Titan IV

Titan IV

Launch of a Titan IVB launch vehicle. (USAF)
Function Heavy expendable launch system
Manufacturer Lockheed Martin
Country of origin United States
Cost per launch $432 million (USD) (1999)
Size
Height 50-62 m (164-207 ft)
Diameter 3.05 m (10 ft)
Mass 943,050 kg (2,079,060 lb)
Stages 3-5
Capacity
Payload to LEO 21,680 kg (47,790 lb)
Payload to Polar LEO 17,600 kg (38,800 lb)
Payload to GSO 5,760 kg (12,690 lb)
Payload to HCO 5,660 kg (12,470 lb)
Associated rockets
Family Titan
Comparable Atlas V, Delta IV-H
Launch history
Status Retired
Launch sites SLC-40/41, Cape Canaveral
SLC-4E, Vandenberg AFB
Total launches 39[1]
(IVA: 22, IVB: 17)
Successes 35
(IVA: 20, IVB: 15)
Failures 4 (IVA: 2, IVB: 2)
First flight IV-A: 14 June 1989
IV-B: 23 February 1997
Last flight IV-A: 12 August 1998
IV-B: 19 October 2005
Notable payloads Lacrosse
DSP
Milstar
Cassini-Huygens
Boosters (IV-A) - UA1207
No. boosters 2
Engines United Technologies UA1207
Thrust 14.234 MN (3,200,000 lbf)
Specific impulse 272 seconds (2667 N·s/kg)
Burn time 120 seconds
Fuel Solid
Boosters (IV-B) - USRM
No. boosters 2
Engines Hercules USRM
Thrust 15.12 MN (3,400,000 lbf)
Specific impulse 286 seconds (2805 N·s/kg)
Burn time 140 seconds
Fuel Solid
First stage
Engines LR-87
Thrust 2,440 kN (548,000 lbf)
Specific impulse 302 seconds (2962 N·s/kg)
Burn time 164 seconds
Fuel N2O4/A-50
Second stage
Engines 1 LR-91
Thrust 467 kN (105,000 lbf)
Specific impulse 316 seconds (3100 N·s/kg)
Burn time 223 seconds
Fuel N2O4/A-50
Third stage (Optional) - Centaur-T
Engines 2 RL-10
Thrust 147 kN (33,100 lbf)
Specific impulse 444 seconds (4354 N·s/kg)
Burn time 625 seconds
Fuel LH2/LOX

The Titan IV family (including the IVA and IVB) of rockets were used by the U.S. Air Force.[2] They were launched from Cape Canaveral Air Force Station, Florida,[3] and Vandenberg Air Force Base, California.[4] At the time of its introduction, the Titan IV was the "largest unmanned space booster used by the Air Force."[5]

As originally conceived in the mid-1980s, the Titan IV was only intended to complement the space shuttle and fly a mere ten times. However, the Challenger Disaster caused a renewed dependence on expendable launch vehicles so that the program was significantly expanded. Under the original plan, the Titan IV would only be paired with Centaur stages and fly exclusively from LC-40 at Cape Canaveral, but the post-Challenger program would also involve flying IUS (Integrated Upper Stage) or even no upper stages. LC-41 at the Cape would also be converted for Titan IV use along with SLC-4E and 4W at Vandenberg. The latter, a Titan II/IIIB pad, would be completely rebuilt for Titan-Centaur launches. The end of the Cold War a few years later caused Department of Defense programs to be scaled back significantly so that one of the planned VABF Titan IV sites was cancelled. Even with the reduced schedule, there were still almost forty Titan IVs scheduled as of 1991 and a new, improved SRB casing using lightweight composite materials would be introduced.

The Titan IV was the last of the Titan family of rockets. It was retired in 2005 due to its high cost of operation. The final launch (B-30) from Cape Canaveral AFS occurred on April 29, 2005, and the final launch from Vandenberg AFB occurred on October 19, 2005.[6]

Lockheed Martin Space Systems built the Titan IVs near Denver, Colorado, under contract to the government.[1]

Features

LR91-AJ-11 rocket engine

The Titan IV was developed to provide assured capability to launch Space Shuttle–class payloads for the Air Force. The Titan IV could be launched with no upper stage, or either of two upper stages, the IUS (Inertial Upper Stage), and the Centaur rocket upper stage.

The Titan IV was made up of two large solid-fuel rocket boosters and a two-stage liquid-fueled core. The two storable liquid fuel core stages used Aerozine 50 fuel and nitrogen tetroxide oxidizer. These propellants are hypergolic (ignite on contact) and are liquids at room temperature, so no tank insulation is needed. This allows the launcher to be stored in a ready state for extended periods. However, both propellants are extremely toxic.

