Scramjet Engine

Context:

The DRDO has successfully completed a ground test of the scramjet engine for hypersonic missiles, marking a significant milestone in their development.

Scramjet Technology Development:

• Developed by: Defence Research and Development Laboratory (DRDL), Hyderabad
• Focus: Long-duration supersonic combustion ramjet (scramjet) technology
• Enables hypersonic speeds (greater than Mach 5)
• Outperforms traditional air defense systems, making it harder to intercept
• Nations like the US, Russia, China, and India are in a global race to develop hypersonic weapons
• Hypersonic missiles deliver rapid and high-impact strikes while evading current air defense systems
• Key achievements
  • Endothermic Scramjet Fuel: Developed indigenously by DRDL in collaboration with industry partners
    • Provides dual benefits: Significant cooling improvement and ease of ignition
  • Thermal Barrier Coating (TBC): Developed using advanced ceramic technology to withstand extreme temperatures beyond the melting point of steel
    • Jointly developed by DRDL and DST facilities

Scramjet Engine:

• Improvement over Ramjet: Efficiently operates at hypersonic speeds and allows supersonic combustion
• Features:
  • Air-Breathing Engine: Operates without moving parts, handling supersonic airflows at speeds of 1.5 km/second
  • Flame Stabilization: Uses innovative techniques to sustain continuous flames in extreme airflow conditions, likened to “keeping a candle lit in a hurricane”
  • Advanced Computational Tools: DRDO used Computational Fluid Dynamics (CFD) simulations to predict engine performance and refine its design

Different types of engines:

Aspect	Turbojet	Ramjet	Scramjet
Operation	Compresses air using a turbine; burns fuel	Uses forward motion to compress air	Advanced ramjet with supersonic combustion
Speed Efficiency	Subsonic to low supersonic speeds	Supersonic speeds (Mach 3 to 6)	Hypersonic speeds (greater than Mach 5)
Combustion Process	Subsonic airflow combustion	Subsonic airflow combustion with compression	Supersonic airflow combustion
Fuel Type	Aviation fuel (kerosene or hydrocarbons)	Aviation fuel or hydrocarbons	Hydrogen as fuel and the Oxygen from the atmospheric air as the oxidiser
Moving Parts	Includes turbines and compressors	No moving parts; uses air compression	No moving parts; advanced flame stabilization
Operational Capability	Suitable for slower speeds and takeoff	Needs assistance to reach supersonic speeds	Needs assistance to reach hypersonic speeds
Efficiency	Less efficient at high speeds	Efficient at sustained supersonic speeds	Extremely efficient at hypersonic speeds
Applications	Commercial aircraft, military fighter jets	Supersonic missiles, supersonic flights	Hypersonic missiles, space vehicles, weapons
Examples	Subsonic cruise missile Nirbhay	BrahMos Supersonic Cruise Missile	Hypersonic Glide Vehicles (HGVs), Hypersonic Cruise Missiles (HCMs)

Source: IE

---

Previous Year Question

Consider the following statements:
1. Ballistic missiles are jet-propelled at subsonic speeds throughout their flights, while cruise missiles are rocket-powered only in the initial phase of flight.
2. Agni-V is a medium-range supersonic cruise missile, while BrahMos is a solid-fuelled intercontinental ballistic missile.
Which of the statements given above is/are correct?

[UPSC Civil Services Exam – 2023 Prelims]

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Answer: (d)
Explanation:
Ballistic missiles are not jet-propelled at subsonic speeds throughout their flights. Instead, they are rocket-powered and follow a ballistic trajectory. On the other hand, cruise missiles are jet-powered throughout their flight, not just in the initial phase.
Agni-V is actually an intercontinental ballistic missile (ICBM), not a medium-range supersonic cruise missile. BrahMos, on the other hand, is a supersonic cruise missile, not a solid-fuelled intercontinental ballistic missile.

---