THE PRINCIPLES OF MISILES

The Roman verb mittere, which meaning "to send," is where the term "missile" originates. A missile is essentially a self-propelled guided munition. During World War Two, Nazi Germany created the first missiles. They were only produced in tiny quantities and were merely radio-controlled by the operator.

A missile is an intelligent unmanned rocket that is built to deliver a payload to a specific location with the intention of destroying the item or target.

Classification of missile

Missiles are generally classified on the basis of their type, Launch Mode, Range, Propulsion, Warhead and Guidance Systems.

Depending on Type

• Cruise Missile A cruise missile is a guided weapon used against land-based targets that stays in the atmosphere for the most of its flight path and travels at a relatively constant speed. They employ jet engine technology and fly within the earth's atmosphere. In powered flight, they are governed by aerodynamics. Large warheads may be accurately and efficiently delivered over great distances by cruise missiles. Modern cruise missiles may fly on a non-ballistic, extremely low-altitude trajectory, reach supersonic or high subsonic speeds, and are self-navigating.
• Such missiles are categorised as follows based on their speed

1) Subsonic cruise missile

2) Supersonic cruise missile

3) Hypersonic cruise missile

• 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 kilometer 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.
• Ballistic Missile: To deliver one or more warheads on a designated target, a ballistic missile travels along a ballistic trajectory. Just a small portion of the time that these weapons are in flight is directed; the majority is driven by gravity. While intercontinental ballistic missiles (ICBMs) are launched on a sub-orbital trajectory, short-range ballistic missiles remain inside the Earth's atmosphere.
• Unlike cruise missiles, which are aerodynamically directed while in powered flight, these weapons belong to a different class.
• Ballistic missiles are categorised based on their maximum range, which is the distance from the point of launch to the point of impact of the last payload component measured along the surface of the spheroid of the earth. The payload of the missile is enormous. The distance the missile travels justifies the transport of a lethal payload. Both ships and land-based facilities can fire ballistic missiles. For instance, the Indian defence forces are presently using the ballistic missiles Prithvi I, Prithvi II, Agni I, Agni II, and Dhanush.

based on the Launch Mode

• Surface-to-Surface Missile: A guided projectile launched from a hand-held, vehicle-mounted, trailer-mounted, or stationary installation is referred to as a surface-to-surface missile. As the launch platform is immobile, it is frequently propelled by a rocket motor or occasionally by an explosive charge.
• Surface-to-Air Missile: A surface-to-air missile is made to be fired from the ground in order to take out aerial targets such as aeroplanes, helicopters, and even ballistic missiles. As they guard against any enemy aircraft strikes, these missiles are sometimes referred to as air defence systems.
• Surface (Coast)-to-Sea Missile: A surface (coast)-to-sea missile is made to be fired from a land base towards targets that are ships in the water.
• Air-to-Air Missile : An air-to-air missile is fired from an aircraft in order to take out the adversary's aircraft. 4 Mach is the missile's maximum speed.
• Air-to-Surface Missile: An air-to-surface missile is made to be fired from military aircraft and it may either hit land targets on the surface of the ocean or both land and sea targets. The missiles are primarily directed by GPS signals, laser guidance, infrared guidance, and optical guidance. Depending on the target's kind, the type of guidance will vary.
• Sea-to-Sea Missile: These missiles are intended to be launched from one ship to another ship.
• Sea-to-Surface (Coast) Missile: A sea-to-surface missile is made to be launched from a ship and strike targets that are located on land.
• Anti-Tank Missile: An anti-tank missile is a guided weapon whose main purpose is to strike and obliterate strongly fortified tanks and other armoured battle vehicles. Aircraft, helos, tanks, and shoulder-mounted launchers can all be used to fire anti-tank missiles.

Based on Range

The greatest range that the missiles can go is the basis for this sort of classification. Following is the fundamental classification:

• Short-range missiles, traveling less than 1,000 kilometers (approximately 620 miles);
• Medium-range missiles, traveling between 1,000–3,000 kilometers (approximately 620-1,860 miles);
• Intermediate-range Ballistic missiles, traveling between 3,000–5,500 kilometers (approximately 1,860-3,410 miles); and
• Intercontinental ballistic missiles (ICBMs), traveling more than 5,500 kilometers.