The Titan IV could be launched from either coast: SLC-40 or 41 at Cape Canaveral Air Force Station near Cocoa Beach, FL and at SLC-4E, at Vandenberg Air Force Base launch sites 60 miles north of Santa Barbara in California. Choice of launch site depended on mission parameters and mission goals.

Background

The Titan rocket family was established in October 1955 when the Air Force awarded the Glenn L. Martin Company (now part of 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 complemented the Atlas ICBM as the second underground, vertically stored, silo-based ICBM. Both stages of the Titan I used liquid oxygen and RP-1 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 missile developed for the USAF at that time. The Titan II had newly developed engines which used Aerozine 50 and nitrogen tetroxide as fuel and oxidizer therefore allowing the Titan II to be stored underground ready to launch.

The Titan IV was flown in a variety of configurations depending on the launch needs, including no upper stages, IUS stages, or Centaur stages.[7]

Titan III development began in 1964 with the Titan IIIA. Years later, the Titan IVB evolved from the Titan III family and is similar to the Titan 34D. While the launcher family had an extremely good reliability record in its first two decades, this began to change in the 1980s with the loss of a Titan 34D in 1985 followed by the disastrous explosion of another in 1986 due to a SRM failure.

The Titan IV-B vehicle was intended to use the new composite-casing SRBs manufactured by Alliant Technologies rather than the old steel-casing SRBs produced by Chemical Systems Division (Titan IV-A would use the CSD motors). However, there were numerous development problems with them and so Lockheed-Martin put out a request to CSD to supply a few more of the old-style SRBs.

In a preview of the growing privatization of space exploration in the 21st century, Lockheed-Martin were placed in charge of Titan procurement. This was the first time an American launch vehicle was put entirely in the hands of a private contractor instead of a government agency.

On August 2, 1993, Titan IV K-11 lifted from SLC-4E carrying a NOSS SIGNIT satellite. Unusual for DOD launches, the Air Force invited the civilian press to cover the launch and it became more of a story than intended when the booster exploded 101 seconds after liftoff. Investigation found that another SRB burn-through had occurred, albeit much higher up and later in the flight than 34D-9. This incident was found to have been caused by an improper repair job on one of the SRB motors.[8]

After Titan 34D-9, extensive measures had been put in place to ensure proper SRB operating condition which included X-raying the motor segments during prelaunch checks. The SRBs that went onto K-11 had originally been shipped to Cape Canaveral where X-rays revealed anomalies in the solid propellant mixture in one segment. Repair work was done on it, but further X-rays were still enough for CC personnel to disqualify them from flight. The SRBs were then shipped to Vandenberg and approved.

The repair work on the SRBs had involved workers making a pie-shaped cut in the propellant block to remove the defective area. However, most of CSD's qualified personnel had left the program by this point and so the repair crew in question did not know the proper procedure. After replacement, they neglected to seal the area where the cut in the propellant block had been made. The result was a near-repeat of 34D-9; a gap was left between the propellant and SRB casing so that another burn-through occurred during launch.

In 1997, a Titan IV-B rocket launched Cassini–Huygens, a pair of probes sent to Saturn. It was the only use of a Titan IV for a non-DOD launch. Cassini is currently in orbit around Saturn, while Huygens landed on Titan on January 14, 2005.

1998 saw the worst accident when a launch of a Navy ELINT satellite from Cape Canaveral failed around 40 seconds into the flight. An electrical failure caused the Titan to suddenly pitch downward, the resulting aerodynamic stress causing one of the SRMs to separate. The ISDS (Inadvertent Separation Destruct System) automatically triggered, rupturing the SRB and taking the rest of the launch vehicle with it. At T+45 seconds, the Range Safety Officer sent the destruct command to ensure any remaining large pieces of the booster were broken up.[9]

Investigation showed that Titan K-17, which was several years old and the last Titan IV-A to be launched, had dozens of damaged or chafed wires and should never have been launched in that operating condition, however the Air Force put extreme pressure on launch crews to meet program deadlines. The ultimate cause of the failure was an electrical short that caused a momentary power dropout to the guidance computer at T+39 seconds. After power was restored, the computer sent a spurious pitch down and yaw to the right command. At T+40 seconds, the Titan was travelling at near supersonic speed and could not handle this action without suffering a structural failure. In any case, the Titan's fuselage was filled with numerous sharp metal protrusions that made it nearly impossible to install, adjust, or remove wiring without it getting damaged. Quality control at Lockheed's Denver plant, where Titan vehicles were assembled, was described as "awful".

An extensive recovery effort was launched, both to diagnose the cause of the accident and recover debris from the classified satellite. All of the debris from the Titan had impacted offshore, between three and five miles downrange, and at least 30% of the booster was recovered from the sea floor. Debris continued to wash ashore for days afterward, and the salvage operation continued until October 15.

