Category THE DEVELOPMENT. OF PROPULSION. TECHNOLOGY. FOR U. S.. SPACE-LAUNCH. VEHICLES,. 1926-1991

The solid-rocket motors for the Titans III and IV carried the evo­lution of solid-propellant technology from the significant achieve­ments of the Polaris and Minuteman to a new level. The next step yielded the still larger solid-rocket boosters (SRBs) on the Space Shuttles. After UTC had developed the 7-segment solid-rocket mo­tors for the Titan, NASA decided in March 1972 to use SRBs on the shuttle. Even before this decision, the Marshall Space Flight Center had provided contracts of $150,000 each to the Lockheed Propulsion Company, Thiokol, UTC, and Aerojet General to study configura­tions of such motors. Using information from these studies, NASA issued a request for proposals (RFPs) on July 16, 1973, to which all four companies responded with initial technical and cost proposals in late August 1973, followed by final versions on October 15.

Because the booster cases would be recoverable, unlike those for the Titan III, and because they had to be rated to carry astronauts, they needed to be sturdier than their predecessors. Lockheed, UTC, and Thiokol all proposed segmented cases without welding. Al­though Aerojet had been an early developer of such cases, it ignored a requirement in the RFP and proposed a welded case without seg­mentation, arguing that such a case would be lighter, less costly, and safer, with transportation by barge to launch sites from Aero-

jet’s production site. Had Aerojet won the contract, it is possible that the Challenger disaster never would have occurred. However, the source evaluation board with representatives from five NASA centers and the three military services ranked Aerojet last, with a score of 655 for mission suitability. By contrast, respective scores for Lockheed, Thiokol, and UTC were 714, 710, and 710. The board selected Thiokol as winner of the competition, based on its cost, the lowest of the three, and also its perceived managerial strengths. NASA announced the selection on November 20, 1973.19

Since Thiokol had plants in Utah, NASA administrator James C. Fletcher’s home state, the decision was controversial. Lockheed pro­tested, but the General Accounting Office decided on June 24, 1974, that “no reasonable basis" existed to question the validity of NASA’s decision. Thiokol, meanwhile, proceeded with design and develop­ment based on interim contracts, the final one for design awarded on June 26, 1974, followed by one for development, testing, and produc­tion on May 15, 1975.20

Part of the legacy from which Thiokol developed the technol­ogy for its SRBs came from the air force’s Large Segmented Solid Rocket Motor Program (designated 623A), of which Aerojet’s test­ing of 100-inch-diameter solids in the early 1960s had been an early part. In late 1962 the Air Force Rocket Propulsion Laboratory at Edwards AFB inaugurated a successor program. Its purpose was

to develop large solid motors that the DoD and NASA could use for space-launch vehicles. The air force provided funding for 120- and 156-inch-diameter segmented motors and for continuation of work on thrust-vector-control systems. NASA then paid for part of the 156-inch and all of a 260-inch program. In the course of test­ing thrust-vector-control systems, Lockheed had developed a Lock – seal mounting structure that allowed the nozzle to gimbal, and Thiokol later scaled it up to the size required for large motors, call – 270 ing it Flexseal.

Chapter 7 Lockheed tested both 120- and 156-inch motors in the program, and Thiokol tested 156-inch motors with both gimballed (Flexseal) and fixed nozzles. These tests concluded in 1967, as did those for 260-inch-diameter motors by Aerojet and Thiokol. There were no direct applications of the 260-inch technologies, but participation in the 120- and 156-inch portions of the Large Segmented Solid Rocket Motor Program gave Thiokol experience and access to designs, ma­terials, fabrication methods, and test results that contributed to de­velopment of the solid-rocket boosters for the Space Shuttle. The firm also drew upon its experience with Minuteman.21

The design for the solid-rocket booster was intentionally conser­vative, using a steel case of the same type (D6AC) used on Minute – man and the Titan IIIC. The Ladish Company of Cudahy, Wiscon­sin, made the cases for each segment without welding, using the rolled-ring forging process that it had helped develop for the Titan IIIC. In this process, technicians punched a hole in a hot piece of metal and then rolled it to the correct diameter. For the shuttle, the diameter turned out to be 12.17 feet (146 inches), with the overall length of the booster being 149 feet. Each booster consisted of four segments plus fore and aft sections. The propellant consisted of the same three principal ingredients used in the first stage of the Min – uteman missile, ammonium perchlorate, aluminum, and PBAN polymer. Its grain configuration was an 11-point star in the forward end converging into a large, smooth, tapered cylindrical shape. This combination yielded a theoretical specific impulse of more than 260 lbf-sec/lbm.22

Marshall Space Flight Center sought “to avoid inventing any­thing new" in the booster’s design, according to George Hardy, proj­ect manager for the solid-rocket booster at Marshall from 1974 to 1982. The best example of this approach was the PBAN propellant. Other propellants offered higher performance, but with cost and hu­man-rating being prime considerations, Thiokol employed a tried – and-true propellant used on the first stage of Minuteman and in the navy’s Poseidon missile. As Thiokol deputy director for the booster,

John Thirkill, said in 1973, “Over the last fifteen years, we’ve loaded more than 2,500 first stage Minuteman motors and around 500 Poseidon motors with this propellant."23

The configuration of the propellant grain caused the thrust to vary, providing the boost required for the planned trajectory but keeping the acceleration to 3 Gs for the astronauts. For the first six shuttle missions, the initial thrust was 3.15 million pounds per booster. The 11-point star in the forward section of the SRB had long, narrow points, providing an extensive burning surface. As the points burned away, the surface declined, reducing the thrust as the point of maximum dynamic pressure approached at about 60 sec­onds into the launch. At 52 seconds after liftoff, the star points had burned away to provide a cylindrical perforation in both the forward and rear segments of the booster. As this burned, expanding its di­ameter, the thrust increased slightly from the 52nd to about the 80th second. Thereafter, it tapered to zero as the burning consumed the propellant at about the 120th second, when the SRBs separated from the rest of the shuttle. The separated boosters, slowed by para­chutes, soon fell into the ocean.24

A major drawback of the PBAN propellant was that about 20 per­cent of its exhaust’s weight consisted of hydrogen chloride, which not

only was toxic and corrosive but could damage the ozone layer that protected Earth from excessive ultraviolet radiation. NASA studies of the possible ozone depletion showed, however, that it would be slight, so there was no need to shift to a less powerful propellant.25

Once the Ladish Company had forged the motor cases in Wiscon­sin, the segments traveled by railroad to a firm named Cal Doran near Los Angeles. There, heat treatment imparted greater strength and toughness to the D6AC steel. Then the segments went further 272 south to Rohr Industries in Chula Vista, near San Diego, for the Chapter 7 addition of tang-and-clevis joints to the ends of the segments. On these joints, shuttle designers had departed from the Marshall ad­vice “to avoid inventing anything new." Although the shuttle field joints resembled those for Titan IIIC, in many respects they dif­fered. One key change lay in orientation. For the Titan solid-rocket motor, the single tang pointed upward from a lower segment of the case and fit into the two-pronged clevis, which encased it. This pro­tected the joint from rain or dew dripping down the case and enter­ing the joint. In the shuttle, the direction was reversed.

A second major difference lay in the Titan joint’s having used only one O-ring, whereas the shuttle employed two. Insulation on the inside of the Titan motor case protected the case, and with it, the O-ring, from excessive heating. To keep the protective mecha­nisms from shrinking in cold temperatures and then possibly al­lowing a gas blow-by when the motor was firing, there were heating strips on the Titan. Both the Titan and the shuttle used putty to improve the seal provided by the O-ring(s), but the shuttle added the second O-ring for supposed further insurance. It did not include heating strips, however. One further difference in the joints was in the number of pins holding the tang and clevis together. Whereas the Titan motor had used 240 such pins fitting into holes in the tang and clevis and linking them, the shuttle had only 177, despite its larger diameter.26 There is no certainty in counterfactual history, but perhaps if the shuttle designers had simply accepted the basic design of the Titan tang-and-clevis joints, the Challenger accident would not have occurred because of leaking hot gases through a field joint that ignited the external tank.

Unlike the field joint, the nozzle for the solid-rocket boosters did follow the precedents of the Titan solid-rocket motors and the Large Segmented Solid Rocket Motor Program. The shuttle employed car­bon-phenolic throats to ablate under the extreme heating from the flow and expansion of the hot gases from the burning propellant in the motor itself. In the case of the shuttle, the propellants burned at a temperature of 5,700°F, so ablation was needed to vaporize and

thereby prevent thermal-stress cracking followed by probable ejec­tion of portions of the nozzle. As of June 1979, the expansion ratio of the nozzle was 7.16:1, used for the first seven missions. Start­ing with the eighth mission, modifications of the nozzle increased the initial thrust of each motor from 3.15 million to 3.3 million pounds. These changes extended the length of the nozzle exit cone by 10 inches and decreased the diameter of the nozzle throat by 4 inches. The latter change increased the expansion ratio to 7.72:1, thereby adding to the booster’s thrust.27

The nozzle was partially submerged, and for gimballing, it used the Flexseal design Thiokol had scaled up in the 156-inch motor testing from the Lockheed’s Lockseal design. It was capable of eight degrees of deflection, necessitated among other reasons by the shuttle’s now-familiar roll soon after liftoff to achieve its proper trajectory. Having less thrust, the space shuttle main engines were incapable of achieving the necessary amount of roll, and the liq­uid-injection thrust-vector-control system used on the Titan solid – rocket motors would not have met the more demanding require­ments of the shuttle. Hence the importance of the Lockseal-Flexseal development during the Large Segmented Solid Rocket Motor Pro­gram supported by both NASA and the air force.28

Although there were only four segments of the solid-rocket boosters that were joined by field joints, there were actually 11 sec­tions joined by tang-and-clevis joints. Once they had been through machining and fitting processes, they were assembled at the factory into four segments. The joints put together at the factory were called factory joints as distinguished from the field joints, which techni­cians assembled at Kennedy Space Center. Thiokol poured and cast the propellant into the four segments at its factory in Brigham City, Utah, usually doing so in matched pairs from the same batches of propellant to reduce thrust imbalances. At various times, the solid – rocket motors used four different D6AC-steel cases, with slight variations in thickness.29

In part because of its simplicity compared with the space shut­tle main engine, the solid-rocket booster required far less testing than the liquid-propellant engine. Certification for the SSMEs had required 726 hot-fire tests and 110,000 seconds of operation, but the solid-rocket boosters needed only four developmental and three qualification tests with operation of less than 1,000 seconds total— 0.9 percent of that for the SSMEs. There were, however, other tests. One was a hydroburst test on September 30, 1977, at Thiokol’s Wa­satch Division in Utah. This demonstrated that, without cracking, a case could withstand the pressures to which it would be subjected

during launch. A second hydroburst test on Sept ember 19, 1980 (with only the aft dome, two segments, and the forward dome), was also successful. There were other tests of the tang-and-clevis joints that put them under pressure until they burst. They withstood pres­sures between 1.72 and 2.27 times the maximum expected from liftoff through separation.30

The first developmental static test, DM-1 on July 18, 1977, at Thiokol’s Wasatch Division was successful, but the motor deliv – 274 ered only 2.9 million pounds of maximum thrust compared with Chapter 7 an expected 3.1 million. There were other anomalies, including ex­cessive erosion in parts of the nozzle. Modification included addi­tional ammonium perchlorate in the propellant and changed nozzle coatings. DM-2 on January 18, 1978, was another success but led to further adjustments in the design. It turned out that the rubber insulation and polymer liner protecting the case were thicker than necessary, leading to reduction in their thickness. This lowered their weight from 23,900 to 19,000 pounds. There were also modi­fications in the igniter, grain design, and nozzle coating to reduce the flame intensity of the igniter, the rate of thrust increase for the motor, and erosion of portions of the nozzle. As the motor for DM-3 was being assembled, a study of the DM-2 casing revealed that there had been an area with propellant burning between segments. This required disassembling the motor and increasing the thickness of a noncombustible inhibitor on the end of each segment. Designers also extended the rubber insulation to protect the case at the joints. This delayed the DM-3 test from July to October 19, 1978.

Again, the test was satisfactory; but although the thermal protec­tion on the nozzle had been effective, the igniter once more caused the thrust to rise too quickly. Designers could see no evident solu­tion to the rapid rate of thrust increase, an apparent tacit admis­sion that engineers did not fully understand the complex combus­tion process. It did seem evident, though, that the rate had to rise quickly to preclude thrust imbalances between the two motors, so the engineers went back to an igniter design closer to that used in the DM-1 test and simply accepted the rapid thrust rise (for the moment, at least). On February 17, 1979, DM-4 ended the four de­velopmental tests with a successful firing. The qualification tests, QM-1 through -3 from June 13, 1979, to February 13, 1980, were all successful. These seven tests furnished the data needed to qualify the solid-rocket motor for launch—excluding the electronics, hy­draulics, and other components not Thiokol’s responsibility. Other tests on booster recovery mechanisms, complete booster assem­blies, loads on the launch pad and in flight, and internal pressure

took place at Marshall and at the National Parachute Test Range, El Centro, California. The program completed all of these tests by late May 1980, well before the first shuttle flight.31 Of course, this was after the first planned flight, so if the main-engine development had not delayed the flights, presumably the booster development would have done so to some degree.

Smaller Solid-Propellant Stages and Boosters

Even early in launch-vehicle history, some missile programs had al­ready begun to influence solid-propellant developments. In 1956, a creative group of engineers at Langley’s Pilotless Aircraft Research Division (PARD) began formulating ideas that led to the Scout launch vehicles. This group included Maxime A. Faget, later famous for designing spacecraft; Joseph G. Thibodaux Jr., who promoted the spherical design of some rocket and spacecraft motors beginning in 1955; Robert O. Piland, who put together the first multistage rocket to reach the speed of Mach 10; and William E. Stoney Jr., who be­came the first head of the group responsible for developing the Scout, which he also christened. Wallops, established as a test base for the National Advisory Committee for Aeronautics’ (NACA) Langley Memorial Aeronautical Laboratory in 1945, had a history of using rockets, individually or in stages, to gather data at high speeds on both aircraft models and rocket nose cones. These data made it pos­sible to design supersonic aircraft and hypersonic missiles at a time when ground facilities were not yet capable of providing comparable information. It was a natural step for engineers working in such a pro­gram to conceive a multistage, hypersonic, solid-propellant rocket that could reach orbital speeds of Mach 18.32

THIS BOOK ATTEMPTS TO Fill A GAP IN THE LITERATURE about space-launch vehicles (and in the process, strategic missiles, from which launch vehicles borrowed much technology). There are many excellent books about rocketry. (The Note on Sources discusses many of them.) But none covers the ways in which the technology in the United States developed from its beginnings with Robert Goddard and the German V-2 project through the end of the cold war. This book concentrates on propulsion technology to keep its length manageable, but it occasionally mentions structures and guidance/control in passing, especially in chapters 1 and 2.

Besides the lack of coverage of the evolution of rocket technol­ogy in the existing literature, there is a severe problem with accu­racy of details. Apparently reputable sources differ about matters as simple as lengths and diameters of vehicles and details about thrust. I cannot claim to have provided definitive measurements, but I have tried to select the most plausible figures and have pro­vided various references in endnotes that readers can consult to find for themselves the many discrepancies.

I have been working on some aspects of this book since 1992. I initially wrote a much longer manuscript, organized by project, that covered the entire gamut of major technologies. I have organized this much shorter volume by types of propulsion with overviews in chapters 1 and 2 to provide context and cover factors in technology development that do not fit comfortably in chapters 3-7.

In researching and writing both manuscripts, I received help from a huge number of people. I apologize in advance for any I in­advertently neglect to mention or whose names I have forgotten. I especially want to thank Roger Launius. As my boss at the NASA History Office, he provided unfailing encouragement and support for my initial research. Now as editor for the series in which this book will appear, he has continued that support. Michael Neufeld at the Smithsonian National Air and Space Museum (NASM) shared his own research on the V-2 with me and arranged for me to consult the captured documents held by his institution. He also read many chapters in draft and offered suggestions for improvement. I am fur­ther greatly indebted to NASM for granting me the Ramsey Fellow­ship for 1991-92 and allowing me to continue my research there with the support of archivists, librarians, curators, docents, and vol­unteers, including John Anderson, Tom Crouch, David DeVorkin, Marilyn Graskowiak, Dan Hagedorn, Gregg Herken, Peter Jakab,

Mark Kahn, Daniel Lednicer, Brian Nicklas, George Schnitzer, Paul Silbermann, Leah Smith, Larry Wilson, Frank Winter, and Howard S. Wolko.

Special thanks are due to Glen Asner of the NASA History Divi­sion, who read an earlier version of this book and offered detailed editorial advice at a time when NASA intended to publish the book. Glen’s advice was extremely valuable, as was that of three anony­mous NASA readers. Then Texas A&M University Press accepted the book for publication. Glen and Steven Dick, NASA chief histo­rian, graciously relinquished the manuscript to Texas A&M.

Chapters 1, 2, 6, and 7 contain material I published earlier in chapter 6 of To Reach the High Frontier: A History of U. S. Launch Vehicles, ed. Roger D. Launius and Dennis R. Jenkins (Lexington: University Press of Kentucky, 2002). The material in the present book results from much research done since I wrote that chapter, and it is organized differently. But I am grateful to Mack McCor­mick, rights manager, the University Press of Kentucky, for con­firming my right to reuse the material that appeared in the earlier version his press published.

A number of people read earlier versions of the material in this book and offered suggestions for improvement. They include Matt Bille, Roger Bilstein, Trong Bui, Virginia Dawson, Ross Felix, Pat Johnson, John Lonnquest, Ray Miller, Fred Ordway, Ed Price, Milton Rosen, David Stumpf, and Jim Young. Many other people provided documents or other sources I would otherwise have been unable to locate easily, including Nadine Andreassen, Liz Babcock, Scott Carlin, Robert Corley, Dwayne Day, Bill Elliott, Robert Geisler, Robert Gordon, Edward Hall, Charles Henderson, Dennis Jenkins, Karl Klager, John Lonnquest, Ray Miller, Tom Moore, Jacob Neufeld, Fred Ordway, Ed Price, Ray Puffer, Karen Schaffer, Ronald Sim­mons, Ernst Stuhlinger, Ernie Sutton, Robert Truax, and P. D. Um – holtz. Archivists, historians, and librarians at many locations were unfailingly helpful. Here I can only single out Air Force Historical Research Agency archivist Archangelo Difante and Air Force Space and Missile Systems Center historian and archivist (respectively) Harry Waldron and Teresa Pleasant; China Lake historian Leroy Doig; Laguna Niguel archivist Bill Doty; Clark University Coordi­nator of Archives & Special Collections Dorothy E. Mosakowski; NASA archivists Colin Fries, John Hargenrader, Jane Odom, and Lee Saegesser; and JPL archivists John Bluth, Barbara Carter, Dudee Chiang, Julie Cooper, and Margo E. Young for their exceptional assistance. Several reference librarians at the Library of Congress should be added to the list, but I do not know their names.

I also want to thank everyone who consented to be interviewed (included in endnote references) for their cooperation and agreement to allow me to use the information in the interviews. In addition, many people discussed technical issues with me or provided other technical assistance. These include Ranney Adams, Wil Andrepont, Stan Backlund, Rod Bogue, Al Bowers, George Bradley, Robert Cor­ley, Daniel Dembrow, Mike Gorn, Mark Grills, John Guilmartin, Burrell Hays, J. G. Hill, Ken Iliff, Fred Johnsen, Karl Klager, Franklin Knemeyer, Dennis B. Mahon, Jerry McKee, Ray Miller, Ed Price, Bill Schnare, Neil Soderstrom, Woodward Waesche, Herman Way – land, and Paul Willoughby. Finally, I offer my deep appreciation to my excellent copyeditor, Cynthia Lindlof; my in-house editor, Jen­nifer Ann Hobson; editor-in-chief Mary Lenn Dixon; and everyone else at Texas A&M University Press for their hard work in getting this book published and marketed. To all of the people above and others whose names I could not locate, I offer my thanks for their assistance.

