Defense Technology

Defense Technology: Quick Revision Notes for Competitive Exams (SSC CGL, UPSC)

1. Missile Technology

  • Missile: A self-propelled guided weapon system.
  • Propulsion:
    • Solid Propellant: Pre-mixed fuel+oxidizer (e.g., AP, HTPB). Stable, ready-to-use. (e.g., most SRBM).
    • Liquid Propellant: Fuel and oxidizer stored separately. Higher specific impulse but complex. (e.g., Cryogenic engines).
  • Guidance Systems:
    • Command Guidance: Manual control from ground.
    • Beam Riding: Missile rides a radar/laser beam.
    • Inertial Navigation System (INS): Uses gyroscopes & accelerometers. Jam-proof.
    • Terminal Guidance: Seeker (Radar/IR/IIR) activates in final phase for high accuracy.

2. Classification of Missiles

  • By Range:
    • SRBM (Short Range): < 1000 km
    • MRBM (Medium Range): 1000 – 3000 km
    • IRBM (Intermediate Range): 3000 – 5500 km
    • ICBM (Intercontinental): > 5500 km
  • By Launch Mode & Target:
    • Surface-to-Surface (SSM) (e.g., Agni, Prithvi)
    • Surface-to-Air (SAM) (e.g., Akash, QRSAM)
    • Air-to-Air (AAM) (e.g., Astra, Python-5)
    • Air-to-Surface (ASM) (e.g., BrahMos Air-launched)
    • Anti-Satellite (ASAT) (e.g., Mission Shakti)
    • Anti-Tank Guided Missile (ATGM) (e.g., Nag, HELINA)

3. Key Indian Missile Systems

  • Agni Series: Surface-to-Surface Nuclear-Capable Ballistic Missiles.
    • Agni-I (700 km), Agni-II (2000 km), Agni-III (3000 km), Agni-IV (4000 km), Agni-V (>5000 km, ICBM), Agni-P (Prime, advanced MRBM).
  • Prithvi: First indigenous SRBM.
    • Prithvi-I (Army, 150 km), Prithvi-II (Air Force, 250 km), Prithvi-III (Navy, 350 km).
  • BrahMos: Supersonic cruise missile (Indo-Russian JV).
    • Speed: Mach 2.8-3.0. Range: ~290 km (extended to 450 km). “World’s fastest supersonic cruise missile.”
  • Nag/HELINA: 3rd Gen Fire-and-Forget ATGM. Range: 4km (Nag), 7km (HELINA).
  • Astra: Beyond Visual Range Air-to-Air Missile (BVRAAM).
  • Akash: Medium Range Surface-to-Air Missile (SAM).
  • Mission Shakti (2019): Anti-Satellite (ASAT) missile test. Used a PDV Mk-II missile to destroy a live satellite in Low Earth Orbit (LEO).

4. Key Defense Programs & Platforms

  • INS Vikrant: India’s first indigenous aircraft carrier (IAC-1).
  • Dhanush Artillery Gun: Indigenous 155mm/45caliber towed howitzer.
  • Arjun MBT: Indigenous Main Battle Tank.
  • Tejas: Indigenous Light Combat Aircraft (LCA) by HAL.
    • Tejas Mk1, Mk1A, and future Mk2.
  • AMCA: Advanced Medium Combat Aircraft (5th Gen stealth fighter program).
  • LCA Navy: Naval variant of Tejas for aircraft carriers.

5. Electronic Warfare & Defense Systems

  • Electronic Warfare (EW): Use of EM spectrum to deny, deceive, or attack enemy capabilities.
  • Radar: Radio Detection and Ranging.
    • SONAR: Sound Navigation and Ranging (for underwater detection).
    • LIDAR: Light Detection and Ranging.
  • Stealth Technology: Uses design & materials (Radar Absorbent Material – RAM) to reduce Radar Cross-Section (RCS).
  • Ballistic Missile Defense (BMD) Program: Two-tier shield (Prithvi Air Defense – PAD for high altitude, Advanced Air Defense – AAD for endo-atmospheric interception).

6. Important Organizations & Terms

  • DRDO: Defence Research and Development Organisation.
  • DPSU: Defence Public Sector Undertaking (e.g., HAL, BEL).
  • HAL: Hindustan Aeronautics Limited.
  • BEL: Bharat Electronics Limited.
  • BEML: Bharat Earth Movers Limited.
  • OFB: Ordnance Factory Board (now corporatized into 7 new PSUs).
  • MIRV: Multiple Independently Targetable Re-entry Vehicle (single missile with multiple warheads).
  • MARV: Maneuverable Re-entry Vehicle (can change trajectory).
  • Hypersonic Speed: Mach 5 and above (\(Mach 5 = 5 \times SpeedOfSound\)).

Physics & Formulae in Defense Tech

1. Mach Number: Ratio of object’s speed to the speed of sound in the surrounding medium.

\( M = \frac{v}{a} \)

Where \(v\) is the object’s speed and \(a\) is the local speed of sound (~343 m/s in air at 20°C).

2. Kinetic Energy of Impact: Crucial for understanding projectile damage.

\( KE = \frac{1}{2}mv^2 \)

Where \(m\) is mass and \(v\) is velocity. Note: Damage increases with the square of velocity.

3. Range of a Ballistic Missile (Simplified): For a given burnout velocity \(v_b\).

\( R \approx \frac{v_b^2}{g} \)

Where \(g\) is acceleration due to gravity. This shows why achieving high velocity is critical for long range.

4. Thrust (Rocket Equation):

\( F = \dot{m}v_e + (p_e – p_a)A_e \)

Where \(\dot{m}\) is propellant mass flow rate, \(v_e\) is exhaust velocity, \(p_e\) is exhaust pressure, \(p_a\) is ambient pressure, and \(A_e\) is exit area.

Important Constants & Values

  • Speed of Sound (in air at sea level, 15°C): 340 m/s or 1224 km/h.
  • Speed Classifications:
    • Subsonic: M < 1.0
    • Transonic: M ≈ 1.0
    • Supersonic: 1.0 < M < 5.0
    • Hypersonic: M ≥ 5.0
  • g (Acceleration due to gravity): 9.8 m/s²
  • Low Earth Orbit (LEO) Altitude: 160 km to 2000 km (Mission Shakti target was at ~300 km).
  • 1 Kiloton (kt) TNT equivalent: \(4.184 \times 10^{12}\) Joules.
  • 1 Megaton (Mt) TNT equivalent: \(4.184 \times 10^{15}\) Joules.
Defense Technology