A cutaway illustration of Saturn 1 launch vehicle mission. The Saturn I, first of the Saturn launch vehicles' family, is a two-stage vehicle with a low-earth-orbit payload capability of approximately 25,000 pounds. The research and development program was plarned in two phases or blocks; one for first stage development (Block I) and the second for first and second stage development (Block II). The S-I (first) stage consisted of a cluster of nine propellant tanks and eight H-1 engines built by Rocketdyne, yeilding a total thrust of 1,500,000 pounds. The second stage of Saturn I, identified as S-IV, was designed as a single cylinder with a common bulkhead separating the liquid oxygen from the liquid hydrogen. Propulsion was provided by six RL-10 engines built by Pratt Whitney, capable of producing a combined thrust of 90,000 pounds. Of the 10 Saturn I's planned, the first eight were designed and built at the Marshall Space Flight Center. The remaining two were built by the Chrysler Corporation.