The Titan II was an intercontinental ballistic missile (ICBM) developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later adapted as a medium-lift space launch vehicle (these adaptations were designated Titan II GLV and Titan 23G) to carry payloads to Earth orbit for the United States Air Force (USAF), National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA). Those payloads included the USAF Defense Meteorological Satellite Program (DMSP), NOAA weather satellites, and NASA's Gemini crewed space capsules. The modified Titan II SLVs (Space Launch Vehicles) were launched from Vandenberg Air Force Base, California, up until 2003.
Titan II missile Part of the Titan rocket family, the Titan II ICBM was the successor to the Titan I, with double the payload. Unlike the Titan I, it used hydrazine-based hypergolic propellant which was storable and reliably ignited. This reduced time to launch and permitted it to be launched from its silo. Titan II carried the largest single warhead of any American ICBM.
LGM-25C missile The missile consists of a two-stage, rocket engine powered vehicle and a re-entry vehicle (RV). Provisions are included for in-flight separation of Stage II from Stage I, and separation of the RV from Stage II. Stage I and Stage II vehicles each contain propellant and pressurization, rocket engine, hydraulic and electrical systems, and explosive components. In addition, Stage II contains the flight control system and missile guidance system. Stage I contained three gyros and the Autopilot. The Autopilot attempted to keep the missile straight during first stage flight and sent commands to the Inertial Measurement Unit (IMU) on the 2nd stage. The IMU would compensate and send steering commands to the engine actuators.
Airframe The airframe is a two-stage, aerodynamically stable structure that houses and protects the airborne missile equipment during powered flight. The missile guidance system enables the shutdown and staging enable relay to initiate Stage I separation. Each stage is 10 feet (3.0 m) in diameter and has fuel and oxidizer tanks in tandem, with the walls of the tanks forming the skin of the missile in those areas. External conduits are attached to the outside surface of the tanks to provide passage for the wire bundles and tubing. Access doors are provided on the missile forward, aft and between-tanks structure for inspection and maintenance. A removable cover for tank entry is located on the forward dome of each tank.
Stage I airframe The Stage I airframe consists of an interstage structure, oxidizer tank forward skirt, oxidizer tank, inter-tank structure, and fuel tank. The interstage structure, oxidizer tank forward skirt, and inter-tank structure are all fabricated assemblies using riveted skin, stringers and frame. The oxidizer tank is a welded structure consisting of a forward dome, tank barrel, an aft dome and a feedline. The fuel tank, also a welded structure, consists of a forward dome, tank barrel, aft cone, and internal conduit.
Stage II airframe The Stage II airframe consists of a transition section, oxidizer tank, inter-tank structure, fuel tank and aft skirt. The transition section, inter-tank structure and aft skirt are all fabricated assemblies using riveted skin, stringers and frame. The oxidizer tank and fuel tank are welded structures consisting of forward and aft domes.
Missile characteristics The following data is from publication T.O. 21M-LGM25C-1 – via Wikisource. (Dash 1)
Guidance The first Titan II guidance system was built by ACDelco. It used an IMU (inertial measurement unit, a gyroscopic sensor) made by ACDelco derived from original designs from MIT Draper Labs. The missile guidance computer (MGC) was the IBM ASC-15. Stage I contained three gyros and the Autopilot. The Autopilot attempted to keep the missile straight during first stage flight and sent commands to the IMU on the 2nd stage. The IMU would compensate and send steering commands to the engine actuators. When spares for this system became hard to obtain, it was replaced by a more modern guidance system, the Delco Universal Space Guidance System (USGS). The USGS used a Carousel IV IMU and a Magic 352 computer.
Launching Titan II missiles were designed to be launched from underground missile silos that were hardened against nuclear attack. This was intended to allow for the United States to survive a nuclear first strike by an enemy and be able to retaliate with a second strike response. The authority to order the launch of a Titan II was vested exclusively in the US President. Once an order was given to launch, launch codes were sent to the silos from SAC HQ or its backup in California. The signal was an audio transmission of a thirty-five-letter code.
The two missile operators would record the code in a notebook. The codes were compared to each other and if they matched, both operators proceeded to a red safe containing the missile launch documents. The safe featured a separate lock for each operator, who unlocked it using a combination known only to themself. The safe contained a number of paper envelopes with two letters on the front. Embedded in the thirty-five letter code sent from HQ was a seven-letter sub-code. The first two letters of the sub-code indicated which envelope to open. Inside was a plastic "cookie", with five more letters written on it. If the cookie matched the remaining five digits in the sub-code, the launch order was authenticated. The message also contained a six-letter code that unlocked the missile. This code was entered on a separate system that opened a butterfly valve on one of the oxidizer lines on the missile engines. Once unlocked, the missile was ready to launch. Other portions of the message contained a launch time, which might be immediate or might be any time in the future.
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