year of service without a single major accident, becoming the first aircraft in USAF service history to be so fortunate.
On December 11, 1959, an F-105B piloted by Brig. Gen. Joseph Moore (commander of the 4th TFW) set a new world speed record of 1216.48 mph over a 100-kilometer closed circuit.
The other two squadrons of the 4th Tactical Fighter Wing (the 334th and 336th) received F-105Bs by the end of 1960. These squadrons were destined to be the only USAF operational combat units to use the F-105B. The fourth squadron of the 4th TFW (the 333rd TFS) was not reequipped until 1961, when the first F-105Ds became available.
These three squadrons were assigned the duties of carrying out Category III testing at Williams AFB in Arizona and at Nellis AFB in Nevada. The number of available F-105Bs remained insufficient to equip all of the squadrons and serviceability was low due to lack of spares and the chronic unreliability of the electronic components. Problems with maintenance and serviceability continued through 1961, and the F-105B required about 150 maintenance hours for each hour spent in the air. However, whenever everything was working as advertised, the F-105B handled well and had a good performance. Most F-105B deficiencies were eventually corrected under Project Optimize.
Despite the aircraft’s large size and weight, in May of 1963 the F-105B was selected to replace the F-100C Super Sabres of the Thunderbirds flight demonstration team. The last of nine specially modified F-105Bs was delivered on April 16, 1964, ten days before the first scheduled public performance with the new planes. The aircraft had the 20-mm cannon and associated ammunition, the Doppler equipment, and other associated military items deleted and replaced with ballast and a baggage compartment. A smoke system was installed in the bomb bay, with a pair of pipes on the ventral fuselage surface directing smoke oil into the aircraft’s exhaust. Standard F-105B flaps and landing gear were replaced by those from the later F-105D. Four of the Thunderbirds F-105Bs were fitted with a steel tail to withstand the increased stress when flying in the slot or when performing the “knife edge” maneuver. This also made it possible for the aircraft to fly the “slot” position without risking thermal damage to the fin from the exhaust of the lead aircraft. Despite some misgivings about the use of so large and heavy an aircraft as the F-105, the team had few problems in adapting to the Thunderchief.
The Thunderbirds team flew a few demonstrations with their F-105Bs, but a serious accident occurred in May. Captain Devlin was killed when his F-105B (57-5801) disintegrated after hitting a mast. The modifications directed as a result of this accident prevented the use of the F-105Bs in any more public airshows. Because of its heavy schedule, the Thunderbirds team was hastily re-equipped with eight F-100D Super Sabres. The F-100Ds remained with the Thunderbirds until 1969, when the team re-equipped with F-4E Phantoms. The remaining F-105Bs were brought back to combat standards and were delivered to the 141st TFS of the New Jersey Air National Guard.
Aircraft from the first F-105B production blocks were powered by the J75-P-5 engine, but the F-105B-20-RE block was given the J75-P-19 engine with an additional thousand pounds of thrust. Subsequently, this engine was retrofitted to earlier production block aircraft.
The F-105B’s service with the USAF was relatively brief, being superseded by the all-weather F-105D version beginning in 1964. The surviving USAF F-105Bs were then transferred to the Air National Guard. The first surplus F-105Bs reached the 108th TFG, New Jersey ANG on April 16, 1964. The New Jersey ANG retained a few F-105Bs until 1981, when they were finally sent off to the boneyards.
Although the Air Force disposed of most of its F-105Bs during 1964-65, they retained a few F-105Bs for training purposes at McConnell AFB in Kansas until late 1969. A few F-105Bs served with the 508th Tactical Fighter Wing of the Air Force Reserve at Hill AFB in Utah beginning in 1973, the last examples finally going off to the boneyards in 1981. At least five have been turned over to museums.
The following Air Force units flew the F-105B:
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4th Tactical Fighter Wing, Seymour Johnson AFB
- 334th Tactical Fighter Squadron (June 1959-Jan 1964)
- 335th Tactical Fighter Squadron (May 1958-June 1960)
- 336th Tactical Fighter Squadron (Aug 1959-Jan 1964)
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508th Tactical Fighter Wing, Hill AFB
- 466th Tactical Fighter Squadron (Jan 1973-May 1981)
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177th Tactical Fighter Group, New Jersey ANG, NAFEC Atlantic City
- 119th Tactical Fighter Squadron (June 1970-Jan 1973)
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108th Tactical Fighter Group, New Jersey ANG, McGuire AFB. Changed designation to 108th TFW in Dec 1974.
- 141st Tactical Fighter Squadron (April 1964-May 1981)
Serials of F-105B:
54-100/103 Republic F-105B-1-RE Thunderchief 0100 at McClellan Aviation Museum, CA 54-104 Republic F-105B-5-RE Thunderchief 54-105 Republic JF-105B-1-RE Thunderchief 54-106/107 Republic F-105B-5-RE Thunderchief 54-108 Republic JF-105B-1-RE Thunderchief 54-109/110 Republic F-105B-5-RE Thunderchief 54-111 Republic F-105B-6-RE Thunderchief 54-112 Republic JF-105B-2-RE Thunderchief 57-5776/5784 Republic F-105B-10-RE Thunderchief 5782 to Thunderbirds 57-5785/5802 Republic F-105B-15-RE Thunderchief 5790 to Thunderbirds 5793 to Thunderbirds 5797 to Thunderbirds 5798 to Thunderbirds 5801 to Thunderbirds 5802 to Thunderbirds 57-5803/5840 Republic F-105B-20-RE Thunderchief 57-5841/5845 Cancelled contract (believed for F-105B)
Sources:
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United States Military Aircraft Since 1909, Gordon Swanborough and
Peter M. Bowers, Smithsonian, 1989.
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The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.
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Fighters of the United States Air Force, Robert F. Dorr and
David Donald, Temple Press Aerospace, 1990.
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American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
-
Post-World War II Fighters, 1945-1973, Marcelle Size Knaack,
Office of Air Force History, 1986.
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The World Guide to Combat Planes, William Green, MacDonald, London, 1966
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The World’s Fighting Planes, William Green, Doubleday, 1964.
-
The Aircraft of the World, William Green and Gerald Pollinger, Doubleday,
1965.
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The Thunder Factory, Joshua Stoff, Motorbooks, 1990.
-
F-105 Thunderchief in Detail and Scale, Bert Kinzey, Kalmbach Books,
1993.
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Thud Part 1, Christian Jacquet, Air Fan International, Vol 1, No 3,
March 1996.
-
Thud Part 2, Christian Jacquet, Air Fan International, Vol 1, No 4,
May 1996.
-
Warplane Classic–Republic F-105 Thunderchief, Larry Davis, International Air Power Review,
Vol 6, 2002.
