- Family: Atlas
- Length: 31.4 m
- Diameter: 3.66 m
- Launch Mass: 3 T
- Low Earth Orbit Capacity: 68 kg
The SM-65B Atlas was manufactured by Convair with the first launch on 1958-07-19. SM-65B Atlas has 1 successful launches and 0 failed launches with a total of 1 launches. The Convair SM-65B Atlas, or Atlas B, also designated X-12 was a prototype of the Atlas missile. First flown on 19 July 1958, the Atlas B was the first version of the Atlas rocket to use the stage and a half design with an operational sustainer engine and jettisonable rocket booster section. Unlike later Atlas models, the Atlas B used explosive bolts to jettison the booster section.