The first uprated Titan 4 booster was launched from Cape Canaveral, Florida, on 22 February, carrying a US Air Force Defense Space programme missile early-warning satellite into geostationary orbit (GEO). The $200 million, TRW-built DSP was boosted into its final orbit by the Boeing IUS upper stage.
The flight of the new Lockheed Martin Titan 4B was described as a "landmark launch for America" by the USAF, which has invested $950 million in the programme since it was initiated in 1987. Seventeen launches of this most powerful unmanned booster in the USA are planned by about 2004.
The 62m (200ft)-tall, 1.29 billion kilogramme Titan 4B uses new twin solid-rocket boosters called Solid Rocket Motor Upgrade (SRMU), built by Alliant TechSystems. The original Titan 4 solid-rocket motors are built by United Technologies.
The boosters carry the Titan 4B until T+138s, when the Aerojet central core first-stage liquid engine ignites 7s before SRMU burnout.
The 7,560kN (1.69 million lb)-thrust SRMUs have three-segment filament wound graphite composite casings and high-performance solid propellant with better performance and control. The original Titan 4 solid-rocket motors have seven segments.
The Titan 4B also has advanced avionics among its other upgrades. Unlike the original solid-rocket motors, the new boosters are attached to the core vehicle in a new assembly building at Cape Canaveral, rather than on the pad, improving processing time.
The use of the 34m-high SRMUs increases the performance of the Titan 4B/IUS from 2,364kg to GEO to 2,860kg. There are two other versions of the Titan 4 booster, one with no upper stage (which is most usually launched from Vandenberg AFB, California) and the Titan 4 Centaur.
Low-Earth orbit (LEO) capability will be increased from 17,770kg to 20,900kg by the SRMUs, while the Centaur model's Titan will now be able to place 5,773kg into GEO compared with 4,545kg with the solid-rocket motors. LEO polar orbit launches from Vandenberg will carry a payload of 17,650kg, an increase of 3,175kg.
Source: Flight International