The Air Force had pushed for a "launch on demand" program for DOD payloads, something that was almost impossible to pull off especially given the lengthy preparation and processing time needed for a Titan IV launch (at least 60 days). General Chuck Horner, shortly before retiring in 1994, had referred to the Titan program as "a nightmare". The 1998-99 schedule had called for four launches in less than 12 months. The first of these was Titan K-25 on May 9, 1998 which successfully orbited an Orion SIGNIT satellite. The second was K-17, and the third, delayed thanks to the investigation around K-17's failure, was K-32 on April 9, 1999 which carried a DSP early warning satellite. The IUS second stage failed to ignite, leaving the payload in a useless orbit. Investigation into this failure found that wiring harnesses in the IUS had been wrapped too tightly with electrical tape so that a plug failed to disconnect properly and prevented the two IUS stages from separating.

The fourth launch was K-26 on April 30, which carried a Milstar communications satellite. During the Centaur's flight, an uncontrolled roll motion developed, causing the upper stage and payload rotate at ever-increasing rate. This threw the stage off course so when it came time for restart, the Centaur cartwheeled out of control and left its payload in a useless orbit. This failure was found to be the result of an incorrectly programmed equation in the guidance computer. The error caused the roll rate gyro data to be ignored by the flight computer, resulting in open-loop firing of the roll control thrusters until the RCS fuel was depleted.

In 1988-89, The R. M. Parsons Company designed and built a full scale steel tower and deflector facility, which was used to test the Titan IV Solid Rocket Motor Upgrade (SRMU). The launch and the effect of the SRMU thrust force on the space shuttle vehicle were modeled. To evaluate the magnitude of the thrust force, the SRMU was connected to the steel tower through load measurement systems and launched in-place. It was the first full-scale test conducted to simulate the effects of the SRMU on the main space shuttle vehicle.[10]

In the early 1980s, General Dynamics conceived of using a Space Shuttle to lift a Lunar Module into orbit and then launch a Titan IV rocket with an Apollo-type Service Module to rendezvous and dock—making a moonship for a lunar landing. The plan required the Space Shuttle and Titan IV to use aluminium-lithium alloy fuel tanks instead of aluminum to make a greater payload weight for takeoff. The original plan never came to fruition, but in the 1990s the Shuttle was converted to aluminum-lithium tanks to rendezvous with the highly inclined orbit of the Russian Mir Space Station.

The Titan IV-B became obsolete with the advent of the Atlas V rocket and the Delta IV heavy rocket booster launch vehicles in 2005. Aside from that, the Titan family had become extremely expensive to fly by the 1990s and there were also growing safety concerns over its toxic propellants. The next-generation ELVs such as Delta IV would use only solid motors and cryogenic propellants, as well they would be completely new, modern designs not derived from a 1960s missile system. In 2014, the National Museum of the United States Air Force in Dayton, Ohio, began a project to restore a Titan IV-B rocket. This effort was successful, and on June 8, 2016 its display was opened.[11]

General characteristics

Program cost

In 1990, the Titan IV Selected Acquisition Report estimated the total cost for the acquisition of 65 Titan IV vehicles over a period of 16 years to US$18.3 billion (inflation-adjusted US$ 33.2 billion in 2016).[13]

Launch history

See also

References

  1. 1 2 "Lockheed Martin's Last Titan IV Successfully Delivers National Security Payload to Space". October 19, 2005.
  2. ↑ "Space and Missile System Center Mission and Organization" (PDF). Space and Missile Systems Center's History Office. Retrieved September 20, 2008.
  3. ↑ Titan 4B and Cape Canaveral
  4. ↑ Titan 4B and Vandenberg Air Force Base
  5. ↑ "Titan IV". USAF Air University. 1996.
  6. ↑ Nemiroff, R.; Bonnell, J., eds. (27 October 2005). "The Last Titan". Astronomy Picture of the Day. NASA. Retrieved 2008-09-20.
  7. ↑ Titan 4
  8. ↑ Titan 403A
  9. ↑ Titan Centaur 401A
  10. ↑ Chalhoub, Michel S., (1990) "Dynamic Analysis, Design, and Execution of a Full Scale SRMU Test Stand," Parsons Engineering Report No. 027-90
  11. ↑ http://www.nationalmuseum.af.mil/Upcoming/PressRoom/News/ArticleDisplay/tabid/466/Article/792421/national-museum-of-the-us-air-force-fourth-building-now-open.aspx
  12. ↑ Michael Timothy Dunn (Dec 1992). "Analysis of Titan IV launch responsiveness" (PDF). Air Force Institute of Technology. Retrieved 2011-07-08.
  13. ↑ Kingsbury, Nancy R. (September 1991). "TITAN IV LAUNCH VEHICLE --- Restructured Program Could Reduce Fiscal Year 1992 Funding Needs" (PDF). US General Accounting Office.
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