LIQUID HYDROGEN AS A PROPULSION FUEL,1945-1959

 

PART III : 1958-1959

12. Saturn, 1959

 

 

The Gathering Storm over Saturn Configurations

 

[230] The agreement of 21 October 1959 transferring Saturn and its development team to NASA left the upper stage configuration as the major unresolved issue. The proposal to use a Titan as the second stage had been delayed by the ARPA directive in July. At the time of the transfer agreement, ABMA was restudying Saturn upper stages. This study was assigned to a vehicle analysis group headed by H. H. Koelle and assisted by Francis L. Williams.

 

Koelle, like von Braun and Ehricke, had become interested in rockets at an early age. A German pilot during World War II, he was shot down by American antiaircraft fire in early 1945. Continuing his interests in rockets after the war, he founded the German Space Society in 1948. Von Braun brought him to the United States in 1955; Koelle specialized in analysis, planning, and designing advanced space vehicles. His large group was assisted by aerospace contractors who also had sizable staffs of advanced design specialists.

 

In 1959, Koelle's group participated in the Army's bid for a role in manned spaceflight. In March, the Army high command authorized the study of a space project called "Project Horizon," the establishment of an Army lunar outpost which proponents referred to as "high ground."16 The Project Horizon study, completed in June, is an example of very advanced planning; it is of interest here because of the Saturn configurations proposed and some of ABMA's mid-1959 thinking about the use of liquid hydrogen. Launch vehicles for the lunar mission were designated Saturns I and II. The study also considered a much larger vehicle of 53 meganewtons (12 million lb of thrust) using eight F-1 engines and hydrogen-oxygen upper stages, but concluded that this giant vehicle was not needed for the basic mission.

 

Saturn I for Project Horizon (fig. 55) had three stages. The first was a clustered tank and engine stage using eight Rocketdyne H-1 engines of 837 kilonewtons ( 188 000 lb of thrust) each, with kerosene and oxygen as propellants. The second stage was essentially a first-stage Titan 1, 3 meters in diameter and powered by two AeroJet LR-89 engines with a thrust of 841 kilonewtons ( 190 000 lb) each, also using kerosene and oxygen. The third stage was a Centaur powered by two Pratt & Whitney RL-10 engines of 67 kilonewtons (15 000 lb thrust) each, using liquid hydrogen-oxygen. Saturn I was essentially the same configuration ABMA was advocating when work was stopped by the July ARPA directive.


drawing of Saturn 1 rocket

[231] Fig. 55. Saturn I as sketched for Project Horizon by the Army Ballistic Missile Agency, 9 June 1959. The first stage used a cluster of tanks and eight engines with a total thrust of 6.7 MN (1.5 million lb); the second stage used two of the same engines burning RP (kerosene) and oxygen. The third stage was a Centaur powered by two hydrogen-oxygen engines.

 

[232] Saturn II was a second generation vehicle with four stages. The first stage was similar to Saturn I but with uprated engines to provide a total thrust of 9 meganewtons (2 million lb). The second stage was powered by two new proposed engines of 2.2 meganewtons (500 000 lb thrust) each, using liquid hydrogen-oxygen. The third stage was powered by two other newengines of 445 kilonewtons(100 000 lb thrust) each, also using liquid hydrogen-oxygen. The fourth stage was powered by a single engine of the same type as in the third stage. Saturn II, therefore, would use liquid hydrogen-oxygen in all of its upper stages.17

 

In subsequent months, ABMA became much more conservative in its thinking about Saturn upper stages and, ironically, resisted NASA proposals to proceed with liquid hydrogen-oxygen. The reasoning of both parties and the confrontation that was barely avoided complete our story.

 

NASA had participated in a May 1959 decision recommending the Titan-based second stage for Saturn, which had been stopped by ARPA in July. After the September meeting of the York-Dryden committee on large vehicles, Eldon Hall, Francis Schwenk, and Alfred Nelson began to study Saturn and upper stage configurations. Hall was a leading analyst of flight propulsion and vehicles during his 15 years at the NACA Lewis laboratory. Schwenk was also a propulsion systems analyst who had worked at the Lewis laboratory for eight years before coming to NASA headquarters in 1958. Nelson had been a propulsion analyst at Wright Field for 17 years before joining the group in March 1959.

