SM-65C Atlas
Atlas C awaiting launch (USAF)
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| Function | Prototype ICBM |
|---|---|
| Manufacturer | Convair |
| Country of origin | United States |
| Launch history | |
| Status | Retired |
| Launch sites | LC-12, CCAFS |
| Total launches | 6 |
| Successes | 3 |
| Failures | 3 |
| First flight | 24 December 1958 |
| Last flight | 24 August 1959 |
The SM-65C Atlas, or Atlas C was a prototype of the Atlas missile. First flown on 24 December 1958, the Atlas C was the final development version of the Atlas rocket, prior to the operational Atlas D. It was originally planned to be used as the first stage of the Atlas-Able rocket, but following an explosion during a static test on 24 September 1959, this was abandoned in favor of the Atlas D. Atlas C was similar to Atlas B, but had a larger LOX tank and smaller RP-1 tank due to technical changes to the Rocketdyne engines. Improvements in materials and manufacturing processes also resulted in lighter-weight components than the Atlas A and B. Booster burn time was much longer than the A/B series, up to 151 seconds. All launches took place from LC-12 at CCAS.
The Alas C test program began with the successful flight of 3C on December 24, 1958. All systems performed well and the extended booster burn time was carried out with no ill effects. On January 27, Missile 4C experienced a complete Mod III GE guidance system failure at T+80 seconds. The propellant utilization system operated fuel rich, resulting in low sustainer thrust following BECO, and LOX depletion caused simultaneous sustainer/vernier cutoff 5 seconds earlier than the planned SECO. In addition, a malfunction of the pneumatic system caused decay of fuel tank pressure starting at T+120 seconds. Tank pressure remained high enough to maintain structural integrity through powered flight, the intermediate bulkhead possibly ruptured at T+320 seconds, at which point tank pressures had dropped below a safe limit. Because of the guidance system failure, no separation signal was received by the reeentry vehicle. Impact occurred about 40 miles short of the target point in the South Atlantic.
Missile 5C (February 20) performed well until BECO, at which point the fuel staging disconnect valve failed, causing a gradual fuel leak and decay in tank pressures. When propellant levels in the tank dropped low enough, the open staging disconnect valve allowed helium pressure gas to escape, causing a more rapid pressure loss. At approximately T+168 seconds, the intermediate bulkhead reversed, followed by explosion of the missile at T+172 seconds.
Missile 7C (March 19) suffered a guidance system failure at T+85 seconds, followed by premature BECO at T+129 seconds. A backup command from the missile programmer jettisoned the booster section at T+151 seconds. After the premature booster cutoff, the missile became unstable because it was impossible for the autopilot to gimbal the sustainer engine with the booster section still attached. Missile stability was partially regained after booster jettison, then completely lost after SECO. No cutoff command was issued to the sustainer or verniers because of the guidance system failure, sustainer cutoff occurred at T+282 seconds, but the exact reason for it was not determined. During the vernier solo phase, the missile started tumbling. VECO took place at T+311 seconds when the vernier start tanks became depleted. Reentry vehicle separation also did not occur.
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