From the first flight of the Titan IIIC in 1965 to the last flight of the Titan IVB four decades later, the Titan III and IV family of launch vehicles were the most powerful rockets available to lift America’s largest defense-related payloads into space. And with the exception of a handful of payloads launched on the Space Shuttle before policy changes in the wake of the Challenger disaster were in full force, the Titans were the largest rocket available to NASA to lift its largest unmanned payloads to high Earth orbit and beyond as well. Now that they are long retired and we have reached the half century mark since their first flights, this is a good time revisit the origins of the iconic Titan IIIC rocket and the role it played in launching the first of the constellations of high tech satellites upon which America’s modern war fighting capability depends.

The Origins of the Titan III

During the late 1950s and early 1960s, the USAF and Martin Marietta (one of the corporate ancestors of today’s aerospace giant, Lockheed Martin) performed a series of studies on the feasibility of adapting their Titan II ICBM for use as a satellite launch vehicle. One of the fruits of this effort was NASA’s selection of the Titan II as the Gemini Launch Vehicle (GLV) in October 1961 for their follow on to the Mercury program (see “The Launch of Gemini 1”). The USAF also sought to develop its own independent launch capability to orbit a growing list of defense-related payloads. On October 13, 1961 the Titan III was officially selected as the launch vehicle for the USAF.

The Titan III launch vehicle concept was based on a modular approach that could lift payloads into a variety of orbits and included a heavy lift capability that was, for political reasons, independent of NASA’s Saturn family of launch vehicles. At the core of all versions of the Titan III was a modified two-stage Titan II ICBM that was structurally reinforced to handle heavier payloads and extra stages. Like the Titan II ICBM and GLV, the engines of the 3-meter in diameter Titan III core used nitrogen tetroxide as an oxidizer and a blend of hydrazine and unsymmetrical dimethyl hydrazine (UDMH) known as Aerozine-50 as a fuel. In addition to being storable (theoretically enabling the Titan III to remain fueled on the pad for a quick-response launch option), this toxic propellant combination is hypergolic or ignites spontaneously on contact thus simplifying engine design in the process.

The engines in the first two stages of the initial models of the Titan III were slightly modified versions of the ones originally employed by the Titan II ICBM and possessed the same performance characteristics. The 22.3-meter long first stage used a pair of LR-87-9 engines built by Aerojet (now part of Aerojet Rocketdyne) to generate 1,910 kilonewtons of thrust at sea level (the Titan II ICBM and GLV used LR-87-3 and LR-87-5 engines, respectively). The 7.9-meter long second stage was fitted with an Aerojet LR-91-9 engine generating 445 kilonewtons of thrust. These two stages were employed in the first version of the Titan IIIB which was used primarily to orbit the KH-8 Gambit 3 spy satellites starting in 1966. The KH-8, whose design incorporated a Lockheed Agena D upper stage for orbit insertion and in-orbit maneuvering, was too heavy for the Atlas and Thor rockets used to lift earlier Agena-based spy satellites and required the more powerful Titan IIIB.

While the Titan IIIB was capable of meeting USAF medium-class payload needs for low Earth orbit, an additional upper stage with much flexibility was required for a variety higher altitude missions. To meet this requirement, a restartable third stage was developed by Martin Marietta called the Transtage. Like the first two stages of the Titan III, the 7.6-meter long Transtage employed Aerozine-50 and nitrogen tetroxide as propellants for a pair of Aerojet AJ10-138 engines. Similar in design to the larger AJ10-137 engine being developed by Aerojet at this time for the Apollo Service Module, this pair of gimbaled, pressure-fed engines had ablatively cooled thrust chambers and radiatively cooled nozzle assemblies generating a total of 71 kilonewtons of thrust. The Transtage carried a modified Titan II inertial guidance system to control not only itself but also the other Titan III stages during ascent. The Transtage was designed for up to 6.5 hours of autonomous operation in orbit with multiple engine restarts. The Transtage gave the Titan III flexibility in placing payloads in low, medium or high-earth orbits or even on escape trajectories to the Moon or beyond. The launch vehicle consisting of the modified Titan II core with the new Transtage was designated the Titan IIIA. Theoretically the Titan IIIA, which was almost 38 meters tall, was capable of placing up to about four metric tons into low orbit or about a metric ton into a geosynchronous transfer orbit.

