This cutaway drawing shows the S-IVB stage in its Saturn IB configuration. As a part of the Marshall Space Flight Center's (MSFC) "building block" approach to the Saturn development, the S-IVB stage was utilized in the Saturn IB launch vehicle as a second stage and, later, the Saturn V launch vehicle as a third stage. The stage was powered by a single J-2 engine, initially capable of 200,000 pounds of thrust.