SM-65D Atlas

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Atlas D (SM-65D)
Atlas-icbm-erection-large.jpg
Launch sequence of an Atlas D ICBM test, April 22, 1960
Function ICBM
Expendable launch system
Manufacturer Convair
Country of origin United States
Launch history
Status Retired
Launch sites LC-11, 12, 13 & 14, CCAFS
LC-576, VAFB
Total launches 135
Successes 103
Failures 32
First flight April 14, 1959
Last flight November 7, 1967

The SM-65D Atlas, or Atlas D, was the first operational version of the U.S. Atlas missile. Atlas D was first used as an intercontinental ballistic missile (ICBM) to deliver a nuclear weapon payload on a suborbital trajectory. It was later developed as a launch vehicle to carry a payload to low Earth orbit on its own, and later to geosynchronous orbit, to the Moon, Venus, or Mars with the Agena or Centaur upper stage.

Atlas D launches were conducted from Cape Canaveral Air Force Station, at Launch Complexes 11, 12, 13 and 14, and Vandenberg Air Force Base at Launch Complex 576.

The Atlas D testing program began with the launch of Vehicle 3D from LC-13 on April 14, 1959. At liftoff, the LOX fill/drain valve failed to close, resulting in a steady oxidizer leak and loss of pressure to the propellant feed system. The right booster engine thus reached only 75% of its maximum thrust at liftoff. In addition, LOX spilling down the side of the missile exploded on contact with the engine, causing considerable damage to it. The Atlas lifted and flew at an oblique angle until T+26 seconds when an explosion in the boattail caused the right booster engine to separate from the vehicle. The burning missile pitched over and with all control lost, the Range Safety Officer issued the destruct command at T+35 seconds.[1]

On May 18, Atlas 7D was prepared for a night launch. The test was conducted with the Mercury astronauts in attendance in order to showcase the vehicle that would take them into orbit, but 60 seconds of flight ended in another explosion, prompting Gus Grissom to remark "Are we really going to get on top of one of those things?". This failure was traced to improper separation of a pin on the right launcher hold-down arm, causing helium pressurization gas to escape so that the RP-1 tank depressurized and ruptured the LOX tank above it.[1]

Atlas 5D in June suffered loss of thrust at staging due to another valve problem, but the fifth test on July 29 was successful, and after another flight on August 11, the Atlas D was reluctantly declared operational. Subsequent tests in the fall and winter all performed well, although the launch of a boilerplate Mercury capsule on Atlas 10D (Big Joe) in September was a partial success because the booster engines failed to separate.

With this string of successful Atlas tests, NASA, Convair, and the Air Force were lulled into a sense of security that was rudely ended on March 13, 1960 when Atlas 51D suffered combustion instability and was destroyed by Range Safety only three seconds after liftoff. A second disaster occurred on April 8 when 48D experienced the same problem, but this time failed to make it off the pad before exploding, severely damaging it in the ensuing holocaust. With two launch facilities now in need of repair, attention shifted to LC-12 where Atlas 56D flew over 9000 miles with an instrumented nose cone, impacting the Indian Ocean.

Meanwhile, Missile 23D in May lost control shortly after liftoff from Vandenberg AFB due to an electrical short. There were multiple problems at Pad 576B with service tower umbilicals that were ultimately traced to erroneous construction of the pad itself.[citation needed]

Most Atlas D launches were sub-orbital missile tests; however several were used for other missions, including orbital launches of manned Mercury, and unmanned OV1 spacecraft. Two were also used as sounding rockets as part of Project FIRE. A number were also used with upper stages, such as the RM-81 Agena, to launch satellites.[2]

For Mercury, the Atlas D was used to launch four manned Mercury spacecraft into low Earth orbit.[2] The modified version of the Atlas D used for Project Mercury was designated Atlas LV-3B.

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