The Republic F-105 Thunderchief, also called as the "Thud", was the first single-seat supersonic, all-weather strike fighter-bomber used by the U.S. Air Force. First flown on October 2, 1955, the Thunderchief entered service in 1958. Aside from being the largest, single-engine tactical aircraft in history, the F-105 was notable for its large internal bomb bay and unique swept-forward engine inlets in the wing roots. The wing was highly swept and incorporated low-speed ailerons and high-speed spoilers for lateral control, and a droop-snoot leading edge. Originally designed to deliver nuclear weapons at supersonic speeds, the F-105 Thunderchief, like the B-52, was pressed into service delivering iron bombs to North Vietnam. In this role the F-105 excelled and by the end of 1970 the F-105 had flown 75% of the bombing missions to North Vietnam. With over 20,000 Thunderchief sorties were flown, with 382 aircraft lost (nearly half of the 833 produced) including 62 operational casualties. Although it lacked the agility of smaller MiG fighters, USAF F-105s demonstrated the effectiveness of guns, and were credited with downing 27.5 enemy aircraft.
The F-105D variant was the definitive production model of the Thunderchief series. The D-model was an all-weather strike fighter bomber, fitted with monopulse and Doppler radar for night or bad weather operations. This radar was capable of terrain avoidance commands. The original weapons bay, designed for nuclear stores, was sealed and fitted with additional fuel tanks. Bombs were carried on multiple weapons racks on the centerline of the fuselage, and on wing pylons. The aircraft was fitted with a retractable in-flight refueling probe. During the Vietnam War, F-105 units operated from bases in Thailand. First flew on June 9 1959, the F-105D entered service with 335th TFS in 1960.
The last F-105D was withdrawn from USAF service on July 12, 1980. A total of 610 D Model of the Thunderchief were built.