It goes (almost) without saying that these people bear no respon­sibility for the interpretation and details I provide in the following pages. I hope, however, that they will approve of the uses I have made of their materials, suggestions, comments, and information.

THE DEVELOPMENT OF PROPULSION TECHNOLOGY FOR U. S. SPACE-LAUNCH VEHICLES, 1926-1991

With its development overlapping that of Atlas and other launch ve­hicles, the Scout series of boosters was unique in being the first mul­tistage booster to operate exclusively with solid-propellant motors. It remained the smallest multistage vehicle in long-term use for or­bital launches. And it was the only launch vehicle developed under the auspices of Langley Research Center, which made many con­tributions to space efforts but, as the oldest of NASA’s component organizations, had a long heritage of aeronautical rather than space – related research. Like the Delta, with which it shared many stages, Scout proved to be long-lasting and reliable. But in contrast with Delta, it suffered through a difficult gestation and childhood.55

Because, like Delta, it used much technology that had already been developed elsewhere, Scout’s problems lay less in the design – and-development area than was true with many other rockets, al­though there were several developmental difficulties. But Scout’s problems were primarily matters of systems engineering and quality control. Following a series of early failures, the program underwent a reliability improvement and recertification process, after which one Scout engineer stated that he and his colleagues had “all un­derestimated the magnitude of the job" when they had undertaken its development. “The biggest problem we had was denying the ex­istence of problems that we did not understand." Once the project accepted that it had such problems and examined them, it learned from the process and went on to produce a long-lived, reliable, small launcher used by NASA, the DoD, and foreign countries.

Scout’s payload capability increased almost fourfold by its fi­nal flight in 1994. At that time, it had launched a great variety of scientific and applications payloads, Transit navigation satellites, and experiments to help understand the aerodynamics of reentry, among other types of missions. Counting two partial successes as failures, Scout had 103 successful missions out of 118 for an overall 70 8 7 percent success rate, according to one source. The 15 failures

Chapter 2 were mostly in the early years, with 12 of them occurring by June 1964. In the 91 missions since that time, only 6 failures or partial failures occurred for a 94 percent success rate.56

During 1956, the idea for Scout arose at Langley’s Pilotless Air­craft Research Division (PARD) on remote Wallops Island in the At­lantic Ocean off Virginia’s Eastern Shore. There, several engineers conceived of a four-stage solid-propellant launch vehicle. Between July 1, 1960, and March 29, 1962, Scout had nine developmental flights from Wallops, with six of them counted as successes. Several

FIG. 2.9

Launch of Scout ST-5 (Scout Test 5) on June 30, 1961, from Wallops Island, Virginia—a failure because the third stage of the Scout did not ignite, which prevented the satellite from going into orbit. (Photo courtesy of NASA)

Blue Scout Junior. All of them used the Castor I (the regular Scout second-stage motor) in place of the usual Algol I in the first stage, and the Antares I (the regular Scout third-stage motor) in the sec­ond stage. The third stage used the Aerojet 30-KS-8000 motor, also known as Alcor. The motor for the fourth stage of most Blue Scout Juniors was a unit designed by the Naval Ordnance Test Station, known as NOTS model 100A. The B version of the same motor later became the fifth-stage propulsion unit for NASA Scouts using that many stages.58

The first Blue Scout Junior launched on September 21, 1960, be­fore the fourth-stage motor’s development was complete, but ap­parently the vehicle did use a NOTS 100A. In all, there were 25 known Blue Scout Junior launches from Cape Canaveral, Vanden – berg (or the navy’s nearby Point Arguello), and Wallops Island, with the last one on November 24, 1970. All were suborbital, 22 of them successful, for an 88 percent success rate, although the telemetry and payloads sometimes failed. The configurations of the vehicles varied, depending on the mission, with some launches using only three stages and a supersonic combustion ramjet test employing only one.59

The Blue Scout 1 was a three-stage version of the Scout. Its first (successful) launch occurred at Cape Canaveral on January 7, 1961. Blue Scout 2 was a four-stage vehicle. Most sources list only three flights in 1961. But other sources continue to list launch vehicles as Blue Scouts, so the precise history of the vehicle is quite nebu­lous. The navy procured some of them at least as late as fiscal year 1967, and the air force, until fiscal year 1976. Of the first 92 Scouts, NASA paid for 54; the navy, 19; and the air force, 14, with the other 5 being funded by the Atomic Energy Commission or European us­ers. Whereas earlier Blue Scout vehicles had been launched by uni­formed (“blue suit") air force personnel, on January 10, 1970, an agreement between NASA and the DoD stated that NASA would contract for Scout launches from Vandenberg AFB for both itself 72 and the DoD. Thus, it appears that there was a gradual blurring of Chapter 2 the lines between Blue and NASA Scouts. But whichever they were called, they continued to perform launch services for the armed forces as well as the civilian space agency.60

Meanwhile, a number of Scout failures in the early years led in 1963 to a major review of the program. This revealed that no two Scout failures had been caused by the same problem. But the large number of failures, including many recent ones, suggested a need for greater procedural consistency and for requalifying all Scout vehicles then in storage awaiting launch. As Eugene Schult, head

of the Langley Scout Project Office in 1990, remembered, “We did things differently at Wallops than at the Western Test Range. The Air Force had its own way of doing things; the contractor had his ways; and we had our ways. It was a problem trying to coordinate them."61

To address these problems, a team from NASA, the LTV Missile Group of the Chance Vought Corporation (the airframe and prime contractor for Scout), and the air force initiated procedures that brought the manufacturing and launch teams in closer contact to improve coordination and quality control. (Obviously, this entailed exchange of information as well.) In addition, all 27 existing Scout vehicles went back to the LTV plant for disassembly and X-ray or microscope inspection. Standardization became the order of the day. The first recertified Scout, S-122R, with the R indicating that it had been refurbished and recertified, launched from Vandenberg December 19, 1963. It was the beginning of a series of 26 launches through October 1966 with only 1 failure, for a 96 percent success rate.62 Standardization and quality control had greatly improved re­liability, showing the value of improved management and better systems engineering.

In this period and after, Scout continued to develop, with new stages replacing those already in use. These changes increased the payload and other capabilities of the Scout system. Beginning on April 26, 1967, Scout also began launching (under agreement with Italy) from the San Marcos platform off the coast of Kenya, Africa, on the equator. From there, Scout could place satellites into orbits not achievable by launches from Cape Canaveral, let alone Wallops and Vandenberg, the three U. S. launch sites for the vehicle. As a re­sult of a long series of improvements, the payload capacity of Scout increased from only 131 pounds into a 300-mile circular orbit for the original Scout in 1960 to 454 pounds by October 30, 1979. The Scout continued in operation through August 5, 1994, with all of the remaining launches using this last (G-1) configuration.63

Operating for nearly three and a half decades, Scout obviously was successful. Neither its payload capacity nor reliability matched those of the Delta. But it filled a niche in the launch-vehicle spec­trum, or it would not have lasted so long. In the process, it had to overcome some initial growing pains. Many of its motors and other components experienced developmental problems, including the Castor I, Antares I, and Altair II, as well as heat shields, a fourth – stage frangible diaphragm, and the nozzles on the Algol IIA and IIB. Thus, like other missiles and launch vehicles, Scout also suffered from the frequent inability of designers to foresee problems their

handiwork might face. But as in so many other cases, engineers were able to correct the problems once they understood them and/ or brought their experience and knowledge to bear on available data.

One example of this influence was a second stage used on the Delta launch vehicle featuring an Aerojet engine designated AJ10-118F. This was the F model in a series of engines originally derived from the Vanguard second stage. This particular engine was similar to the Transtage propulsion unit (AJ10-138), but the two were not identical. Both used a fiberglass combustion chamber impregnated with resin and an ablative lining for cooling. Like the Titan II en­gines, both used a mixture of 50 percent hydrazine and 50 percent UDMH as the fuel, igniting hypergolically with a nitrogen-tetroxide oxidizer. This replaced the IRFNA used on earlier versions of the AJ10-118 and increased the specific impulse from more than 265 to upward of 290 lbf-sec/lbm. The F version of the engine had a thrust of between 9,235 and 9,606 pounds, well above the roughly 7,575 pounds of the earlier versions, and it was capable of up to 10 starts in orbit. The new engine completed its preliminary design in 1970 but did not fly until July 23, 1972.59

Another Delta upper stage that used storable propellants was TRW’s TR-201 second-stage engine. Design of this engine began in October 1972, its combustion chamber made of quartz phenolic, with cooling by ablation as had been true of the AJ10-118F, but the TR-201 weighed only 298 pounds in contrast to the Aerojet engine’s reported dry weight of 1,204 pounds. Both engines burned nitrogen tetroxide with a 50/50 mixture of hydrazine and UDMH, igniting hypergolically, but the TRW propulsion unit yielded 9,900 pounds of thrust, whereas the Aerojet unit yielded a maximum of 9,606 pounds. The newer system did provide only 5 instead of 10 restarts.60

In 1957, after a five-stage rocket vehicle at Wallops had reached speeds of Mach 15, PARD engineers began to study in earnest how to increase the speed of solid-propellant combinations even further. The group learned that Aerojet had developed the largest solid – propellant motor then in existence as part of its effort to convert the Jupiter to a solid-propellant missile for use aboard ship. Called the Jupiter Senior, the motor was 30 feet long and 40 inches in di­ameter, and it weighed 22,650 pounds, more than 3 times as much as the contemporary Sergeant missile’s motor. Using a propellant of polyurethane, ammonium perchlorate, and aluminum, the Jupiter Senior motor provided a thrust of up to about 100,000 pounds for 40 seconds in two successful static firings in March-April 1957. It eventually amassed a record of 13 static tests and 32 flights without a failure, and it prepared the way for the Aerojet motors used in Polaris and Minuteman.

About the time that the PARD engineers learned about Jupiter Senior, they found out Thiokol had discovered a way to improve the Sergeant motor by shifting from the polysulfide binder used on the missile to a polybutadiene-acrylic acid binder with metallic addi­
tives. This offered a possible 20 percent increase in specific impulse. These developments led Stoney to analyze a four-stage vehicle with the Jupiter Senior as stage one, the improved Sergeant as stage two, and two Vanguard X248 motors as the third and fourth stages. Even after Sputnik, in early 1958 NACA Headquarters told the PARD team that it would not be receptive to developing a fourth launch vehicle when Vanguard, Jupiter C, and Thor-Able were well along in development or already available.33

However, with plans moving forward for what became NASA, in March 1958 NACA Headquarters asked Langley Aeronautical Laboratory to prepare a program of space technology. As a neces­sary part of this program, Langley included Scout—only later an acronym meaning Solid Controlled Orbital Utility Test system—to investigate human space flight and problems of reentry. The pro­gram called for $4 million to fund five vehicles for these purposes. By May 6, 1958, when Scout had become part of the space program, further analysis suggested that the third stage needed to be larger than the X248. But by then, plans for America’s space efforts were becoming so extensive that the extra costs for such development were hardly significant. By that time Langley had also arranged a contract with Thiokol for four improved Sergeant motors.34

Langley assigned Stoney as project officer but gave Thibodaux’s Rocket Section at PARD the responsibility for the initial five con­tracts needed to develop the Scout. A contract with Aerojet for the first stage became effective on December 1, 1958. The name of the Aerojet first stage changed from Jupiter Senior to Aerojet Senior, also called Algol I. As developed by December 1959, the motor was 29.8 feet long and 40 inches in diameter. With a steel case and poly­urethane-aluminum-ammonium perchlorate propellant configured in an eight-point gear (a cylinder with eight gear-shaped, squared – off “points" radiating from it), it yielded a specific impulse of only about 215 lbf-sec/lbm and a low mass fraction of 0.838 but an aver­age thrust of upward of 100,000 pounds depending upon the ambi­ent temperature.35

This was a far cry from the huge boosters for the Titans and Space Shuttle, but it became the first stage of the successful Scout pro­gram. Thiokol’s second stage presented some problems. The firm was finding it difficult to adapt a new propellant for what came to be called the Castor I (or TX-33-35) second-stage motor. Initial static firings had been successful, but then Thiokol encountered unspecified difficulties that had to be overcome. Although the grain design was the same as for the Sergeant, the Castor used a poly­butadiene acrylic acid-aluminum-ammonium perchlorate propel-

lant (also employed as an interim propellant on Minuteman I) and was 20.5 feet long to Sergeant’s 16.3 feet, with an identical 31-inch diameter. Once Thiokol engineers overcame developmental prob­lems with the propellant, the Castor yielded a specific impulse of almost 275 lbf-sec/lbm to only 186 for Sergeant (although the two figures were not comparable because for Scout, the Castor was used at altitude with a larger expansion angle than for Sergeant, which launched on the ground). According to figures supplied by Thiokol, 278 Castor’s average thrust was 64,340 pounds compared to Sergeant’s Chapter 7 41,200.36

The initial four-stage Scout with all stages live flew on July 1, 1960, in the first of nine developmental flights labeled ST-1 through ST-9 (for Scout Tests 1-9), all launched from Wallops. NASA treated them as operational missions, having them carry Explorer space­craft, ionospheric probes, and one reentry payload. The December 4, 1960, launch of ST-3 was the first attempted orbital mission with the Scout. The Algol IA first stage performed properly, but the Cas­tor IA second stage did not ignite because of human failure to detect a defect in the ignition system. ST-4 on February 16, 1961, thus became the first entirely solid-propellant launch vehicle to achieve orbit.37

From these (by later standards) somewhat primitive beginnings, the Scout went on to incorporate more sophisticated technologies. For instance, the Antares IIA, designed by Allegany Ballistics Labo­ratory and produced by Hercules at its Bacchus Works in Magna, Utah, marked a considerable improvement over the first stage – three motor for the Scout, also a Hercules product. The Antares IIA featured a composite, modified, double-base propellant includ­ing ammonium perchlorate, HMX, nitrocellulose, nitroglycerin, and aluminum. Even with a smaller nozzle expansion ratio, this yielded an increase in average thrust from about 13,000 pounds for the older motor to about 21,000 for X259 Antares IIA. This stage first launched on March 29, 1962, in an early (A1) version. The A2 completed its development in June of that year, almost simultane­ously with Hercules’ second stage for Polaris A2, which also used a composite-modified double-base propellant, although one without HMX and with a lower level of performance (probably reflecting the fact that the Polaris motor had an earlier date of development completion by about six months). For Polaris, HMX usage awaited the A3 version, with the Antares IIA actually using it before the missile, reversing the usual practice for launch vehicles to borrow technology from missiles.38

About this time, some earlier Scout technologies found use in other programs. For example, the thrust-augmented Thor (TAT), which entered the launch-vehicle inventory in 1963, incorporated three Thiokol TX-33-52 (Castor I) solid-propellant rocket boosters to supplement the power of the liquid-propellant first stage. The TAT consisted of a Thor with about 170,000 pounds of thrust and three Castor I solid-propellant rocket boosters, which increased liftoff thrust to 331,550 pounds.39

The TAT soon gave way to a further improved vehicle with a re­placement for the Castor I. The air force’s Space Systems Division had announced contracts for a long-tank Thor (called Thorad) to replace the thrust-augmented Thor in January 1966. Douglas would provide the new Thor, with thrust augmentation continuing to be provided by Thiokol; only for the Thorad, the three solid motors would be Castor IIs. The Thorad was more than 70 feet long, as compared with 56 feet for the TAT. The added length came mainly in the form of the extended tanks that increased the burning time of the first stage. For the Castor II (TX-354-5), basically developed (as the TX-354-3) in 1964 for the Scout second stage, among other appli­cations, Thiokol kept the steel case used on Castor I but substituted carboxy-terminated polybutadiene for the polybutadiene-acrylic acid used as the binder for the earlier version, keeping aluminum and ammonium perchlorate as fuel and oxidizer. This increased the specific impulse from under 225 for the Castor I to more than 235 lbf-sec/lbm for Castor II and the total impulse from 1.63 million to 1.95 million pounds, improving the payload capacity for the Thorad by 20 percent over the TAT.40

A further major advance in propulsion technology for the Scout came in 1977-79 when, under contract to the Vought Corporation, Thiokol produced a new third-stage motor at its Elkton Division in Maryland. This was the Antares IIIA (TE-M-762, Star 31), employ­ing a HTPB-based binder combined with ammonium perchlorate and aluminum. This propellant increased the specific impulse from about 285 for the composite-modified double-base propellant used by Hercules in the Antares IIB to more than 295 lbf-sec/lbm. In ad­dition to the higher-performance propellant, Thiokol used a com­posite case made of Kevlar 49 and epoxy. Introduced commercially in 1972, Kevlar 49 was DuPont’s registered trademark for an aramid (essentially nylon) fiber that combined light weight, high strength, and toughness. Lighter than fiberglass, it yielded a mass fraction of

0.923 compared with Antares IIB’s already high 0.916. Burning much longer than the propellant in the Antares IIB, the one in the Antares IIIA produced a lower average thrust, but its total impulse at the high altitudes in which it operated was 840,000 pounds compared with 731,000 pounds for the Antares IIB. No doubt because of the higher erosive propensities of the Antares IIIA motor, which had a higher chamber pressure than the Antares IIB, the newer motor used 4-D carbon-carbon (pyrolitic graphite) for the nozzle-throat insert.41

Launched initially at the end of October 1979, the Scout version G1 with the Antares IIIA as its third stage appears to have been the first launch vehicle to use an HTPB propellant, but the first use of the substance may have been on an improved Maverick tactical (air-
to-surface) missile. Thiokol provided the Maverick’s initial motor, with development starting in 1968, but under contract to the Air Force Rocket Propulsion Laboratory at Edwards AFB, Aerojet had begun in August 1975 to develop the improved motor with HTPB propellant. By October 1976, Aerojet had produced 12 demonstra­tion verification motors. Aerojet did get production orders for some version of an improved Maverick motor. But interestingly, an orga­nization called the ATK Tactical Systems Company, producer of the Maverick heavy warheads, later claimed to be under contract to pro­vide a rocket motor very similar to the Aerojet design with an HTPB propellant, an HTPB liner, an aluminum case, an 11-inch diameter, and a glass phenolic exit cone, all features of Aerojet’s motor.42

Another motor that used HTPB was Thiokol’s Star 48, used on the Payload Assist Module (PAM)—a third stage on the Delta and an upper-stage motor used from the Space Shuttle. Thiokol began developing the motor in 1976. The firm made the Star 48 motor case with titanium and used the recently developed advanced com­posite, carbon-carbon, for the nozzle’s exit cone. The PAM was an offshoot of Minuteman, stage three, which Thiokol began produc­ing in 1970 essentially using the original Aerojet design. The pur­pose of the PAM on the shuttle was to propel satellites from a low parking orbit (about 160 miles above Earth) to a higher final orbit, including a geosynchronous transfer orbit. It used the same basic HTPB-aluminum-ammonium perchlorate propellant as Thiokol’s Antares IIIA rocket motor.43

The Inertial Upper Stage (IUS) featured a much more problematic set of motors using HTPB propellant. Designed under management of the Space and Missile Systems Organization (SAMSO—a recom­bination of the air force’s Ballistic and Space Systems Divisions) primarily for use with the Space Shuttle (for when orbiter payloads needed to be placed in geosynchronous orbit), IUS became a difficult stage to develop for a variety of complicated reasons. Many of them were technical, but the major ones involved management. Some, but far from all, of the management problems resulted from the fact that the IUS, which initially stood for Interim Upper Stage, was conceived as a temporary expedient until a more capable Space Tug could fly with the shuttle. When the Space Tug was not terminated but “just slid out year-by-year under budget pressure," as one air force general expressed it, the IUS shifted from being a minimal modification of an existing upper stage such as Transtage or Agena to become, starting about 1978, a projected “first line vehicle in the Space Transportation System." Yet “considerable cost reduction pressure [remained ] as an outgrowth of the interim stage thinking."

