[1] The S-I stage was powered by eight H-1 rocket engines[2] burning RP-1 fuel with liquid oxygen (LOX) as oxidizer.

The design of the S-I was based on Jupiter and Redstone tanks to leverage existing chains.

The S-I stage was developed by Chrysler and consisted of 9 tanks that were previously used on existing rockets.

The first four launches had no fins on the S-I, but the remaining six added them to improve stability during atmospheric flight.

The S-I was partially loaded with propellant to lessen the destruction if an anomaly occurred near or on the pad.