Saturn A-1

Saturn A-1, studied in 1959, was projected to be the first version of Saturn I and was to be used if necessary before the S-IV liquid hydrogen second stage became available.
It was designed as a three stage vehicle. The S-I first stage would propel the Saturn A-1 into space, continuing the flight with a Titan I missile based second stage. Finally a Centaur C high-energy double-engine third stage could send a payload into its final Earth orbit or to other planets.
The Saturn A-1 never flew, but all proposed stages were used on different launch vehicles. Today, they are all retired.