Friday, August 28, 2015
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 and Manned Orbiting Laboratory, though both programs were cancelled before any astronauts flew. The majority of the launcher's payloads were DoD satellites, namely for military communications and early warning, though one flight 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.
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 SRM-equipped Titans (IIIC, IIID, IIIE, 34D, and 4) launched with only the SRMs firing at liftoff, the core stage not activating until SRM jettison at two minutes into launch. The Titan IIIA (an early test variant flown in 1964-65) and IIIB (flown from 1966-87 with various upper stages) had no SRMs. The Titan III launchers provided assured capability and flexibility for launch of large-class payloads.
As the IIIC consisted of mostly proven hardware, launch problems were generally only caused by the upper stages and/or payload. The second flight in October 1965 failed when the Transstage disintegrated in orbit and a flight the following August was lost when the shroud broke up at T+78 seconds, triggering an RSO destruct. The only other total failure was in 1978 when the Titan's second stage malfunctioned and had to be destroyed.
The first Titan IIIC 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 last IIIC was launched in March 1982.
The Titan IIIC weighed about 1,380,000 lb (626,000 kg) at liftoff and consisted of a two-stage Titan core and upper stage called the Titan Transtage, both burning hypergolic liquid fuel, and two large UA1205 solid rocket boosters.
The solid boosters were ignited on the ground and were designated "stage 0". Each booster composed of five segments and was 10 ft (3.0 m) in diameter, 85 ft (26 m) long, and weighed nearly 500,000 lb (230,000 kg). They produced a combined 2,380,000 lbf (10,600 kN) thrust at sea level and burned for approximately 115 seconds. Solid booster jettison occurred at approximately 116 seconds.
About two seconds later, the first core stage ignited. Designated the Titan 3A-1, this stage was powered by two Aerojet LR-87-11 engines that burned about 240,000 lb (110,000 kg) of Aerozine 50 and nitrogen tetroxide (NTO) and produced 526,000 lbf (2,340 kN) thrust over 147 seconds. The Aerozine 50 and NTO were stored in structurally independent tanks to minimize the hazard of the two mixing if a leak should have developed in either tank.
The second core stage, the Titan 3A-2, contained about 55,000 lb (25,000 kg) of propellant and was powered by a single Aerojet LR-91-11, which produced 102,000 lbf (450 kN) for 145 seconds.
The upper stage, the Titan Transtage, also burned Aerozine 50 and NTO. Its two Aerojet AJ-10-138 engines were restartable, allowing flexible orbital operations including orbital trimming, geostationary transfer and insertion, and delivery of multiple payloads to different orbits. This required complex guidance and instrumentation. Transtage contained about 22,000 lb (10,000 kg) of propellant and its engines delivered 16,000 lbf (71 kN).