Titan IV provides access to space for the United States government's largest payloads. In 1989, a follow-on procurement to the existing Titan IV space lift vehicle resulted in the Titan IVB model. The upgraded rocket incorporates significant technology advancements to improve operational processing time and increase overall reliability. The first Titan IVB launch carried a Defense Support Program satellite into space from Cape Canaveral Air Station, Florida in February 1997.
Titan 4B is being phased out in favor of the heavy Delta 4 and Atlas 5 variants. One Titan 4B launch occurred in 2004, and the final two Titan 4B missions are scheduled for 2005.
During a Titan IV launch the strap-on solid rocket motors are fired first. When the solid propellant is almost depleted (approximately 130 seconds into flight), the first stage is fired and the solid motors are separated from the vehicle. The second stage and upper stage are fired as the previous stage is depleted of fuel and separated.
The Titan IVB uses a "clean vehicle" approach for delivering hardware to the launch sites. This method shifts production-oriented tasks, such as liquid rocket engine installation and electronic system installation, back to the factory. When the vehicle is shipped to the launch site it requires only check-out testing and a minimum of final installations. Processing of the Solid Rocket Motor Upgrade (SRMU) occurs in the new Solid Motor Assembly and Readiness Facility (SMARF) at Cape Canaveral AS and the Solid Motor Processing Facility (SMPF) at Vandenberg Air Force Base, California. These facilities allow work to be reduced from two shifts per day to a single shift. With these improvements, 43 days were eliminated from the overall processing timeline for Titan IVB boosters at Cape Canaveral AS and 134 days at Vandenberg AFB.
The Titan IVB common core design provides a standard mechanical and electrical configuration to the various upper stages and payloads. With this feature, all Titan IVB vehicles are identical up to the interface just below the payload fairing. The Titan IVB standard vehicle design allows hardware to be quickly reallocated to different missions as launch dates or national priorities are changed. It also eliminates the need for unique engineering and specialized processes for each individual core vehicle.
Titan 401 with the Centaur-G upper stage payload capability with the Hercules Solid Rocket Motor Upgrade (SRMU) increases to 13,560 pounds into geosynchronous orbit.
Titan 402 with the IUS upper stage with SRMU is launched from Cape Canaveral can put 50,000 pounds into an 80 X 95 nm low Earth orbit at a 28.5 degree inclination.
Titan 403 is a Titan 4 with no upper stage (NUS) launched from Vandenberg AFB. It has a 66-foot payload fairing. With the new Hercules booster, the payload mass goes to 41,400 Ib. into a 100-nm circular orbit from Vandenberg. The 403 configuration launched from the West Coast is the same as the 405 version launched from Cape Canaveral.
Titan 404 is a Vandenberg configuration with no upper stage. The payload fairing size and orbital parameters are secret. Payload capacity with SRMU is 36,700 Ib.
Titan 405 is a Titan 4 with no upper stage (NUS) launched from Vandenberg AFB. It has a 66-foot payload fairing. With the new Hercules booster, the payload mass goes to 41,400 Ib. into a 100-nm circular orbit from Vandenberg. The 403 configuration launched from the West Coast is the same as the 405 version launched from Cape Canaveral.
Obsolete technology and unprocurable hardware necessitated upgrades to the Titan IV's electrical systems. The new systems on the Titan IVB were designed to improve overall reliability and maintainability. Guidance system technology advancements include ring laser gyros and a new computer that doubles data processing capability. The system is packaged in a single guidance control unit which weighs 40 pounds less than its Titan IVA equivalent. By using modern parts and manufacturing techniques, the recurring cost of the guidance system has been decreased by more than 50 percent. A new data distribution and acquisition system provides higher data rates and more accurate telemetry for systems evaluation. The upgraded wide-band telemetry system has improved capability for additional launch vehicle and payload environments data.
The Titan IVB procurement also provided an opportunity to bring the Flight Termination System (FTS) into a configuration that meets the latest range safety requirements. The Titan IVB automatic and command destruct systems are completely redundant. The system was streamlined by combining multiple functions in a new flight termination controller.
