CRUISE MISSILE TECHNOLOGY

BY,

SHUBHAM KUMAR1201335083

12ME44SYNERGY INSTITUTE OF TECHNOLOGY BHUBANESWAR

Introduction:A cruise missile is an unmanned self-propelled (till the time of

impact) guided vehicle that sustains flight through aerodynamic lift for most of its flight path and whose primary mission is to place an ordnance or special payload on a target. They fly within the earth’s atmosphere and use jet engine technology. These vehicles vary greatly in their speed and ability to penetrate defences.

Tomahawk Cruise missile

CONTENTS WORKING

TYPES

PROPULSION SYSTEM

SPEED

FLIGHT TRAJECTORY

LAUNCHING TECHNIQUES

GUIDANCE SYSTEM

WAR HEADS

INDIAN MISSILES

ADVANTAGE & DISADVANTAGE

CONCLUSION

General design:

WORKING

Cruise missiles all have basically the same parts: an engine, often a jet with an air intake, propels the missile through the air. There's a spot for fuel, and a spot for the warhead, or explosive carried inside.Cruise missiles were designed to carry nuclear warheads, but most cruise missiles, and all that have actually been used in war, carry conventional, non-nuclear explosives. The front end of a cruise missile usually has a guidance system. Cruise missiles, with wings and engines, often resemble pilot-less planes.

TYPES

LAND ATTACK MISSILESThese are the cruise missiles which are designed to hit stationary or moving targets on land. The first cruise missile used in combat, the V1, was a land attack cruise missile

ANTI-SHIP MISSILESAnti-ship missiles are similar in structure to LACMs, but they differ from them in guidance systems and warheads. AShMs were first developed during WW2 but never saw action

PROPULSION

Jet engines are the main propulsion system for a cruise missile. In jet engines, there are many types which are used on different missiles depending on the requirement.Turbofan and Turbojet engines are used in subsonic cruise missilesRamjet and Scramjet engines are used in supersonic and hypersonic cruise missilesSome supersonic cruise missiles like Klub, make use of a rocket motor in their terminal stage to propel them faster than the speed of sound. But very few make use of rocket motor propulsion as it gives very less range when compared to a jet engine.

SPEED

Subsonic cruise missile flies at a speed lesser than that of sound. It travels at a speed of around 0.8 Mach. The well-known subsonic missile is the American Tomahawk cruise missile. Some other examples are Harpoon of USA and Exocet of France.

Supersonic cruise missile travels at a speed of around 2-3 Mach i.e.; it travels a kilometre approximately in a second. The modular design of the missile and its capability of being launched at different orientations enable it to be integrated with a wide spectrum of platforms like warships, submarines, different types of aircraft, mobile autonomous launchers and silos. The combination of supersonic speed and warhead mass provides high kinetic energy ensuring tremendous lethal effect. BRAHMOS is the only known versatile supersonic cruise missile system which is in service.

Hypersonic cruise missile travels at a speed of more than 5 Mach. Many countries are working to develop hypersonic cruise missiles. BrahMos Aerospace is also in the process of developing a hypersonic cruise missile, BRAHMOS-II, which would fly at a speed greater than 5 Mach.

FLIGHT TRAJECTORY•SEA SKIMMING / TERRAIN HUGGING

Anti-ship cruise missiles generally follow a sea skimming profile. This means that the missile flies just a few meters above the water surface. This flight profile makes the missile invisible to enemy radar until it is just round 30 km away from the ship due to the earth’s curvature. Land attack missiles generally follow a terrain hugging profile. This means that they closely follow the ups and downs of the terrain and remain hidden from detection by radars due to their low altitude.

•HIGH ALTITUDE PROFILESome cruise missiles fly exclusively at a high altitude and then dive down towards their target. This flight profile gives a very long range to the missiles as the thin air at high altitudes gives very low resistance to the flight of the missile and reduces fuel consumption of the engine. The disadvantage of this flight profile is that the missile becomes easy to detect and shoot down.

•MIXED ALTITUDE PROFILE

Many cruise missiles follow a mixed trajectory. Once they are launched, they fly at high altitude for optimum range and when they approach their target, they climb down to a few meters altitude and make their final approach towards the target. This offers the range advantage of high altitude flight and the radar evading ability of the sea skimming flight. Many modern cruise missiles follow this flight profile and some of them go supersonic at the terminal sea skimming phase.

LAUNCHING TECHNIQUES•COLD LAUNCHIn this technique, the missile is ejected from its launch tube using compressed air. The missile boosters fire once the missile is ejected clear of the ship. Since the missile booster is not ignited in the launch tube itself, the launcher and its surroundings don’t get heated up. Hence the launch is termed as a cold launch.

•HOT LAUNCHIn this technique, the missile booster ignites when the missile is in its launcher itself. The missile is thrust out of the launcher under its own propulsion. This type of launch gives what is known as a back blast and heats up the launcher and its surroundings. Hence it is termed as a hot launch.

Guidance systems: The purpose of a guidance system is to direct the

missile to target .

Guidance systems vary greatly.

Use of an automatic target recognition (ATR) algorithm/device in the guidance system increases accuracy of the missile.

