LIQUID HYDROGEN AS A PROPULSION FUEL,1945-1959

 

PART III : 1958-1959

12. Saturn, 1959

 

Saturn Vehicle Team

 

[235] Following the decision to transfer Saturn to NASA, Richard Horner and Herbert York worked out an agreement for NASA to exercise technical guidance of the project until the formal transfer took place. The agreement provided for a Saturn committee, consisting of NASA and DoD members with a NASA chairman, to provide "advice and assistance" in technical matters. The first and most pressing technical decision was on the upper stages, and Horner requested Silverstein to establish a Saturn Vehicle Team "to prepare recommendations for the guidance of the development and, specifically, for selection of upper stage configurations." Horner made his request on 17 November and wanted the recommendations within thirty days. Silverstein lost no time In getting his team organized.22 It consisted of:

 

Abe Silverstein, Chairman

NASA

Col. Norman C. Appold

USAF

Abraham Hyatt

NASA

Thomas C. Muse

DDR&E

G. P. Sutton

ARPA

Wernher von Braun

ABMA

Eldon W. Hall, Secretary

NASA

 

A brief review of the member's attitudes towards hydrogen is in order.

 

Silverstein's strong advocacy of hydrogen as a high-energy fuel for aircraft and rockets was well known. Research on hydrogen as a rocket fuel at the NACA Lewis laboratory had been under his direction since 1950. He had initiated a large program on hydrogen for high-altitude aircraft in 1955 and strongly supported more work on hydrogen for rockets. He was familiar with Hall's Saturn studies showing the advantages of using hydrogen-oxygen in the upper stages and was convinced this was the way to go.

 

Colonel Appold had been the Air Force's manager of the Suntan project using hydrogen for a high-altitude aircraft. In the spring of 1958, he had supported proposals that led later to the initiation of Pratt & Whitney's development of a hydrogen-oxygen rocket engine for Centaur. A large amount of money had been spent on Suntan; and after its cancellation, Appold remained interested in obtaining tangible returns on that investment in technology and facilities. As the only Air Force member of the team, however, Appold had other concerns. The Air Force believed that the Glenn L. Martin Company had its hands full with the Titan ICBM program and took a very dim view of ABMA vehicle proposals using modified Titans, which could interfere with Martin's [236] work on ICBMS.23 On the other hand, the Air Force was mildly interested in a two stage Saturn as a possible launch vehicle for an advanced Dynasoar-an application that did not need high-energy propellants. Appold, therefore, represented somewhat conflicting views within the Air Force.

 

Abe Hyatt came from Russia as a small boy, served in the marines during World War II, and rose to chief scientist of the Navy's Bureau of Aeronautics before joining NASA as a flight vehicle and propulsion expert in 1958. He headed launch vehicle and propulsion at NASA headquarters and reported to Silverstein; Eldon Hall worked for him. The three were in agreement on the need to use hydrogen in the upper stages of Saturn from the outset.

 

Thomas C. Muse worked eleven years as an aeronautical engineer at NACA's Langley laboratory and Douglas Aircraft before joining the Secretary of Defense's staff as an aeronautics expert in 1950. He was neutral with respect to high-energy fuel preferences but recognized their value.24

 

George P. Sutton, chief scientist of ARPA, was the author of the standard rocket propulsion textbook widely used in the United States since it first appeared in 1949. He came to ARPA from Rocketdyne and, like Muse, was neutral on the subject ofliquid hydrogen. He was, however, a strong advocate for ARPA interests.

 

At the time the Saturn Vehicle Team was organized, Wernher von Braun was cold to the idea of using liquid hydrogen. While it is true that his organization proposed Saturn configurations using liquid hydrogen, the early versions would use hydrogen only in the third stage; this was the Centaur and it was being developed by someone else. Of more immediate concern to von Braun was getting confirmation of his plans for the first stage from his new boss, NASA, and settling the long-delayed decision on the second stage. Having been convinced that a cluster of existing engines made sense for early development of the Saturn first stage, he was now equally convinced that a smaller cluster of the same engines made sense for the second stage as well. He could concentrate on building and flight-testing the first two stages, useful for earth-orbital missions, while General Dynamics-Astronautics developed the hydrogen-fueled Centaur as a potential third stage for Saturn. During the Centaur development, already a year old, there would be time to "work out the bugs" in using hydrogen before von Braun had to face the task of adapting it to a third stage.25 H is plan was logical but flawed, as we shall see.

