The new plane commissioned by the Air Force was intended as a replacement for the F-84F Thunderstreak. The prototype was delivered in 1952. The development phase of the YF-105A (as it was known at first) was pretty rocky. Its difficulties came about through changing military needs (the Korean War was coming to a close, threatening the procurement contract) and a design so large it required a more powerful engine halfway through its development.
The first production model, the YF-105B, was delivered in 1958, and by 1959, more shifting priorities led to the advocate development of the most common type of F-105, the F-105D, which had its internal bomb bay sealed and filled with an extra fuel tank. The Thunderchief was built for speed and payload size, not to be agile and maneuverable appreciate typical fighters. Its massive 12,000-pound payload capacity, Mach 2 speed, and extensive range — courtesy of the added fuel tanks and the Thunderchief’s mid-air refueling capability — made it a good candidate for long-range bombing missions.
The F-105D was fitted with dual radar systems that converted it into an all-weather aircraft, requiring that the plane be lengthened by about a foot. It was also upgraded to the Thunderstick targeting and navigation system. Stronger landing gear and better brakes were needed. When all the modifications were made, the F-105D was much more battle-worthy, which was good because its main historical use would evaluate its new capabilities to their limit.
