During the war, North American Aviation (NAA) was given several 59,600 lbf (264.9 kN)[3] V-2 engines to examine and convert from metric to SAE measurements.

The US Army requested a further boost to 150,000 lbf (670 kN) for their Jupiter missile, and the Air Force used the same version for their Thor, producing the Rocketdyne S-3D (or LR-79).

Additionally, the X-1 removed the entire start tank system and replaced it with a small solid fuel rocket engine that fed its exhaust through the gas generator to spin the turbopumps.

Finally, the X-1 introduced a new lubrication system that added a small amount of additive to the RP-1 fuel as it flowed through the various components.

Saturn started as a paper project to meet a new US Department of Defense requirement for a heavy-lift vehicle able to lift 10,000 to 40,000 pounds into low Earth orbit (LEO), or accelerating 6,000 to 12,000 lb to escape velocity.

Calculations demonstrated that a total thrust of about 1 million pounds would be needed, greatly limiting their engine selection.

In order to demonstrate peaceful intent, the US decided to spin out its various non-military rocketry programs to a new agency, which would evolve as NASA.

As the Army had lost interest in large rockets, they agreed to turn over von Braun's ABMA team to NASA, becoming the Marshall Space Flight Center.

[8] Shortly after these plans were made, in July 1958 ARPA visited ABMA and told von Braun that they still had $10 million in their budget to spend before the handover, and asked if there was any way to effectively use the money.

Von Braun called in Koelle and showed them a model of the Juno V, but the ARPA visitors noted that the E-1 engine wouldn't be ready by 1960.

This produced hot gas which was allowed to build up until reaching a pressure of 600–700 psi, after which a bursting diaphragm released it into the turbine which drove the fuel turbopumps.

This began the process of pumping fuel and oxidizer into the gas generator and the engine, and the hot gases from the SPGG provided the initial energy required to ignite the fuel/oxidizer mix.