The beginning of the Space Age was ushered in by a series of Soviet space spectaculars which clearly demonstrated that the Soviet Union had an immense lead in rocket technology. One of the more compelling measures of this lead was payload capability: typical Soviet spacecraft were over an order of magnitude heavier than their miniaturized American counterparts. But even before the end of the first year of the Space Age, a group of engineers at the Army Ballistic Missile Agency (ABMA) lead by German rocket pioneer Wernher von Braun were already developing a heavy-lift launch vehicle, initially called the Juno V, that would dwarf even the largest Soviet rocket (see “Juno V: The Birth of the Saturn Rocket Family”). Eventually dubbed “Saturn”, this evolving family of launch vehicles would be capable of orbiting payloads with a mass of tens of tons.

While the Department of Defense (DoD) and the Advanced Research Projects Agency (ARPA) initially embraced the von Braun team’s Saturn concept with enthusiasm, by the close of 1958 fiscal realities combined with uncertainties about mission requirements were already threatening to derail Saturn’s aggressive development schedule. By November of 1958 the plan called for the construction of five Saturn test vehicles: One for static tests and four for an initial suborbital flight test program to be completed by the last quarter of 1961. To keep this schedule, ABMA requested $60 million for Fiscal Year 1960 but this request was cut to $50 million by the Budget Bureau. A further blow was dealt to the infant Saturn program when on December 9, 1958 the DoD refused to grant the program a “DX” top priority rating. Such a rating, which would place the program first in line for required materials and talent, would have greatly facilitated the development of the new rocket.

Finding a Customer

To further complicate matters, there was the question of who Saturn’s customers would be, whose requirements would drive development and even who would ultimately control the ABMA, its facilities and invaluable engineering talent. By the end of 1958, the USAF was well on its way towards monopolizing most aspects of military space activities. While the US Navy would find some specialized niches that allowed its own space program to survive, the US Army was slowly being pushed out of the picture all together. This was nothing more than a continuation of a trend that started in 1956 with a government policy decision that gave control of all long range missile development to the USAF with the US Army (and subsequently the ABMA) role being phased out.

Even as the Saturn program was beginning to ramp up in late 1958, the USAF had already written it off preferring instead to use a home-grown variant of their own Titan ICBM then under development. It was anticipated that this heavy-lift version of the Titan, designated “Titan-C”, would be able to meet all the DoD’s anticipated future heavy lift requirements. This has indeed proven to be the case since the Titan-C studies lead to the development of the successful Titan III family of launch vehicles. The Titan III and its descendants were used to launch large DoD payloads for almost a third of a century (see “The First Missions of the Titan IIIC”).

While the USAF was not interested in developing Saturn, the DoD and the US Army were. The DoD supported the development of the Titan-C but felt that the Saturn design offered much more growth potential. The US Army also wanted the Saturn to support their series of proposed space initiatives including building a lunar colony as part of “Project Horizon”. But as 1959 wore on it became increasingly clear that the Army would not be given the nod to undertake any mission that would require the Saturn. With a long wish list of potential future missions that would require a heavy lift capability, NASA was probably Saturn’s best potential customer.

But NASA also anticipated the need to develop launch vehicles even larger than the original Saturn. In addition, NASA management wanted such an ambitious and important hardware development effort to be done in house. Aware that ABMA would probably fade along with the Army’s long range missile and space ambitions, in January 1959 NASA began to seek control of von Braun and his rocket team along with other ABMA assets. NASA had already acquired the Jet Propulsion Laboratory and felt that ABMA with their Redstone facility in Huntsville, Alabama would be an invaluable addition to the fledgling agency. But throughout most of 1959 these overtures did not result in any sort of decision one way or another. So much ambiguity about the future of ABMA and Saturn only worsened the program’s scheduling problems and even potential cancellation.

All these uncertainties had the greatest impact on determining the upper stage configuration of the Saturn. The first stage design with its cluster of eight H-1 engines fed by a cluster of propellant tanks based on Jupiter and Redstone tooling was already settled. But for the Saturn test program to proceed beyond the initial four test flights, a decision would have to be made on the upper stages. One decision made was to use the advanced Centaur (being developed by the USAF) as the upper-most stage of Saturn. While there were those who advocated using a modified ICBM (e.g. the Atlas or Titan) as Saturn’s second stage, many felt that the development of high energy, hydrogen-fueled stages offered much more potential in the long run. The ultimate selection, however, would have to be based on the payload requirements of Saturn’s customer and their development horizon. These were open questions at the beginning of 1959 with no official resolution readily at hand.

