The Titan III launch vehicle was the result of an effort by military planners to increase low orbit payload weight to 25,000 pounds, establish a high degree of standardization, and provide significantly greater economies of operation, using a vehicle assembled from standard building blocks and possessing high reliability and mission flexibility. The choice for the core was Titan II, most powerful American ICBM. The concept grew to include a new pressure fed third stage topped by a control module and a standard payload fairing. This basic "core," designated Titan IIIA, would be capable of lofting significant payload weights-5,800 pounds into a low (100 nautical mile) circular orbit or 3,600 pounds into a 1,000 nautical mile circular orbit. The technically unique element of the system was the addition of solid propellant motors to vastly augment an otherwise nominal payload capacity. [(3)]
The Titan III designation was initially used in mid-1959 for a two stage 160-inch diameter non-cryogenic missile (with a Centaur third stage) as a successor to Titan II with a capability of fulfilling the Saturn space mission. [(4)] Initially there was no specific role for Titan III, apart from the X-20 Dyna Soar. The Manned Orbiting Laboratory (MOL) became a candidate in December 1963. [(5)]
Titan III was based on a design concept which called for full exploitation of existing technology. The first stage of the core was a modified Titan II stage with simplified propulsion and electrical systems. The Aerojet-General LR-87 first stage engine differed from the Titan II engine in having an altitude start capability and insulation around the engine compartment to protect against heat radiated by the solid motors. Like the first stage, the second stage was essentially a variation on Titan II design, with a reinforced structure and more reliable propulsion. [(6)]
Motors of Titan III size and thrust had never been manufactured and tested. The design for each motor was fixed at five interchangeable 121 inch diameter segments plus forward and aft closures. At the end of World War II solid propellant rockets, while used in some minor weapons applications, were still in their development infancy. But during the 1950's solid propellant technology accumulated gains in metallurgy, chemistry and high temperature materials. By 1957, large solid rocket motors up to 60 inches in diameter, containing as much as 25,000 pounds of propellant, had been assembled and successfully fired. Contracts were awarded for an advanced "second generation" intercontinental ballistic missile, the Minuteman. The Navy was developing the Polaris solid propellant intermediate range missile at about the same time. Validity of the concept was demonstrated on 1 September 1959 when the first large size solid propellant, flight weight motor, over 24 feet long and over five feet in diameter, weighing over 50,000 pounds, was successfully fired.
Despite the engineering effort involved in the development of Minuteman, the "breakthrough" idea of segmented motors held the potential to create motors of massive size. A segmented solid motor was made of huge single-castings (grains) stacked on top of each other, with the ends knocked out and in a single casing made by bolting together the several segment walls. In March 1959, Wright Air Development Center's Solid Rocket Branch (Power Plant Laboratory) at Edwards Air Force Base invited industry to bid on demonstrating a segmented solid motor, with a contract awarded on 5 August 1960. Aerojet demonstrated the first such rocket motor on 3 June 1961 -- a 100 inch diameter single center segment motor which delivered 450,000 pounds of thrust for 45 seconds. On 29 August a two segment motor delivered 460,000 pounds of thrust and operated for 67 seconds. These were the highest thrust performances so far recorded for any solid propellant motor. United Technology Corporation continued privately funded development and testing of a single-segment, 256,000 pound thrust motor and a two-segment, 482,000 pound thrust motor. The segmented solid motor concept, new high performance solid propellants, and lightweight materials promised large gains in space vehicle performance. Technical evolution merged with military necessity to create the combined solid-liquid propulsion techniques utilized in the Titan III launch vehicle. [(7)]
Titan IIIA was a two-stage liquid-propellant vehicle that employed two solid-propellant motors to augment the thrust capability of the basic vehicle during lift-off. When a vehicle is launched without the solid-propellant motor, using only the two liquid stages, it is known as a core-only vehicle. Development of a third generation Titan began in 1961 when the need for a larger payload capability became evident. Titan IIIA flew four development missions, then was integrated into the IIIC configuration.
Titan IIIB used radio guidance with a 5-ft diameter Agena upper stage and payload fairing (PLF), the Ascent Agena upper stage with strapdown guidance and a 10-ft PLF, and a stretched core with the same two upper stages and PLFs for low-Earth orbits (LEO) from WSMC. The last launch of the Titan IIIB core-only vehicle from the Western Space and Missile Center in the mid-1970s.
Titan IIIC/Transtage, with other various upper stages, achieved greater mission and flight plan flexibility. It flew from Cape Canaveral Air Force Station. Some flights involved four to eight payloads that were integrated from as many as three different payload sources.
