• Defence Research & Development Laboratory (DRDL), a Hyderabad-based laboratory of Defence Research and Development Organisation (DRDO), achieved a significant milestone in the field of hypersonic weapon technology. 

• DRDL conducted long-duration Active Cooled Scramjet Subscale Combustor ground testing for more than 1,000 seconds at the newly built state-of-the-art Scramjet Connect Test Facility in Hyderabad on April 25. 

• The ground-test is in continuation of the earlier test reported for 120 seconds in January 2025. With the successful test, the system will be soon ready for full scale flight worthy combustor testing.

• This test validates the design of long duration scramjet combustor as well as test facility. 

• It is an outcome of an integrated effort put by the DRDO labs along with industry & academia and paves a strong base for the nation’s Hypersonic Cruise Missile Development Programme.

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:

• 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.

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