Moreover, the air force was developing the vehicle under “a con­tract structure which strongly incentivized performance, but only provided limited cost incentives."44

The IUS ultimately overcame its birth pangs to become “an inte­gral part of America’s access to space for both military and civilian sectors." It had its beginnings in 1969 when presidential direction gave impetus to studies leading to the Space Shuttle. Since the shut­tle would be incapable of reaching geosynchronous and other high 282 orbits, the IUS ultimately became the solution. The DoD agreed to Chapter 7 develop it, proposing in 1975 that it use solid propellants to hold down costs.

In August 1976, the air force selected Boeing Aerospace Com­pany as the prime IUS contractor. The contract provided incentives for meeting performance and cost targets, but Boeing was liable for only 10 percent of cost overruns. Moreover, cost projections for IUS had been based on assumptions, according to Maj. Gen. William Yost of the air force, that “the M-X and Trident missile programs would develop most of the solid rocket motor technology. . . needed by the IUS. Unfortunately, the schedules for those programs slipped far enough that the IUS program became the leader in developing the solid rocket motor technology necessary to meet our perfor­mance requirements." This led the contractor to increase “spend­ing to insure that he will achieve his performance goals and earn the performance fees." As a condition of revising the contract with Boeing in 1979, the air force insisted that the firm’s apparent “man­agement deficiencies be resolved," and Boeing appointed a new pro­gram manager, assigned senior managers to oversee major subcon­tractors, and instituted formal review to correct the problems.45

Boeing had begun a planned 18-month preliminary design phase in August 1976 when it won the contract, to be followed by a 28- month development phase. This would have made the IUS avail­able by June 1980. Soon after winning the basic contract, Boeing subcontracted with CSD to design and test the solid motors to be used in the IUS. CSD chose to use a hydroxy-terminated polybu­tadiene propellant, as had Thiokol in the Antares IIIA motor for Scout. CSD selected a carbon-carbon material for the nozzle, which would be manufactured using a new process that held costs to a low level. It was making the case out of Kevlar. Thiokol was also using the same or similar materials on the contemporary Antares motor, raising questions about the extent to which CSD was taking the lead “in developing the solid rocket motor technology" needed for the IUS (as Yost claimed), but it appears that CSD and Thiokol

were, in effect, competing for that lead from 1977 to 1979, with Thiokol winning the contest.46

At first things seemed to be going well with motor development. CSD conducted a series of tests in 1977 to prove the adequacy of the nozzle and motor. It subjected the nozzles to successful 85-second tests at the Air Force Rocket Propulsion Laboratory on June 10 and July 15. A follow-on 145-second test of the nozzle at the laboratory on October 7 was again successful. Moving to the Arnold Engineer­ing Development Center (AEDC), CSD subjected a full-scale mo­tor with 21,000 pounds of propellant to a 154-second test, which it completed successfully. On May 26, 1978, a further test of the nozzle material using the carbon-carbon made with the new, cost­saving technique again occurred without problems in a 140-second test firing at the Rocket Propulsion Laboratory.

But on October 19, 1978, a test of the Kevlar case at AEDC re­sulted in its bursting at only 750 pounds per square inch of water pressure instead of CSD’s prediction of 1,050 pounds. The firm de­cided that defective manufacturing equipment caused the failure. After redesigning the equipment and strengthening the structure of the case, AEDC conducted six more tests between January and September 1979. Five of them were successful, with the cases with­standing higher pressures than specified. By this time, the design of the IUS had evolved into two stages with similar larger and smaller motors. A test firing of the large motor was scheduled on Octo­ber 17, 1978. Inspection of the motor revealed some propellant that was improperly cured, resulting in softness and blistering, delaying the test. With the propellant recast, the test occurred on March 16, 1979, with a 145-second firing that generated more than 50,000 pounds of thrust. Engineers vectored the nozzle several times, dem­onstrating its ability to direct the thrust for course corrections. A follow-on test of the small motor occurred on June 25, again with the nozzle moving. Both tests were successful.47

Most other tests in 1979 went well in most respects, but cracks had appeared in the nozzle of the small motor. Moreover, a special feature of the nozzle for the smaller motor was an extendable exit cone, which was added to the design in 1978. This was a series of conical pieces that in the final design (as of 1983) telescoped out (ex­tended) and fit over one another to increase the nozzle expansion ratio from 49.3:1 without the extension to 181.1:1 with the pieces extended. Although the design, which would be used only on some missions, increased the weight of the motor, it added about 15 lbf- sec/lbm to the specific impulse. Unfortunately, about half the exit

cones for the small motors were defective. Finally, five motors proved to have more “bad" propellant. Boeing and CSD said they could still be tested, but Aerospace Corporation, advising SAMSO, disagreed.

On October 1, 1979, SAMSO formed a tiger team of experts from several organizations (including NASA, the Rocket Propulsion Lab­oratory, and Aerospace Corporation) to investigate technical con­cerns and management. This resulted in the management changes at Boeing already mentioned and a change in one supplier. CSD had 284 been making the large Kevlar motor cases, and Brunswick Corpora – Chapter 7 tion made the small one, which the team found to be superior. As a result, Brunswick became the supplier of both sets of cases.

During 1980, the production team solved the other problems. For example, the cracks in the nozzle of the smaller motor proved to result from unequal expansion of two materials. A silica-phenolic insulation material expanded faster than the carbon-carbon next to it. The solution was to wrap the silica phenolic with graphite to limit expansion. The problem with the exit cones resulted from the methods of the supplier, Kaiser, still learning about the prop­erties of carbon-carbon. A change in tooling and ply patterns plus improved quality-control procedures provided the solution. The degraded propellant had all come from a single batch and was us­able in tests. As a result, three rocket motor tests of each motor (small and large) during 1980 at the AEDC were successful. (All of these development tests at AEDC simulated conditions the motors would actually face in flight at altitude.) There were further prob­lems with propellant cracks, delamination of the carbon material in the extendable exit cones, and the mechanism for extending the exit cones, but engineers solved them, too.48

The various technical and managerial problems had led to more than two years of delay and to cost overruns that basically dou­bled the originally projected cost of the IUS. Although many of the problems resulted from contractual arrangements and the initial, interim character of the upper stage, many of them involved fabri­cation methods and quality control. They showed that despite more than two and a half decades of continuous rocket development, rocket engineering in the United States still required constant at­tention to small details and, where new technology was involved, a certain amount of trial and error, although Thiokol’s success with Antares IIIA showed that sometimes the process of innovation could go more smoothly. (But not always, as Thiokol’s later prob­lems with the shuttle solid-rocket boosters showed.) Because the IUS was designed principally for use on the Space Shuttle, NASA’s

delays with that program made the stretch-out of the IUS schedule less problematic than it could have been.49

On October 30, 1982, the first Titan 34D and the first IUS to­gether successfully launched a Defense Satellite Communications Satellite II and the first DSCS III into geosynchronous orbit from Cape Canaveral. As planned, the second-stage burn achieved low – Earth orbit, with the first IUS motor carrying the third stage and the satellites into transfer orbit. The second IUS motor placed the payloads in geostationary orbit, with hydrazine thrusters making final adjustments in the placement of each satellite. During launch the telemetry failed, attributed to a leak in the seal of a switch. But the guidance/control system, flying “blind" (without telemetry) or external control from Earth autonomously carried out the provi­sions of the flight plan, as designed.50

As completely designed, the IUS was roughly 17 feet long and had a maximum diameter of 9.25 feet. Fully loaded, the large, first – stage motor (SRM-1) carried 21,400 pounds of ammonium perchlo – rate-HTPB-aluminum propellant, but the propellant load could be reduced as required for specific missions (as was done with the first launch). The smaller, second-stage motor (SRM-2) could carry up to 6,000 pounds of the same propellant. The propellant-delivered specific impulse of SRM-1 was upward of 295, that for SRM-2 about 290, increased to more than 300 lbf-sec/lbm with the extendable exit cone.51

To mention just one other use of an HTPB propellant, this tech­nology came to the Delta with the Castor IVA strap-ons. A Cas­tor IV (TX-526) had actually replaced the Castor II strap-ons in De­cember 1975 for the Delta model 3914, but it was a reversion from the carboxy-terminated polybutadiene used in the older strap-on to polybutadiene-acrylic acid (PBAA) as the binder. The reason for the shift may have been cost, since the Castor IV at 29.8 feet long and 40 inches in diameter contained much more propellant than the 19.8-foot by 31-inch Castor II, and CTPB was more expensive than PBAA. But in the early 1980s, Goddard Space Flight Center (man­ager of the Delta program) shifted to an uprating with the Castor IVA. Tested and qualified in 1983, the new motors were not intro­duced then because of the impending phaseout of the Delta in favor of the Space Shuttle. With the post-Challenger resurrection of ex­pendable launch vehicles, McDonnell Douglas proposed incorporat­ing the Castor IVAs on Delta II as a low-risk improvement. The new strap-ons kept the steel case and graphite nozzle throat material. But they used the HTPB-aluminum binder with a higher loading of

solids. This increased the average thrust for the same-sized motor from 85,105 to 98,187 pounds.52

Analysis and Conclusions

Although the solid-propellant breakthrough achieved by the Polaris and Minuteman programs provided many technologies to launch ve­hicles, others followed. These included the carbon-phenolic throat, segmenting, and the tang-and-clevis joints for the Titan SRM; Flex-
seal nozzles used on the Space Shuttle’s huge solid-rocket boosters; and the use of HMX in the propellant for the Antares IIA stage of the Scout launch vehicle. Although it apparently found its first use on an improved motor for the Maverick tactical missile, HTPB propellant seems to have first appeared on a launch vehicle in the Scout G1.

Although sometimes innovations occurred without many appar­ent problems, as in Thiokol’s use of HTPB in the Scout’s Antares IIIA, the IUS, employing many similar technologies, faced a whole host of difficulties, many of them technical. The field joints for the shuttle caused the Challenger tragedy, and when Hercules devel­oped the solid-rocket motor upgrade for the Titan IVB, technical problems delayed launch of the first uprated launch vehicle until well beyond the period covered by this history. Rocket engineers continued to advance the state of their art, but often they could do so only by trial and error. There was no such thing as a mature rocket science that could guide them effortlessly through the design of new technologies, but accumulated experience, data, computers, instrumentation, and telemetry allowed practitioners to solve most problems.

DURING THE LAST 45 YEARS, LAUNCH VEHI­cles have propelled countless spacecraft and sat­ellites into space, in the process revolutionizing life on planet Earth. Americans have become de­pendent upon satellites for everything from what they watch on television to how they wage war. Space telescopes and other spacecraft have greatly expanded our knowledge of the universe. What en­abled the United States to develop the technology for access to space so quickly? One major contribu­tor was the cold war, whose terminus is the end point for this book. Had it not been for the Soviet threat, symbolized by Sputnik, the enormous ex­penditures needed to develop U. S. missiles, launch vehicles, and satellites would have been lacking.1

There seems to be no accurate compilation of total expenditures on missiles and launch vehicles during the cold war. Obviously, however, the out­lays were enormous and constituted a virtual sine qua non for the speedy development of the technol­ogy. An early (1965) estimate of the total costs for ballistic missiles to that point in time suggested a figure of $17 billion, equal to some $106 billion in 2005 dollars. Including missile sites, which were irrelevant to launch vehicles, this figure also cov­ered factories for producing propellants, engines, airframes, and guidance/control systems; test fa­cilities; ranges with their testing, tracking, and control equipment; laboratories; and much else.2 A further indicator of the huge costs of missiles and launch vehicles was the $9.3 billion (nearly $55 billion in 2005 dollars) spent on the Saturn launch – vehicle family.3

Fears of Soviet missile attacks and the spend­ing they stimulated were one factor in the develop­ment of launch-vehicle technology. They also pro­vided the context for a second major contributor, the work of heterogeneous engineers in stimulating Congress, several presidential administrations, and the American people to invest the money needed

Monkey Baker posing with a model of a Jupiter vehicle, one of which launched it into space in an early example of the use of a missile as a launch vehicle, part of the space race inaugurated by the Soviets’ launch of Sputnik. (Photo courtesy of NASA)

for rapid development. Without individuals like Trevor Gardner, John von Neumann, Bernard Schriever, Theodore von Karman, Wernher von Braun, and William F. “Red" Raborn, funding for mis­siles and rockets (with their frequent failures in the early years) would not have been forthcoming.

As missiles and launch vehicles increased in size and complexity, it is not surprising that many of them experienced failure. Ameri­cans recognized the arcane nature of the technology by their use of the term “rocket science" to describe it. Ironically, the rocket “scientists" could not always predict the problems the technology encountered in operation. Methods of testing rockets and missiles, technical reports, computer tools, and other supporting infrastruc­ture continued to grow. But as recently as 2003, when the Columbia disaster occurred, NASA discovered once again that it did not fully understand all aspects of rocket behavior despite extensive experi­ence. Hardly an isolated case, this major accident simply reempha­sized that predictability of rocket behavior had been problematic from Robert Goddard’s inability to reach the altitudes he had fore­cast until very near the present. If we define rocket science as a body of knowledge complete and mature enough to allow accurate predic­tions of problems, then clearly, such a science does not exist. Maybe it will someday, but what we currently have is rocket engineering.

Of course, there are other ways of defining science. And recent science has hardly been immune from uncertainties, such as those

regarding the big bang theory about how the universe arose. More­over, the success of rocket developers in resolving unanticipated problems and getting their creations to work certainly compares 290 favorably with scientists’ accommodations of unexpected data by Chapter 8 adjustment of theories. The difference lies in science’s basic quest to understand the universe as compared with rocket engineers’ ef­fort to make their vehicles meet design goals. These engineers used any available resources to reach that end, including science. Cer­tainly the engineers, especially those engaged in developing engi­neering theory (often called engineering science), wanted to under­stand how rockets worked. But often they had to “fix" problems in the absence of such fundamental understanding. In such cases, they had to resort to trial and error, finding a solution that worked without necessarily understanding why it worked. Accumulated knowledge, engineering theory, and intuition helped in correcting problems, but the solution did not always work when a particular technology had to be scaled up to a larger size. Sometimes, in fact, innovative solutions ran counter to existing theory.

This reality shows that the basic process of developing rockets constituted engineering, not science. Such an argument tallies with the general theses of Edwin Layton, Walter Vincenti, and Eugene S. Ferguson about engineering in general as different from science— especially their points about engineers’ focus on doing as opposed to scientists’ knowing, on the importance of design for engineers, and on the role of art in that design. Vincenti, especially, proposed more historical analysis of the ways engineers sometimes must make de­cisions in the absence of complete or certain knowledge.4

Research for this book did not start with the thought of apply­ing Vincenti, Layton, and Ferguson’s arguments to rocket technol­ogy. Instead, as I gathered information about the process of missile and launch-vehicle development, I became increasingly convinced that it fit the mold of engineering, not science. This is particularly true in the areas of injection, ignition, and propulsion of liquid pro­pellants and of combustion instability in solids. Problems in these areas occurred in the design of the V-2, the H-1, F-1, and space shut­tle main engines as well as many solid-propellant motors. A. O. Tischler, NASA assistant director for propulsion, in 1962 called in­jector design “more a black art than a science."5 With the passage of time, the art became less “black," but art it remained.

Problems with rocket design were not exclusive to propulsion. As early designs had to be scaled up or modified with new and bet­ter materials to improve performance, unanticipated problems con­tinued to occur through the end of the period of this book and be-

yond. Failure to understand the behavior of foam covering the Space Shuttle’s external tank as it rose through the atmosphere continued beyond the Columbia disaster. Problems in developing the solid – rocket motor upgrade for the Titan IVB persisted beyond the end of the cold war. These and other instances demonstrate the continu­ing uncertainties accompanying rocket engineering, especially in an environment where speed and cost control limited basic research.

In the face of this unpredictability, it is noteworthy that missile and launch-vehicle technology evolved as quickly as it did. Design and development engineers did exceptionally well to find innova­tive solutions to problems and allow the technology to advance as successfully as it did.

Another key to the speedy development of rocket technology was the process of innovation. Sadly, known sources often shine little light on the individuals or processes involved. Interviews and corre­spondence with rocket engineers sometimes yield information.6 But even the principals in a particular development frequently cannot remember who came up with a discovery or how it came about. En­gineers typically worked in large teams to design rocket systems or components. And many innovations involved more than one firm. Otto Glasser at the Western Development Division offered an inter­esting analogy for the difficulty of finding out who contributed sig­nificantly to innovation under such circumstances: “If you were to back into a buzz saw could you tell me which tooth it is that cut you?"7

Many innovations did not arise from initial design but occurred in response to problems during testing. Examples of these that seem to fit Glasser’s “which tooth?" analogy include the process of roll­ring forging developed by UTC, Westinghouse, and the Ladish Com­pany and UTC’s tape-wrapped, carbon-phenolic nozzle throat for the Titan solid-rocket motors. The companies doing the innovating are clear, but we do not know which individuals were the principal innovators. How Aerojet engineers fixed problems with the Trans – tage (ranging from a weakness in a nozzle extension to malfunction­ing bipropellant valves) likewise remains somewhat mysterious. Regardless, all of these technologies appear to exemplify trial-and – error engineering.

What we do know about innovations in rocket development sug­gests that they did not follow a single pattern. Hugh Aitken pro­vided a felicitous description in his book about radio technology, saying that it involved “a process extending over time in which information from several sources came to be combined in new ways."8 In the case of missiles and launch vehicles, large numbers of firms, institutions, and organizations helped provide the requi-

site information. Among those that contributed were firms such as Aerojet, Rocketdyne, Pratt & Whitney, Douglas, the Martin Com­pany, UTC/CSD, and Thiokol; and other organizations like the air 292 force’s Western Development Division and its successors, the ar – Chapter 8 my’s counterparts at Redstone Arsenal, the navy’s special projects office and its successors, NASA Headquarters and various centers (notably JPL, Langley, Lewis, and Marshall for rocketry), the Naval Ordnance Test Station and its successors, the Air Force Rocket Pro­pulsion Laboratory (under various names), the Arnold Engineering Development Center, the Chemical Propulsion Information Agency (CPIA) and its predecessors, and the Armour Institute (later Illinois Institute of Technology).

During developmental planning, representatives from entities like these met to exchange ideas and information. Then, if prob­lems arose for which there were no known explanations and/or no evident solutions, as often happened, engineers and other experts from perhaps different organizations met to brainstorm and trou­bleshoot. With the enduring problem of combustion instability, for instance, numerous university researchers, as well as other engi­neers, have long been seeking both understanding and solutions.9 Surviving sources indicate that the general process was often com­plex, with no record of specific contributors except the authors of technical reports. But the authors themselves often wrote in the passive voice, masking individual participants beyond the authors themselves, who presumably were involved. Engineers sometimes remembered (but how accurately?) some details of solutions but not always the precise process.