Transtage was designed, developed, and built for a variety of space operations. It incorporates guidance, attitude control, structures, thermal control, tracking, power, instrumentation, propulsion, range safety, retrorockets, and payload delivery subsystems. This flexible space system has carried out missions involving ballistic, low-orbit insertion, synchronous equatorial orbit insertion, orbit trim, orbit transfer, orbital plane change, and multiple payload separation maneuvers. The Eastern Space and Missile Center was the site of its last launching in 1982.
Titan IIID, launched from the Western Space and Missile Center, was similar to the Titan IIIC. Since it did not use an upper stage, its avionics were transferred to stage I and 11.
Titan IIIE was adapted for interplanetary non-DOD use at Eastern Space and Missile Center (ESMC), included a Centaur D-lT upper stage with a 14-ft diameter PLF. Similar to the Titan IIID, the biggest difference was the inertial guidance system's replacement of the radio guidance, packaged in the Centaur D-IT upper stage. It successfully boosted two Viking spacecraft to Mars; two Voyagers to Jupiter, Saturn, and Uranus; and two HELIOS spacecraft to explore inside Mercury's orbit. The last launch of the Titan IIIE took place at the Eastern Space and Missile Center in 1977.
Titan IIIM was designed to launch the Manned Orbiting Laboratory (MOL) from the Western Space and Missile Center. Although President Johnson canceled the MOL program, the design for the IIIM was the forerunner of the fourth generation Titan, the Titan 34 series.
The Titan 34B and 34D vehicles are derivatives of the Titan III class and are outgrowths of the Titan IIIM, originally designed to launch the Air Force Manned Orbiting Laboratory (MOL) from Vandenberg AFB. Although the MOL program was cancelled, much of the design effort was transferable to the Titan 34 vehicles. The 34B had a 10-foot diameter payload fairing with a length up to 57.9 feet. This vehicle accommodated a variety of upper stage and payload combinations that were launched into polar and other high-inclination orbits. The 34D is a stretched version of the 34B core vehicle and it incorporated 2 five-and-one-half segment Solid Rocket Motors. This vehicle was used with several upper stages (Inertial Upper Stage (IUS), Agenda, Transtage), payload fairings, and guidance configurations.
Titan 34B had an improved guidance system, increased structural capability to support heavier payloads, a stretched core, and a larger payload fairing system that allowed more space for larger payloads.
Titan 34D was developed to provide the Air Force with an orderly transition from expendable launch vehicles to the Space Shuttle and to provide backup to the Shuttle. Titan 34D used the Inertial Upper Stage in its first launch in 1982, from the Eastern Space and Missile Center. Since the Titan 34D used larger solid propellant motors than the Titan IIID, it had a payload capability that makes it the largest launch vehicle in both size and capability. It weighs 689,300 kilograms at lift-off and generated 12,998 kilonewtons of thrust. (Space Transportation System). The Titan 34D series stretched-core configurations was the most advanced of the Titan family. The Titan 34D used the stretched core of the Titan 34B with 5-1/2 segment SRMs, and has been integrated with several launch vehicle upper stage, PLF, and guidance configurations. The 34D had since evolved into the Titan IV, which provided greater DOD lifting capability.
Commercial Titan III launch vehicle was an upgraded version of the Titan 34D. The enhanced performance upgrades included using the liquid fuel engines used on the Titan IV; stretching Stage 2 17 in.; and incorporating the dual payload carrier. The Commercial Titan was deployed for single and dual payload missions to LEO.
Commercial Titan III-Transtage was a three-stage vehicle using the Transtage, which was developed for the US Air Force space missions. Stages 0, I, and II are identical to those on the Commercial Titan except that the Stage II forward skirt is stretched to accommodate the Transtage propellant tanks and engines, and the avionics system and attitude control system (ACS) are removed from Stage II and placed in Transtage. The Transtage ensures engine restart in a zero-gravity environment. The Commercial Titan m-Transtage was deployed for single and dual payload missions to geosynchronous transfer orbit (GTO).
3. Adapted from: Robert F. Piper, History of Titan III -- 1961-1963, (Air Force Space Systems Division Historical Division, June 1964), page 118.
4. Adapted from: Robert F. Piper, History of Titan III -- 1961-1963, (Air Force Space Systems Division Historical Division, June 1964), page 25.
5. Adapted from: Robert F. Piper, History of Titan III -- 1961-1963, (Air Force Space Systems Division Historical Division, June 1964), page viii.
6. Adapted from: Robert F. Piper, History of Titan III -- 1961-1963, (Air Force Space Systems Division Historical Division, June 1964), page 120.
7. Adapted from: Robert F. Piper, History of Titan III -- 1961-1963, (Air Force Space Systems Division Historical Division, June 1964), pages 126-128.
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