 

Two days after the October agreement to transfer Saturn to NASA, Hall sent Silverstein the results of the analysis his group had been making. Among his conclusions: Saturn was basically a good vehicle and could be uprated by using a 4.5 neganewton F-1 engine to replace four of the eight H-1 engines; and by suitable choice of upper stages, development cost could be minimized. Hall recommended that Saturn development be continued and included a phased program (table 11).

 

Hall's analysis included the new proposed hydrogen-oxygen engine of 668 kilonewtons (150 000 lb thrust) under study by a NASA-DoD group during the year. By agreement with ABMA, the engine was changed to 890 kilonewtons (200 000 lb); it evolved into the J-2 engine by 1960. The NASA B-1 configuration (table 11) was essentially the same as ABMA had proposed as Saturn I of Project Horizon the previous May. Hall was aware of the configuration studies of Koelle and Williams and informed Silverstein that the C-1 configuration in his analysis was similar to the advanced Saturn proposed by ABMA.18

 

The analyses of Saturn by Hall, Schwenk, and Nelson reflected a tradition of NACA and Air Force laboratories. Independent analyses of propulsion systems were not only a means for advancing new concepts, but also for verifying or challenging claims by others. Analyses form the basic framework for interpreting experimental results; it was as routine as tying one's shoe for Silverstein and Hall to do their own analyses of Saturn configurations. This, however, was something new in the experience of ABMA in dealing with headquarters people.

 

At the end of October, Hall had participated with Abe Hyatt and Adelbert Tischler in a technical survey of ABMA vehicles and attended a meeting in the Pentagon on Saturn configurations. From these meetings, he prepared a table of various Saturn configurations proposed by ABMA, which is reproduced as table 12.19 The next day....

 


 

[233] TABLE 11.- NASA Saturn Configuration, 23 October 1959.

Configuration

Stage

Name/dia., m

Propellants

No./Type Engine

Stage thrust kN, MN
(k, M lb)

B-1

1

Saturn

RP-O2

8/H-1

6.7 MN (1.5 M)

2

Titan with thicker skin/3

RP-O2

2/LR-87

1.8 MN (400 k)

3

Centaur as proposed for Atlas

H2-O2

2/RL-10

134 kN (30 k)

B-2

1

Same as B-1

2

High-energy stage

H2-O2

2/new 667-kN engines

1.3 MN (300 k)

3

Enlarged Centaur

H2-O2

2/uprated RL-10

greater than 6.7 MN (1.5 M)

C-2

1

Uprated Saturn

RP-O2

1/F-1 & 4/H-1

not specified

2

High-energy stage

H2-O2

4/uprated 667-kN engines

greater than 2.7 MN (600 k)

3

Same as Stage 2 of B-2

4

Same as Stage 3 of B-2


 

....he fixed a critical eye on the ABMA configurations and compared them with his own .20 In the months since June, ABMA had abandoned the use of a Titan I for the second stage because its 3-meter diameter made the vehicle too long and slender, which increased bending loads from aerodynamic forces. Instead, a diameter of 5.6 meters was favored for the second and third stages in the first two models of proposed Saturns (B-1 and B-2, table 12); the fourth stage of a later model (C) went to the same diameter. A feature of the first three ABMA configurations (B-1, B-2, B-3) was the use of either existing engines or engines under development. This would supposedly shorten development time, as engines traditionally took longer to develop than airframes. For this advantage, ABMA was willing to pay a penalty in size and payload. The second stage of the first three configurations used kerosene and liquid oxygen as propellants. NASA, on the other hand, wanted to start development of a 668 kilonewton (150 000 lb thrust) hydrogen-oxygen engine immediately and use it in the second stage of their second model (NASA B-2). ABMA was concerned about bending problems and the need to develop a new, large, hydrogen-oxygen engine for the second stage. NASA was concerned that ABMA's first configuration (ABMA B-1) would cost so much that the development of the large hydrogen-oxygen engine would be seriously delayed and the advanced configurations might never be attained. Hall noted that the second stage of ABMA's first configuration (B-1) was in the Titan C class, yet the payload capability was less than NASA's B-2, for an equal number of stages. Hall became convinced that the ABMA approach was much less than optimum.

