Saturn and H-1
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. Existing launchers might be extended to reach 10,000 lb to LEO, below the requirements. A new and larger design was needed, and in April 1957, Wernher von Braun handed the preliminary design task to Heinz-Hermann Koelle.[4]
Koelle's solution to reducing the development time was to use a cluster of fuel tanks from Redstone and Jupiter missiles, sit them on top of a single thrust plate, and then attach the required engines to the bottom of the plate. Calculations demonstrated that a total thrust of about 1 million pounds would be needed, greatly limiting their engine selection. Looking for suitable designs, Koelle learned of the E-1 from Rocketdyne's George Sutton. Rocketdyne was developing this 400000 lbf engine for the Titan missile, and it was the largest engine nearing introduction within the time frame that ARPA gave Wernher von Braun to develop what was then known as the "Juno V". The E-1 had originally been developed as a backup engine for the Titan missile, designed specifically to be as simple to develop as possible, in case the Aerojet General LR-87 did not pan out.
The launch of Sputnik that October led to rapid changes in the US rocketry establishment. 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.[5] The handover would take place in 1960.[5]
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. Brainstorming, they decided that the best approach was to make a minor upgrade to Rocketdyne's existing S-3D engines to boost them from 175000 lbf to 200000 lbf, and use eight of these engines instead of four E-1s.[6]
When Koelle returned to Rocketdyne looking for an upgraded version of the S-3D, they instead presented the X-1 and suggested it be used in place of a further upgrade to the S-3. Although experimental, the X-1 was already in the right thrust range and ready for full development. A contract for development was tendered on 15 August 1958,[7] and by early 1959 the name had changed from Juno to Saturn, referring to the succession as the planet after Jupiter, the Jupiter missile being the previous ABMA design.[8]