The penultimate member of the original Titan III family was the Titan IIIC. Added to the sides of the Titan IIIA were a pair of 3-meter in diameter solid rocket motors manufactured by United Technology Corporation. Consisting of five-segments each that were assembled at the launch site, this pair of solid rocket motors made up “Stage 0” of the Titan IIIC and generated a total of 10,500 kilonewtons of thrust at lift off giving the Titan IIIC half again the liftoff thrust of NASA’s Saturn I. These solid motors would lift the Titan III core so that its first stage could ignite at altitude after Stage 0 burnout. The Titan IIIC offered the USAF a heavy-lift capability that could outperform NASA’s Saturn I by placing up to 13 metric tons of payload into low orbit (see “The Largest Launch Vehicles Through History“). In practice, the Titan IIIC, with its adaptable Transtage, was typically used to place lighter payloads into medium to high-altitude Earth orbits including up to about 1,600 kilograms into geosynchronous orbit.

Since the requirements to prepare and launch the Titan IIIC and its payloads far surpassed the capabilities of existing facilities at Cape Kennedy, a totally new ITL (Integrate Transfer and Launch) complex was constructed north of the existing set of launch pads. The ITL included the Vertical Integration Building (VIB) which could support the assembly of up to four Titan III core vehicles at one time. The VIB also housed the launch control center for the Titan III. Completed cores would then be moved by rail to the Solid Motor Assembly Building (SMAB) where the segments of the pair of rocket motors were attached to the rocket. The assembled Titan III rockets were then moved by rail to any one of three pads designated Launch Complex 40, 41 and 42 (although planned, LC-42 was never actually built). Other buildings to support processing, inspection and storage of payloads and rocket components connected by 32 kilometers of rail lines rounded out the ITL facilities.

The First Titan IIIC Launches

The first member of the Titan III family to fly was the Titan IIIA. Although the Titan IIIA could have been used as a medium-class launch vehicle in its own right, in the end it was flown only to support development of the Titan III rocket family. While the first launch on September 1, 1964 failed to reach orbit due to a problem in the pressurization of the Transtage propellant tanks, the following three launches were all successful (see “The First Titan III Launch”). Not only were the modifications to the first two stages of the Titan III core successfully tested, but the restartable Transtage successfully completed an increasingly complex series of in-orbit maneuvers during each successive mission while placing several small Defense Department test satellites into orbit.

After the completion of a 28-month test program on April 28, 1965 with the 14th successful static test firing of the solid rocket motors for the Titan IIIC along with the end of the Titan IIIA test flight program on May 6, the way was now clear for the first launch of the Titan IIIC. The goal of the first flight was rather straightforward: place a heavy dummy payload into low Earth orbit. Titan IIIC number 3C-7 lifted off from LC-40 at 14:00:04 UT on June 18, 1965. As intended, the core’s first stage ignited at altitude as thrust from the pair of solid rocket motors tailed off followed ten seconds later by their separation. The core stages, ending with a single burn of the Transtage, successfully placed the dummy payload into a 167-by-190-kilometer orbit with an inclination of 32.2°. The Transtage later released the dummy payload on the fourth orbit which subsequently decayed on June 29. With a mass of 9.7 metric tons, at the time it was reported that this was the heaviest payload ever placed into orbit by a rocket.

With this success, a more ambitious test flight was planned for the second Titan IIIC mission with a total of ten burns of the Transtage planned. This flight, using vehicle number 3C-4, carried two Defense Department payloads. The first was called the Lincoln Calibration Sphere 2 (LCS 2) built by MIT’s Lincoln Laboratory located in Bedford, Massachusetts in support of an ARPA (Advanced Research Projects Agency) program. Like LCS 1 which was successfully placed into orbit by the last Titan IIIA launch, LCS 2 was a hollow aluminum sphere 1.13 meters across with a mass of 34 kilograms. The primary purpose of the LCS was to provide a passive orbiting target with a cross section of exactly one square meter for radio and radar system sensitivity calibrations. Tracking of LCS 2 would also provide scientifically valuable information on atmospheric density, Earth’s gravitational field and the effects of weather on radio wave propagation. The plan for the second Titan IIIC flight was for LCS 2 to be deployed into a circular 740-kilometer orbit after the second burn of the Transtage.

