Titan (rocket family)
Titan was a family of American intercontinental ballistic missiles and medium- and heavy-lift expendable launch vehicles used between 1959 and 2005. The Titan I and Titan II served as part of the United States Air Force's ICBM arsenal until 1987, while later variants were adapted for space launch purposes. Titan launch vehicles were used for 368 missions in total, including all Project Gemini crewed flights in the mid-1960s, as well as numerous U.S. military, civilian, and scientific payloads—ranging from reconnaissance satellites to space probes sent throughout the Solar System.
Titan I missile
The HGM-25A Titan I, built by the Martin Company, was the first version of the Titan family of rockets. It began as a backup ICBM project in case the SM-65 Atlas was delayed. It was a two-stage rocket operational from early 1962 to mid-1965 whose LR-87 booster engine was powered by RP-1 and liquid oxygen. The ground guidance for the Titan was the UNIVAC ATHENA computer, designed by Seymour Cray, based in a hardened underground bunker. Using radar data, it made course corrections during the burn phase.Unlike decommissioned Thor, Atlas, and Titan II missiles, the Titan I inventory was scrapped and never reused for space launches or RV tests, as all support infrastructure for the missile had been converted to the Titan II/III family by 1965.
Titan II
The Titan II family consists of the Titan II ICBM and two later versions adapted for space launches, the Titan II GLV and the Titan 23G.Titan II missile
Most of the Titan rockets were the Titan II ICBM and their civilian derivatives for NASA. The Titan II used the LR-87-5 engine, a modified version of the LR-87, that used a hypergolic propellant combination of nitrogen tetroxide for its oxidizer and Aerozine 50 instead of the liquid oxygen and RP-1 propellant of the Titan I.The first Titan II guidance system was built by AC Spark Plug. It used an inertial measurement unit made by AC Spark Plug derived from original designs from the Charles Stark Draper Laboratory at MIT. The missile guidance computer was the IBM ASC-15. When spares for this system became hard to obtain, it was replaced by a more modern guidance system, the Delco Electronics Universal Space Guidance System. The USGS used a Carousel IV IMU and a Magic 352 computer. The USGS was already in use on the Titan III space launcher when work began in March 1978 to replace the Titan II guidance system. The main reason was to reduce the cost of maintenance by $72 million per year; the conversions were completed in 1981.
Hypergolic propellants
Liquid oxygen is dangerous to use in an enclosed space, such as a missile silo, and cannot be stored for long periods in the booster oxidizer tank. Several Atlas and Titan I rockets exploded and destroyed their silos, although without loss of life. The Martin Company was able to improve the design with the Titan II. The RP-1/LOX combination was replaced by a room-temperature fuel whose oxidizer did not require cryogenic storage. The same first-stage rocket engine was used with some modifications. The diameter of the second stage was increased to match the first stage. The Titan II's hypergolic fuel and oxidizer ignited on contact, but they were highly toxic and corrosive liquids. The fuel was Aerozine 50, a 50/50 mix of hydrazine and UDMH, and the oxidizer was NTO.Accidents at silos
There were several accidents in Titan II silos resulting in loss of life and/or serious injuries.In August 1965, 53 construction workers were killed in fire in a missile silo northwest of Searcy, Arkansas. The fire started when hydraulic fluid used in the Titan II was ignited by a welding torch.
The liquid fuel missiles were prone to developing leaks of their toxic propellants. At a silo outside Rock, Kansas, an oxidizer transfer line carrying NTO ruptured on August 24, 1978. An ensuing orange vapor cloud forced 200 rural residents to evacuate the area. A staff sergeant of the maintenance crew was killed while attempting a rescue and a total of twenty were hospitalized.
Another site at Potwin, Kansas leaked NTO oxidizer in April 1980 with no fatalities, and was later closed.
In September 1980, at Titan II silo 374-7 near Damascus, Arkansas, a technician dropped an socket that fell, bounced off a thrust mount, and broke the skin of the missile's first stage, over eight hours prior to an eventual explosion. The puncture occurred about 6:30 p.m. and when a leak was detected shortly after, the silo was flooded with water and civilian authorities were advised to evacuate the area. As the problem was being attended to at around 3 a.m., leaking rocket fuel ignited and blew the nuclear warhead out of the silo. It landed harmlessly several hundred feet away. There was one fatality and 21 were injured, all from the emergency response team from Little Rock AFB. The explosion blew the 740-ton launch tube cover into the air and left a crater in diameter.
Missile retirement
The 54 Titan IIs in Arizona, Arkansas, and Kansas were replaced by 50 MX "Peacekeeper" solid-fuel rocket missiles in the mid-1980s; the last Titan II silo was deactivated in May 1987. The 54 Titan IIs had been fielded along with a thousand Minuteman missiles from the mid-1960s through the mid-1980s.A number of Titan I and Titan II missiles have been distributed as museum displays across the United States.
Titan II launch vehicle
The most famous use of the civilian Titan II was in the NASA Gemini program of crewed space capsules in the mid-1960s. Twelve Titan II GLVs were used for Project Gemini. Two flights were uncrewed and the remaining ten carried two-person crews. All of the launches were successful.Titan 23G
Starting in the late 1980s, some of the deactivated Titan IIs were converted into space launch vehicles to be used for launching U.S. Government payloads.Titan 23G rockets consisted of two stages burning liquid propellant. The first stage was powered by one Aerojet LR87 engine with two combustion chambers and nozzles, and the second stage was propelled by an LR91. On some flights, the spacecraft included a kick motor, usually the Star-37XFP-ISS; however, the Star-37S was also used.
Thirteen were launched from Space Launch Complex 4W at Vandenberg Air Force Base starting in 1988. The final such vehicle launched a Defense Meteorological Satellite Program weather satellite on 18 October 2003.
Titan III
The Titan III was a modified Titan II with optional solid rocket boosters. It was developed on behalf of the United States Air Force as a heavy-lift satellite launcher to be used mainly to launch American military payloads and civilian intelligence agency satellites such as the Vela Hotel nuclear-test-ban monitoring satellites, observation and reconnaissance satellites, and various series of defense communications satellites. As USAF project, Titan III was more formally known as Program 624A, Standard Space Launch System, Standardized Space Launch System, Standardized Space Launching System or Standard Space Launching System.The Titan III core was similar to the Titan II, but had a few differences. These included:
- Thicker tank walls and ablative skirts to support the added weight of upper stages
- Radio ground guidance in place of the inertial guidance on ICBM Titan IIs
- Guidance package placed on the upper stages
- Removal of retrorockets and other unnecessary ICBM hardware
- Slightly larger propellant tanks in the second stage for longer burn time; since they expanded into some unused space in the avionics truss, the actual length of the stage remained unchanged.
Avionics
The first guidance system for the Titan III used the AC Spark Plug company IMU and an IBM ASC-15 guidance computer from the Titan II. For the Titan III, the ASC-15 drum memory of the computer was lengthened to add 20 more usable tracks, which increased its memory capacity by 35%.The more-advanced Titan IIIC used a Delco Carousel VB IMU and MAGIC 352 Missile Guidance Computer.