Why in the News? 

Defence Research and Development Laboratory (DRDL) successfully conducted a 120-seconds ground test of an active-cooled Scramjet combustor for the first time in India.

More on the News 

• Indigenous endothermic scramjet fuel, jointly developed by DRDL (Hyderabad based laboratory of Defence Research and Development Organisation (DRDO)) and Industry was used. 
  • An endothermic fuel absorbs heat from its surroundings when it undergoes a chemical reaction.
  • It offers dual benefits of significant cooling improvement and ease of ignition. 
• Another key achievement is the development of state-of-art Ceramic Thermal Barrier Coating (TBC), designed to withstand extreme temperatures encountered during hypersonic flight.
  • Ceramic TBC has high thermal resistance & is capable of operating beyond melting point of steel.
  • It has been jointly developed by DRDL and Department of Science & Technology (DST) Laboratory. 
• The test marks a crucial milestone in developing next-generation hypersonic missiles.
  • India is part of elite club of nations that have successfully tested scramjet engines which includes the USA, Russia, China, etc. 

About Scramjet Engine 

• A scramjet engine means a Supersonic Combusting Ramjet engine.
  • It is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion. 
    • A ramjet is a form of air-breathing jet engine that uses the vehicle's forward motion to compress incoming air for combustion without a rotating compressor.
    • Dual Mode Ramjet (DMRJ) is also a variant of an air-breathing engine. 
• Key Features: 
  • Uses flame stabilisation technique: This holds continuous flame inside the combustor with air speed in excess of 1.5 km/s. 
    • Ignition in it is like 'keeping a candle lit in a hurricane'.
  • Depends on assisted take off: Both ramjets and scramjets cannot produce thrust at zero airspeed, which means they cannot move a space craft from a standstill.
    • Therefore, a scramjet-powered vehicle requires an assisted take off by a rocket to accelerate it to a speed where it begins to produce thrust. 

How does the Scramjet engine work? Air Intake: Vehicle must already be moving at supersonic speeds (above Mach 3). Compression: Incoming air is compressed due to the high velocity of the aircraft. Combustion: Fuel (typically hydrogen) is injected into the compressed air and ignited while maintaining supersonic airflow. Thrust Generation: The expansion of hot gases produces thrust, propelling the vehicle at hypersonic speeds (based on Newton's third law). Newton's Third Law states that for every action (force) in nature there is an equal and opposite reaction.

Advantages of Scramjet Technology 

• Increased Efficiency: It is a more efficient propulsion system than a rocket. 
  • A rocket engine carries both fuel and oxidizer, while a jet engine relies on atmospheric oxygen for combustion.
  • Nearly 70% of the propellant (fuel-oxidiser combination) carried by today's launch vehicles consists of oxidiser.
• Enhanced Space Access: It will reduce the cost of space missions as jet engines are re-usable. 
  • Also, rockets fitted with scramjet engines will be able to carry heavier satellites.
  • An ISRO project called AVATAR is aimed at developing a rocket to launch the ramjets and scramjets engine.
• Higher Speeds: Capable of reaching speeds Mach 6 and beyond.
• Increases Deterrence Power: Enables the development of hypersonic missiles and reconnaissance aircraft.

Conclusion 

Despite technological challenges, scramjet technology holds immense potential for defense and space applications, enhancing deterrence and reducing space access costs. Continued research and innovation will be crucial for overcoming limitations and realizing its full potential.