BA departure from traditional propulsion, new technology aims to make missiles faster, smaller and harder to intercept.
A rotary detonation engine (RDE) achieves this by using a supersonic detonation wave to compress and burn a fuel/air mixture inside an annular chamber to generate thrust.
Unlike traditional engines, it does this without a conventional compressor, making the engine smaller and more efficient. It is not yet ready for operational use, but once the technology matures, it could be used in missiles, high-speed drones and other specialized aircraft that require a smaller engine.
D-Propulse, a startup incubated by the Indian Institute of Technology Madras, tested a five-kilonewton air-breathing propulsion propulsion engine at the Defense Research and Development Organization’s Hyderabad facility in July, achieving Technology Readiness Level (TRL) 5, a milestone that only a few propulsion programs in the world have achieved in this category.
The test was carried out five times over a 24-hour period, with each burn lasting between five and 10 seconds, proving the engine’s combustion process was repeatable.
Because combustion occurs at higher pressure, the engine produces more thrust from a smaller engine with “fewer moving parts.”
It also has the benefit of pressure rise combustion, which helps provide 15 to 25 percent higher thermal efficiency. For the rocket, the benefit goes beyond simple fuel savings.
“Because you have a superior thrust-to-weight ratio, you can build a much smaller rocket around it and still achieve the same distance with the same payload,” said Saurav Jha, founder of D-Propulse.
Initially focusing on surface-to-surface and air-to-surface missiles, Jha said “a whole range of missiles is possible,” emphasizing that RDE’s ability to operate at different angles of attack could allow it to be adapted to different classes of missiles.
He said that in addition to missiles, they are also looking at high-speed unmanned systems, where the RDE could serve as the main propulsion system after the initial boost.
RDE can also offer an advantage when flying at high altitudes since it does not use a conventional air intake to compress the air. But turning the ground engine into a workable system will require extensive testing, since the flight engine will have to run much longer and manage the heat generated during detonation.
“The second most important thing now is increasing runtime,” Jha said, explaining plans to gradually increase engine runtime to 30, 60 and 120 seconds or more by improving heat management and cooling systems.
When it comes to this technology, India is not alone in the race. Several US companies such as RTX, GE Aerospace and Lockheed Martin are working on related programs, and Chinese military research institutes are also developing RDE-based munitions.
Group Captain Rajeev Kumar Narang (retd), senior fellow at the Manohar Parrikar Institute of Defense Research and Analyzes in New Delhi, said the technology still has a way to go from TRL 5 to operational implementation.
He said these efforts must also meet the military’s operational needs and match their development to the platforms they can use.
Pointing out gaps in the system for testing and certification of new propulsion technologies, he said, “The question is, if a company wants to conduct trials, who will formulate the guidelines for its testing? Who will accept the test data? As of now, there is no mechanism for independent certification of small propulsion systems without integrating it with the platforms and user requirements,” Narang said.