The second payload carried on this test flight was the first of the new OV2-series of satellites built as part of the USAF’s Aerospace Research Support Program. A joint program of the Air Force Space Command (AFSC) and Office of Aerospace Research (OAR), the purpose of the OV satellite series was to provide low cost satellites to support USAF space research. The OV1 series of satellites built by General Dynamics were initially designed to be launched as piggyback payloads on suborbital Atlas ICBM test flights and later on surplus Atlas missiles dedicated to OV1 launches (see “Riding Piggyback on an ICBM”).

The OV2 satellites, built by Northrop, were much more complex than the OV1. The main body of the spacecraft was roughly cube shaped with sides about 58 centimeters wide and 61 centimeters tall. Four solar panels holding a total of 20,160 solar cells extended from the upper corners of the structure to provide the spacecraft’s systems and experiments with 63 watts of electrical power. The first satellite in the series, OV2-1, had a total mass of 170 kilograms and carried 59 kilograms of instruments to support 14 experiments that primarily addressed the biological hazards of the near-Earth charged particle environment. The plan was to deploy OV2-1 into a 740-by-7,400 kilometer orbit after the third burn of the Transtage engines.

The second Titan IIIC lifted off from LC-40 at 17:23:59 UT on October 15, 1965 and entered its initial transfer orbit. Unfortunately, during the firing of the core’s second stage, an oxidizer leak had developed in that stage and the Transtage began leaking fuel as well. Upon separation of the Transtage, a minor explosion took place causing the bi-propellant valve in one of the Transtage’s two engines to become stuck in the open position. With the affected engine continuing to fire after the other had shut down as programmed at the scheduled end of the first burn, the Transtage and its attached payloads began to tumble and broke up leaving the Transtage in a 521-by-990 kilometer orbit. The orbital mission was a failure and the satellites were lost.

The First Titan IIIC Comsat Launches

Modifications were made to the Transtage bi-propellant valves and a third test flight using vehicle number 3C-8 was prepared. For this test flight, the Transtage would test its ability to place payloads into 33,725-kilometer high, near-synchronous equatorial orbits in preparation for the deployment of a Defense Department communications satellite (comsat) constellation on future Titan IIIC launches. For this mission, four test payloads were carried. The largest satellite in the mix was the second satellite in the OV2 series. The 194-kilogram OV2-3 was similar to its predecessor but carried a new mix of instruments with a mass of 61 kilogram designed to gather data in support of 15 experiments addressing the effects of solar activity on space radiation and magnetic fields for a nominal two-year mission.

The other three payloads were various communication satellites. Two of them were part of Lincoln Laboratory’s ongoing Lincoln Experiment Satellite (LES) series. The 16-kilogram LES 3 was a polyhedron about 60 centimeters across and was similar in design to the LES 1 and 2 satellites launched during test flights of the Titan IIIA. LES 3 was designed to transmit a UHF beacon for its one-year mission to evaluate factors affecting satellite communications. The larger 52-kilogram LES 4 was a ten-sided polyhedron 85 centimeters across and 91 centimeters tall. It carried test equipment designed to operate in the X-band. The third satellite was the 13-kilogram Oscar 4 built by the amateur radio satellite organization, AMSAT, to provide a long distance radio link for ham radio operators. These would all be microsatellites by today’s definition.

The third Titan IIIC test flight lifted off from LC-41 at 14:00:01 UT on December 21, 1965. While the Transtage with its load of test satellites was successfully placed into a temporary 169-kilometer parking orbit, the oxidizer valve on the Transtage’s attitude control system became stuck open possibly as a result of contamination in the system. Despite the leak, the Transtage completed its second of three planned burns to place itself and payload into a 185-by-33,800-kilometer equatorial transfer orbit. Unfortunately, during the long coast before the final ignition of the Transtage, its attitude control system oxidizer supply was exhausted bringing the mission to a premature conclusion. Ground controllers were able to deploy the three communications satellites which were then able to fulfill many of their original objectives despite being placed into an incorrect orbit. OV2-3 failed to deploy at all and was a total loss.