By early 1959 there were three groups of Saturn configurations under consideration. The “Saturn A” would have a second stage consisting of either the first stage of the Titan I ICBM or a design using a cluster of Jupiter IRBMs. The third stage of Saturn A would be the high-energy Centaur. The second configuration, “Saturn B”, would use a second stage with a cluster of four H-1 engines and a third stage with a cluster of four of Centaur’s RL-10 engines burning liquid hydrogen and LOX generating 267 kilonewtons of thrust. The fourth stage would again be the Centaur. The third configuration, called “Saturn C”, proposed using various configurations of the Centaur’s advanced RL-10 engine, or upgraded variants, in the upper stages.

Hardware Development Proceeds

But while Saturn program managers wrestled with the question of the program’s future, ABMA engineers and the program’s contractors were making excellent progress with Saturn’s enormous first stage. Development of the H-1 engine at North American Aviation’s Rocketdyne division proceeded at a brisk pace. This was entirely due to experience with the direct antecedent of the H-1, the S-3D (used on the Jupiter IRBM), as well as similar size engines employed on the Thor IRBM and Atlas ICBM. Many of the proposed improvements had already been tested on Rocketdyne’s “X-1” experimental rocket engine which began test firings in 1957. The H-1 not only had to generate 10% more thrust than the S-3D, it would have to undergo some other serious modifications. With a cluster of eight of the older engines, a Saturn lift off would be like trying to simultaneously launch eight Jupiter IRBMs off the same pad. And the use of eight engines made it much more likely that one would fail in flight. As a result, the H-1 had to be easier to start and much more reliable than its predecessors.

By the time Rocketdyne got the contract to build the H-1 on September 11, 1958, its engineers already had a laundry list of improvements for the S3-D design under advance study. These were quickly incorporated into the new engine and by December 31, 1958 the H-1 completed its first full power test firing. The first prototype engine, H-1001, was first tested on March 6, 1959 and shipped to ABMA on April 20 for the start of test firings there. While the design goal was for the H-1 to generate 836 kilonewtons of thrust, the initial batch of engines was down rated to just 734 kilonewtons as combustion instability issues were being addressed. This would still result in an impressive liftoff thrust of 5,872 kilonewtons for the first Saturn test flights.

When the last ABMA-built Jupiter IRBM rolled off the assembly line on July 27, 1959, engineers started the modifications needed to build the cluster of Jupiter- and Redstone-based propellant tanks for the Saturn’s first static test article designated “SA-T”. Earlier in the year on January 14, ABMA started modifications the East side of the existing Static Test Tower in ABMA’s East Test Area to handle the Saturn first stage. The plan was for the SA-T to be fitted with increasingly larger clusters of H-1 engines for static test firings. Starting with only a pair of engines, firings would proceed until the full compliment of eight engines were tested at full power. Meanwhile in Cape Canaveral, Florida, construction of Launch Complex 34 which would support the first Saturn test flights officially began on June 3.

But as the development of Saturn hardware and ground support infrastructure were making good progress, uncertainty about the program’s future weighed heavily on everyone. With the realization that the Army would be consigned to playing a minor role in space General Bruce Medaris, who along with von Braun was instrumental in launching the first Explorer satellites (see “Explorer 1: America’s First Satellite”), announced that he was resigning his leadership position at ABMA on October 18, 1959. Echoing the General’s frustration, it was widely known that von Braun was less than pleased with the situation and would quit if Saturn was cancelled. But within days there finally seemed to be some movement towards resolving a number of questions surrounding the Saturn program. On October 21, 1959 President Eisenhower approved the NASA plan to assume control of parts of the ABMA. While the decision would require Congressional approval, the plan called for a transfer of 5,000 workers from ABMA’s Development Operations Division which included the von Braun team.

