DRDO conducts long-duration ground test of scramjet engine

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

• The DRDL successfully conducted an extensive long-duration ground test of its Actively Cooled Scramjet Full Scale Combustor, achieving a run time of over 12 minutes at its state-of-the-art Scramjet Connect Pipe Test (SCPT) Facility.

• The remarkable feat is achieved through a cutting-edge air-breathing engine, which utilises supersonic combustion to sustain long-duration flight. 

• The ground-tests conducted at SCPT facility have successfully validated the design of advanced scramjet combustor, as well as the capabilities of the test facility.

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.

Significance 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 6,100 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.

• In January 2025, DRDL demonstrated a cutting-edge active cooled scramjet combustor ground test for 120 seconds for the first time in India.

• In April 2025, it conducted long-duration Active Cooled Scramjet Subscale Combustor ground testing for more than 1,000 seconds. 

• With the successful test, the system will be soon ready for full scale flight worthy combustor testing.

(The author is a trainer for Civil Services aspirants.)