• The Defence Research and Development Organisation (DRDO) has successfully conducted a ground test of scramjet combustor.

• Defence Research & Development Laboratory (DRDL), a Hyderabad-based laboratory of DRDO, has taken the initiative in developing a long-duration supersonic combustion ramjet or scramjet powered hypersonic technology.

• DRDL recently developed these technologies and demonstrated a cutting-edge active cooled scramjet combustor ground test for 120 seconds for the first time in India.

• The successful ground test marks a crucial milestone in developing next-generation hypersonic missiles.

What is scramjet?

• Ramjet, Scramjet and Dual Mode Ramjet (DMRJ) are the three concepts of air-breathing engines which are being developed by various space agencies. 

• 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. Fuel is injected in the combustion chamber where it mixes with the hot compressed air and ignites. A ramjet-powered vehicle requires an assisted take-off like a rocket assist to accelerate it to a speed where it begins to produce thrust.

• Ramjets work most efficiently at supersonic speeds around Mach 3 (three times the speed of sound) and can operate up to speeds of Mach 6. However, the ramjet efficiency starts to drop when the vehicle reaches hypersonic speeds.

• A scramjet engine is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allows supersonic combustion. Thus it is known as Supersonic Combustion Ramjet, or Scramjet. 

• A dual mode ramjet (DMRJ) is a type of jet engine where a ramjet transforms into a scramjet over Mach 4-8 range, which means it can efficiently operate both in subsonic and supersonic combustor modes.

Highlights of the test:

• The ground test of scramjet combustor showcased several notable achievements, demonstrating its potential for operational use in hypersonic vehicles, like successful ignition and stable combustion.

• Hypersonic missiles are a class of advanced weaponry that travel at speeds greater than Mach 5, that is five times the speed of sound or more than 5,400 kmph. These advanced weapons have the potential to bypass existing air defence systems and deliver rapid and high-impact strikes.

• Several nations including the US, Russia, India and China are actively pursuing hypersonic technology.

• The key to hypersonic vehicles is scramjets, which are air breathing engines capable of sustaining combustion at supersonic speeds without using any moving parts.

• Ignition in a scramjet engine is like “keeping a candle lit in a hurricane”. Scramjet combustor incorporates an innovative flame stabilisation technique that holds continuous flame inside the combustor with air speed in excess of 1.5 km/s.

• Many novel and promising ignition and flame holding techniques were studied through many ground tests in arriving at scramjet engine configuration.

• The indigenous development of endothermic scramjet fuel is central to this breakthrough. The fuel offers dual benefits of significant cooling improvement and ease of ignition. The team developed a special manufacturing process to achieve stringent fuel requirements of DRDL at industrial scale.

• Another key achievement is the development of state-of-the-art thermal barrier coating (TBC) which is designed to withstand extreme temperatures encountered during hypersonic flight.

• A new advanced ceramic TBC having high thermal resistance and capable of operating beyond melting point of steel has been jointly developed by DRDL and Department of Science & Technology (DST) Laboratory. The coating is applied inside the scramjet engine using special deposition methods that enhance their performance and longevity.

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