SM-65F Atlas

Atlas-F (SM-65F)

Launch of an Atlas-F missile
Function	ICBM Expendable launch system
Manufacturer	Convair
Country of origin	United States
Launch history
Status	Retired
Launch sites	LC-11 & 13 CCAFS OSTF-2, LC-576 & SLC-3, VAFB
Total launches	70
Successes	53
Failures	17
First flight	8 August 1961
Last flight	23 June 1981

The SM-65F Atlas, or Atlas-F, was the final operational variant of the Atlas missile, only differing from the Atlas E in the guidance package. 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 Atlas E and F also differed in their launch facilities; Atlas E utilized the same coffin silos as Atlas D missiles, with the missile stored horizontally and raised upright for launch. Atlas F for comparison used a vertical silo with an elevator similar to the Titan I.

Atlas E and F used the MA-3 propulsion system which had a separate gas generator for all three engines, unlike the Atlas D where one gas generator drove both booster turbopumps. In addition, they used pyrotechnic cartridges for rapid starting. Total thrust of the MA-3 was 375,000 pounds.

Most refurbished Atlas F space launches used solid-fueled upper stages, a notable exception being Missile 23F which launched Seasat, a NASA oceanography satellite, on June 27, 1978 using the last-ever Agena stage flown. The final Atlas F launch took place on June 23, 1981 when Missile 87F successfully placed a NOAA weather satellite into orbit.

The first two Atlas F flights from Cape Canaveral in August and November 1961 were successful and the third on December 12 mostly successful. On the 21st, Atlas 6F lifted off of LC-11 carrying a rhesus monkey named Scatback. This was the third launch of a primate on an Atlas in the past month - the first was Mercury-Atlas 5 which successfully lofted a chimpanzee on a three-orbit mission while the second, an Atlas E test, malfunctioned shortly after liftoff and had to be destroyed, claiming the life of the squirrel monkey it was carrying. Atlas 6F performed acceptably until after booster jettison when a hydraulic failure caused loss of sustainer thrust. The capsule separated and splashed down near Ascension Island in the South Atlantic, however the tracking beacon failed to operate and recovery crews could not locate it. They gave up the search and Scatback was officially lost at sea.

So far, the Atlas F test program had gone 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 found that the sustainer LOX turbopump exploded due to the impeller blades rubbing against the metal casing and causing a spark that ignited the LOX. Testing now began at Vandenberg AFB and Missile 15F flew successfully from 576-E on August 1. Nine days later, Missile 57F launched from OSTF-1 and failed to perform its roll maneuver. The pitch sequence was executed properly, but the absence of the roll program prevented the missile from attaining the correct trajectory and it was blown up by Range Safety 52 seconds into the launch. An electrical short in the programmer was found to be the cause of the failure, and ironically, 57F had been instrumented more heavily after an Atlas E test earlier in the year had failed to stage its booster section, but inadequate telemetry measurements made it difficult to determine the exact cause of the malfunction. 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 on November 14 which suffered premature sustainer shutdown due to thrust section overheating. The next launch, Missile 21F, successfully concluded the R&D phase of the Atlas F program.