Titan Space-Launch Vehicles, 1961-91

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