Titan 4 was the last of Lockheed Martin’s ICBM-based Titan booster series. Titan 4B, the final variant, could boost 21.7 metric tons into low earth orbit (LEO) or 5.76 tons into geosynchronous orbit (GEO).
In 1961, the U.S. Air Force decided to add a pair of big five-segment, 3.05 meter diameter “Stage-0” solid rocket motors (SRMs) to a stretched two-stage Titan 2 storable hypergolic propellant core, creating a powerful three-stage space launcher named Titan 3C. (Because it did not start until just before SRM burnout, the Titan core first stage acted as a second stage.) A new restartable Transtage served as an upper stage on high energy missions.
Titan 3A, a three-stage Titan 3 core vehicle without SRMs, flew four Transtage test flights in 1965-66, failing once. Titan 3B, a three-stage Titan 3 core with an Agena third stage, scored 63 success in 68 attempts from 1966 to 1987. Titan 3C, and its Titan 3D and 3E cousins, flew 65 times with 57 successes from 1965 to 1982. A Titan 34D successor, powered by 5.5 segment SRMs, flew 11 successful missions in 15 flights from 1982 to 1989. A commercial Titan 34D variant managed three successes in four tries from 1990 to 1992.
The Titan 4 program began in 1985, when the U.S. Air Force won funding to develop a “Complementary Expendable Launch Vehicle” (CELV) as a back up to the space shuttle. Martin Marietta’s Titan 34D-7 design won the contract. Later, Titan 34D-7 was renamed “Titan 4”.
Titan 4 used upgraded seven-segment SRMs built by United Technologies. The rocket flew 22 times, with 20 successes, during 1989-1998. The rocket flew as a three-stage vehicle from Vandenberg’s SLC 4E. It also flew with IUS or Centaur upper stages from Cape Canaveral’s SLC 40/41 Integrate Transfer Launch (ITL) facility.
Titan 4B, the final Titan, began flying in 1997. It featured Alliant upgraded three-segment SRMs (SRMUs) that produced up to 770.98 tons of thrust each in vacuum. The SRMUs attached to a two-stage, liquid propelled Titan core that was topped by an IUS, a Centaur, or no upper stage. When equipped with a 26.2 meter fairing, Titan 4B stood 62.2 meters tall.
The Titan core first stage was powered by an Aerojet LR87-AJ-11A engine, consisting of two independently operated sets of turbopump/thrust chambers mounted on a common frame. The engines burned nitrogen tetroxide (N2O4) oxidizer with unsymmetrical dimethyl hydrazine (UDMH) fuel to produce a total of 249.98 tons of thrust in vacuum. Gas generators drove the turbopumps. The thrust chambers gimbaled for pitch, yaw, and roll control.
The second stage used a single gimbaled Aerojet LR91-AJ-11A engine, with a single turbopump/thrust chamber. Its main thrust chamber provided pitch/yaw control. Turbopump exhaust passed through a rotating nozzle to provide roll control.
Five Titan versions were cataloged. Titan 401, with a Centaur upper stage, could put 5.76 tons into GEO from Cape Canaveral. This type performed its last mission in 2003. Titan 402 used an IUS upper stage to put 2.86 tons to GEO from the Cape. Titan 403 was a no-upper-stage version that could put 14.89 tons into polar LEO from Vandenberg. When flown from the Cape, this model was called Titan 405. Titan 404 used a classified upper stage that might have been be an upgraded NRL Titan Launch Dispenser. Titan 404 only flew from Vandenberg.
Titan 4 was a critical launch vehicle for its U.S. national defense users. Launch costs grew in later recent years, however, and the rocket suffered delays and failures. Martin’s bid to make Titan a competitive commercial launcher failed during the early 1990s, leaving Titan 4 as a government-dedicated launch system. The launch system suffered four costly failures during the 1990s.
In 1997, the Air Force ordered Lockheed Martin to finish production of 40 Titan 4/4B vehicles. All but one of the vehicles were to be launched, with one stored as a spare.
Also read: Titan 23G – Space Launch Report
Titan 3/4 Launch Sites
Air Force planners initially expected that Titan 3C would launch the X-20 Dynasoar military space plane, but that project was canceled in 1963 in favor of the Manned Orbiting Laboratory (MOL) military space station project. Titan would launch and supply MOL and it would orbit unmanned defense satellites. To handle the expected high launch rate, the Air Force built the first U.S. mobile launch complex, the Integrate Transfer Launch (ITL) facility, much of it on a series of man-made islands in the Banana River adjacent to Cape Canaveral. For more than 35 years, ITL would serve as the U.S. Air Force equivalent of NASA’s LC 39.
ITL consisted of two launch pads, Launch Complex (LC) 40 to the south, built to support MOL launches, and LC 41 to the north, each with its own massive Mobile Service Tower (MST) and fixed Umbilical Tower (UT). Titan core vehicles were first assembled at the south end of the ITL complex in the four-bay Vertical Integration Building (VIB). The vehicles were built up on one of several rail-mobile launch platforms, which straddled a pair of side-by-side standard gauge railroad tracks. The platforms were pulled and pushed about ITL by twin diesel electric locomotives.