Among the factors that conditioned rapid development of mis­sile technology, the existing literature points to interservice com­petition, often as a problem but also as a spur to innovation.10 Vir­tually unnoticed in the literature but probably more important was interservice and interagency cooperation. The CPIA was a key pro­moter of cooperative exchange of information, but not the only one. For instance, the air force saw the navy’s Polaris program as a com­petitor for roles, missions, and funding. The Polaris competition encouraged the air force’s development of its own solid-propellant missile, Minuteman. Yet ironically, Polaris itself might not have been possible without technologies the air force developed. Min – uteman, in turn, borrowed the use of aluminum as a fuel from the navy. Likewise, the air force reluctantly accepted NASA as a devel­oper of rocket technology, and the army was not happy to lose the von Braun team and JPL to the civilian space agency. Both services, however, cooperated with NASA (and vice versa), with the air force

loaning important managers like Samuel Phillips to help NASA with its programs. Moreover, many astronauts came to NASA from the U. S. Marine Corps, the navy, and the air force.11

Technology transfer also contributed to rapid rocket develop­ment, but its details remained almost as elusive as those involving innovation. Federal contracting agencies often precluded contrac­tors from treating innovations developed under government con­tract as trade secrets or company property. Lockheed, for example, was unable to protect its Lockseal technology, permitting Thiokol to increase its size and use it to vector the exhaust from the shuttle solid-rocket boosters under the name Flexseal.

Engineers frequently learned about the rocket technology of one firm or organization, established their credentials, and moved to an-

other organization, carrying their knowledge with them. This helped transfer technology and promote overall rocket development. For instance, after Charles Bartley developed early rubberized, compos – 294 ite solid propellants at JPL, he founded the Grand Central Rocket Chapter 8 Company, which participated in solid-rocket development and then became part of Lockheed Propulsion Company in 1960-61.12 Bart­ley also transferred JPL technologies to Thiokol when it entered the rocket business. Barnet R. Adelman had worked with both liquid and solid propellants at JPL. He then became technical director of the Rocket Fuel Division at Phillips Petroleum and then director of vehicle engineering for the Ramo-Wooldridge Corporation. At Ramo-Wooldridge, he became a major supporter of the Minuteman missile, along with Col. Edward N. Hall. Next, he helped found United Research Corporation (later UTC/CSD). The knowledge he carried with him undoubtedly helped UTC develop the solid-rocket motors for the Titan III and IVA.13 Adelman and other UTC execu­tives’ knowledge of people in the solid-propellant field also enabled them to hire other experienced engineers who furthered the success of the firm.

The previous chapters have covered many other examples of technology transfer through people moving from one organization to another. A well-known example was the von Braun team, in­cluding Krafft Ehricke, who brought German V-2 technology to the United States. Importantly, though, the technology they transferred was only part of the story. Americans, notably Rocketdyne engi­neers, learned much from the V-2 and its German developers, but they went on to create major innovations of their own in develop­ing successor engines, extending from the Redstone to the space shuttle main engine. This synergism contributed in complex ways to American rocket development.

Management systems constituted another factor in the rapid de­velopment of missile and launch-vehicle technology. Without such systems (and the systems engineering they fostered), the various components of rockets would not have worked together with in­creasing reliability to launch their payloads as time passed. Such systems (and the individual management skills that complemented and implemented them) were especially necessary as the numbers of people from industry, government, and universities increased and became interdependent. Growth was rapid. The Atlas missile had only 56 major contractors in 1955. By decade’s end, the number had escalated to roughly 2,000. To keep this many organizations on schedule and to ensure quality control, Gen. Bernard Schriever availed himself of a systems engineering-technical direction con-

tractor (Ramo-Wooldridge). Beyond that problematic arrangement, the Western Development Division instituted a management-con­trol system to keep track of schedules and to deal with problems as they arose. Graphs, charts, and computer tracking permitted Schriever and his successors to keep their projects more or less on schedule.

The enormously complex Polaris system, likewise, led Adm. “Red" Raborn of the navy to oversee development of the Program Evaluation and Review Technique, analogous to Schriever’s system. Critics complained about both systems, but without some such ar­rangements, early missile development could hardly have been as successful and rapid as it was.

George Mueller and Sam Phillips brought these kinds of sys­tems to NASA, enabling it to land astronauts on the Moon in less than a decade from President Kennedy’s 1961 exhortation to do so. These systems allowed Apollo to stay on schedule and within bud­get while still achieving configuration control. The overall success of missile and launch-vehicle development owed much to such arrangements.

The basic processes of rocket engineering did not change abruptly with the end of the cold war about 1991. But the context in which research and development had to occur suffered a drastic shift. It became less urgent for new technologies to appear, while Congress exercised stringent oversight over costs and schedules. Basing itself on studies in the late 1980s and early 1990s, the air force responded to the new environment with the Evolved Expendable Launch Ve­hicle (EELV) program. This replaced Titan II, Delta II, Atlas II, and Titan IV with a new series of boosters capable of launching 2,500 to 45,000 pounds into low-Earth orbit with a 98 percent reliability rate. This exceeded capabilities of previous launch vehicles at costs 25 to 50 percent below earlier figures.

The air force provided four $30 million contracts in August 1995 to Lockheed Martin, Alliant Techsystems (which acquired Hercu­les Aerospace Company, the former Hercules Powder Company, in March 1995), Boeing, and McDonnell Douglas to develop proposals for the EELV vehicles. Out of this process, McDonnell Douglas (later acquired by Boeing) and Lockheed Martin won contracts for actual development.14 The further development of this program is beyond the scope of this book, but the Lockheed Martin Atlas V’s success­ful launch on August 21, 2002, and that of Boeing’s Delta IV on No­vember 20, 2002, suggested that the EELV launchers would capture most of the military market. The use of a Russian RD-180 engine on the Atlas V symbolized the radical change that had occurred

since the end of the cold war. The air force reportedly believed as of August 2002 “that through 2020 the two new EELV families w[ould] reduce the cost per pound to orbit to $7,000 compared with $20,000 296 for the old booster fleet," saving “$10 billion in launch costs"—a Chapter 8 50 percent reduction “compared with launching the same military

payloads on old Delta, Atlas and Titan boosters."15

Similar concerns about cost affected NASA’s efforts to develop new launch vehicles.16 NASA also had to contend with concerns about safety after the Columbia disaster. In 2005-2006, the agency developed a concept for a safer pair of launch vehicles that would use technologies from the Space Shuttle or other existing hardware without the problems of an orbiter with wings that could be struck by debris from an external tank. A crew launch vehicle (named Ares I) would consist of one enlarged solid-rocket booster derived from the shuttle, a stage powered by a Rocketdyne J-2X engine (evolved from the J-2 used on the Saturn V), and a crew capsule at the top of the stack, equipped with an escape rocket to separate the crew from the launch vehicle in the event of problems. In this Apollo-like cap­sule, the crew would face little danger from debris separating from the shuttle on launch, as happened with tragic consequences dur­ing the Columbia launch in 2003 and again (without significant damage) during the launch of Space Shuttle Discovery in 2005 and subsequent shuttle launches in 2006.

For future space exploration, NASA also planned a heavy-lift launch vehicle named Ares V with two solid-rocket boosters, a cen­tral element derived from the shuttle’s external tank, five RS-68 engines modified from the Delta IV, and an earth-departure stage propelled by a J-2X engine. Like Ares I, this vehicle would be config­ured in stages, but the first-stage solid-rocket boosters would flank the central booster tank, with the liquid engines above the tank. Ares V thus resembled a Titan IV in its general configuration. NASA calculated that these two future vehicles would be 10 times as safe as the shuttle and would not cost as much as a completely new vehicle because of the use of proven technologies.17 However, both vehicles were in a state of development and could easily change as further possibilities came under study.

It would be foolhardy to predict how the struggle for cheaper access to space will play out in the new environment ushered in by the fall of the Soviet Union. However, maybe this history of the uncertainties and difficulties of developing launch vehicles in a different environment will highlight the kinds of problems rocket engineers can expect to encounter in a more cost-constrained atmo­sphere. Rocket reliability improved significantly in the 50 years or

so following the serious beginnings of U. S. missile and rocket de­velopment. Recently, launch vehicles have experienced only a 2-5 percent failure rate. By comparison, the first 227 Atlas launches failed 30 percent of the time. Nevertheless, in 2003 the Colum­bia Accident Investigation Board stated, “Building and launching rockets is still a very dangerous business and will continue to be so for the foreseeable future while we gain experience at it. It is unlikely that launching a space vehicle will ever be as routine an undertaking as commercial air travel."18 Knowledge of this reality, coupled with the historical experiences recounted previously, may help contemporary rocket engineers design both cheaper and bet­ter launch vehicles. Perhaps Congress and the American people can also benefit from knowing the kinds of challenges rocket engineers are likely to face.

ALTHOUGH ROCKETS BURNING BLACK POWDER HAD existed for centuries, only in 1926 did Robert H. Goddard, an Amer­ican physicist and rocket developer, launch the first known liquid – propellant rocket. It then took the United States until the mid – 1950s to begin spending significant sums on rocket development. The country soon (January 1958) began launching satellites, and by the end of the cold war (1989-91), the United States had developed extraordinarily sophisticated and powerful missiles and launch ve­hicles. From the Atlas to the Space Shuttle, these boosters placed an enormous number of satellites and spacecraft into orbits or trajecto­ries that enabled them to greatly expand our understanding of Earth and its universe and to carry voices and images from across the seas into the American living room almost instantaneously. What allowed the United States to proceed so quickly from the compara­tively primitive rocket technology of 1955 to almost routine access to space in the 1980s?

This book provides answers to that question and explains the evolution of rocket technology from Goddard’s innovative but not fully successful rockets to the impressive but sometimes problem­atic technology of the Space Shuttle. Although propulsion technol­ogy has often challenged the skills and knowledge of its developers, by and large, its achievements have been astonishing.

This combination of complexity and sophistication caused some inventive soul to coin the term “rocket science." But often in the history of rocketry, so-called rocket scientists ran up against prob­lems they could not fully understand. To solve such problems, they often had to resort to trial-and-error procedures. Even as understand­ing of many problems continually grew, so did the size and perfor­mance of rockets. Each increase in scale posed new problems. It turns out that rocketry is as much art as science. As such, it best fits the definitions of engineering (not science) that students of technol­ogy, including Edwin Layton, Walter Vincenti, and Eugene Ferguson, have provided. (Besides engineering as art, they have discussed the discipline’s emphasis on doing rather than just knowing, on artifact design instead of understanding, and on making decisions about such design in a context of imperfect knowledge.)1

In the light of their findings and the details of rocket development discussed in the present book, I will argue that designers and de­velopers of missiles and space-launch vehicles were fundamentally engineers, not scientists, even though some of them were trained

as scientists. For instance, Ronald L. Simmons received a B. A. in chemistry from the University of Kansas in 1952 and worked for 33 years as a propulsion and explosive chemist at Hercules Powder 2 Company, a year with Rocketdyne, and 13 years for the U. S. Navy, Introduction contributing to upper stages for Polaris, Minuteman, and other mis­siles. He considered himself to be a chemist and as such, a scientist, but admitted that he had done “a lot of engineering." Unconsciously underlining points made about engineering by Vincenti and Layton, he added that it was “amazing how much we don’t know or under­stand, yet we launch large rockets routinely. . . and successfully." He believed that we understood enough “to be successful. . . yet may not understand why."2

This is not to suggest any lack of professional expertise on the part of rocket engineers. Rocketry remains perplexingly complex. In the early years, engineers’ knowledge of how various components and systems interacted in missiles and launch vehicles was necessar­ily limited. But quickly data, theory, and technical literature grew to provide them a huge repository of information to draw upon. Some processes nevertheless remained only partially understood. But when problems occur, as they still do, the fund of knowledge is great, permitting designers and developers to focus their efforts and bring their knowledge to bear on specific kinds of solutions.

Yet often there are no clear answers in the existing literature. En­gineers must try out likely solutions until one proves to be effective, whether sooner or later. In the chapters that follow, I sometimes refer to this approach as cut-and-try (cutting metal and trying it out in a rocket) or trial-and-error. Neither term implies that practition­ers were experimenting blindly. They brought their knowledge and available literature (including science) to bear on the problem, mea­sured the results as far as possible, and made informed decisions. Limited funding and rigorous schedules often restricted this process. Given these circumstances, it is remarkable that they succeeded as often and well as they did. Not rocket science, this cut-and-try methodology was part of a highly effective engineering culture.

This book is about launch-vehicle technology. Because much of it originated in missile development, there is much discussion of missiles. These missiles launch in similar fashion to launch ve­hicles. But they follow a ballistic path to locations on Earth rather than somewhere in space. Their payloads are warheads rather than satellites or spacecraft. Especially in the discipline of propulsion, they have employed similar technology to that used in launch ve­hicles. Many launch vehicles, indeed, have been converted missiles or have used stages borrowed from missiles.

Both types of rockets use a variety of technologies, but this book focuses on propulsion as arguably more fundamental than such other fields as structures and guidance/control. The book starts with Goddard and his Romanian-German rival Hermann Oberth. It fol­lows the development of technology used on U. S. launch vehicles through the end of the cold war. Because the German V-2 influenced American technology and was a (not the) starting place for the Saturn launch vehicles in particular, there is a section on the Ger­man World War II missile and its developers, many of whom, under Wernher von Braun’s leadership, came to this country and worked on the Saturns.

Chapters 1 and 2 provide an overview of missile and rocket de­velopment to furnish a context for the technical chapters that fol­low. Chapters 3 through 7 then cover the four principal types of chemical propulsion used in the missiles and launch vehicles cov­ered in chapters 1 and 2. Chapter 8 offers some general conclusions about the process of rocket engineering as well as an epilogue point­ing to major developments that occurred after the book ends at the conclusion of the cold war. (There is no discussion of attempts at harnessing nuclear [and other nonchemical types of] propulsion— sometimes used in spacecraft—because funding restraints and tech­nical risks precluded their use in production missiles and launch vehicles.)3

The book stops about 1991 because after the cold war ended, de­velopment of launch vehicles entered a new era. Funding became much more restricted, and technology began to be borrowed from the Russians, who had followed a separate path to launch-vehicle development during the Soviet era.

Most readers of this book presumably have watched launches of the Space Shuttle and other space-launch vehicles on television, but maybe a discussion of the fundamentals of rocketry will be useful to some. Missiles and launch vehicles lift off through the thrust pro­duced by burning propellants (fuel and oxidizer). The combustion produces expanding, mostly gaseous exhaust products that a nozzle with a narrow throat and exit cone cause to accelerate, adding to the thrust. Nozzles do not work ideally at all altitudes because of changing atmospheric pressure. Thus, exit cones require different angles at low and higher altitudes for optimum performance. For this reason, rockets typically use more than one stage both to al­low exit cones to be designed for different altitudes and to reduce the amount of weight each succeeding stage must accelerate to the required speed for the mission in question. As one stage uses up its propellants, it drops away and succeeding stages ignite and assume

the propulsion task, each having less weight to accelerate while taking advantage of the velocity already achieved.

Most propellants use an ignition device to start combustion, but so-called hypergolic propellants ignite on contact and do not need an igniter. Such propellants usually have less propulsive power than such nonhypergolic fuels and oxidizers as the extremely cold (cryo­genic) liquid hydrogen and liquid oxygen. But they also require less special handling than cryogenics, which will boil off if not loaded shortly before launch. Hypergolics can be stored for comparatively long periods in propellant tanks and launched almost instantly. This provided a great advantage for missiles and for launches that had only narrow periods of time in which to be launched to line up with an object in space that was moving in relation to Earth.

Solid-propellant motors also allowed rapid launches. They were simpler than and usually not as heavy as liquid-propellant engines. Solids did not need tanks to hold the propellants, high pressure or pumps to deliver the propellant to the combustion chamber, or ex­travagant plumbing to convey the liquids. Normally, rocket firms loaded the solid propellant in a case made of thin metal or compos­ite material. Insulation between the propellant and the case plus an internal cavity in the middle of the propellant protected the case from the heat of combustion, the propellant burning from the cav­ity outward so that the propellant lay between the burning surface and the insulation. The design of the internal cavity provided op­timal thrust for each mission, with the extent of the surface fac­ing the cavity determining the amount of thrust. Different designs provided varying thrust-time curves. Solid propellants did pose the problem that they could not easily accommodate stopping and re­starting of combustion, as liquids could do by using valves. Con­sequently, solids usually served in initial stages (called stage zero) to provide large increments of thrust for earth-escape, or in upper stages. For most of the period of this book, the Scout launch vehicle was unique in being a fully solid-propellant vehicle.

Liquid propellants typically propelled the core stages of launch vehicles, as in the Atlas, Titan, Delta, and Space Shuttle. Upper stages needing to be stopped and restarted in orbit (so they could insert satellites and spacecraft into specific orbits or trajectories af­ter coasting) also used liquid propellants, as did stages needing high performance. But in liquid-propellant engines, the injection of fu­els and oxidizers into combustion chambers remained problematic in almost every new design or upscaling of an old design. Mixing the two types of propellants in optimal proportions often produced instabilities that could damage or destroy a combustion chamber.

This severe problem remained only partly understood, and although engineers usually could find a solution, doing so often took much trial and error in new or scaled-up configurations. Solid propellants were by no means immune to combustion instability, although the problems they faced were somewhat different from those occurring in liquid-propellant engines. And often, by the time solid-propellant instabilities were discovered, design was so far along that it became prohibitively expensive to fix the problem unless it was especially severe.

Besides propulsion, missiles and launch vehicles required struc­tures strong enough to withstand high dynamic pressures during launch yet light enough to be lifted into space efficiently; aerody­namically effective shapes (minimizing drag and aerodynamic heat­ing); materials that could tolerate aerothermodynamic loads and heating from combustion; and guidance/control systems that pro­vide steering through a variety of mechanisms ranging from vanes, canards, movable fins, vernier (auxiliary) and attitude-control rock­ets, and fluids injected into the exhaust stream, to gimballed en­gines or nozzles.4

With these basic issues to deal with, how did the United States get involved in developing missiles and rockets on a large scale? What sorts of problems did developers need to overcome to permit a rapid advance in missile and launch-vehicle technology? The chap­ters that follow answer these and other questions, but maybe a brief summary of how the process worked will guide the reader through a rather technical series of projects and developments.

Launch-vehicle technology emerged from the development and production of missiles to counter a perceived threat by the Soviet Union. In this environment, heavy cold-war expenditures to de­velop the missiles essentially fueled progress. In addition, many other factors (not always obvious to contemporaries) helped further the process. No short list of references documents the complex de­velopment discussed in this book, but one element of the effort was an innovative and flexible engineering culture that brought together a variety of talents and disciplines in a large number of organiza­tions spanning the nation. People from different disciplines joined together in cross-organizational teams to solve both unanticipated and expected problems.

Likewise, supporting problem solving and innovation was a grad­ually developing network that shared data among projects. Although military services, agencies, and firms often competed for roles and missions or contracts, the movement of people among the compet­ing entities, actual cooperation, professional organizations, partner-

ing, federal intellectual-property arrangements, and umbrella or­ganizations such as the Chemical Propulsion Information Agency promoted technology transfers of importance to rocketry. At the 6 same time, the competition spurred development through the urge Introduction to outperform rivals.

A further factor helping to integrate development and keep it on schedule (more or less) consisted of numerous key managers and management systems. In some instances, managers served as heterogeneous engineers, managing the social as well as the tech­nical aspects of missile and launch-vehicle development, stimulat­ing support for rocketry in general from Congress, the administra­tion, and the Department of Defense. By creating this support, they practiced what some scholars have defined as social construction of the technologies in question. At times, managers engaged in both technical direction and heterogeneous engineering, while in other cases technical managers and heterogeneous engineers were sepa­rate individuals.5

Although rocket technology is complex, I have tried to present it in a way that will be comprehensible to the general reader. The primary audience for this book will tend to be scholars interested in the history of technology or propulsion engineers seeking an over­view of the history of their discipline. I have included many ex­amples of problems encountered in the development of missiles and launch vehicles and explained, as far as I could determine, the way they were resolved. Even though I have not written in the techni­cally rigorous language of engineering (or in some cases because of that), I hope my discussion of the evolution of propulsion technol­ogy will engage the interest of everyone from rocket enthusiasts to technical sophisticates.

