Trident SLBM
Left: A Trident I C4 is test-launched.
Right: The more capable Trident II D5 breaks the surface
in a test.
(U.S. Navy Photos)
UGM-96A Trident I C4 Specifications
| Primary Function: | Strategic Nuclear Deterrence
|
| Contractor: | Lockheed Martin Missiles & Space, USA
|
| Propulsion: | Three-stage solid-propellant rocket
|
| Length: | 34ft (10.2m)
|
| Diameter: | 6ft 2in (1.9m)
|
| Launch Weight: | 73,000lbs (32,850kg)
|
| Range: | 4,350nm (5,000mi; 8,050km)
|
| Max. Altitude: | Sub-orbital
|
| Guidance: | Inertial
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| Warheads: | 8 100-KT W76 warheads in 8 Mk 4 MIRVs or 8 Mk 500 Evader MARVs
|
| Deployed: | 1979
|
| Unit Cost: | $13 Million US
|
UGM-133A Trident II D5 Specifications
| Primary Function: | Strategic Nuclear Deterrence
|
| Contractor: | Lockheed Missiles & Space Co., Inc., USA
|
| Propulsion: | Three-stage solid-propellant rocket
|
| Length: | 44ft 7in (13.6m)
|
| Diameter: | 6ft 11in (2.11m)
|
| Launch Weight: | 130,000lbs (58,500kg)
|
| Range: | 6,000nm (6,900mi; 11,000km)
|
| Max. Altitude: | Sub-orbital
|
| Guidance: | Inertial
|
| Warheads: | 8 MIRVs or 8 350-KT MARVs
|
| Deployed: | 1990
|
| Unit Cost: | $30.9 Million US
|
BACKGROUND
The Trident Submarine-Launched Ballistic Missile (SLBM) is currently the most
advanced SLBM in service anywhere in the world. Developed to replace the Poseidon
SLBM, the first Trident I C4 was first launched on 18 January 1977. The C4 was first
deployed in 1979, and will continue to serve until it is completely phased out in the
early 2000's.
A larger version of the Trident, known as the Trident II D5, was first introduced in
1990. The D5 is a 3-staged, 6,000-nautical mile-range missile with a larger size than the C4, and
nearly twice the launch weight. The D5's three stages are all constructed of graphite epoxy, which is
stronger and stiffer than the materials used in the Trident I. The D5 has a greater accuracy than the C4, allowing
it to take part in precision counterforce strikes against superhardened military targets like missile fields and deeply buried C&C
bunkers. The C4's lesser accuracy meant that it was best suited for countervalue strikes against large, open "soft" targets such as cities.
The Trident is launched by expanding gases in the launch tube. Maximum launch depth for both the C4 and the
D5 is 150ft (50m). Once this gas pressure has propelled the missile
clear of the water the Trident's first-stage motor ignites, and an "aerospike" is deployed in front of the missile's
nose: this gives sufficient streamlining to the Trident's blunt nosecone, reducing frontal drag by about 50%, while
keeping the missile as compact as possible for storage and transport aboard the submarine. After roughly 2 minutes of flight,
the Trident is travelling at over 20,000 feet per second (6,100m/s), and its third-stage motor deploys.
The Trident can carry MIRVs (Multiple Independantly-Targetable Re-entry Vehicles), or can alternatively deliver its nuclear warheads
in what are known as MARVs, or Maneoverable Re-entry vehicles. The Trident D5 was designed to be able to accomodate as many as 14 MIRVs, but due to
START Treaty restrictions, no ICBMs or SLBMs are permitted to carry more than 10, and so USN Tridents typically carry eight warheads apiece.
Currently, the Trident is carried on Lafayette- and Ohio-class SSBN's. The Lafayettes carry 16, and the Ohios carry 24. This means that
a single Ohio-class SSBN carries 192 warheads, more firepwer than has been unleashed in all the wars combined. It has been said that a single Ohio SSBN
is the fourth most heavily-armed nation on earth. Under the START-II Treaties signed in 1991, Ohio SSBN's will by the early 2000s carry around 50% of the US
nuclear deterrent capability.
The MIRVs on the Tridents C4 and D5 have a Circular Error Probability (CEP) of around 0.25nm (500m) or so. The Trident's
MARVs, which can maneover in flight, are said to have a CEP of around 0.07nm (122m). The Trident's Mk 5 navigation system includes
a stellar sensor, which uses a star sight in the missile's boost phase, allowing the Trident to correct its trajectory early on
and increase its accuracy.
The Royal Navy also uses the D5 aboard its missile submarines, and the US provides the missiles, while the UK provides the warheads.