When the core was assembled, it would be pulled from the VIB onto the ITL “main line”. After switches were thrown, the vehicle would then be pushed to the Solid Motor Assembly Building (SMAB), where the twin SRMs were added. Then, the vehicle would be pushed to one of the two launch pads, where it would be enshrouded by the MST to allow payload installation. For the Titan IV program, SMAB was replaced by a new building, the Solid Motor Assembly and Readiness Facility (SMARF), that was designed to handle the new SRMU boosters.
ITL was designed to support frequent launches, but the launch rate requirement disappeared when MOL was canceled in 1969 MOL. The site has, as a result, never supported more than four launches in a single year, even when both pads were active. LC 40 remained active, except for rebuilding periods, from 1965 until the end of the program in 2005. LC41 was mothballed in 1969, was reactivated for seven NASA Titan 3E/Centaur launches during 1974-1977, then was mothballed again until it was rebuilt to support Titan 4 beginning in 1989. The pad was finally demolished in 1999 to make way for a new Atlas 5 launch facility.
During the late-1960s, another massive Titan 3 launch pad, Space Launch Complex (SLC) 6, was built at Vandenberg AFB for the MOL project. It was mothballed when MOL was canceled, however, and never hosted any launches. Instead, Titan flew from traditional fixed pads at SLC 4E and SLC 4W. SLC 4W, the west pad, supported as many as eight Titan 3B launches per year until 1987, then was used for space launches of refurbished Titan 23G ICBMs. SLC 4E has typically hosted one or two Titan 3D, 34D, or Titan 4 launches each year.
X-20 and MOL never flew, but Titan 3 did. Titan 3A, a 3C without SRBs, was used for four test launches from Cape Canaveral LC 20 in 1964-65. Titan 3B, basically a Titan 3A with an Agena stage in place of the Transtage, flew only from Vandenberg AFB SLC 4W beginning in 1966. Titan 3C flew from Cape Canaveral from 1965 until 1982.
| LEO Payload (metric tons) 150 km x (1) 28.5 deg (2) 90 deg | GEO Payload (metric tons) | Configuration | LIftoff Height (meters) | Liftoff Mass (metric tons) | |
| Titan 401B | 5.76 t | 2SRMU + Stg1 + Stg2 + Centaur G + PLF | 55.9 m | 940.6 t | |
| Titan 402B | 2.86 t | 2SRMU + Stg1 + Stg2 + IUS + PLF | 55.9 m | 929 t | |
| Titan 403B | 14.89 t (2) | 2SRMU + Stg1 + Stg2 + PLF (VAFB) | 61.9 m | 929 t | |
| Titan 404B | 2SRMU + Stg1 + Stg2 + TLD* + PLF (VAFB) | 61.9 m | 929 t | ||
| Titan 405B | 21.68 t (1) | 2SRMU + Stg1 + Stg2 + PLF (CCAFS) | 61.9 m | 940 t |
*Classified Upper Stage
Vehicle Components
| SRMU Stage 0 (Each) | Titan 4 Stage 1 | Titan 4 Stage 2 | Centaur T (Centaur G’) | IUS | |
| Diameter (m) | 3.2 m | 3.04 m | 3.04 m | 4 m | 2.9 m |
| Length (m) | 34.2 m | 26.37 m | 9.97 m | 8.9 m | 5 m |
| Propellant Mass (tons) | 312.46 t | 155 t | 35 t | 20.95 t | 9.79 t/2.75 t |
| Total Mass (tons) | 349.51 t | 163 t | 39.5 t | 23.88 t | 10.9 t/3.87 t |
| Engine | SRMU | LR87-AJ-11 | LR91-AJ-11 | RL10A-3-3A | IUS |
| Engine Mfgr | Alliant | Aerojet | Aerojet | Pratt & Whitney | Boeing |
| Fuel | HTPB | Aero 50 | Aero 50 | LH2 | HTPB |
| Oxidizer | N2O4 | N2O4 | LOX | ||
| Thrust (SL tons) | 770.91 t | ||||
| Thrust (Vac tons) | 249.98 t | 48.14 t | 14.99 t | 18.9 t/7.8 t | |
| ISP (SL sec) | 259 s | ||||
| ISP (Vac sec) | 286 s | 302 s | 316 s | 444 s | 294 s/303 s |
| Burn Time (sec) | 140 s | 189 s** | 232 s | 600 s | 153 s/104 s |
| No. Engines | 1 | 1 (2 chmbr) | 1 | 2 | 2 stages |
**Titan Stage 1 ignites at T+132 seconds
Vehicle Components Cont’d
| Standard Payload Fairing | Long Payload Fairing | |
| Diameter | 5.9 m | 5.09 m |
| Length | 20 m | 26 m |
| Mass | ||
Titan 401B Launch Sequence (Typical)
| Time | Event | Altitude | |
| T-0 s | SRMU Ignite | 0 km | |
| T+132 s | Stage 1 Ignite | 58 km | |
| T+142 s | SRMU Separate | 66 km | |
| T+211 s | Payload Fairing Jettison | 111 km | |
| T+321 s | Stage 2 Ignite/Separate | 163 km | |
| T+553 s | Centaur Separate/Ignite | 204 km | |
| Varies | Centaur Cutoff No. 1/Parking Orbit Coast | Varies | |
| Varies | 2-3 Centaur Restarts if Required |
