The F-105 Thunderchief was developed by Republic Aviation as a follow on to their F-84F Thunderstreak.  A higher-performance fighter-bomber was envisioned and following a proposal to the USAF, a contract for two YF-105A prototypes was awarded.  First flying in 1955, the aircraft was very large and could carry a huge complement of weapons.  The type entered service in August 1958 and continually evolved with new engines and performance levels.  The final production version of the Thunderchief was the F-105F which was a stretched version with two seat capability.  Outfitted with Radar Homing and Warning (RHAW) electronics, jamming pods, a missile-launch warning receiver and other avionics, the "Wild Weasel" version of the aircraft served in Vietnam beginning in 1966.  The F-105s continued in active service until 1973 and then in the Air National Guard until retired.