A new propulsion technology aims to redefine the future of military aviation. Its secret: a maneuverable, explosive process that could make India the latest global player in hypersonic travel.
Cranking up the heat on speed
The work of a rotating detonation engine (RDE) was born of a somewhat obvious inconvenience. Standard jet and rocket engines are heavy, expensive, and inefficient at high speeds. Powering tomorrow's missiles, drones, and hypersonic aircraft requires a new approach. RDEs are the proposed solution — a technology with four arms to tackle four distinct domains of engine technology. Critics from spending on the government's defense programs to those who believe the Indian aerospace industry simply cannot compete call for better proof that propulsion technology will still pay off. It sparks continuous rotating explosions in a circular combustion chamber instead of burning fuel continuously. This results yields much higher thermal efficiency and massive thrust from a smaller package with fewer parts. At less than 700 degrees Celsius, a rotating detonation engine can still produce 10,000 degrees Celsius at the throat of its nozzle.
"Their rotating detonation engine creates a continuous rotating explosion inside a circular chamber"
The push for new military propulsion technology
In 2025, a startup was founded in the ecosystem of IIT Madras, a stronghold for Indian engineering. In the Indian aerospace industry, researchers, and institutions like the Defense Research and Development Organisation are steadfastly pursuing a new vision for military propulsion. Innovations in propulsion technology could bring a paradigm shift. In July 2026, a milestone was demonstrated — India's first 5 kN air-breathing engine, paired with an aerospike nozzle. Not a scaled-down model, but a full-sized engine operated in relevant real-world conditions.
The deep-dive architecture of a detonation engine
The science behind the engine
Detonations are different from combustion. They are explosive and instantaneou. The detonation wave is perpendicular to flames as the explosive wave moves through the medium. The cylindrical chamber fuels detonation. The expanding gases can escape by flowing into an exhaust. The wave then has to travel back down to to interact with the incoming charge from the injector.
Stealth and speed
Detonation engines operate on the philosophy that extreme speed is the new stealth. By releasing a greater volume of thrust, they can allow modern drones and missiles to move faster and further, for less. This speed unlocks new capabilities, countering traditional detection technologies. If these tested engines become flight-ready, they could fundamentally lower the barrier to entry for hypersonic capabilities. Traditional engine technology cannot work above 5,000 miles per hour. A detonation engine can carry a flying object on the upper atmosphere, where traditional engines stop working, and then down again. If successful, the Indian aerospace business could reduce its dependence on foreign propulsion technologies.
Fuel efficiency
Fuel propellants use up to 50% less fuel than competing conventional rocket and jet engines. There are no moving parts in the engine. Combustion chambers are connected in a ring and propellant is introduced through an injector, combustion occurs and the gas exits through an exhaust. The engine could change military propulsion, with its continuous, circular rotating detonation engine design unlocking new turbo and detonation capabilities.
How it's made
The way to build a detonation engine could be a relatively simple project. The project by D-Propulse, however, should not be underestimated. The challenge is how to build a lightweight and reliable engine with lots of thrust. The company drew up a blueprint of a fighter jet to showcase the enormous potential of their engine technology.
Security and stability
India is now a partner in developing this technology. In November 2023, a joint patent application was filed between the Defence Research and Development Organisation (DRDO), the Indian Institute of Technology Madras (IIT-M), and DRDO-Gas Turbine Research Establishment (GTRE) to develop a Rotating Detonation Engine (RDE). Linchee Guntle, a man who has spent 30 years on motorsports, holds the patent for the engine.
The push for deep-tech innovation
India has 57,000 startups in the aerospace industry, according to the Indian government. There are only a handful of companies in the world doing detonation engine work. This makes it difficult to compare the funding, expertise, and project-specific progress of this company against the others. The opportunity cost of spending on India's defense programs is high, but for India, the detonation engine could be a game-changer.
How to go fast with a detonation engine
Interested in trying out this powerful push? The future of propulsion technology lies in hybrid and electric propulsion systems. For now, here are some steps you can take:
- Understand the basics of combustion: If you are an engineer, the first step is to understand the basics of both combustion and detonation engines.
- Focus on the fuel injection system: You can focus on the fuel injection system or the fuel delivery. Fuel has to be delivered at the right rate and at the right time.
- Get hands on with a conventional engine: Try to rework an existing conventional jet engine or rocket engine to include a detonation chamber. This may shake things up.
- Get funding: DeepRPulse just raised $2.7 million in seed funding, led by the IAN Alpha Fund. This pushes their estimated valuation to $16 million. Either bring similar resources or be ready to start a similar campaign for your own engineering teams.
Questions readers ask
What is a rotating detonation engine (RDE) and how is it different from traditional jet and rocket engines?
A rotating detonation engine (RDE) is a new type of propulsion technology that uses continuous rotating explosions in a circular combustion chamber, unlike standard engines. This design produces significantly higher thermal efficiency and thrust, while being lighter and more compact. Traditional engines burn fuel continuously, which makes them heavier, more expensive, and less efficient at high speeds.
What makes rotating detonation engines more fuel-efficient?
RDEs are more fuel-efficient because they use a detonation process that requires less fuel to produce the same amount of thrust. The detonation wave travels through the fuel and air mixture, and the expanding gases are expelled through the exhaust, creating a continuous cycle. This process allows RDEs to use up to 50% less fuel compared to traditional engines.
How do rotating detonation engines enable hypersonic speeds and stealth capabilities?
RDEs enable hypersonic speeds by producing a massive amount of thrust from a smaller, lighter engine. This allows missiles and drones to travel much faster and further, making them harder to detect and intercept. The extreme speed also acts as a form of stealth, as traditional detection technologies struggle to track objects moving at hypersonic velocities.
What are the main challenges or criticisms faced by Depropulse in developing this technology?
Depropulse faces several challenges, including skepticism from critics who question the feasibility and practicality of RDEs. Additionally, there are concerns about the high costs associated with R&D and the potential for the Indian aerospace industry to compete with established global players. Critics also want more proof that this propulsion technology will deliver on its promises, given the significant government investment in defense programs.
What kind of success has Depropulse achieved so far with this engine technology?
Depropulse has made significant progress with their RDE technology. In July 2026, they demonstrated India's first 5 kN air-breathing engine, complete with an aerospike nozzle. This was a full-sized engine tested under real-world conditions, marking a major milestone in the development of this new propulsion technology.
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