A new small engine for high-speed items

The test ran five times in 24 hours, with each burn lasting five to 10 seconds, proving the repeatability of the engine’s combustion process.

As the combustion takes place at higher pressure, the engine produces more thrust from a smaller engine with “fewer moving parts”.

It also has the advantage of pressure-gain combustion, which helps provide 15-25 per cent higher thermal efficiency. For a missile, the advantage goes beyond just saving fuel.

“Because you have a superior thrust-to-weight ratio, you can build a much smaller missile around this and still reach the same distance with the same kind of payload,” said Saurav Jha, founder of D-Propulse.

With an initial focus on surface-to-surface and air-to-ground missiles, Jha said an “entire suite of missiles is possible”, highlighting that RDE’s ability to operate across different angles of attack could allow it to be adapted to different missile classes.

He said that besides missiles, they are also looking at high-speed unmanned systems, where the RDE could serve as the main propulsion system after an initial boost.

The RDE could also offer an advantage for flights at higher altitudes, as it does not rely on a conventional intake to compress air. But turning the ground-tested engine into an operational system will require extensive testing, as the flight-rated engine would need to operate for much longer and manage the heat generated during detonation.

“The second most important thing right now is to increase the duration of operation,” Jha said, while explaining the plans to gradually extend the engine’s operating time to 30, 60 and 120 seconds and beyond with better heat management and cooling systems.

As for this technology, India is not alone in the race. Several United States-based companies like RTX, GE Aerospace and Lockheed Martin are working on related programmes, while Chinese military research institutes are also developing RDE-powered munitions.

Group Captain Rajiv Kumar Narang (retired), senior fellow at New Delhi-based Manohar Parrikar Institute for Defence Studies and Analyses, said the technology still has some way to go from TRL 5 to operational adoption.

He said the effort must also align with an operational military requirement and match its development with the platforms it could power.

Pointing to gaps in the testing and certification framework for emerging propulsion technologies, he said, “The question is, if the company wants to test, who will formulate guidelines for its testing? Who will accept the testing data? Right now, there is no mechanism for independent certification of small propulsion systems without integrating it with the platforms and user requirements,” said Narang.