Considering Propulsion

• Solid Propulsion: Solid propulsion utilises solid fuel. The fuel is often aluminium powder. The benefit of solid propulsion is that it may be handled while fueled and is simple to store. It can accelerate swiftly to very high speeds. Also, because of how easy it is to use, it is an excellent option anytime a lot of push is required.
• Liquid Propulsion: Liquid is used as fuel in the liquid propulsion technique. Hydrocarbons are the fuels. It is challenging and complex to store a missile with liquid fuel. The missile must also be prepared, which takes time. By utilising valves to restrict the fuel flow during liquid propulsion, propulsion may be readily regulated, and it can even be managed in an emergency. Compared to solid fuel, liquid fuel often provides a higher specific impulse.
• Hybrid Propulsion: Solid propulsion and liquid propulsion are the two stages of hybrid propulsion. The problems of both propulsion methods are offset by this type of propulsion, which also has the benefits of both propulsion systems.
• Ramjet: In contrast to turbojet engines, ramjet engines are turbine-free. By simply moving ahead at a high speed, the air vehicle manages to compress the intake air. Injection and ignition of the fuel occur. The expansion of hot gases following fuel injection and combustion causes the exhaust air to accelerate to a velocity greater than the input air and produces positive push. The air that enters the engine, though, should be moving supersonically. Hence, the airborne vehicle must be travelling at supersonic rates. An airborne vehicle cannot reach supersonic speeds using ramjet propulsion.

• Scramjet: Supersonic Combustion Ramjet is referred to as Scramjet informally. The combustion process of ramjets and scramjets differs in that supersonic air speeds are used in the engine. It is far more complicated aerodynamically than a jet engine, while having a simpler mechanical design. The typical fuel is hydrogen.
• Cryogenic: Cryogenic propellants are liquefied gases kept at extremely low temperatures; typically, liquid oxygen serves as the oxidizer and liquid hydrogen serves as the fuel. Special insulated containers and vents that let gas escape from the evaporating liquids are needed for cryogenic propellants. Pumped from the storage tanks to an expansion chamber and then injected into the combustion chamber, where they are combined and ignited by a flame or spark, is the liquid fuel and oxidizer. The hot exhaust gases are fired out of the nozzle to provide thrust when the fuel expands during combustion.

based on Warhead

• Conventional Warhead: A conventional warhead consists of high-explosive materials. It contains a chemical explosive, and its death procedures entail the chemical explosive detonating and the metal case shattering that follows.
• Strategic Warhead: A strategic warhead contains radioactive elements that, when activated, produce a tremendous amount of radioactivity capable of eradicating whole cities. Typically, they are built for mass annihilation.

Using guidance systems as a foundation

• Wire Guidance: While this system and radio command have many similarities, it is less vulnerable to electronic defences. A wire (or wires) that are released from the missile after launch are used to transmit the command signals.
• Command Guidance: Using radio, radar, or laser impulses, tiny cables, or optical fibres, command guiding entails tracking the projectile from the launch site or platform and delivering orders. Radar or optical equipment at the launch site, as well as radar or television pictures relayed from the missile, may be used for tracking.
• Terrain Comparison Guidance: Cruise missiles always employ Terrain Comparison (TERCOM). Sensitive altimeters are used by the system to measure the profile of the ground directly underneath and compare the results to data that has already been saved.
• Terrestrial Guidance: This system continuously gauges the angles of the stars and compares them to the pre-programmed angles anticipated on the missile's intended course. When a change in trajectory is needed, the guidance system instructs the control system.
• Inertial Guidance: This system is fully integrated into the missile and is set up before launch. Three accelerometers installed on a platform space-stabilized by gyros record accelerations along three axes that are mutually perpendicular to one another. These accelerations are then twice integrated, with the first integration providing velocity and the second providing position. The system then instructs the control system to maintain the pre-programmed trajectory. Surface-to-surface and cruise missiles both employ these technologies.
• Beam Rider Guidance: The beam rider idea uses an external radar station, either on land or at sea, to emit a beam of radar energy in the direction of the target. The surface radar transmits a guiding beam that modifies its angle as the target travels across the sky while also tracking it.
• Laser Guidance: A laser beam is focused on the target during laser guiding, when it reflects off the object and disperses. A laser seeker on the missile can find even the tiniest bit of radiation. The navigation system receives the laser scatters' direction from the seeker. The missile is launched in the direction of the target, the seeker searches for laser reflections, and the guidance system directs the missile towards the target, which is the source of the laser reflections.
• RF and GPS Reference: Two examples of technology utilised in missile guiding systems are RF (Radio Frequency) and GPS (Global Positioning System). The GPS signal is used by a missile to locate its target. The weapon makes trajectory adjustments and sends orders to control surfaces as it flies by using this information. In an RF reference, the missile locates the target by using RF waves.