Titan IVB pre-launch vehicle check-out and launch countdown are controlled by a new automated ground processing system, called Programmable Aerospace Ground Equipment (PAGE). During the countdown, PAGE controls vehicle processing, continuously monitoring vehicle systems status and trends. In the event of a vehicle or ground system malfunction, PAGE can hold or abort the launch process up to ignition of the solid rocket motors. The new PAGE system will eliminate obsolete hardware and resolve maintenance problems with the existing system.
SRMU Solid Rocket Motor Upgrade
The new SRMU provides increased payload capacity and improved safety, reliability, and launch site operability, while reducing cost per pound of payload. The SRMU features a three-segment design. Light-weight graphite composite cases coupled with the use of high performance propellant results in a 25 percent increase in lift capability. The number of critical field joints has been reduced from eight on a Titan IVA to two on the Titan IVB, with each field joint having redundant seals. Five full-scale static test firings qualified the motor design in 1993.
The Hercules Solid Rocket Motor Upgrade, a new light-weight graphite-epoxy solid rocket motor, added 25 percent additional carrying capability, boosting Titan IV's lift capacity to LEO from 40,000 pounds to 48,000 pounds. Originally planned to be operational by 1990, the first SRMU-equipped Titan, the K-24 vehicle, was launched in February 1997.
The development of a new Solid Rocket Motor Upgrade provided increased reliability, producibility, and performance, giving the Titan IV 25 percent more carrying capability. The Centaur structural limit is 11.5 K-lbs. Payload to GEO for Titan IV Centaur/SRMU could be increased with structural modifications to the Centaur. No current direction or funding exists to modify the Centaur for increased capability. [(10)]
A crane accident in September 1990 at Edwards AFB damaged the test stand, delaying the PQM-1 test until April 1991, and delayed the SRMU ILC to May 1992. On 1 April 1991, an explosion occurred during the static firing test of the SRMU Preliminary Qualification Motor No. 1 (PQM-1). This test accident caused significant damage to the test facility and required a modification of the SRMU propellant grain configuration. [(11)]
After extensive analysis, it was determined that the failure resulted from a design flaw in the solid propellant grain, causing a critical failure where the solid rocket motor segments are joined. After extensive modelling, the grain was redesigned and the problem corrected. A critical design review was completed in February 1992 and a retest of the first motor was scheduled for April 1992 on the rebuilt test stand. [(12)]
The SRMU static firing (PQM-1') slipped from February 1991 to April 1992 because of the SRMU PQM-1 test explosion. The PQM-1 test failure also delayed the SRMU ILC from May 1992 to August 1993. The SRMU static firing (PQM-1') slipped from April 1992 to May 1992 due to production schedule delays for the test "aft skirt" which is the attachment between the SRMU and the test stand. The SRMU static firing (PQM-1') further slipped from May to June 1992 due to weather conditions (i.e. winds) at the test site. PQM-1' was successfully tested on 12 June 1992, and was followed by four additional successful qualification motor firings through September 1993. The fifth and final SRMU qualification test was conducted in September 1993. SRMU casting began in November 1993, and the first SRMU flightset was delivered during March 1994. The SRMU ILC was delayed from August 1993 to July 1994 due to further delays in the qualification test program. Hercules subcontractor experienced unexpected problems during the R&D phase of the SRMU Program such as the determination of higher than expected vibration environments. SRMU ILC has been delayed from July 1994 to July 1996 due to delays in the development of the Flight Termination System (FTS). [(13)]
Hercules Corp., the developer of the SRMU, filed a lawsuit against Martin Marietta Corp., the prime contractor for the Titan IV. The suit sought $450 million in damages from Martin Marietta for breach of Martin's obligation to cooperate and not interfere with Hercules' performance of its subcontract. Further, Hercules contended it should be excused from performance of its subcontract and that it should be compensated for Martin's failure to consummate a follow-on buy with the Air Force for 10 ship-sets. Martin Marietta filed a counter suit for $100 million for failure to perform. [(14)]
In late August 2003 the launch of a classified reconnaissance spacecraft by a $500 million Titan 4 rocket was delayed [again] to early September 2003 because of issues with the launcher and its clandestine cargo. Liftoff had been targeted for Thursday morning from Cape Canaveral Air Force Station's Complex 40. The mission was already running several days late as the result of a nitrogen tetroxide leak while the rocket was being fueled 12 August 2003.
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