F-105 Thunderchief: the low-level bomber that carried the Vietnam air war

The F-105 Thunderchief was designed as a Cold War fighter-bomber able to deliver tactical nuclear bombs at low altitudes. Built to fly fast and close to the ground, it proved agile at low level, and it earned recognition both for the damage it could inflict and the punishment it could absorb, according to an account of the type's development and combat use.

Republic Aviation had already produced several aircraft carrying the Thunder name, among them the P-47 Thunderbolt, the F-84 Thunderjet, the swept-wing F-84F Thunderstreak, the RF-84 Thunderflash and the XF-84H, known unflatteringly as the Thunderscreech.

Chief designer Alexander Kartveli began studies in the early 1950s on a replacement for the F-84, partly to continue the company's relationship with the United States Air Force. The proposal, designated AP-63 for Advanced Project, was drawn up against an Air Force requirement for a large new nuclear-capable fighter-bomber able to penetrate enemy defences at high speed and low altitude.

Republic's early AP-63 concept was in effect an enlarged RF-84F with an internal weapons bay sized to carry a tactical nuclear weapon. In 1952 the company put a revised AP-63 proposal to the Air Force and won backing for continued development instead of further work on the existing F-84 line, including a scaled-up RF-84F. A contract followed in September 1952 covering development, preproduction, tooling and engineering, along with a verbal order for 199 production aircraft.

After a sequence of orders, cancellations and reorders, two YF-105As were built at the company's Farmingdale plant on Long Island, New York, and both were shipped to Edwards Air Force Base in California. In service over North Vietnam the type flew at treetop level carrying heavy payloads and, despite substantial losses, returned day after day against the country's dense air defences.