 

Von Braun's negative attitude towards hydrogen extended far into his background. About 1937, he had observed attempts by Walter Thiel to operate a small rocket engine with liquid hydrogen at Kummersdorf, and the greatest impression he retained was of the numerous line leaks and difficulties of handling liquid hydrogen. It left him with a healthy respect for the safety and fire hazards involved. This attitude would be helpful later in the successful development of the Saturn V, but at the moment was a major roadblock to his acceptance of liquid hydrogen for Saturn I's second stage. At Fort Bliss in the 1940s, von Braun's group had considered a variety of propellants for possible use in the V-2 for a high-altitude sounding mission, The V-2 structure and engine were so heavy that substituting a very low-density fuel like hydrogen would have resulted in poor performance. Krafft Ehricke, who worked for von Braun at Fort Bliss and later at Huntsville, recalls von Braun's objections to low-density propellants. [237] So does Richard Canright, who wrote a paper on the importance of exhaust velocity and density during that period.26

 

Eldon Hall, the team's secretary, was the sharp analyst who had worked closely with Silverstein since 1955 on the application of liquid hydrogen for high-altitude aircraft and was intimately acquainted with its problems. He had studied very light structures. He had extensive analytical experience in both aircraft and rocket performance. Like Silverstein, he was familiar with liquid-hydrogen research at the Lewis laboratory and had confidence in its practicality. Hall's earlier analyses of Saturn configurations had convinced him that to keep vehicle mass within reasonable limits, the upper stages should use high-energy propellants; and of all the candidates, the combination of liquid hydrogen-oxygen was the closest to practical application.27 He and Silverstein shared a common understanding and view, and Hyatt-sandwiched between them at NASA-had been persuaded to their view.

 

Silverstein, therefore, had three working group members favoring his view: Appold, Hyatt, and Hall. Von Braun was the chief opponent-the man who had to be convinced. Silverstein knew that winning von Braun to his view was essential to his and NASA's plans. Von Braun probably was unaware of the extent of NASA's Saturn studies or the intensity of their views on its upper stages. Certainly von Braun wanted to establish good working relationships with his new organization, and he wanted to get on with the job of building large launch vehicles. Although the stage was set for a confrontation, nobody wanted it. Silverstein drew upon all of his skill as chairman to guide the discussions, and he counted on Hyatt and Hall to be strong advocates for his own views. The three met during the course of the team's work to discuss how best to persuade von Braun to their view.28

 

The vehicle team met for the first time on Friday, 27 November. It met four more times and concluded its work on 15 December, with oral and written reports to the NASA administrator.29

 

The first meeting was devoted entirely to briefings: C. Beyer on management aspects of Saturn, E. M. Cortright on NASA missions for Saturn, R. Smith on the Dynasoar program, Wernher von Braun and H. H. Koelle on the technical aspects of the ABMA Saturn systems study, F. L. Williams on the development and funding of the same study, and J. C. Goodwyn on ARPA's evaluation of the study. Upper stages were discussed the next day. Von Braun stressed the importance of an immediate decision and the need to use second stages of 5.6 meters in diameter to lessen bending loads. ABMA was now opposed to using the 3-meter-diameter Titan I as the Saturn second stage, but still favored a modified Titan of larger diameter using RP-oxygen engines.

 

By the second meeting, the team had agreed on a report outline and assignments of members to write the first five sections, two of which were critical. One of these, about possible Saturn configurations and their performance, was assigned to Koelle of ABMA and Hall and Schwenk of NASA headquarters. The other, on evaluation of Saturn configurations, was assigned to Goodwyn of ARPA, Williams of ABMA, and Hall of NASA. Conclusions and recommendations remained the responsibility of the entire team. The subgroups assigned to prepare the five sections began their work while also participating in meetings of the vehicle team as a whole.

 

[238] By 3 December a consensus had emerged on one point: to recommend the Saturn first stage under development at ABMA. Attention then shifted to upper stage configurations. A short pitch for solids got little support; von Braun was strongly opposed, because that would combine the handling difficulties of both liquids and solids. Muse argued against a program involving many vehicle changes in favor of going directly to the final desired configuration. Hall noted in the minutes that hydrogen's energy was needed in the upper stages for most missions-although not for Dynasoar-so hydrogen problems had to be faced and solved. Since Dynasoar had an alternative launch vehicle under study, why not go directly to a hydrogen upper stage for Saturn? The problem was really the second stage engine. One solution was to use a stage powered by a cluster of four Pratt & Whitney Centaur engines uprated to a thrust of 89-111 kilonewtons (20 000-25 000 lb) each. At the meeting the next day, von Braun was still not convinced about using hydrogen-oxygen in the second stage. He pointed out that no brand new rocket engine had ever been developed in less than four years and that the development of a liquid hydrogen-liquid oxygen engine more than ten times larger than the Pratt & Whitney engine might take even longer. For this reason, he was not willing to abandon conventional fuels. He also wanted to determine in greater detail the problems with hydrogen-oxygen.