Decisions Made

With the decision to make von Braun’s team part of NASA, the Saturn program quickly came into focus. On December 15, 1959 the Saturn Vehicle Committee made the final recommendation for the Saturn upper stage configuration: the Saturn C which would use hydrogen-fueled upper stages. This configuration offered more growth potential than the Saturn A. And if the time and expense were to be expended on developing the new upper stages for the Saturn B, it made better sense to use all high energy cryogenic upper stages for only slightly more additional risk.

Using a building block approach, a series of five different stages designated “S-I” through “S-V” would be combined to create three increasingly more capable Saturn launch vehicles. The first stage for these rockets, designated S-I, was already under development by ABMA. For the Saturn C-1 (whose name would be simplified to just “Saturn I” in early 1963), the second stage would consist of a 5.7-meter in diameter S-IV stage powered by four engines derived from the RL-10 producing a total of as much as 89 kilonewtons of thrust. This would be topped by the 3-meter in diameter Centaur designated S-V in the studies. This configuration, which would be capable of sending over four tons to the Moon, could meet NASA’s early heavy lift requirements yielding the largest space launch vehicle of its time (see “The Largest Launch Vehicles through History”).

Anticipating the need for even more payload capability, growth versions of the Saturn C were identified. The Saturn C-2 would use the same S-I stage of the C-1 but would have a new second stage called S-III. The 5.6 meter in diameter S-III stage would sport a pair of larger hydrogen fueled engines, eventually known as the J-2, to produce as much as 890 kilonewtons of thrust. The third and fourth stages C-2 would be the S-IV and S-V stages used as the upper stages of the C-1.

The final configuration, Saturn C-3, would need an upgraded S-I stage to produce at least 9,000 kilonewtons of thrust at liftoff instead of 6,700 kilonewtons of the baseline S-I under development. One option considered was to replace the four inboard H-1 engines with a single F-1 engine. The second stage of this rocket, designated S-II, would use four J-2 engines to produce as much as 3,600 kilonewtons of thrust. The third, fourth and fifth stages of the Saturn C-3 would be the S-III, S-IV and S-V – the same upper stage combination employed on the C-2. At the beginning of February 1960, Rocketdyne got the contract to build the J-2 and prospective bidders were briefed on the S-II. Around the same time, the Saturn program finally got the “DX” rating it needed to keep to its development schedule. The future of the Saturn program finally seemed bright.

S-I Testing Begins

The SA-T test article was installed at the Static Test Tower East on February 28, 1960 after fit checks with a S-I tail section mockup had been completed. After tests on the SA-T were finished, it was fitted with two H-1 engines, H-1006 and H-1008, for an initial static test firing designated SAT-01. The first test firing, lasting only 8 second, started at 10:58 AM CST on March 28. For the second test, SAT-02 which took place at 11:15 AM CST on April 6, two more engines were added for a seven-second test firing. SAT-03 took place at 5:28 PM CST on April 29 with all eight H-1 engines firing for eight seconds. Over the coming weeks, the burn time was gradually increased until a total burn time of 121 seconds was achieved during SAT-08 at 5:09 PM CDT on June 15 completing the initial test series with SA-T.

In the meantime, assembly of the first Saturn flight article, SA-1, had started by the end of May. And after years of uncertainty, von Braun’s team was officially transferred to NASA along with their facilities in Huntsville and at the Eastern Test Range on Cape Canaveral, Florida. On July 1, 1960 the new NASA facility officially became the George C. Marshall Space Flight Center. While the Saturn program was finally under way and its future secure, it was still only the first step in a decade-long journey which culminated in the first manned lunar landings.

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Related Reading

“Juno V: The Birth of the Saturn Rocket Family”, Drew Ex Machina, October 6, 2018 [Post]

“The Largest Launch Vehicles through History”, Drew Ex Machina, February 19, 2018 [Post]

General References

David Baker, The Rocket, Crown Publishers, 1979

Roger E. Bilstein, Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles, University Press of Florida, 2003

Oswald H. Lange, “Development of the Saturn Space Carrier Vehicle”, in Astronautical Engineering and Science, Ernst Stuhlinger, Frederick I. Ordway III, Jerry C. McCall, and George C. Bucher (editors), McGraw-Hill, pp 1-24, 1963

Alan Lawrie, Saturn I/IB: The Complete Manufacturing and Test Records, Apogee Books, 2008

George P. Sutton, History of Liquid Propellant Rocket Engines, AIAA, 2006