SPACE-LAUNCH – VEHICLE TECHNOLOGY

evolved from the development of early rockets and missiles. The earliest of these rockets that led to work on launch vehicles themselves was Robert Goddard’s in 1926, generally regarded as the first

liquid-propellant rocket to fly. But it was not until the mid-1950s that significant progress on large missiles occurred in the United States, greatly stimulated by the cold war between the United States and the Soviet Union. (Of course, the Germans had already devel­oped the A-4 [V-2] in the 1940s, and the United States launched a se­ries of reconstructed German V-2s in the New Mexico desert from 1946 to 1952.) Missile development was especially important in furthering the development of launch vehicles because many mis­siles became, with adaptations, actual stages for launch vehicles. In other cases, engines or other components for missiles became the bases for those on launch vehicles. By 1966 large, powerful, and comparatively sophisticated launch vehicles had already evolved from work on early missiles and rockets.

Soon after the engineers at Wallops began developing Scout, those at the Redstone Arsenal started work on the Saturn family of launch vehicles. Whereas the solid-propellant Scout was the runt among American launch vehicles, the liquid-fueled Saturn became the gi­ant. The standard Scout at the end of its career was a four-stage vehicle about 75 feet in height, but the Saturn V, with only three stages, stood almost 5 times as tall, about 363 feet. This made the Saturn taller than the Statue of Liberty—equivalent in height to a 36-story building and taller than a football field was long. Com­posed of some 5 million parts, it was a complex mass of propellant tanks, engines, plumbing fixtures, guidance/control devices, thrust structures, and other elements. Its electrical components, for exam­ple, included some 5,000 transistors and diodes, all of which had to be tested both individually and in conjunction with the rest of the vehicle to ensure that they would work properly when called upon. The Scout could launch only 454 pounds into a 300-mile orbit, but the Saturn V sent a roughly 95,000-pound payload with three astro­nauts on board toward six successful lunar orbits.64

Using clustering of rocket engines in its lower stages to achieve its massive initial thrust, the Saturn V was based on the earlier development of vehicles that ultimately came to be designated the Saturn I and the Saturn IB. These two interim space boosters were, in turn, based upon technologies developed for the Redstone, Ju­piter, Thor, Atlas, Centaur, and other vehicles and stages. Thus, although the Saturn family constituted the first group of rockets developed specifically for launching humans into space, it did not so much entail new technologies as it did a scaling up in size of 74 existing or already developing technology and an uprating of engine Chapter 2 performance. Even so, this posed significant technological hurdles and, often, a need to resort to empirical solutions to problems they raised. Existing theory and practice were inadequate for both the massive scale of the Saturns and the need to make them sufficiently reliable to carry human beings to an escape trajectory from Earth’s immediate vicinity out toward the Moon.65

The organization under Wernher von Braun at the Army Ballistic Missile Agency (ABMA)—which became NASA’s Marshall Space Flight Center (MSFC) in mid-1960—began the initial research and

development of the Saturn family of vehicles. In response to DoD projections of a need for a very large booster for communication and weather satellites and space probes, ABMA had begun in April 1957 to study a vehicle with 1.5 million pounds of thrust in its first stage. Then the formation of the Advanced Research Projects Agency (ARPA) on February 7, 1958, led ABMA to shift from initial plans to use engines still under development. Despite the crisis resulting from Sputnik, ARPA urged the use of existing and proven engines so that the new booster could be developed as quickly as possible at a minimal cost. ABMA then shifted to use of eight uprated Thor – Jupiter engines in a cluster to provide the 1.5 million pounds of thrust in the first stage, calling the new concept the Juno V. This led to an ARPA order on August 15, 1958, initiating what von Braun and others soon started calling the Saturn program, a name ARPA officially sanctioned on February 3, 1959.66

Under a contract signed on September 11, 1958, the Rocketdyne Division of North American Aviation in fact supplied an H-1 engine that was actually more than an uprated Thor-Jupiter powerplant. It resulted from research and development on an X-1 engine that the Experimental Engines Group at Rocketdyne began in 1957. Mean­while, the engineers at ABMA did some scrounging in their stock of leftover components to meet the demands of ARPA’s schedule within their limited budget. The schedule called for a full-scale, static firing of a 1.5-million-pound cluster by the end of 1959. In­stead of a new, single tank for the first stage, which would have required revised techniques and equipment, the ABMA engineers found rejected or incomplete 5.89-foot (in diameter) Redstone and 8.83-foot Jupiter propellant tanks. They combined one of the Jupi­ter tanks with eight from the Redstone to provide a cluster of pro­pellant reservoirs for the first-stage engines. In such a fashion, the Saturn program got started, with funding gradually increased even before the transfer of the von Braun group to NASA.67

Initially called the Saturn C-1, the Saturn I (properly so-called after February 1963) was at first going to have a third stage, but between January and March 1961, NASA decided to drop the third stage and to use Pratt & Whitney RL10 engines in the second stage. These were the same engines being developed for Centaur. Mean­while, on April 26, 1960, NASA had awarded a contract to the Doug­las Aircraft Company to develop the Saturn I second stage, which confusingly was called the S-IV. Unlike the Centaur, which used only two RL10s, the S-IV held six of the engines, requiring consider­able scaling up of the staging hardware. Using its own experience as well as cooperation from Centaur contractors Convair and Pratt &

Whitney, Douglas succeeded in providing an SL-IV stage in time for the January 29, 1964, first launch of a Saturn I featuring a live second stage. This was also the first launch with 188,000-pound – thrust H-1 engines in the first stage, and it succeeded in orbiting the second stage.68

Development of the Saturn I posed problems. Combustion insta­bility in the H-1 engines, stripped gears in an H-1 turbopump, slosh­ing in first-stage propellant tanks, and an explosion during static testing of the S-IV stage all required redesigns. But apart from the sloshing on the first Saturn I launch (SA-1), the 10 flights of Saturn I (from October 27, 1961, to July 30, 1965) revealed few problems. There were changes resulting from flight testing, but NASA counted all 10 flights successful, a tribute to the thoroughness and extensive ground testing of von Braun’s engineers and their contractors.69

At 191.5 feet tall (including the payload), Saturn I was still a far cry from Saturn V. The intermediate version, Saturn IB, consisted of a modified Saturn I with its two stages (S-IB and S-IVB) redesigned to reflect the increasing demands placed upon them, plus a further developed instrument unit with a new computer and additional flexibility and reliability. The S-IVB would serve as the second stage of the Saturn IB and (with further modifications) the third stage of the Saturn V, exemplifying the building-block nature of the devel­opment process. The first stage of the Saturn IB was also a modified S-I, built by the same contractor, Chrysler. The cluster pattern for the eight H-1 engines did not change, although uprating increased their thrust to 200,000 and then 205,000 pounds per engine. In its second stage, the Saturn IB had a new and much larger engine, the J-2, with thrust exceeding that of the six RL10s used on the Saturn I. Like the RL10s, it burned liquid hydrogen and liquid oxygen.70

Rocketdyne won a contract (signed on September 10, 1960) to develop the J-2, with specifications that the engine ensure safety for human flight yet have a conservative design to speed up avail­ability. By the end of 1961, it had become evident that the engine 76 would power not only stage two of Saturn IB but both the second Chapter 2 and third stages of the Saturn V. In the second stage of Saturn V, there would be a cluster of five J-2s; on the S-IVB second stage of Saturn IB and the S-IVB third stage of Saturn V, there would be a single J-2 a piece. Rocketdyne engineers had problems with injec­tors for the new engine until they borrowed technology from the RL10, a further example of shared information between competing contractors, facilitated by NASA.71

After completion of its development, the Saturn IB stood 224 feet high. Its initial launch on February 26, 1966, marked the first flight

tests of an S-IVB stage, a J-2 engine, and a powered Apollo space­craft. It tested two stages of the launch vehicle plus the reentry heat shield of the spacecraft. Except for minor glitches like failures of two parachutes for data cameras, it proved successful. Other flights also succeeded, but on January 27, 1967, a ground checkout of the vehicle for what would have been the fourth flight test led to the di­sastrous Apollo fire that killed three astronauts. The test flights of Saturn IB concluded with the successful launching and operation of the command and service modules (CSM), redesigned since the fire. Launched on October 11, 1968, the Saturn IB with a 225,000-pound – thrust J-2 in the second stage performed well in this first piloted Apollo flight. This ended the Saturn IB flights for Apollo, although the vehicle would go on to be used in the Skylab and Apollo-Soyuz Test Projects from 1973 to 1975.72

Development of some parts used exclusively for the Saturn V be­gan before design of other components common to both the Saturn IB and the Saturn V. For instance, on January 9, 1959, Rocketdyne won the contract for the huge F-1 engine used on the Saturn V (but not the IB); however, not until May 1960 did NASA select Rocket – dyne to negotiate a contract for the J-2 common to both launch ve­hicles. Configurations were in flux in the early years, and NASA did not officially announce the C-1B as a two-stage vehicle for Earth – orbital missions with astronauts aboard until July 11, 1962, renam­ing it the Saturn IB the next February. (NASA Headquarters had already formally approved the C-5 on January 25, 1962.) Thus, even though the Saturn IB served as an interim configuration between the Saturn I and the Saturn V, development of both vehicles over­lapped substantially, with planning for the ultimate moon rocket occurring even before designers got approval to develop the interim configuration.73

Burning RP-1 as its fuel with liquid oxygen as the oxidizer, the F-1 did not break new technological ground—in keeping with NASA guidelines to use proven propellants. But its thrust level required so much scaling up of the engine as to mark a major advance in the state of the art of rocket making. Perhaps the most intricate design feature of the F-1, and certainly one that caused great difficulty to engineers, was the injection system. As with many other engines, combustion instability was the problem. On June 28, 1962, during an F-1 hot-engine test at the rocket site on Edwards AFB, combus­tion instability led to the meltdown of the engine. Using essentially trial-and-error methods coupled with high-speed instrumentation and careful analysis, a team of engineers had to test perhaps 40 or 50 design modifications before they eventually found a combination of

baffles, enlarged fuel-injection orifices, and changed impingement angles that worked.74

Despite all the effort that went into the injector design, accord­ing to Roger Bilstein, it was the turbopump that “absorbed more design effort and time for fabrication than any other component of the engine." There were 11 failures of the system during the de­velopment period. All of them necessitated redesign or a change in manufacturing procedures. The final turbopump design provided the speed and high volumes needed for a 1.5-million-pound-thrust engine with a minimal number of parts and high ultimate reliabil­ity. However, these virtues came at the expense of much testing and frustration.75

There were many other engineering challenges during design and development of the Saturn V. This was especially true of the S-II second stage built by the Space and Information Systems Division of North American Aviation. Problems with that segment of the huge rocket delayed the first launch of the Saturn V from August until November 9, 1967. But on that day the launch of Apollo 4 (flight AS-501) without astronauts aboard occurred nearly without a flaw.76

After several problems on the second Saturn V launch (includ­ing the pogo effect on the F-1 engines) prevented the mission from being a complete technical success, engineers found solutions. As a result, the third Saturn V mission (AS-503, or Apollo 8) achieved a successful circumlunar flight with astronauts aboard in late 1968. Following two other successful missions, the Apollo 11 mission between July 16, 1969, and July 24, 1969, achieved the first of six successful lunar landings with the astronauts returning to Earth, fulfilling the goals of the Apollo program.77

With Saturns I and IB as interim steps, Saturn V was the culmi­nation of the rocket development work von Braun’s engineers had been carrying on since the early 1930s in Germany. In the interim, the specific engineers working under the German American baron 78 had included a great many Americans. There had been a continual Chapter 2 improvement of technologies from the V-2 through the Redstone, Jupiter, and Pershing missiles to the three Saturn launch vehicles.

Not all of the technologies used on Saturn V came from von Braun’s engineers, of course. Many technologies in the Saturn V resulted from those developed on other programs in which von Braun’s team had not participated or for which it was only partly responsible. This is notably true of much liquid-hydrogen technol­ogy, which stemmed from contributions by Lewis Research Cen­ter, Convair, Pratt & Whitney, Rocketdyne, and Douglas, among

others—showing the cumulative effects of much information shar­ing. But Marshall engineers worked closely with the contractors for the J-2, S-II, and S-IVB stages in overcoming difficulties and made real contributions of their own. This was also true in the develop­ment of the Saturn engines. Rocketdyne had started its illustrious career in engine development by examining a V-2 and had worked with von Braun and his engineers on the Redstone engine, a pro­cess that continued through Jupiter and the Saturn engines. But a great many of the innovations that led to the F-1 and J-2 had come more or less independently from Rocketdyne engineers, and even on the major combustion-instability and injector problems for the F-1, Rocketdyne’s contributions seem to have been at least as great as those from Marshall engineers. In other words, it took teamwork, not only among Americans and Germans at Marshall but among Marshall, other NASA centers, industry, universities, and the U. S. military to create the Apollo launch vehicles. Air force facilities and engineers at Edwards AFB, Holloman AFB, and the Arnold En­gineering Development Center also made key contributions to fac­ets of Saturn development.

Another key ingredient in the success of Saturn rocket develop­ment was the management system used at ABMA and the NASA Marshall Space Flight Center. As at Peenemunde, von Braun re­tained his role as an overall systems engineer despite other com­mitments on his time. At frequent meetings he chaired, he con­tinued to display his uncanny ability to grasp technical details and explain them in terms everyone could understand. Yet he avoided monopolizing the sessions, helping everyone to feel part of the team. Another technique to foster communication among key technical people was his use of weekly notes. Before each Monday, he required his project managers and laboratory chiefs to submit one-page summaries of the previous week’s developments and prob­lems. Each manager had to gather and condense the information. Then von Braun wrote marginal comments and circulated copies back to the managers. He might suggest a meeting between two in­dividuals to solve a problem or himself offer a solution. Reportedly, the roughly 35 managers were eager to read these notes, which kept them all informed about problems and issues and allowed them to stay abreast of overall developments, not just those in their separate areas. In this way, the notes integrated related development efforts and spurred efforts to solve problems across disciplinary and orga­nizational lines.78

Superficially, these “Monday notes" seemed quite different from Schriever’s “Black Saturdays" and Raborn’s PERT system. They

were certainly less formal and more focused on purely technical so­lutions than on cost control. But in the technical arena, von Braun’s system served the same systems-engineering function as the other systems.

While the Saturn I was undergoing development and flight test­ing, significant management changes occurred in NASA as a whole. From November 18, 1959 (when NASA assumed technical direc­tion of the Saturn effort), through March 16, 1960 (when the space agency took over administrative direction of the project and formal transfer took place), to July 1, 1960 (when both the Saturn program and the von Braun team of engineers transferred to the Marshall Space Flight Center), the administrator of NASA remained the capable and forceful but conservative T. Keith Glennan. Glennan had organized NASA, adding JPL and Marshall to the core centers inherited from the National Advisory Committee for Aeronautics, NASA’s predecessor.79

Once John F. Kennedy became president in early 1961 and ap­pointed the still more forceful and energetic but hardly conservative James E. Webb to succeed Glennan, there were bound to be man­agement changes. This was further ensured by Kennedy’s famous exhortation on May 25, 1961, “that this nation. . . commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to earth." The commitment that followed gave an entirely new urgency to the Saturn program. To coordinate it and the other aspects of the Apollo program, NASA re­organized in November 1961. Even before the reorganization, Webb chose as head of a new Office of Manned Space Flight (OMSF) an engineer with Radio Corporation of America who had been project manager for the Ballistic Missile Early Warning System (BMEWS). D. Brainerd Holmes had finished the huge BMEWS project on time and within budget, so he seemed an ideal person to achieve a simi­lar miracle with Apollo.80

Holmes headed one of four new program offices in the reorga – 80 nized NASA Headquarters, with all program and center directors Chapter 2 now reporting to Associate Administrator Robert C. Seamans Jr., who also took over control of NASA’s budget. Webb apparently had not fully grasped Holmes’s character when he appointed him. The second NASA administrator had previously considered Abe Sil – verstein to head OMSF and rejected him because he wanted too much authority, especially vis-a-vis Seamans. Holmes, however, turned out to be “masterful, abrasive, and determined to get what he needed to carry out his assignment, even at the expense of other programs." Within two weeks of joining NASA, the confrontational

FIG. 2.10

Wernher von Braun (center) showing the Saturn launch system to Pres. John F. Kennedy and Deputy NASA Administrator Robert Seamans (left) at Cape Canaveral, November 16, 1963. (Photo courtesy of NASA)

as unlikely that a lunar landing could be achieved during Kenne­dy’s decade “with acceptable risk." They believed it would be late 1971 before a landing could occur. Mueller took the two men to Seamans’s office to repeat the findings. Seamans then told Mueller privately to find out how to get back on schedule, exactly the au­thority and leverage Mueller had evidently sought.83

On November 1, 1963, Mueller then instituted two major changes that offered a way to land on the Moon by the end of the decade and greatly strengthened his position. One change was all-up testing. In 1971 Mueller claimed he had been involved with the development of all-up testing at Space Technology Laboratories, although he may or may not have known that his organization had opposed the idea when Otto Glasser introduced it as the only way he could conceive to cut a year from development time for Minuteman at the insis­tence of the secretary of the air force. In any event, all-up testing had worked for Minuteman and obviously offered a way to speed up testing for the Saturn vehicles.84

NASA defined all-up testing to mean a vehicle was “as complete as practicable for each flight, so. . . a maximum amount of test information is obtained with a minimum number of flights." This conflicted with the step-by-step procedures preferred by the von Braun group, but on November 1, Mueller sent a priority message to Marshall, the Manned Spacecraft Center (MSC) in Houston, and the Launch Operations Center (LOC) in Florida. In it he announced a deletion of previously planned Saturn I launches with astronauts aboard and directed that the first Saturn IB launch, SA-201, and the first Saturn V flight, AS-501, should use “all live stages" and in­clude “complete spacecraft." In a memorandum dated October 26, 1963, Mueller wrote to Webb via Seamans, enclosing a proposed NASA press release about all-up testing: “We have discussed this course of action with MSFC, MSC, and LOC, and the Directors of these Centers concur with this recommendation," referring specifi­cally to eliminating “manned" Saturn I flights but by implication, 82 to the all-up testing. The press release stated that “experience in Chapter 2 other missile and space programs" had shown it to be “the quickest way of reaching final mission objectives" (a further example of how shared information was important to missile and launch-vehicle programs).85

If Mueller had really discussed all-up testing with the center di­rectors, this was not apparent at Marshall, where von Braun went over the message with his staff on November 4, creating a “furor." Staff members recalled numerous failed launches in the V-2, Red­stone, and Jupiter programs. William A. Mrazek believed the idea

of all-up testing was insane; other lab heads and project managers called it “impossible" and a “dangerous idea." Although von Braun and his deputy, Eberhard Rees, both had their doubts about the idea, in the end they had to agree with Mueller that the planned launches of individual stages would prevent landing on the Moon by the end of the decade. All-up testing prevailed despite von Braun’s doubts.86 And once again, it worked.

