Trident II-D5 SLBM - The U.S. Navy's Nuclear Armed Submarine Launched Ballistic Missile

SLBM is a Navy acronym for Submarine Launched Ballistic Missile.

Missile Guidance is provided to the missile by the MK-6 Astro-Inertial
Guidance System, and is capable of receiving GPS updates.

The astro-inertial guidance uses star positioning to fine-tune the accuracy of the
inertial guidance system after launch. As the accuracy of a missile is dependent
upon the guidance system knowing the exact position of the missile at any
given moment during its flight, the fact that stars are a fixed reference point
from which to calculate that position makes this a potentially very effective
means of improving accuracy. In the Trident system, this was achieved by a
single camera that was trained to spot just one star in its expected position.

These missiles, and their fourteen, hidden, undetectable launch platforms known
as Ohio Class SSBN submarines, constitute one-third of the nuclear triad
of the United States. Their mission is one of "nuclear deterrence".

The submarines are designed specifically for stealth, and the missiles are
designed for the precise delivery of a significant number of nuclear
warheads.

General Characteristics: SLBM

Contractor:
* Lockheed Martin Space

Unit Cost:
* $30.9 million

Propulsion:
* 3 Solid Fuel Rocket Motors

Length:
* 44.5 feet (13.579m)

Diameter:
* 6 ft. 11 inches (2.11m)

Weight:
* 130,000 pounds

Range:
* >7,500 miles

Maximum Speed:
* Approximately 18,030 mph (29,020 km/h) (Mach 24; 8,060 m/s) (terminal phase)

Guidance System:
* MK-6 Astro-Inertial Guidance System

Steering System:
* Single movable nozzle actuated by a gas generator

Launch Platform:
* SSBN Submarines

Warhead Options:
* 1 to 8 MK-5 RV/W88 (455 kt) or
* 1 to14 MK-4 RV/W76-0 (100 kt) or
* 1 to14 MK-4A RV/W-76-1 (90 kt)
* Single or Multiple W76-2 (5-7 kt)

The Trident II D-5 Launch Sequence Occurs As Follows:

Before the launch sequence is initiated, the on-board MARK 6 navigation system
is activated. The specified mission trajectory is loaded onto the flight computer.

Once the launch command is given, a steam generator system is activated,
igniting a fixed solid-grain small rocket motor. The rocket motor exhaust is
fed into cooling water, causing expanding gas within the launch tube to force
the missile upward, and out of the submarine.

Within seconds, the missile breaches the surface, and the first-stage Thrust
Vectoring Control (TVC) subsystem ignites. This enables hydraulic actuators
attached to the first-stage nozzle.

Soon thereafter, the first-stage motor ignites and burns for approximately 65
seconds until the fuel is expended. Also, an aerospike atop the missile deploys
to shape airflow.

When the first-stage motor ceases operation, the second-stage TVC subsystem
ignites. The first-stage motor is then ejected by ordnance within the interstage
casing.

Once the first stage is cleared, the second-stage motor ignites and burns for
approximately 65 seconds. The nose fairing is then jettisoned, separating
from the missile.

When the nose fairing is cleared of the missile, the third-stage TVC subsystem
ignites, and ordnance separates the second-stage motor. The third-stage
motor then ignites, pushing the equipment section the remaining distance
(approx. 40 seconds) of the flight.

When the third-stage motor reaches the targeted area, the Post Boost Control
System (PBCS) ignites, and the third-stage motor is ejected. The astro-inertial
guidance star check verifes the accuracy of the inertial guidance system. If it
is not quite aligned to where it should be, it would indicate that the inertial
system was not precisely on target, and a correction would be made.

The equipment section, with the MIRV, then aims the reentry vehicles (RV)
towards earth, and the payload is then released from the MIRV platform.
To prevent the PBCS correctional thrust from interfering with the RV when
released, the equipment section initiates the Plume Avoidance Maneuver (PAM).
If the RV will be disrupted by the PBCS nozzle's thrust, the nearest nozzle will
shut off until the RV is away from the MIRV. The PAM is used only when a
nozzle's plume will disrupt the area near an RV. The PAM is a specialized
design feature added to the Trident II to increase accuracy.

Trident II - D5 SLBM Documentary Video

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