Types of guidance systems:

• Inertial navigation system• TERCOM (Terrain Contour Matching)• DSMAC (Digital Scene-Mapping Area Correlator)• Satellite navigation

Inertial navigation system: An inertial navigation system includes at least a

computer and a platform containing accelerometers, gyroscopes, or other motion-sensing devices.

Accelerometers measure the vertical, lateral, and longitudinal accelerations of the controlled missile .

Gyroscopes measure the angular velocity of the system.

Inertial navigation system:

Tercom(Terrain contour matching): It uses a pre-recorded contour map of the terrain that

is compared to measurements made during flight by an on-board radar altimeter.

The missile's radar altimeter feeds measurements into a smaller buffer, and averages them out to produce a single measurement.

The series of such numbers a strip of measurements similar to those held in the maps. The two are compared to overlay the strip on the known map, and the positioning of the strip within the map produces a location and direction.

The guidance system then uses this information to correct the flight path of the missile.

DSMAC(Digital scene-mapping area correlator): A series of photographs are taken from surveillance

aircraft and are put into a carousel in the missile.

Another camera takes pictures out of the bottom of the missile.

A computer compares the two images and attempts to line up areas of high contrast.

This system is very slow and its role is being taken up by TERCOM.

Satellite navigation: Another way to navigate a cruise missile is by using a

satellite positioning system, such as GPS .

Satellite navigation systems are precise and cheap.

If the satellites are interfered with (e.g. destroyed) or if the satellite signal is interfered with (e.g. jammed), the satellite navigation system becomes inoperable.

The GPS-based navigation is useful in a conflict with a technologically unsophisticated adversary.

LASER

A laser guidance system is generally used on short range cruise missiles. A laser targeting system paints the target. A laser sensor in the nose of the missile detects the painted target and flies towards it. This targeting system is unreliable as the presence of dust and smoke in the battlefield can mess with the lasers and the painted target may not always be visible to the missile. If laser guidance is used on a long range missile, it is mainly as a secondary and terminal targeting system to hit a target among a group of non-hostiles.

WAR HEADS

Cruise missiles are equipped with different kinds of warheads depending on the type of target they’re supposed to hit. Some of the common warheads are•High Explosive Incendiary•High Explosive Fragmentation•Semi-Armour Piercing•Submunitions dispenser•Nuclear

(i) Conventional Warhead: A conventional warhead contains high energy explosives. It is filled with a chemi al explosive and relies on the detonation of the explosive and the resulting metal casing fragmentation as kill mechanisms.

(ii) Strategic Warhead: In a strategic warhead, radio active materials are present and when triggered they exhibit huge radio activity that can wipe out even cities. They are generally designed for mass annihilation.

BRAHMOS

The BrahMos is a short range ramjet supersonic cruise missile that can be launched from submarines, ships, aircraft or land. It is a joint venture between the Russian Federation's NPO Mashinostroeyenia and India's Defence Research and Development Organisation (DRDO) who have together formed BrahMos Aerospace Private Limited. The name BrahMos is a portmanteau formed from the names of two rivers, the Brahmaputra of India and the Moskva of Russia.

It is the world's fastest cruise missile in operation. The missile travels at speeds of Mach 2.8 to 3.0. The land-launched and ship-launched versions are already in service, with the air and submarine-launched versions currently in the testing phase.An air-launched variant of BrahMos is planned which came out in 2012 and made India the only country with supersonic cruise missiles in their army, navy, and air force. A hypersonic version of the missile, BrahMos-II, is also presently under development with speed of Mach 7 to boost aerial fast strike capability. It is expected to be ready for testing by 2017

NIRBHAYNirbhay is an all-weather low-cost long-range cruise missile with stealth and high accuracy. The missile has a range of more than 1000 km. It weighs about one tonne and has a length of 6 metres. It carries a ring laser gyroscope for high-accuracy navigation and a radio altimeter for the height determination. It is capable of being launched from multiple platforms on land, sea and air and shall be inducted into Indian Navy, Army, and Air Force. In particular, Nirbhay is being adapted for the Indo/Russian Su-30MKI. The missile is capable of carrying nuclear warheads.

The missile has a loitering capability, i.e., it can go round a target and perform several manoeuvres and then re-engage it. With two side wings, the missile is capable of flying at different altitudes ranging from 500 m to 4 km above the ground and can also fly at low altitudes (like low tree level) to avoid detection by enemy radar. It is capable of delivering 24 different types of warheads depending on mission requirements and uses an inertial navigation system for guidance. The missile supplements Brahmos by delivering warheads farther than the 290 km range of Brahmos.

Advantages of Cruise missile: The big advantage of the cruise missile is its

smallness and cost.

Its small size also improved the weapon’s chances of penetration.

The map matching system (TERCOM) is combined with an inertial navigational system in a system called TAINS. This not only gets the cruise to its target but also with an accuracy.

Disadvantages of cruise missiles:

The lack of a human pilot means you can't re-use the thing.

Their low and slow flight means they can be engaged by a much wider variety of systems, including MANPADS and SAMs.

Conclusions: Currently cruise missiles are among the most

expensive of single-use weapons, up to several million dollars apiece. However, they are cheaper than human pilots when total training and infrastructure costs are taken into account.

Guidance System used in cruise missile is a complex system which involves several systems working in tandem. it is essential that guidance system is properly designed for accurate interception of targets.

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