The second change introduced on November 1 entailed a reor­ganization of NASA, placing the field centers under the program offices once again, rather than under Seamans. Mueller obtained authority over Marshall, the MSC, and the LOC (renamed Kennedy Space Center in December).87

One aspect of the Marshall effort that did not fit with Mueller’s management concepts was the proclivity for technical decisions in Huntsville to be based on their merits instead of schedule or cost. This was true even though project managers were supposed to get jobs done “on time and within budget." A concern with time, bud­get, and what had come to be called configuration control, however, had become very important in the Minuteman program and quickly spread to NASA when Mueller arranged for Brig. Gen. Samuel Phil­lips to come to NASA as deputy director and then director (after Oc­tober 1964) of the Apollo program. The slender, handsome Phillips had moved from his post as director of the Minuteman program in August 1963 to become vice commander of the Ballistic Systems Division. He arrived at NASA Headquarters in early January 1964 and soon arranged for the issue in May of a NASA Apollo Configu­ration Management Manual, adapted from an air force manual.88

Phillips had expected resistance to configuration management from NASA. He was not disappointed. Mueller had formed an Apollo Executive Group consisting of the chief executives of firms working on Apollo plus directors of NASA field centers, and in June 1964, Phillips and a subordinate who managed configuration control for him presented the system to the assembled dignitaries. Von Braun objected to the premises of Phillips’s presentation on the ground that costs for development programs were “very much unknown, and configuration management does not help." He contended that it was impossible for the chairman of a configuration control board to know enough about all the disciplines involved to decide intel­ligently about a given issue. Phillips argued that if managers were doing their jobs, they were already making such decisions.

Von Braun retorted that the system tended to move decisions higher in the chain of management. William M. Allen of Boeing coun­tered that this was “a fundamental of good management." When von

Braun continued to argue the need for flexibility, Mueller explained that configuration management did not mean that engineers had “to define the final configuration in the first instance before [they knew] that the end item [was] going to work." It meant defining the ex­pected design “at each stage of the game" and then letting everyone know when it had to be changed. Center directors like von Braun did not prevail in this argument, but resistance continued in industry as well as NASA centers, with the system not firmly established until about the end of 1966.89

Mueller and Phillips introduced other management procedures and infrastructure to ensure control of costs and schedules. Phillips converted from a system in which data from the field centers came to Headquarters monthly to one with daily updates. He quickly con­tracted for a control room in NASA Headquarters similar to the one he had used for Minuteman, with data links to field centers. A com­puterized system stored and retrieved the data about parts, costs, and failures. Part of this system was a NASA version of the navy’s Program Evaluation and Review Technique (PERT), developed for Polaris, which most prime contractors had to use for reporting cost and scheduling data.90

Despite von Braun’s resistance to configuration management, Phillips recalled in 1988, “I never had a single moment of problem with the Marshall Space Flight Center. [Its] teamwork, cooperation, enthusiasm, and energy of participation were outstanding." Phillips added, “Wernher directed his organization very efficiently and par­ticipated in management decisions. When a decision had been made, he implemented it—complied, if you will, with directives." In part, no doubt, Phillips was seeing through the rose-colored glasses of memory. But in part, this reflected von Braun’s propensity to argue until he was either convinced that the contrary point of view was correct or until he saw that argument was futile. Then he became a team player.

Phillips had been at the receiving end of V-2s in England during 84 World War II, and he was prepared to dislike the German baron who Chapter 2 had directed their development. But the two became friends. He commented that von Braun “could make a person feel personally important to him and that [his or her] ideas were of great value." When asked about von Braun’s contributions to the space program, Phillips observed that a few years before, he probably would have said that American industry and engineering could have landed on the Moon without German input. But in 1988 he said, “When I think of the Saturn V, which was done so well under Wernher’s direction and which was obviously. . . essential to the lunar mis-

sion, . . . I’m not sure today that we could have built it without the ingenuity of Wernher and his team."91

The contributions of Mueller and Phillips were probably more critical to the ultimate success of Apollo than even von Braun’s. Phillips hesitated about characterizing Mueller but did say that “his perceptiveness and ability to make the right decision on important and far-reaching [as well as] complex technical matters" was “pretty unusual." On the other hand, Mueller’s biggest shortcoming, ac­cording to Phillips, was “dealing with people." John Disher, who admired Silverstein but characterized Mueller as the “only bona – fide genius I’ve ever worked with," had to observe that although his boss was “always the epitome of politeness, . . . deep down he [was] just as hard as steel." Also, human space program director of flight operations, Chris Kraft, who dealt with a great many people and frequently clashed with Mueller, had to say that “I’ve never dealt with a more capable man in terms of his technical ability." Difficult though Mueller was, without him and Phillips, American astronauts probably would not have gotten to the Moon before the end of the decade.92

Both men brought to NASA some of the culture and many of the management concepts used in the air force, plus the navy’s PERT system. These added to the amalgam of cultures already present in the space agency. Inherited from the National Advisory Com­mittee for Aeronautics (NACA) was a heavy research orientation coupled with a strong emphasis on testing. Von Braun’s Germans had brought a similar culture from their V-2 and army experience, together with a tendency to over-engineer rocket systems to ensure against failure. JPL had added its own blend of innovation plus a strong reliance on theory and use of mathematics that was also part of the V-2 experience. The Lewis Research Center brought to the mix its experience with liquid hydrogen, and the Langley Research Center brought the testing of rockets at Wallops Island and a wind – tunnel culture (present also at Ames Research Center). All of these elements (and the management styles that accompanied them) con­tributed to the Saturn-Apollo effort.

Before the defense establishment transferred the technology from Project Suntan to rocketry, it had to be nudged by a proposal from Convair’s Krafft Ehricke. Called to service in a Panzer division on the western and then eastern fronts during World War II, the young German was still able to earn a degree in aeronautical engineering at the Berlin Technical Institute. He was fortunate enough to be as­signed to Peenemunde in June 1942, where he worked closely with Thiel. Although he came to the United States as part of von Braun’s group and moved with it to Huntsville, Ehricke was a much less conservative engineer than von Braun. Whether for that reason or others, he transferred to Bell Aircraft in 1952 when it was working on the Agena upper stage and other projects. Not happy there either by the time he left (when he believed interest had shifted away from space-related projects), he heeded a call from Karel Bossart to work at Convair in 1954.5

At the San Diego firm, Ehricke initially served as a design spe­cialist on Atlas and was involved with Project Score. By 1956, he was beginning to study possible boosters for orbiting satellites but could find no support for such efforts until after Sputnik I. Then, General Dynamics managers asked him to design an upper stage for Atlas. (Consolidated Vultee Aircraft Corporation merged into General Dynamics Corporation on April 29, 1954, to become the Convair Division of the larger firm.) Ehricke and other engi­neers, including Bossart, decided that liquid hydrogen and liquid oxygen were the propellants needed. Ehricke worked with Rock – etdyne to develop a proposal titled “A Satellite and Space Devel­opment Plan." This featured a four-engine stage with pressure feeding of the propellants, neither Rocketdyne nor Ehricke be­ing aware of Pratt & Whitney’s pumps. In December 1957, James Dempsey, vice president of the Convair Division, sent Ehricke and another engineer off to Washington, D. C., to pitch the design to the air force.6

The air service did not act on the proposal, but on February 7,

1958, Ehricke presented it to the new Advanced Research Projects Agency, created by the Department of Defense. For a time, ARPA exercised control over all military and civilian space projects before relinquishing the civilian responsibility to NASA in October 1958. Thereafter, for a year, ARPA remained responsible for all military space projects, including budgets. The new agency made Ehricke aware of Pratt & Whitney’s hydrogen pumps and encouraged Con – vair to submit a proposal using two 15,000-pound-thrust, pump-fed engines, which it did in August 1958. That same month, ARPA is­sued order number 19-59 for a high-energy, liquid-propellant upper stage to be developed by Convair-Astronautics Division of General Dynamics Corporation, with liquid-oxygen/liquid-hydrogen en­gines to be developed by Pratt & Whitney.7

In October and November 1958, at ARPA’s direction the air force followed up with contracts to Pratt & Whitney and Convair for the development of Centaur, but NASA’s first administrator, Keith Glen – nan, requested that the project transfer to his agency. Deputy Secre – 176 tary of Defense Donald Quarles agreed to this arrangement in prin – Chapter 5 ciple, but ARPA and the air force resisted the transfer until June 10,

1959, when NASA associate administrator Richard E. Horner pro­posed that the air force establish a Centaur project director, locate him at the Ballistic Missile Division in California, but have him report to a Centaur project manager at NASA Headquarters. NASA would furnish technical assistance, with the air force providing ad­ministrative services. The DoD agreed, and the project transferred to NASA on July 1, 1959. Lieutenant Colonel Seaberg from the Sun­tan project became the Air Research and Development Command project manager for Centaur in November 1958, located initially at command headquarters on the East Coast. Seaberg remained in that position with the transfer to NASA but moved his location to BMD. Milton Rosen became the NASA project manager. In November 1958, Ehricke became Convair’s project director for Centaur.8

Complicating Centaur’s development, in the fall of 1958 NASA engineers had conceived of using the first-stage engine of Vanguard as an upper stage for Atlas, known as Vega. NASA intended that it serve as an interim vehicle until Atlas-Centaur was developed. Under protest from Dempsey that Convair already had its hands full with Atlas and Centaur, on March 18, 1959, NASA contracted with General Dynamics to develop Atlas-Vega. With the first flight of the interim vehicle set for August 1960, Vega at first became a higher priority for NASA than Centaur. As such, it constituted an impediment to Centaur development until NASA canceled Vega on

December 11, 1959, in favor of the DoD-sponsored Agena B, which had a development schedule and payload capability similar to Ve­ga’s but a different manufacturer (Bell).9

Besides Vega’s competition for resources until this point, another hindrance to development of Centaur came from liquid hydrogen’s physical characteristics. Its very low density, extremely cold boiling point, low surface tension, and wide range of flammability made it extremely difficult to work with. Ehricke had some knowledge of this from working with Thiel, but the circumstances of the contract with the air force limited the amount of testing he could perform to overcome hydrogen’s peculiarities.10

One limitation was funding. When ARPA accepted the initial proposal and assigned the air force to handle its direction, the stipu­lations were that there be no more than $36 million charged by Convair-Astronautics for its work, that a first launch attempt occur by January 1961, and that the project not interfere with Atlas devel­opment. At the same time, Convair was to use off-the-shelf equip­ment as well as Atlas tooling and technology as much as possible. Funding for the Pratt & Whitney contract was $23 million, bringing the total initial funding to $59 million for the first six launches the contract required, not including the costs of a guidance/control sys­tem, Atlas boosters, and a launch complex. Ehricke believed that, until it was too late, the limited funding restricted the necessary ground testing his project engineers could do. Also restrictive was the absence of the DoD’s highest priority (known as DX), which meant that subcontractors who were also working on projects with the DX priority could not give the same level of service to Centaur as they provided to higher-priority projects.11

Under these circumstances, Convair and Pratt & Whitney pro­ceeded with designs for the Centaur structure and engines. The Centaur stage used the steel-balloon structure of Atlas, with the same 10-foot diameter. The lightness of the resulting airframe seemed necessary for Centaur because of liquid hydrogen’s low den­sity, which made the hydrogen tank much larger than the oxygen tank. Conventional designs with longerons and ring frames would have created a less satisfactory mass fraction than did the pressur­ized tanks with thin skins (initially only 0.01 inch thick). The el­liptical liquid oxygen tank was on the bottom of the stage. To create the shortest possible length and the lowest weight, the engineers on Ehricke’s project team made the bottom of the liquid-hydrogen tank concave so that it fit over the convex top of the oxygen tank.

This arrangement solved space and weight problems (saving about 4 feet of length and roughly 1,000 pounds of weight) but created oth-

ers in the process. One resulted from the smallness of the hydrogen molecules and their extreme coldness. The skin of the oxygen tank had a temperature of about — 299°F, which was so much “warmer" than the liquid hydrogen at — 423°F that the hydrogen would gasify from the relative heat and boil off. To prevent that, the engineers de­vised a bulkhead between the two tanks that contained a fiberglass – covered Styrofoam material about 0.2 inch thick in a cavity between two walls. Technicians evacuated the air from the pores in the Styro­foam and refilled the spaces with gaseous nitrogen. They then welded the opening. When they filled the upper tank with liquid hydrogen, the upper surface of the bulkhead became so cold that it froze the nitrogen in the cavity, thus creating a vacuum as the nitrogen con­tracted into the denser solid state, a process called cryopumping.12

Because of the limited testing, it was not until the summer and early fall of 1961 that the Centaur engineers and managers learned of heat transfer across the bulkhead that was more than 50 times the amount expected. It turned out that there were very small cracks in the bulkhead through which the hydrogen was leaking and destroy – 178 ing the vacuum, causing the heat transfer and resultant boil-off of Chapter 5 the fuel. This necessitated venting to avoid excessive pressure and explosion in the hydrogen tank. But the venting depleted the fuel, leaving an insufficient quantity for the second engine burn required of Centaur for coasting in orbit and then propelling a satellite into a higher orbit.

General Dynamics had used Atlas manufacturing techniques for the materials on the bulkhead. Atlas’s quality-control procedures permitted detection of leaks in bulkheads down to about 1/10,000 inch. Inspections revealed no such leaks, but the engineers learned in the 1961 testing that hydrogen could escape through even finer openings. Very small cracks that would not be a problem in a liquid – oxygen tank caused major leakage in a liquid-hydrogen tank.13

By the time Convair-Astronautics had discovered this problem, NASA had assigned responsibility for the Centaur project to the Marshall Space Flight Center (on July 1, 1960), with Seaberg’s Cen­taur Project Office remaining at BMD in California. Hans Hueter became director of Marshall’s Light and Medium Vehicles Office in July, with responsibility for managing the Centaur and Agena upper stages. During the winter of 1959-60, NASA also established a Cen­taur technical team following the cancellation of the Vega project. This team consisted of experts at various NASA locations to rec­ommend ways the upper stage could be improved. In January 1960, navy commander W. Schubert became the Centaur project chief at NASA Headquarters.14

From December 11 to 14, 1961, John L. Sloop visited General Dy­namics/ Astronautics (GD/A) to look into Centaur problems, par­ticularly the one with heat transfer across the bulkhead. Sloop had been head of Lewis Laboratory’s rocket research program from 1949 until 1960, when he moved to NASA Headquarters. There in 1961 he became deputy director of the group managing NASA’s small and medium-sized launch vehicles. Following his visit, he wrote, “GD/A has studied the problem and concluded that it is not practi­cal to build bulkheads where such a vacuum [as the one Ehricke’s team had designed] could be maintained." The firm also believed “that the only safe way to meet all Centaur missions is to drop the integral tank design and go to separate fuel and oxidizer tanks." Sloop disagreed: “If a decision must be made now, I recommend we stick to the integral tank design, make insulation improvements, and lengthen the tanks to increase propellant capacity."15

Sloop’s optimism was justified. After the Centaur team began “a program of designing and testing a number of alternate designs," tests revealed that adding nickel to the welding of the double bulk­head (and elsewhere), significantly increased the single-spot shear strength of the metal at —423°F.16

Centaur development experienced many other problems. Several of them involved the engines. After enduring “inadequate facilities, slick unpaved roads, mosquitoes, alligators, and 66 inches of rain in a single season" while developing the 304 engine for Suntan at West Palm Beach, Pratt & Whitney engineers also “discovered the slippery nature of hydrogen." The extreme cold of liquid hydrogen precluded using rubber gaskets to seal pipe joints, designers hav­ing to resort to aluminum coated with Teflon and then forced into flanges that mated with them. There had to be new techniques for seals on rotating surfaces, where carbon impregnated with silver found wide use. Another concern with the cryogenic hydrogen was that the liquid not turn to gas before reaching the turbopumps. The engineers initially solved that problem by flowing propellants to the pumps before engine start, precooling the system.17

The turbopump for the 304 engine used oil to lubricate its bear­ings. This had to be heated to keep it from freezing in proximity to the cold pump, creating a temperature gradient. To solve this prob­lem for the RL10, the Pratt & Whitney engineers coated the cages holding the bearings with fluorocarbons similar to Teflon and ar­ranged to keep the bearings cold with minute amounts of liquid hydrogen. This produced the same effect as lubrication, because it turned out that the main function of oil was to keep the bearings from overheating. The substance from which Pratt & Whitney nor-

mally made its gears, called Waspalloy, bonded in the hydrogen en­vironment. Engineers replaced it with carbonized steel coated with molybdenum disulfide for dry lubrication. This solved the bonding problem but subjected some unlucky engineers to observing tests of the new arrangement by using binoculars from an observation post with only a screen door. Late at night, alligator croakings and other noises created uneasiness for many young observers unused to swamp sounds.18

The first component tests of the combustion chamber for the RL10, including stainless-steel regenerative-cooling tubes brazed with silver, took place in May 1959. As with many other initial tests of combustion chambers, there were signs of burnthrough, so the engineers changed the angle at which the hydrogen entered the tubes and aligned the tubes more carefully so they did not pro­trude into the exhaust stream. Engine firings two months after this showed that the changes had solved the burnthrough problem, but the chamber’s conical shape produced inefficient burning. Engi­neers changed the design to a bell shape and conducted a successful 180 engine run in September 1959, less than a year from the date of the Chapter 5 initial contract.19

A major innovation in the design of the RL10 took advantage of the cold temperature of liquid hydrogen in order to dispense with a gas generator to drive the turbopump. The cryogenic fuel passed from the tank into the tubes of the combustion chamber for cooling. As it did so, it absorbed heat, which caused the fuel to vaporize and expand. This provided enough kinetic energy to drive the turbine that operated both the liquid-hydrogen and liquid-oxygen pumps. It also provided the power for the hydraulic actuators that gimballed the engine. This process, called the “bootstrap" cycle, still used hy­drogen-peroxide boost pumps to start the process. Hydrogen per­oxide also powered attitude-control rockets and ullage-control jets that propelled the Centaur forward in a parking orbit and thereby forced the liquid hydrogen to the rear of the tanks. There it could be pumped into the engines for ignition.20

Before the RL10 underwent its first test in an upright position on a test stand in its two-engine configuration for the Centaur, it under­went 230 successful horizontal firings. It produced 15,000 pounds of thrust and achieved a specific impulse of about 420 lbf-sec/lbm at an expansion ratio of 40:1 through its exhaust nozzle. As required by its missions in space, it reliably started, stopped, and restarted so that it could coast in a parking orbit until it reached the optimum point for injection into an intended orbit (or trajectory for interplan­etary voyages). On November 6, 1960, two RL10s, upright for the

first time on a test stand at the Pratt & Whitney facility in Florida, fired at the same time and did so successfully—for a short time un­til a problem occurred with the timer on the test stand. When en­gineers repeated the test the next day, only one engine fired. The other filled with hydrogen and oxygen until the flame from the first engine caused an explosion that damaged the entire propulsion sys­tem beyond repair.

