Barrow Built

Vanguard (Trident) Class, 1993 -

They are the largest submarines manufactured in the UK, displacing 15,900 tonnes submerged, twice the displacement of the Resolution class Polaris submarines which they replace. The Vanguard submarines are based at the Royal Naval Base at Faslane in Scotland.

HMS Vanguard leaving Faslane

First of class HMS Vanguard

MISSILES

The Vanguard Class has the capacity to carry 16 Trident missiles. The Trident II or D5 missile (designated UGM-133A) is a strategic submarine-launched ballistic missile (SLBM) manufactured by Lockheed Martin Missiles and Space.

The missile carries a number of multiple independently targeted re-entry vehicles (MIRVS), each armed with a yield of 100 to 120 kilotons. The Trident II missile can carry up to twelve MIRVs. Trident II (D5) was first deployed in 1990 and is planned to be deployed past 2020.

The Trident II (D5) is a three-stage, solid-propellant, inertially guided FBM with a range of more than 4,000 nautical miles (4,600 statute miles) at supersonic speed.

Weight is 65 tonnes. Trident II is launched by the pressure of expanding gas within the launch tube. When the missile attains sufficient distance from the submarine, the first stage motor ignites, the aerospike extends and the boost stage begins. Within about two minutes, after the third stage motor kicks in, the missile is traveling in excess of 20,000 feet (6,096 meters) per second.

The missile's inertial guidance system calculates flight behaviour and guidance. After the third rocket motor has separated, the warhead carrier takes a star-sighting to confirm position and manoeuvres to the point at which the warheads can be released to free-fall onto the target.

The accuracy of strike on the target is given by the circle of equal probability (CEP) value, which is the radius of the circle within which half the strikes will impact. The Mark 6 guidance system on Trident II gives a CEP of 120 m.

TORPEDOES

Vanguard is fitted with four 533 mm torpedo tubes and carries the Tigerfish and Spearfish torpedoes supplied by BAE Systems. Tigerfish Mark 24 Mod 2 torpedo is a wire-guided torpedo with a 134 kg warhead and active and passive homing. Range is 13 km with active and 29 km with passive homing. Spearfish is a wire guided torpedo with both active and passive homing to a range of 65 km.

ELECTRONIC WARFARE

The submarine is fitted with two SSE Mark 10 launchers for deployment of Type 2066 and 2071 decoys. The submarine's electronic support measures (ESM) intercept system is the UAP Mark 3 supplied by Racal.

SENSORS

Vanguard is equipped with the BAE Systems Type 2054 composite sonar system. Type 2054 is a multi-mode multi-frequency suite, which includes the 2046, 2043 and 2082 sonar systems. The Vanguard's towed sonar array is the Type 2046, which provides passive search capability and operates at very low frequency. The Type 2043 is the hull mounted active and passive mode search sonar and the Type 2082 sonar provides passive intercept and ranging capability.

The submarine is fitted with the CK51 search periscope and the CH91 attack periscope from Pilkington Optronics. These periscopes include TV camera and thermal imager as well as optical channel. All above water sensors are combined into self-protection masts in the submarine's fin.

The submarine's navigation radar is the Type 1007 I-band radar supplied by Kelvin Hughes.

PROPULSION

The Vanguard class submarine's main nuclear powered propulsion system is based on the second-generation Rolls-Royce PWR 2, which was developed specifically for the Vanguard Class. Current generations of PWR allow submarines to circumnavigate the world about 20 times, whereas the latest development of PWR would allow circumnavigation 40 times without refuelling.

The other main items of machinery are two GEC turbines, and a single shaft with a pump jet propulsor. There are two Paxman diesel alternators, and two turbo generators from WH Allen. The propulsion system provides a maximum submerged speed of 25 knots.

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