2. 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
5. 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.
6. TYPES
LAND ATTACK MISSILES
These 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 MISSILES
Anti-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
7. 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
missiles
Ramjet and Scramjet engines are used in supersonic and
hypersonic cruise missiles
Some 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.
8. 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.
9. 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 PROFILE
Some 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.
10. •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.
11. LAUNCHING TECHNIQUES
•COLD LAUNCH
In 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 LAUNCH
In 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.
12. 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.
13. Types of guidance systems:
• Inertial navigation system
• TERCOM (Terrain Contour Matching)
• DSMAC (Digital Scene-Mapping Area Correlator)
• Satellite navigation
14. 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.
16. 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.
17. The guidance system then uses this information to
correct the flight path of the missile.
18. 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.
19.
20. 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.
21.
22. 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.
23. 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.
24. 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
25. NIRBHAY
Nirbhay 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.
26. 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.
27. 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.
28. 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.