Atlas-Able

The Atlas-Able was a space launch vehicle operated by the US Air Force from 1959-1960. It was derived from the SM-65 Atlas ICBM. The Atlas booster used two Rocketdyne XLR-89 engines as booster engines, and one Rocketdyne XLR-105 engine as the sustainer engine. The Able upper stage was attached to the top of the Atlas booster. The Atlas booster 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 Atlas-Able conducted only 3 flights total, with 0 successes.

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