SM-65F Atlas

The SM-65F Atlas, or Atlas-F, was the final operational variant of the Atlas missile. It first flew on 8 August 1961, and was deployed as an operational ICBM between 1961 and 1966. Following retirement as an ICBM, the Atlas-F, along with the Atlas-E, was refurbished for orbital launches as the Atlas E/F. The last Atlas E/F launch to use a rocket which had originally been built as an Atlas-F was conducted on 23 June 1981.

The first two Atlas F flights from Cape Canaveral in August and November 1961 were successful and two more in December partially successful. So far, the Atlas F test program had gone quite well and nobody was prepared for the upcoming disaster on April 9, 1962 when Missile 11F exploded only one second after liftoff from LC-11. Subsequent investigation revealed that the Atlas had suffered a catastrophic failure of the LOX turbopump. Testing now began at Vandenberg AFB and Missile 15F flew successfully on August 1. Atlas 57F on the 10th was another loss, this time due to a guidance failure at T+57 seconds that necessitated destruction of the vehicle by Range Safety. The next test launch took place from the now-repaired LC-11 at the Cape two days later and all subsequent R&D flights went without a hitch except for 13F in November which suffered premature engine shutdown due to overheating. After the flight of Atlas 21F in December, the vehicle was declared operational.

Operational tests of the Atlas F were mostly successful, but two flights from Vandenberg (Atlas 45F in October 1963 and Atlas 3F in April 1964) suffered stuck engine valves and fell back onto the pad at liftoff. In 1965, the Atlas was retired from service as an ICBM and remaining missiles used for suborbital and orbital launches over the next few decades. The last flight of an original Atlas F was in 1985 and there were two failures during the 20 years as a satellite launcher. One was an attempted launch of an unknown military test payload in April 1975 (a glob of LOX/kerosene gel fell into the flame pit at ignition and damaged the Atlas's main engines, causing it to gradually fail during ascent) and the other was a botched weather satellite launch in May 1980 (a fuel leak caused the Atlas's engines to underperform and burn too long, but the satellite kick motor was unaware of this and fired while still attached to the booster, ending up in a useless orbit).

Atlas-F launches were conducted from Cape Canaveral Air Force Station, at Launch Complexes 11 and 13, and Vandenberg Air Force Base at OSTF-2, LC-576 and SLC-3.