 

Von Braun expressed concern over aerodynamic heating of liquid hydrogen which required encapsulation of the Centaur stage during flight through the atmosphere-a problem he felt had not been adequately studied for a hydrogen second stage for Saturn. Tank loading and venting problems on the launch pad, with their attendant fire hazards, were other concerns.

 

By 10 December, Hall had prepared a working draft of the report which contained a recommendation that the second stage be powered by a cluster of four Pratt & Whitney RL-10 (hydrogen-oxygen) engines uprated to 89 kilonewtons (20 000 lb of thrust) each. The stage diameter was 5.5 meters and length, 10.7. There was also a recommendation for Centaur as the third stage and initiation of development of a hydrogen-oxygen engine of 667 to 890 kilonewtons (150 000 to 200 000 lb of thrust) for later Saturn stages.

 

It was inevitable that at some point during the work of Silverstein's team and its subgroups, the ABMA and NASA representatives would clash head on. Frank Williams, in Koelle's ABMA group on future projects, recalled that the ABMA team was initially so opposed to the use of hydrogen that plans were made "to confront Silverstein with not no but hell no!" Williams worked hard assembling a four-hour presentation containing great technical detail including cost, probabilliy of success, and impact on Saturn I development schedule, and came to Washington all charged up "to shoot Silverstein out of the saddle." Silverstein was the first to speak and, according to Williams, gave a generalized argument for hydrogen with no technical details: this is the challenge for the long haul; hydrogen is the best fuel; sure it has problems but we can solve them if we dedicate ourselves. Williams considered it a talk along philosophical rather than technical lines and was eager to spring up in rebuttal after von Braun introduced him. To Williams's open-mouthed astonishment, von Braun said, in effect: Abe has a good point. Williams never got the chance to present his arguments. He, not Silverstein, had been "shot out of the saddle"-by his own boss.30

 

Eldon Hall's group at NASA headquarters tangled with Koelle's advanced design group at ABMA on another occasion, which proved to be decisive. The NASA [239] headquarters analysts were using their slide rules to calculate vehicle performance whereas ABMA analysts used a complex program requiring large computer runs. It was not an equal match, but the NASA headquarters analytical group (Hall, Schwenk, and Nelson) had a great deal of experience and judgment. They had noticed that all the Saturn configurations showing promise had at least one upper stage using hydrogen-oxygen. Configurations that used only "conventional" (lower performance) propellants had total masses up to twice as great as those using hydrogen-oxygen stages. The configuration favored by ABMA at one point used four ICBM engines burning RP-oxygen to power the second stage and a modified hydrogen-oxygen Centaur as the third stage. Hall calculated that, by simply replacing the RP-oxygen second stage with the Centaur alone, the resulting two-stage vehicle would lift nearly as much payload to earth orbit as the three-stage ABMA configuration. Hall so argued at one meeting and von Braun considered it incredible. He telephoned Huntsville, where the computer was kept busy all night. The following morning, ABMA telephoned von Braun that Hall was right-the payload without the RP-oxygen stage was indeed close to that with it!31 It was a powerful and convincing argument for the use of high-energy upper stages. This, and the persuasive arguments of Silverstein, convinced von Braun that hydrogen-oxygen for all the upper stages of Saturn was the way to go.

 

The meeting of 14 December was spent on the proposed report. Sutton questioned the payload figures and wanted to wait for the final "official values" from ABMA, but time was running out. He also argued unsuccessfully for considerably more study before making specific recommendations and questioned the wisdom of omitting a large diameter Titan I as a possbile second stage. By then, however, the von Braun team not only opposed the modified Titan I, because of its high bending stresses, but now strongly supported hydrogen-oxygen in all upper stages. Oswald Lange, representing von Braun, successfully argued that the large diameter Titan I with RP-oxygen was a "dead end" course, and the report so indicated. On 15 December the Saturn Vehicle Team endorsed the recommendation that all upper stages of Saturn be fueled with hydrogen and oxygen. Silverstein, with help from Hall, quickly prepared the final report which bears the same date. The unanimous decision for hydrogen in Saturn's upper stages was a victory for the skillful chairman and his quiet but sharp secretary.


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