Atlas ICBM

The SM-65 Atlas was an ICBM operated by the US Air Force from 1959-1964. The Atlas used two Rocketdyne XLR-89 engines as booster engines, and one Rocketdyne XLR-105 engine as the sustainer engine. The Atlas used a stage-and-a-half staging method where the two booster engines would share the same fuel tanks as the sustainer engine, but would then shut down and separate from the vehicle mid-flight. The W49 thermonuclear warhead was mounted on top of the Atlas booster. The SM-65 Atlas eventually developed into many space launch vehicles, such as the Atlas-Agena, Atlas-Able, Atlas-Centaur, and Mercury-Atlas.

Note: The booster engines will automaticly shut down and separate from the vehicle at 20,000m.