The Titan IIIC was an expendable launch system used by the United States Air Force from 1965 until 1982. It was the first Titan booster to feature large solid rocket motors and was planned to be used as a launcher for the Dyna-Soar, though the spaceplane was cancelled before it could fly. The majority of the launcher's payloads were DoD satellites, for military communications and early warning, though one flight (ATS-6) was performed by NASA. The Titan IIIC was launched exclusively from Cape Canaveral while its sibling, the Titan IIID, was launched only from Vandenberg AFB.
History The Titan rocket family was established in October 1955 when the Air Force awarded the Glenn L. Martin Company (later Martin Marietta and now Lockheed Martin) a contract to build an intercontinental ballistic missile (SM-68). It became known as the Titan I, the nation's first two-stage ICBM, and replaced the Atlas ICBM as the second underground, vertically stored, silo-based ICBM. Both stages of the Titan I used kerosene (RP-1) and liquid oxygen (LOX) as propellants. A subsequent version of the Titan family, the Titan II, was similar to the Titan I, but was much more powerful. Designated as LGM-25C, the Titan II was the largest USAF missile at the time and burned Aerozine 50 and nitrogen tetroxide (NTO) rather than RP-1 and LOX. The Titan III family consisted of an enhanced Titan II core with or without solid rocket strap-on boosters and an assortment of upper stages. All Solid Rocket Motor SRM-equipped Titans (IIIC, IIID, IIIE, 34D, and IV) launched with only the SRMs firing at liftoff, the core stage not activating until T+105 seconds, shortly before SRM jettison. The Titan IIIA (an early test variant flown in 1964–65) and IIIB (flown from 1966 to 1987 with an Agena D upper stage in both standard and extended tank variants) had no SRMs. The Titan III launchers provided assured capability and flexibility for launch of large-class payloads. All Titan II/III/IV vehicles contained a special range safety system known as the Inadvertent Separation Destruction System (ISDS) that would activate and destroy the first stage if there was a premature second stage separation. Titans that carried Solid Rocket Boosters (SRBs) (Titan IIIC, IIID, 34D, and IV) had a second ISDS that consisted of several lanyards attached to the SRBs that would trigger and automatically destroy them if they prematurely separated from the core, said "destruction" consisting mainly of splitting the casings open to release the pressure inside and terminate thrust. The ISDS would end up being used a few times over the Titan's career. Another slight modification to SRB-equipped Titans was the first stage engines being covered instead of the open truss structure on the Titan II/IIIA/IIIB. This was to protect the engines from the heat of the SRB exhaust. Titan III/IV SRBs were fixed nozzle and for roll control, a small tank of nitrogen tetroxide was mounted to each motor. The N2O4 would be injected into the SRB exhaust to deflect it in the desired direction. As the IIIC consisted of mostly proven hardware, launch problems were generally only caused by the upper stages and/or payload.
Launch history
The first Titan IIIC (3C-7) flew on June 18, 1965, and was the most powerful launcher used by the Air Force until it was replaced by the Titan 34D in 1982. The second launch (3C-4) in October 1965 failed, when the Transtage suffered an oxidizer leak and was unable to put its payload (several small satellites) into the correct orbit. The third launch (3C-8) in December experienced a similar failure.
The fourth IIIC launch (3C-11 on June 16, 1966) was used to send the LES 4 (Lincoln Experimental Satellite 4) into orbit. It was a US Air Force experimental communications satellite launched along with OV2-3, LES 3, and Oscar 4 from Cape Canaveral aboard a single Titan 3C rocket. It transmitted in X-band. The fifth Titan IIIC (3C-12 on August 26, 1966) failed shortly after launch when pieces of the payload fairing started breaking off. Around 80 seconds, the remainder of the shroud disintegrated, causing loss of launch vehicle control as well as the payload (a group of IDCSP satellites intended to provide radio communication for the US Army in Vietnam). The Titan performed a cartwheel, causing SRM #1 to break off the stack, activating its ISDS system and blowing up the entire launch vehicle. The exact reason for the shroud failure was not determined, but the fiberglass payload shrouds used on the Titan III up to this point were replaced with a metal shroud afterwards. A Titan IIIC in November 1970 (3C-19) failed to place its missile early warning satellite (DSP 1) in the correct orbit due to a Transtage guidance problem and a 1975 launch (3C-25) of two DSCS II (DSCS-2 5 and DSCS-2 6) military communication satellites left in LEO by a Transtage power failure. On March 25, 1978, a launch of two DSCS II satellites (3C-35 with DSCS-2 9 and DSCS-2 10) performed normally through stage 1 powered flight and part of stage 2 flight. At T+425 seconds, a hydraulic line ruptured from overpressurization caused by a malfunction of the hydraulic pump, causing immediate loss of system pressure. Engine gimbaling control was lost and the Titan began tumbling. The guidance system sensed negative acceleration and sent an automatic shutdown command to the engine. The Range Safety destruct command was sent at T+630 seconds, sending the DSCS satellites into the Atlantic Ocean. The last IIIC (3C-38 with DSP 10) was launched in March 1982.
Design
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