A tape recording of the countdown suggested that the problem had stemmed from the faulty operation of a test-stand sequencer, so engineers did not suspect difficulties with the engine itself. By Janu­ary 12, 1961, they repaired the test stand and tested another pair of engines. This time, they put a blast wall between the two engines and installed a shutoff valve on the hydrogen tank. They also sepa­rated the exhaust systems for the two engines by a greater distance. During this test, there was no problem with the sequencing, but the explosion recurred. In the vertical position, engineers learned, grav­ity was affecting the mixing of the oxygen with the hydrogen differ­ently than it had in the horizontal position. So in a further instance of cut-and-try engineering, designers had to adjust the method of hydrogen feed. They also designed a method of measuring the den­sity of the mixture to ensure the presence of enough oxygen for igni­tion. With these adjustments, the two engines fired simultaneously in the vertical test stand on April 24, 1961. Following this success, the engines completed 27 successful dual firings at Pratt & Whitney and 5 more at the rocket site on Edwards AFB in California. They then passed the flight-rating test from October 30 to November 4, 1961, in which they completed 20 firings equivalent in duration to six Centaur missions.21

To protect the liquid hydrogen in its tank from boiling off while the vehicle was on the launching pad and during ascent through the atmosphere, engineers had designed four jettisonable insulation panels made of foam-filled fiberglass. These were about a centime­ter (0.39 inch) thick, held on the tank by circumferential straps. To keep air from freezing between the tank and the insulating foam, thereby bonding the panels to the tank, engineers designed a helium system to purge the air. To limit the weight penalty imposed by the panels (1,350 pounds), they had to be jettisoned as soon after launch as the atmosphere thinned and the ambient temperature dropped.22

Because of delays resulting from the engine ignition problem, dif­ficulties with elaborate test instrumentation (such as a television camera and sensors inside the liquid-hydrogen tank), and other is­sues, an Atlas LV-3 with a Centaur upper stage did not launch for the first time until May 8, 1962, 15 months later than planned. The

THRUST- 15,000 LB (ALTITUDE) THRUST DURATION-470SEC SPECIFIC IMPULSE-433SEC ENGINE WT DRY-298 LB EXIT-TO THROAT AREA RATIO – 40 ТОЇ

PROPELLANTS-LOX & LH2 PROPELLANT FLOW RATE – 35 LB/SEC

CONTRACTOR-

PRATT & WHITNEY SYSTEM-SAT I/S-1V (6 ENGINES) CENTAUR (2 ENGINES)

l-RM-D IND 8І4ЮВ

goals of the test flight were to proceed through the boost phase with jettison of the insulation and a nose fairing, followed by Centaur’s separation from the Atlas. With only a partial load of fuel, the Cen­taur was to coast for 8 minutes, reignite, and burn for 25 seconds.23

On the launch, the two stages rose normally until they ap­proached maximum dynamic pressure (with resultant aerodynamic buffeting) as the vehicle got close to the speed of sound 54.7 sec­onds into the launch. Then, an explosion occurred as the liquid – hydrogen tank split open. Initially, engineers decided that aerody­namic forces had destroyed the insulation and ruptured the tank. About five years later, tests suggested that the real culprit was dif­ferential thermal expansion between a fiberglass nose fairing and the steel tank, causing a forward ring to peel off the tank.24

Even before this launch, the difficulties with engine develop­ment, resultant schedule delays, and problems such as the one with the bulkhead between the hydrogen and oxygen tanks had led to close scrutiny of the Centaur project and danger of its cancellation. Following John Sloop’s visit to General Dynamics to look into such problems, he had expressed concerns about the firm’s organization. Krafft Ehricke, the program director, had only five men reporting directly to him, and Deane Davis, the project engineer, had direct charge of only two people. Many other people worked on Centaur (27 of them full-time), but most of them were assigned to six oper-

ating divisions not directly under project control. Sloop wrote, “As far as I could tell in three days of discussion, the only people who have direct and up-to-date knowledge of all Centaur systems are Mr. Ehricke and Mr. Davis." Marshall Space Flight Center had “a very competent team of four men stationed at GD/A," and they were well aware of the “management deficiencies" emphasized in Sloop’s comments.25

Hans Hueter wrote on January 4, 1962, to GD/A president James Dempsey stating his concern about the way the Centaur Program Office was organized in “relation to the line divisions." He men­tioned that the two of them had discussed this issue “several times" and reiterated his and other NASA employees’ “impression that the systems engineering is carried on singlehandedly by your ex­cellent associates, Krafft Ehricke and Dean [sic] Davis." He added, “The individual fields such as propulsion, thermal and liquid be­havior, guidance and control, and structures are covered in depth in the various engineering departments but coordination is sorely lacking."26

In response to NASA’s concerns about this matrix organization, Dempsey shifted to a “projectized" arrangement in which roughly 1,100 employees at Astronautics were placed under the direct au­thority of the Centaur program director. Ehricke was reassigned as the director of advanced systems and Grant L. Hansen became Cen­taur program director and Astronautics vice president on February 1, 1962. Trained as an electrical engineer at Illinois Institute of Tech­nology, Hansen had worked for Douglas Aircraft from 1948 to 1960 on missile and space systems, including the Thor, with experience in analysis, research and development, design, and testing. He came to GD/A in 1960 to direct the work of more than 2,000 people on Atlas and Centaur. After February 1962, Ehricke continued to offer Hansen advice. Although he was imaginative and creative, the com­pany had decided Ehricke “wasn’t enough of a[n] S. O.B. to manage a program like this." Hansen proved to be effective, although it is only fair to note that he was given authority and an organization Ehricke had lacked.27 S. O.B. or not, had Ehricke started with Hansen’s or­ganization and adequate funding, Centaur development could have been smoother from the beginning. In any event, this sequence of events showed how management arrangements and technical prob­lems interacted.

Several other programmatic changes occurred around this time. On January 1, 1962, for example, NASA (in agreement with the DoD) transferred the Centaur Project Office from Los Angeles to Huntsville, Alabama, and converted existing air force contracts to

NASA covenants. Lieutenant Colonel Seaberg ceased being proj­ect manager, and Francis Evans at Marshall Space Flight Center as­sumed those duties under Hueter’s direction. By this time, funding had grown from the original $59 million to $269 million, and the number of Centaur vehicles to be delivered had risen from 6 to 10.28

Meanwhile, following the May 8, 1962, explosion, a congressional Subcommittee on Space Sciences, chaired by Rep. Joseph E. Karth (D-Minnesota), began hearings on the mishap. In a report issued on July 2, 1962, the parent Committee on Science and Astronautics in the U. S. House of Representatives stated that “management of the Centaur development program has been weak and ineffective both at NASA headquarters and in the field."29 NASA did not immediately make further changes, but Marshall management of Centaur posed problems. These came out in the hearings, prompting unfavorable comment in the committee report. Von Braun had remarked about GD/A’s “somewhat bold approach. In order to save a few pounds, they have elected to use some rather, shall we say, marginal solu­tions where you are bound to buy a few headaches before you get 184 it over with." Hansen agreed that his firm was inclined “to take a Chapter 5 little bit more of a design gamble to achieve a significant improve­ment, whereas I think they [Marshall engineers] build somewhat more conservatively." The congressional report noted, “Such a dif­ference in design philosophy can have serious consequences."30

Ehricke characterized the design approach of the von Braun team as “Brooklyn Bridge" construction. The contrast between that and the approach of General Dynamics appears in an account of a Mar­shall visit to GD/A that Deane Davis wrote at an unspecified date soon after Marshall took over responsibility for Centaur in July 1960. A group led by von Braun and including Hueter and structures chief William Mrazek had come to GD/A for a tour and briefings on Atlas and Centaur. Mrazek and Bossart had gotten into a discussion of the structure of the steel-balloon tanks, with Mrazek (according to Davis’s account) unwilling to admit that they could have any structural strength without ribs. Bossart took him out to a tank and handed him a fiberglass mallet containing lead to give it a weight of 7 pounds. It had a rubber cover and a 2-foot handle. Bossart invited Mrazek to hit the tank with it. After a tap and then a harder whack, he could not find a dent. Bossart urged him to “stop fiddling around. Hit the damned thing!" When Mrazek gave it a “smart crack," the mallet bounced back so hard it flew about 15 feet, knocking off the German’s glasses on the way and leaving only a black smear (no dent) on the tank. Davis wrote that Hueter was as amazed as Mrazek by the strength of the tank.31

This account is difficult to accept entirely at face value because Mrazek had already designed the Redstone with an integral-tank structure that was hardly as light as Bossart’s steel balloon but was also not quite bridgelike. Nevertheless, even in 1962 von Braun was clearly uncomfortable with Bossart’s “pressure-stabilized tanks," which he called “a great weightsaver, but. . . also a continuous pain in the neck" that “other contractors, for example the Martin Co., for this very reason have elected not to use." No doubt because of such concerns, von Braun sought quietly to have the Centaur can­celed in favor of a Saturn-Agena combination.32

Faced with this situation, on October 8, 1962, NASA Headquar­ters transferred management of the Centaur program to the Lewis Research Center, to which Silverstein had returned as center di­rector in 1961 from his position at NASA Headquarters. A “sharp, aggressive, imaginative, and decisive leader," Silverstein could be “charming or abrasive," in the words of John Sloop. Deane Davis, who worked with him on Centaur, called him a “giant among gi­ants" and a man he “admired, adored, hated, wondered about—and mostly always agreed with even when I fought him. Which was of­ten." Under Silverstein’s direction, the Lewis center required much more testing than even the Marshall group had done. Lewis tested everything that could “possibly be proven by ground test." Yet de­spite such aggressive oversight, Grant Hansen expressed admiration for Lewis and its relationship with his own engineers.33

Because the RL10 had been planned for use on Saturn as well as Centaur, its management remained at Marshall. The reason given for Centaur’s transfer was that it would allow the Huntsville engi­neers to concentrate on the Saturn program. A NASA news release quoted NASA administrator James Webb, “This, I feel, is necessary to achieve our objectives in the time frame that we have planned. It will permit the Lewis Center to use its experience in liquid hydro­gen to further the work already done on one of the most promising high energy rocket fuels and its application to Centaur. . . ."34

Long before this transfer, engineers from the Cleveland facility had been actively involved in helping solve both engine and struc­tural problems with the vehicle. Their involvement included use of an altitude chamber at their center. Other facilities, including a rocket sled track at Holloman AFB, New Mexico, had also been involved in Centaur development. For example, in 1959 GD/A had done some zero-G testing in an air force C-131D aircraft at Wright- Patterson AFB (and also, at some point, in a KC-135). The same year, the firm had acquired a vacuum chamber for testing gas ex­pansion and components. With additional funding (to a total of

about $63 million) in 1960, GD/A extended testing to include use of the vacuum test facility at the air force’s Arnold Engineering Development Center in Tullahoma, Tennessee, zero-G test flights using Aerobee rockets, and additional static ground testing, includ­ing modifying test stand 1-1 at the rocket site on Edwards AFB for Centaur’s static tests. In 1961, when GD/A’s funding rose to $100 million, there were wind-tunnel tests of the Centaur’s insulation panels at NASA’s Langley Research Center, additional zero-G test­ing, and construction of a coast-phase test stand to evaluate the attitude-control system.35

At Lewis, Silverstein decided to direct the Centaur project him­self, assisted by two managers under his personal direction and some 41 people involved with technical direction. Some 40 Mar­shall engineers helped briefly with the program’s transition. By Janu­ary 1963, the changeover was mostly complete and Centaur had acquired a DX priority. Then, costs for Centaur were estimated at $350 million, and containing them became an issue. Despite this, Silverstein decided that the first eight Centaurs after the transfer 186 would constitute test vehicles. By this time, Surveyor spacecraft Chapter 5 had been assigned as Centaur payloads, and Silverstein determined that none of them would be launched until the test vehicles had demonstrated Centaur’s reliability.36

By February 1963, Silverstein had appointed David Gabriel as Centaur manager but placed the project office in the basement of his own administrative building so he could continue to keep tabs on the project. Some continuity with the period of Marshall man­agement came in the retention of Ronald Rovenger as chief of the NASA field office at GD/A. Instead of 4, his office rose to a comple­ment of 40 NASA engineers. It took until April 1964, but Lewis renegotiated the existing contracts with GD/A into a single cost- plus-fixed-fee document for 14 Centaur upper stages plus 21 test articles. The estimated cost of the agreement was roughly $321 mil­lion plus a fixed fee of $31 million, very close to the estimate of $350 million at the beginning of 1963. However, Silverstein felt the need for a second contract to cover further modifications resulting from Lewis’s technical direction. Soon the Lewis staff working on Centaur grew to 150 people. Silverstein continued to give the proj­ect his personal attention and made a major decision to abandon temporarily the use of a parking orbit and restart for Surveyor. This required a direct ascent to the Moon, considerably narrowing the “window" for each launch.37

These and other changes under Lewis direction did not imme­diately solve all of Centaur’s problems. Test flights and resultant

difficulties are summarized in table 5.1, beginning with Atlas – Centaur 2 (AC-2).38

Data from instrumentation on the insulation panels over the liq­uid-hydrogen tank on AC-2 showed conclusively that the design for the panels used on AC-1 was not adequate. Engineers designed thicker panels with heavier reinforcement, increasing their weight 188 by almost 800 pounds. This made it all the more important to jet – Chapter 5 tison them at about 180 seconds after launch to get rid of the un­wanted weight. A minor redesign fixed the problem with the drive – shaft that failed on AC-3. To fix the problem on AC-4 with liquid hydrogen moving away from the bottom of the tank where the fuel had to exit, however, required investigation and multiple modifica­tions. A slosh baffle in the liquid-hydrogen tank helped limit move­ment of the fuel away from the tank bottom. Screens in the ducts bringing bleed-off hydrogen gas back to the tank reduced energy that could disturb the liquid. On the coasting portion of AC-4’s orbit, liquid hydrogen had gotten into a vent intended to exhaust gaseous hydrogen, thereby releasing pressure from boil-off. The liq­uid exiting into the vacuum of space created a sideward thrust that tumbled the Centaur and Surveyor models. Fixing this problem re­quired a complete redesign of the venting system.

A further change increased thrust in both the yaw – and pitch – control engines as well as those that settled liquid hydrogen in the bottom of the tank during coast. The added thrust in both types of engines helped keep the Centaur on course and hold the easily dis­placed liquid hydrogen in the bottom of its tank. Fortunately, these changes were unnecessary before the launch of AC-5 but were im­plemented for AC-8, which also incorporated the uprated RL10A – 3-3 engine with slightly greater specific impulse from a larger expansion ratio for the exhaust nozzle and an increased chamber pressure.39

Meanwhile, in response to the explosion on AC-5, engineers locked the Atlas valves in the open position. AC-6 amounted to a semioperational flight. The Surveyor model went to the coordi­nates in space it was intended to reach (simulating travel to the Moon) even without a trajectory correction in midcourse. With AC-7 shifted to a later launch and AC-8 having problems with hy­drogen peroxide rather than liquid hydrogen, the Atlas-Centaur combination was ready for operational use, although there would be one more research-and-development flight sandwiched between launches of operational spacecraft (AC-9; see table 5.1). Atlas – Centaur performed satisfactorily on all of the Surveyor launches, although two of the spacecraft had problems. But five of the seven missions were successful, providing more than 87,000 photographs and much scientific information for Apollo landings and lunar stud­ies. Surveyors 1, 2, and 4 all used single-burn operations by Centaur, but Surveyors 3 and 5-7 employed dual-burn trajectories. On Sur­veyors 5-7 the Atlases were all SLV-3Cs with longer tanks, hence greater propellant volumes. The SLV-3C flew only 17 missions but was successful on all of them before being replaced by the SLV-3D, used with the advanced Centaur D-1A.40

The D-1A resulted from a NASA decision to upgrade the Cen­taur, with the Lewis Research Center responsible for overseeing the $40 million improvement program, the central feature of which was a new guidance/control computer, developed at a cost of about $8 million. Among payloads for the Centaur D-1A were Intelsat com­munications satellites. With the first launch of Intelsat V, having more relay capacity (and weight), on December 6, 1980, the Centaur began to use engines that were adjusted to increase their thrust (per engine) from the original 15,000 to about 16,500 pounds. The 93.75 percent success rate for the 32 SLV-3D/D-1A (and D-1AR) launches showed that Silverstein’s insistence on extended testing and detailed oversight had paid off.41

During the early 1980s, General Dynamics converted to new ver­sions of Atlas and Centaur. The Atlas G added 81 inches to the length of the propellant tanks, and Pratt & Whitney made several changes to the Centaur engines, including removal of the boost pump, for a significant weight savings. There was no change in the RL10’s thrust, but further modification shifted from hydrogen per­oxide to the more stable hydrazine for the attitude-control and pro­pellant-settling engines. This made the RL10A-3-3A a substantially different machine than its predecessor, the RL10A-3-3.42

As of early 1991, the Centaur had had a 95 percent success rate on 76 flights. This included 42 successes in a row for Centaur D-1

and D-1A between 1971 and 1984. The vehicle, as well as its Atlas booster, would continue to evolve into the 21st century, with the successful launch of an Atlas V featuring a Russian RD-180 engine and a Centaur with a single RL10 engine, signifying both the end of the cold war and the continuing evolution of the technology. Meanwhile, development of the Centaur had led to the use of liq­uid-hydrogen technology both on upper stages of the Saturn launch vehicle and on the Space Shuttle. Despite a difficult start and con­tinuing challenges, the Centaur had made major contributions to U. S. launch-vehicle technology.43

The history of space-launch-vehicle technology in the United States dates back to the experimenting of U. S. physicist and rocket developer Robert H. Goddard (1882-1945). A fascinating character, Goddard was supremely inventive. He is credited with 214 patents, many of them submitted after his death by his wife, Esther. These led to a settlement in 1960 by the National Aeronautics and Space Administration (NASA) and the three armed services of $1 million for use of more than 200 patents covering innovations in the fields of rocketry, guided missiles, and space exploration. In the course of his rocket research, Goddard achieved many technological break­throughs. Among them were gyroscopic control of vanes in the ex­haust of the rocket engine, film cooling of the combustion chamber, parachutes for recovery of the rocket and any instruments on it, streamlined casing, clustered engines, a gimballed tail section for stabilization, lightweight centrifugal pumps to force propellants into the combustion chamber, a gas generator, igniters, injection heads, and launch controls, although he did not use them all on any one rocket.1

Despite these impressive achievements, Goddard had less de­monstrable influence on the development of subsequent missiles and space-launch vehicles than he could have had. One reason was that he epitomized the quintessential lone inventor. With excep – 8 tions, he pursued a pattern of secrecy throughout the course of his Chapter 1 career. This secretiveness hindered his country from developing missiles and rockets as rapidly as it might have done had he devoted his real abilities to the sort of cooperative development needed for the production of such complex devices.

Educated at Worcester Polytechnic Institute (B. S. in general science in 1908) and Clark University (Ph. D. in physics in 1911), Goddard seems to have begun serious work on the development of rockets February 9, 1909, when he performed his first experiment on the exhaust velocity of a rocket propellant. He continued experi­mentation and in 1916 applied to the Smithsonian Institution for $5,000 to launch a rocket within a short time to extreme altitudes (100-200 miles) for meteorological and other research. He received a grant for that amount in 1917. From then until 1941 he received a total of more than $200,000 for rocket research from a variety of civilian sources.2

In 1920 he published “A Method of Reaching Extreme Altitudes" in the Smithsonian Miscellaneous Collections. As Frank Winter has stated, this “publication established Goddard as the preemi­nent researcher in the field of rocketry" and “was unquestionably very influential in the space travel movement. . . ."3 However, im­portant and pathbreaking as the paper was, it remained largely theoretical, calling for “necessary preliminary experiments" still to be performed.4 Following the paper’s publication, with partial hiatuses occasioned by periods of limited funding, Goddard spent the rest of the interwar period performing these experiments and trying to construct a rocket that would achieve an altitude above that reached by sounding balloons.

