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10th December 2022 (7 Topics)

Hot test of the scramjet engine was conducted successfully


In a quest to launch satellites in predetermined orbits at a low cost, India has crossed a key milestone by successfully conducting a hot test for its scramjet’s engine.



  • ISRO has conducted a hot test for its air-breathing scramjet engine.
    • A hot test system is a 100% production test used to check all the engine operating parameters as they would function in real time.
  • The test was conducted at its Propulsion Research Complex at Mahendragiri in the Tirunelveli district of Tamil Nadu.
  • The test lasted for 11 seconds.

What is a scramjet engine?

  • A scramjet engine is an improvement over the ramjet engine.
  • India is the fourth country to demonstrate the flight testing of a Scramjet Engine.
  • Thus, it is known as Supersonic Combustion Ramjet or Scramjet.
  • In scramjet engines, the combustion takes place in supersonic airflow.
  • Such engines use oxygen from the atmosphere in the combustion of fuel.

The scramjet advantages:

  • Scramjet engine draws oxygen from the atmosphere:
    • It results in significant savings in terms of the weight of the oxidizer that does not have to be carried onboard.
    • These savings directly translate to higher payload capacity, and/or extended flight range for the vehicle.
  • Vehicles can be cruised in a controlled manner:
    • scramjets allow for a certain level of on-demand acceleration and deceleration by regulating the fuel burn rate, enabling improved control.
  • Difficult to intercept: Enhanced level of manoeuvrability of a scramjet-powered hypersonic vehicle adds to the degree of unpredictability of its flight path, making interception much harder than for a ballistic missile.

The main types of Jet engines based on how air is compressed in the engine are:

  • Turbo Jet: Turbo jet engine is an air-breathing jet engine. This is one of the most common types of jet engines. It is still widely used in aeroplanes.
  • Ramjet: High-speed forward motion is used to compress the air (no compressor). Fuel is injected into the combustion chamber where it mixes with the hot compressed air and ignites.
    • The average speed of a Ramjet is 3-6 Mach.
    • But the ramjet efficiency starts to drop when the vehicle reaches hypersonic speeds.
    • Missiles and other flight systems designed for supersonic speeds (above Mach 1 and below Mach 5) commonly use a ramjet engine.
  • Scramjet: Here also, the high-speed forward motion is used to compress the air (no compressor).
    • It is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion.
    • Speed is greater than 6 Mach (Six times the speed of Sound).

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