 


 

[234] TABLE 12. -Summary of ABMA Saturn Configurations, November 1959.

Configuration

Stage

Name/dia., m

Propellants

No./Type engine

Stage thrust kN,
MN (k, M lb)

Initial

1

Saturn

RP-O2

8/H-1

6.7 MN (1.5 M)

2

Titan/3

RP-O2

2/LR-87

1.8 MN (400 k)

3

Centaur/3

H2-O2

2/RL-10

134 kN (30 k)

B

1

Saturn

RP-O2

8/H-1

6.7 MN (1.5 M)

2

Titan/4.1

RP-O2

2/LR-87

1.6 MN (360 k)

3

Centaur/3

H2-O2

2/RL-10

134 kN (30 k)

B-1

1

Saturn

RP-O2

8/H-1

6.7 MN (1.5 M)

2

/5.6

RP-O2

4/LR-87

3.9 MN (880 k)

3

/5.6

H2-O2

4/RL-10

356 kN (80 k)

4

/3

H2-O2

2/RL-10

178 kN (40 k)

B-2

1

Saturn

RP-O2

8/H-1

8.9 MN (2 M)

2

/5.6

RP-O2

4/LR-87

3.9 MN (880 k)

3

/5.6

H2-O2

6/RL-10

534 kN (120 k)

4

/3

H2-O2

2/RL-10

178 kN (40 k)

B-3

1

Saturn

RP-O2

8/H-1 or 4/H-1 + 1/F-1

8.9 MN (2 M)

2

/5.6

RP-O2

4/LR-87

3.9 MN (880 k)

3

/5.6

H2-O2

2/new

1.3 MN (300 k)

4

/5.6

H2-O2

4/RL-10

356 kN (80 k)

B-4

1

Saturn

RP-O2

8/H-1

6.7 MN (1.5 M)

2

/5.6

H2-O2

4/new

2.7 MN (600 k)

3

/5.6

H2-O2

2/new

1.3 MN (300 k)

4

/5.6

H2-O2

4/RL-10

356 kN (80 k)

C

1

Saturn

RP-O2

8/H-1 or 4/H-1 + 1/F-1

8.9 MN (2 M)

2

/6.5

H2-O2

6/new

4.0 MN (900 k)

3

/5.6

H2-O2

2/new

1.3 MN (300 k)

4

/5.6

H2-O2

4/RL-10

356 kN (80 k)

 

Source: "Report on Technical Survey of ABMA Activities," Eldon W. Hall, NASA headquarters, 2 Nov. 1959.


 

Hall got strong support for his views on hydrogen-oxygen for upper stages in a separate but concurrent action. In October 1959, Homer Joe Stewart, NASA's director of program planning and evaluation, wrote a classic memorandum comparing the performance of Atlas-Vega, Atlas-Agena B, and Atlas-Centaur. Differing only in upper stage configurations, Vega used kerosene-oxygen in its upper stage; Agena B, UDMH and nitric acid; Centaur, hydrogen-oxygen. Stewart concluded that since the payloads of Atlas-Vega and Atlas-Agena B were the same, one should be cancelled; subsequently, Vega was. Regarding hydrogen-oxygen, Stewart stated:

 

Each oxygen-hydrogen stage that is substituted for a conventional propellant stage in a multistage vehicle will increase the payload for a deep space mission two or more times. The figure may be about six times for a marginal conventional propellant system (ratio of payload to first-stage gross weight 0.002). A figure of two to three times is a reasonable generalization. Therefore, substituting oxygen-hydrogen [235] for conventional propellants in two stages of a multistage booster vehicle would increase the payload four to nine times.21

 

While Hall was studying Saturn configurations, Richard Horner, NASA's general manager, initiated an action on ABMA's transfer that provided the mechanism for resolving the issue of Saturn's upper stage configuration.


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