After experiencing frustrating problems using solid propellants, Goddard switched to liquid propellants in 1921. But it was not until March 26, 1926—nine years after his initial proposal to the Smith­sonian—that he was able to achieve the world’s first known flight of a liquid-propulsion rocket at the farm of Effie Ward, a distant relative, in Auburn, Massachusetts. Goddard continued his rocket research in the desert of New Mexico after 1930 for greater isola­tion from human beings, who could reveal his secrets as well as be injured by his rockets. But when he finally turned from develop­ment of high-altitude rockets to wartime work in 1941, the highest altitude one of his rockets had reached (on March 26, 1937) was estimated at between 8,000 and 9,000 feet—still a long way from his stated goals.5

One reason he had not achieved the altitudes he originally sought was that he worked with a small number of technicians instead of cooperating with other qualified rocket engineers. He achieved sig­nificant individual innovations, but he never succeeded in design­ing and testing all of them together in a systematic way so that the entire rocket achieved the altitudes he sought. Trained as a scien­tist, Goddard failed to follow standard engineering practices.6

More important than this shortcoming was his unwillingness to publish technical details of his rocket development and testing. At the urging of sponsors, he did publish a second paper, titled “Liq­uid-Propellant Rocket Development," in 1936 in the Smithsonian Miscellaneous Collections. There, Goddard addressed, much more explicitly than in his longer and more theoretical paper of 1920, the case for liquid-propellant rockets, stating their advantages over powder rockets—specifically their higher energy. Although he did discuss some details of the rockets he had developed and even in­cluded many pictures, in general the rather low level of detail and the failure to discuss many of the problems he encountered at every step of his work made this paper, like the earlier one, of limited usefulness for others trying to develop rockets.7

In 1948, Esther Goddard and G. Edward Pen dray did publish his notes on rocket development. These contained many specifics missing from his earlier publications, but by that time the Germans under Wernher von Braun and his boss, Walter Dornberger, had developed the A-4 (V-2) missile, and a group at the Jet Propulsion Laboratory (JPL) in Pasadena, California, had also advanced well be-

yond Goddard in developing rockets and missiles. He patented and developed a remarkable number of key innovations, and the two pa­pers he did publish in his lifetime significantly influenced others to pursue rocket development. But both the Germans under von Braun and Dornberger and the U. S. effort at JPL demonstrated in varying degrees that it took a much larger effort than Goddard’s to achieve the ambitious goals he had set for himself.

Because of Goddard’s comparative secrecy, Romanian-German rocket theoretician Hermann Oberth (1894-1989), oddly, may have contributed more to U. S. launch-vehicle technology than his American counterpart. Unlike Goddard, Oberth openly published 12 the details of his more theoretical findings and contributed to their Chapter 1 popularization in Germany. Because of these efforts, he was signifi­cantly responsible for the launching of a spaceflight movement that directly influenced the V-2 missile. Then, through the immigration of Wernher von Braun and his rocket team to the United States af-

ter World War II, Oberth contributed indirectly to U. S. missile and spaceflight development.

Born almost 12 years after Goddard on June 25, 1894, in the partly Saxon German town of Hermannstadt, Transylvania, Oberth attended a number of German universities but never earned a Ph. D. because none of his professors would accept his dissertation on rocketry. Undaunted by this rejection, Oberth nevertheless “re­frained from writing another" dissertation on a more acceptable and conventional topic.8

He succeeded in publishing Die Rakete zu den Planetenraumen (The Rocket into Interplanetary Space) in 1923. Although Goddard always suspected that Oberth had borrowed heavily from his 1920 paper,9 in fact Oberth’s book bears little resemblance to Goddard’s paper. Not only is Die Rakete much more filled with equations but it is also considerably longer than the paper—some 85 pages of smaller print than the 69 pages in Goddard’s paper as reprinted by the Amer­ican Rocket Society in 1946. Oberth devoted much more attention than Goddard to such matters as liquid propellants and multiple – stage rockets, whereas the American dealt mostly with solid pro­pellants and atmospheric studies but did mention the efficiency of hydrogen and oxygen as propellants. Oberth also set forth the basic principles of spaceflight to a greater extent than Goddard had done in a work much more oriented to reporting on his experimental re­sults than to theoretical elaboration. Oberth discussed such matters as liquid-propellant rocket construction for both alcohol and hydro­gen as fuels; the use of staging to escape Earth’s atmosphere; the use of pumps to inject propellants into the rocket’s combustion cham­ber; employment of gyroscopes for control of the rocket’s direction; chemical purification of the air in the rocket’s cabin; space walks; microgravity experiments; the ideas of a lunar orbit, space stations, reconnaissance satellites; and many other topics.10

The book itself was influential. Besides writing it, Oberth collab­orated with Max Valier, an Austrian who wrote for a popular audi­ence, to produce less technical writings that inspired a great deal of interest in spaceflight.11 According to several sources, Oberth’s first book directly inspired Wernher von Braun (the later technical direc­tor of the German Army Ordnance facilities at Peenemunde where the V-2 was developed, subsequently director of NASA’s Marshall Space Flight Center) to study mathematics and physics, so necessary for his later work. Von Braun had already been interested in rocketry but was a poor student, especially in math and physics, in which he had gotten failing grades. However, in 1925 he had seen an ad for Oberth’s book and ordered a copy. Confronting its mathematics,

he took it to his secondary school math teacher, who told him the only way he could understand Oberth was to study his two worst subjects. He did and ultimately earned a Ph. D. in physics.12 Without Oberth’s stimulation, who knows whether von Braun would have become a leader in the German and U. S. rocket programs?

Similarly, von Braun’s boss at Peenemunde, Walter Dornberger, wrote to Oberth in 1964 that reading his book in 1929 had opened up a new world to him. And according to Konrad Dannenberg, who had worked at Peenemunde and come to the United States in 1945 with the rest of the von Braun team, many members of the group in Germany had become interested in space through Oberth’s books. Also in response to Oberth’s first book, in 1927 the German Society for Space Travel (Verein fur Raumschiffart) was founded to raise money for him to perform rocket experiments. He served as presi­dent in 1929-30, and the organization provided considerable practi­cal experience in rocketry to several of its members (including von Braun). Some of them later served under von Braun at Peenemunde, although they constituted a very small fraction of the huge staff there (some 6,000 by mid-1943).13

Both Goddard and Oberth exemplified the pronouncement of Goddard at his high school graduation speech “that the dream of yesterday is the hope of today and the reality of tomorrow."14 But ironically it appears to have been Oberth who made the more im­portant contribution to the realization of both men’s dreams.15 In any event, both men made extraordinary, pioneering contributions that were different but complementary.

While NASA was just getting started with the massive development effort for the Saturn launch vehicles, the air force began work on what became the Titan family of launch vehicles, beginning with the Titan IIIs and ending with Titan IVBs. Essentially, most of these vehicles consisted of upgraded Titan II cores with a series of upper

stages plus a pair of huge segmented, solid-propellant, strap-on mo­tors to supplement the thrust of the Titan II core vehicle. And after September 1988, a limited number of actual Titan IIs, refurbished and equipped with technology and hardware from the Titan III program, joined the other members of the Titan family of launch vehicles. Be­ginning in June 1989, the Titan IV with a stretched core and seven (instead of Titan III’s five or five and a half) segments in its solid – rocket motors became the newest member of the Titan family.93

By September 1961, the DoD had agreed to the concept of com­bining a suitably modified Titan II with strap-on solid motors to sat­isfy military requirements; and the following month, a DoD-NASA Large Launch Vehicle Planning Group recommended the Titan III, as the vehicle had come to be designated. It would feature 120-inch – diameter solid motors and would serve both DoD and NASA needs “in the payload range of 5,000 to 30,000 pounds, low-Earth orbit equivalent."94

Although the air force’s Space Systems Division, which oversaw development of the Titan III, was later to complain about “daily redirection" of the program from the office of the director of de­fense, research and engineering, initially the launch vehicle got off to a quick start. Titan II contractor Martin Marietta Company (so – named since October 10, 1961, as a result of Martin’s merger with the American Marietta Company) won a contract on February 19, 1962. A second contract, highly significant in its requirements for development of new technology, covered the large solid-propellant rocket motors to boost the Titan III. On May 9, 1962, the air force selected a new firm, named United Technology Corporation (UTC), to develop the solid-rocket motors.95

Not long after the founding of UTC in 1958 (under the name United Research Corporation), United Aircraft Corporation pur­chased a one-third interest in the rocket firm, later becoming its sole owner. When United Aircraft changed its name to United Technologies Corporation in 1975, its solid-propellant division be – 86 came Chemical Systems Division (CSD). Formerly a contributor Chapter 2 to Minuteman, UTC’s second president, Barnet R. Adelman, had been an early proponent of segmentation for large solid-rocket mo­tors to permit easier transportation. Other firms, including Aerojet, Lockheed, and Thiokol, participated in the early development of the technology, but UTC developed its own clevis joint design to connect the segments of such boosters and its own variant on the propellant used for Minuteman to provide the propulsion.96

Because there was a Titan IIIA that did not include the solid- rocket motors, some of the Titan III first-stage engines would fire

at ground level, whereas those used on the Titan IIIC would start at altitude after the solid-rocket motors lifted the vehicle to about 100,000 feet. Titan III also featured a new third stage known as Transtage.97 This featured a pressure-fed engine using the same pro­pellants as stages one and two. Aerojet won this contract in addi­tion to those for the first two stages, with a two-phase agreement signed in 1962 and 1963. Aerojet designed the Transtage engine to feature two ablatively cooled thrust chambers and a radiatively cooled nozzle assembly.98

The Transtage engine could start and stop in space, allowing it to place multiple satellites into different orbits on a single launch or to position a single satellite in a final orbit without a need for a sepa­rate kick motor. In August 1963, tests at the simulated-altitude test chamber of the air force’s Arnold Engineering Development Center (AEDC) in Tullahoma, Tennessee, confirmed earlier suspicions that the combustion chamber would burn through before completing a full-duration firing. How Aerojet solved this and other problems is not explained in the sources for this book, only that it required “ex­tensive redesign and testing."99 Obviously, Aerojet engineers had not anticipated these problems in their initial design. Clearly, this was another example of the roles of testing and problem solving in rocket development as well as the involvement of multiple organi­zations in the process.

In any event, engine deliveries did not occur in mid-December, as initially planned, but in April 1964. Additionally, Aerojet had to test the engine at sea level and extrapolate the data to conditions at altitude. When the data from the simulated-altitude tests at AEDC came back, the extrapolated data were 2.5 percent higher than the Arnold figures. This might seem a small discrepancy to the casual reader. But since the program needed exact performance data to project orbital injection accurately, Aerojet had to investigate the discrepancy. The explanation proved to be simple, but it illustrates the difficulty of pulling together all relevant data for development of something as complex as a rocket engine, even within the same firm. It also meant that engineers did not have their procedures “down to a science" but sometimes operated with an incomplete understand­ing of the phenomena they were testing in programs where fund­ing and schedules precluded thorough and meticulous research. It turned out that other engineers working on a solid rocket had al­ready learned to decrease the calculations by 2.5 percent to extrapo­late for conditions at altitude. Once aware of this, Transtage engi­neers found several references to this correction in the literature. But obviously, they initially had failed to find those references.100

There were several problems with the Titan IIIC, resulting in 4 failures in 18 launches from September 1, 1964, to April 8, 1970.101 In ensuing years, there were many versions of the Titan III. Besides the Titan IIIA, there was a Titan 23C with uprated thrust for the core liq­uid stages and a simplified and lightened thrust-vector-control sys­tem for the solid-rocket motors. The 23C flew 22 times by March 6, 1982, with 19 successful missions and 3 failures. Overall, between the original Titan IIIC and the Titan 23C versions, Titan IIIC had 33 successful launches and 7 failures for a success rate of 82.5 per­cent. Four of the 7 failures were due to Transtage problems, without which the overall vehicle would have had a much more successful career.102

Another version of the Titan III was the Titan IIIB with an Agena D replacing the Transtage in the core stack of three stages. The Ti­tan IIIB did not use solid-rocket boosters. With the Agena D’s 5,800 pounds of thrust compared with Transtage’s roughly 1,600, the Ti­tan IIIB could launch a 7,920-pound payload to a 115-mile Earth orbit compared with 7,260 pounds for the Titan IIIA. At some point, certainly by 1976, a stretched version of the first stage converted the vehicle to a 24B configuration. And in 1971 a Titan 33B ver­sion first operated, featuring an “Ascent Agena"—so-called because it became purely a launch stage instead of staying attached to the payload to provide power and attitude control while it was in orbit. Between June 29, 1966, and February 12, 1987, various versions of the Titan IIIB (including 23B and 34B) with Agena D third stages launched some 68 times with only 4 known failures—a 94 percent success rate.103

On November 15, 1967, the Titan III Systems Program Office be­gan designing, developing, and ultimately producing the Titan IIID, which essentially added Titan IIIC’s solid-rocket motors to the Ti­tan IIIB. Perhaps more accurately, it can be considered a Titan IIIC without the Transtage. By this time, Air Force Systems Command had inactivated Ballistic and Space Systems Divisions (BSD and 88 SSD) and reunited the two organizations into the Space and Mis – Chapter 2 sile Systems Organization (SAMSO), headquartered in the former SSD location at Los Angeles Air Force Station. The D models car­ried many photo-reconnaissance payloads that were too heavy for the B models. The Titan IIID could carry a reported 24,200 pounds of payload to a 115-mile orbit, compared with only 7,920 for the B model.104 The D model appears to have launched 22 heavy-imaging satellites from June 15, 1971, to November 17, 1982. All 22 launches seem to have been successful, giving the Titan IIID a perfect launch

record.105

On June 26, 1967, NASA contracted with Martin Marietta to study the possibility of using a Titan-Centaur combination for mis­sions such as those to Mars and the outer planets in the solar sys­tem. When this possibility began to look promising, in March 1969, NASA Headquarters assigned management of the vehicle to the Lewis Research Center, with follow-on contracts going to Martin Marietta (via the air force) and General Dynamics/Convair (directly) to study and then develop what became the Titan IIIE and to adapt the Centaur D-1 for use therewith.106 The Titan IIIE and Centaur D-1T were ready for a proof flight on February 11, 1974. Unfortu­nately, the upper stage failed to start. But from December 10, 1974, to September 5, 1977, Titan IIIE-Centaurs launched two Helios so­lar probes, two Viking missions to Mars, and two Voyager missions to Jupiter and Saturn, all successful.107

By the mid – to late 1970s, air force planners perceived a need for still another Titan configuration to carry increasingly large payloads such as the Defense Satellite Communication System III (DSCS III) satellites into orbit before the Space Shuttle was ready to assume such responsibilities. (The first DSCS III weighed 1,795 pounds, a significant jump from the DSCS II weight of 1,150 pounds.) Even after the shuttle became fully operational, the Titan 34D, as the new vehicle came to be called, would continue in a backup role in case the shuttle was unavailable for any reason. The air force con­tracted with Martin Marietta in July 1977 for preliminary design, with a production contract for five Titan 34D airframes following in January 1978. SAMSO retained program responsibility for the Titan family of vehicles, and it contracted separately with suppli­ers of the component elements. It appears that the long-tank first stage was the driving element in the new vehicle. This seems to be the premise of a 1978 article in Aviation Week & Space Technol­ogy stating that CSD’s solid-rocket motors (SRMs) would add half a segment “to make them compatible with the long-tank first stage." Thus, the SRMs contained five and a half segments in place of the five used on previous Titans.108

Equipped with these longer solid-rocket motors and an uprated Transtage, the Titan 34D could carry 32,824 pounds to a 115-mile orbit, as compared with 28,600 pounds for the Titan IIIC. The 34D could lift 4,081 pounds to geosynchronous orbit, which compared favorably with 3,080 pounds for the IIIC but not with the 7,480 pounds the Titan IIIE-Centaur could carry to the same orbit.109

A quite different but important upper stage had its maiden launch on the first Titan 34D and later launched on several Titan IVs. This was the Inertial Upper Stage (IUS) that sat atop stage two on the

first Titan 34D launch. Unlike the rest of the booster, this stage was anything but easy to develop. In August 1976, the air force selected Boeing Aerospace Company as the prime IUS contractor. Soon after­ward, Boeing subcontracted with CSD to design and test the solid mo­tors to be used in the IUS. CSD chose to use a hydroxy-terminated poly­butadiene propellant (also being used by Thiokol in the Antares IIIA motor for Scout, developed between 1977 and 1979). Problems with the propellant, case, and nozzles delayed development of IUS. Vari­ous technical and managerial problems led to more than two years of delay in the schedule and cost overruns that basically doubled the originally projected cost of the IUS. These problems showed that despite more than two and a half decades of rocket development, rocket engineering still often required constant attention to small details and, where new technology was involved, a certain amount of trial and error. Including its first (and only) IUS mission, the Titan 34D had a total of 15 launches from both the Eastern and Western Test Ranges between October 1982 and September 4, 1989. There were 3 failures for an 80 percent success rate.110

By the mid-1980s, the air force had become increasingly uncom­fortable with its dependence on the Space Shuttle for delivery of military satellites to orbit. Eventually, this discomfort would lead to the procurement of a variety of Titan IV, Delta II, and Atlas II ex­pendable launch vehicles, but the air service also had at its disposal 56 deactivated Titan II missiles in storage at Norton AFB. Conse­quently, in January 1986 Space Division contracted with Martin Marietta to refurbish a number of the Titan IIs for use as launch vehicles. Designated as Space Launch Vehicle 23G, the Titan II had only two launches during the period covered by this book, on Sep­tember 5, 1988, and the same date in 1989, both carrying classified payloads from Vandenberg AFB. For a polar orbit from Vandenberg, the Titan II could carry only about 4,190 pounds into a 115-mile orbit, but this compared favorably with the Atlas E. Although the Atlas vehicle could launch about 4,600 pounds into the same orbit, 90 it required two Thiokol TE-M-364-4 solid-rocket motors in addition Chapter 2 to its own thrust to do so.111

The Titan IV grew out of the same concern about the availability of the Space Shuttle that had led to the conversion of Titan II mis­siles to space-launch vehicles. In 1984 the air force decided that it needed to ensure access to space in case no Space Shuttle was available when a critical DoD payload needed to be launched. Con­sequently, Space Division requested bids for a contract to develop a new vehicle. Martin Marietta proposed a modified Titan 34D and won a development contract on February 28, 1985, for 10 of the

vehicles that became Titan IVs. Following the Challenger disaster, the air force amended the contract to add 13 more vehicles.112

The initial version of the new booster (later called Titan IVA) had twin, 7-segment solid-rocket motors produced by CSD as a subcon­tractor to Martin Marietta. These contained substantially the same propellant and grain configuration as the Titan 34D but with an ad­ditional 1.5 segments, bringing the length to about 122 feet and the motor thrust to 1.394 million pounds per motor at the peak (vacuum) performance. The Aerojet stages one and two retained the same con­figurations as for the Titan 34D except that stage one was stretched about 7.9 feet to allow for more propellant and thus longer burning times. Stage two, similarly, added 1.4 feet of propellant tankage.113

The first launch of a Titan IV took place at Cape Canaveral on June 14, 1989, using an IUS as the upper stage. There were four more Titan IV launches during the period covered by this book, but the vehicle went on to place many more satellites into orbit into the first years of the 21st century.114 Including the 14 Titan II missiles reconfigured into launch vehicles after the missiles them­selves were retired, 12 of which had been launched by early 2003, there had been 214 Titan space-launch vehicles used by that point in time. Of them, 195 had succeeded in their missions and 19 had failed, for a 91.1 percent success rate.115 This is hardly a brilliant record, but with such a variety of types and a huge number of com­ponents that could (and sometimes did) fail, it is a creditable one. It shows a large number of missions that needed the capabilities of the Titan family members for their launch requirements.

However, if the handwriting was not yet quite on the wall by 1991, it had become clear by 1995 that even in its Titan IVB con­figuration, the Titan family of launch vehicles was simply too ex­pensive to continue very far into the 21st century as a viable launch vehicle. Based on studies from the late 1980s and early 1990s, the air force had come up with what it called the Evolved Expendable Launch Vehicle (EELV) program to replace the then-existing Delta II, Atlas II, Titan II, and Titan IV programs with a family of boosters that would cost 25 to 50 percent less than their predecessors but could launch 2,500 to 45,000 pounds into low-Earth orbit with a 98 percent reliability rate, well above that achieved historically by the Titan family.116