As the causes of the latest string of Transtage problems were diagnosed and corrected, work pushed ahead to prepare for the next launch of the Titan IIIC. This would be the first launch of the Initial Defense Communication Satellite Program (IDCSP). Run by the Defense Communication Agency with the USAF in charge of the space segment and the US Army responsible for the ground segment, the IDCSP was an experimental X-band comsat constellation built by Philco to provide strategic and tactical communications for the US military around the globe. The initial plan was for a total of 22 satellites each with a mass of 45 kilograms (making these microsatellites by today’s standards) to be deployed by a total of three Titan IIIC launches into near-synchronous orbits. Each spin stabilized satellite was a 24-sided polyhedron 81 centimeters across and 91 centimeters tall. Each satellite was capable of supporting up to 600 voice or 6,000 teletype channels between appropriately equipped ground stations.

For a typical launch, up to eight IDCSP satellites would be carried on a truss structure mounted on top of the Transtage. Once in a near-synchronous orbit, the satellites would be deployed one at a time over the course of three minutes and allowed to drift randomly at an average rate of 28.5° per day into a more or less evenly spaced belt of satellites above the Earth’s equator where they would support long distance communications. For the first launch, only seven IDCSP satellites were carried. The eighth slot on this flight was occupied by a Gravity Gradient Test Satellite (GGTS). The 47-kilogram GGTS 1 was similar in configuration to the IDCSP satellites but included a pair of 16-meter long booms to test gravity gradient attitude control for future high altitude payloads.

The fourth Titan IIIC, vehicle number 3C-11, lifted off from LC-41 at 14:00:01 UT on June 16, 1966. This time the Transtage successfully completed its three burns to enter a 33,670-by-33,892 kilometer orbit with an inclination of 0.25°. GGTS 1 was the first to be ejected and stabilized itself as planned. All seven IDCSP satellites were deployed into near-synchronous orbits that drifted an average of 27.8° per day. Initial communications tests between the ground station at Fort Dix, New Jersey and sites in California, England and Germany were very successful and proved the utility of satellite communications to support global military operations

While the next launch of the Titan IIIC using vehicle number 3C-12 carrying the second batch of IDCSP satellites was unsuccessful on August 26, 1966 when the payload fairing failed during ascent, this would prove to be the last Titan IIIC launch failure during its development program. The third batch of eight IDCSP satellites was successfully placed into orbit by the seventh Titan IIIC flight using vehicle number 3C-13 launched on January 28, 1967. Although the IDCSP constellation was meant to be experimental, it proved to be so valuable that it was quickly expanded with additional launches and transitioned into operational use especially in support of America’s quickly escalating involvement in southeast Asia. The Titan IIIC and the payloads it carried were quickly becoming vital parts of America modern defense planning.

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Related Videos

Here is a short Universal Newsreel about the first Titan IIIC launch on June 18, 1965.

Here is 1967 USAF documentary film providing an excellent overview of the Titan III and its ground facilities entitled “For Today and Tomorrow”.

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Related Reading

“The First Titan III Launch”, Drew Ex Machina, September 1, 2014 [Post]

“The Largest Launch Vehicles Through History”, Drew Ex Machina, February 19, 2018 [Post]

“Riding Piggyback on an ICBM”, Drew Ex Machina, January 21, 2015 [Post]

General References

David Baker, The Rocket: The History and Development of Rocket & Missile Technology, Crown Publishing, 1978

J.D. Hunley, U.S. Space-Launch Vehicle Technology: Viking to Space Shuttle, University Press of Florida, 2008

“Segmented Solid Ready for Flight”, Flight International, p. 804, May 20, 1965

“Aerospace Research Support Program”, TRW Space Log, Vol. 5, No. 4, pp. 15-17, Winter 1965-66

“Lincoln Experimental Satellite”, TRW Space Log, Vol. 5, No. 4, pp. 28-30, Winter 1965-66

“U.S. Military Comsat System Planned”, Flight International, pp. 75-77, January 13, 1966

“Initial Defense Communication Satellite Program”, TRW Space Log, Vol. 6, No. 2, pp. 34-36, Summer 1966