Underwater weapon systems
The modern torpedo is a powerful weapon which can destroy targets at 40 kms with a speed of 50 knots and a destruction potential equivalent to 400-600 kg of TNT.
Underwater weapons are designed to attack submarines or surface vessels. They can be of three types i.e. guided weapons, non-guided weapons and rocket and mortar weapons. Guided weapon is a torpedo, which is very powerful and most commonly used thus the focus here will be on the mighty torpedo. Non-guided weapons are mines and depth charges. Rockets and mortar weapons, such as anti-submarine grenades and anti-submarine rockets have the advantage of rapid response time since they travel to the target through air and also have the advantage of being less susceptible to decoys etc. A hybrid of this category is the rocket launched torpedo, which is carried to the proximity of the target via a rocket.
The modern torpedo is a powerful weapon which can destroy targets at 40 kms with a speed of 50 knots and are of two types, the heavyweight, launched from submarines, and the lightweight which is launched from ships, dropped from aircraft (both fixed wing and helicopters) or delivered by a rocket. They can be straight-running, wireguided and fire and forget. A modern torpedo could have a speed of 50 knots, range of 40 km, should have a combined acoustic and wake homing with an acquisition range of about 5 km and a destruction potential equivalent to 400-600 kg of TNT. The normal size is 6.5 metres in length with a standard diameter of 533mm or 650mm but will depend on the size of the launch tube. Salient sub-systems are:
Propulsion. Torpedo propulsion is of two types i.e. electrical propulsion powered by batteries and thermal engine powered by combustible fuel.
Propulsion motors. With the advent of Permanent Magnetic Motors, greater power to weight ratio has been achieved and brushless motors allow a continuously variable speed control. Faster torpedoes need more powerful motors.
Homing. The terminal guidance of the torpedo is provided by the homing system, which comprises of homing head and the signal-processing unit. Homing can be acoustic or wake. Homing head of most modern torpedoes have acoustic sensors which can be passive or active. In the passive mode the sensor receives the noise created by the target, whereas in the active mode the torpedo transmits acoustic energy and it receives the echoes reflected from the target. In wake homing a torpedo detects and homes on to bubbles that are created in the wake of the target and is effective only against surface ships.
Guidance. Torpedoes can be controlled by a submarine by means of a wire which provides a two-way communication between the submarine and torpedo. The wire used in modern torpedoes has a length of about 50-60 km, high data handling capacity and is made of fibre optic cable.
Warhead design. The desired explosive
MU90 lightweight torpedo