Cruise Missiles: Precision Strike Capabilities and Propulsion Systems

Cruise missiles are advanced unmanned vehicles propelled by jet engines, capable of launching from various platforms such as ground, air, or sea. They fly within the atmosphere, often at low altitudes, making them difficult to detect due to their small radar signature. These missiles are highly versatile, delivering payloads ranging from conventional explosives to nuclear warheads.

An Overview Of Different Cruise Missiles and Its Propulsion

Brahmos Missile [UPSC 2023]

• Two-stage Missile: with a solid propellant booster engine at first stage which propels it to supersonic speed.
• Liquid Ramjet (second stage): steers missile closer to 3 Mach in cruise phase.
• Range: Has a range of 450 km and speed of 2.8 Mach
• Warhead Capacities: Ship-launched and land-based missiles can carry a 200 kg warhead.
  • Whereas the aircraft-launched variant can carry a 300 kg warhead.
• Naming: Named after the rivers Brahmaputra and Moskva, it has been jointly developed by DRDO (India) and NPOM (Russia).
• Principle: Operates on Fire and Forget principle up to a maximum altitude of 15 km (minimum altitude: 5m). 

Nirbhay Missile

• All weather long-range subsonic cruise missile, which can carry nuclear warheads (450 kg) up to 1000 km.
• Cruise speed of 0.8 Mach and designed for all three wings of the armed forces.

Moskit Missile

• Procured from Russia, it is a ship-launched/land-based supersonic ramjet cruise missile with a range of 120 km.

Cruise Missile Propulsion

• Ramjet: Air-breathing jet engine (without major moving parts) relies on the craft’s forward motion to draw in air and on a specially shaped intake passage to compress the air for combustion. 
  • The combustion that produces thrust in the ramjet occurs at a subsonic speed in the combustor. 
  • Inefficiencies of Ramjet Propulsion: For a vehicle traveling supersonically, the air entering the engine must be slowed to subsonic speeds by the aircraft inlet resulting in formation of shock waves that cause performance losses; 
    • As a result, ramjet propulsion above Mach 5 is highly inefficient. 
  • Launch Requirements for Ramjets: Ramjets work best at speeds of Mach 2 and higher. Since ramjets develop no static thrust, some means for launching them at high velocity is required.
• Scramjet engine (Supersonic Combustion Ramjet) is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion in the chamber. 
  • A dual mode ramjet (DMRJ) is a type of jet engine where a ramjet transforms into scramjet over Mach 4-8 range, operating efficiently both in subsonic and supersonic combustor modes.
• Solid Fuel Ducted Ramjet (SFDR) Technology based propulsion enables the missile to intercept aerial threats at very long range at supersonic speeds. 
  • The system utilises a solid fuelled air-breathing ramjet engine which enhances efficiency.

Ballistic Missile vs Cruise Missile [UPSC 2023]

• Ballistic missile– a rocket-propelled self-guided strategic weapons system that follows a ballistic trajectory (powered initially by a rocket or series of rockets but then follows an unpowered trajectory that arches upwards before descending) to deliver a payload from its launch site to a predetermined target. 
  • Diverse Payload: Ballistic missiles can carry conventional high explosives as well as chemical, biological, or nuclear munitions. 
  • Multifaceted Launch Platforms: They can be launched from aircraft, ships, and submarines in addition to land-based silos and mobile platforms. 
  • High Trajectory Paths: These missiles have high flight paths, often extending into space.
• Cruise missiles are unmanned vehicles that are propelled by jet engines (powered throughout the flight). 
  • Versatile Launch: They can be launched from ground, air, or sea platforms and can deliver all types of payload. 
  • Low-Altitude Flight: Cruise missiles remain within the atmosphere for the duration of their flight and can fly as low as a few meters off the ground. 
  • Stealth and Guidance: Flying low to the surface of the earth expends more fuel but makes a cruise missile very difficult to detect (also due to smaller radar cross-section). 
    • Cruise missiles are generally self-guided, with some missiles allowing manual manoeuvrability. 

Conclusion

Cruise missiles represent a significant advancement in military technology, providing precision strike capabilities across different terrains and environments. 

• Their ability to operate stealthily and deliver diverse payloads underscores their strategic importance in modern warfare scenarios. 
• Whether launched from ships, submarines, aircraft, or land-based platforms, cruise missiles play a crucial role in enhancing defense capabilities and ensuring national security.

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