Defense & Aerospace · India
Air force engineers call it the Holy Grail.
India just opened three separate paths to build one.
Within weeks of each other, India saw three distinct engine breakthroughs: a strategic intent between Reliance and Rolls-Royce to build fighter jet engines for the AMCA, DRDO's delivery of a 350 kg-class expendable turbojet for missiles and drones, and a Chennai startup's successful test of a 5 kN rotating detonation engine. None of these are finished stories. Together, they mark the most serious push India has made toward owning its own engine ecosystem.
A fighter jet engine is often called the most complex machine in any air force's inventory — and the hardest one to build indigenously.
The Most Complex Machine in Any Air Force
Every fighter jet, every cruise missile, needs something to actually propel it.
Air force veterans have a name for that something. They call the jet engine the Holy Grail of military engineering.
Nothing else in an entire defence ecosystem is considered more complex, or more sophisticated, to build from scratch.
That's exactly why recent engine news out of India is worth paying close attention to.
In the span of a few weeks, three separate engine stories surfaced. A fighter jet engine partnership. A missile engine delivery. And a genuinely rare technology breakthrough from a small private startup.
Major Gaurav Arya, discussing the developments on The Chanakya Dialogues, framed the timing itself as the real story worth asking about.
Why is India suddenly hearing so much about engines, all at once?
The answer runs through three very different programs, at three very different stages of maturity.
A Partnership That Isn't a Partnership Yet
The biggest headline belongs to Reliance Industries and Rolls-Royce.
On August 14, the two companies announced a strategic intent to jointly develop India's indigenous combat engine for the Advanced Medium Combat Aircraft, or AMCA — India's fifth-generation fighter jet program.
It's worth being precise about what that actually means. No joint venture exists yet. Nothing has been finalized.
What exists is a joint statement, describing an intent to explore forming a dedicated Aerospace Gas Turbine Complex in India.
That complex, if it materializes, would cover the entire engine life cycle: design, development, manufacturing, testing, production, and long-term maintenance support.
Anant Ambani, Executive Director at Reliance Industries, framed the intent around sovereign capability. India's strategic autonomy, he said, requires owning critical technologies outright.
Rolls-Royce, for its part, described the move as building toward a robust, self-reliant aerospace ecosystem in the country.
A statement of intent isn't a finished engine. But two companies of this size rarely issue joint statements without a genuine plan to follow through.
Why This Needs an Indian Company With Billions to Spare
It's worth asking why a conglomerate like Reliance, with no prior aerospace engine history, is the one stepping into this deal.
Rolls-Royce brings something obvious: decades of proven engine technology and manufacturing track record.
What it needs from an Indian partner is different. Building a fighter jet engine ecosystem is extraordinarily capital intensive.
Billions of dollars are required, spent well before any meaningful profit arrives. Analysts covering the deal describe the spending pace bluntly: money poured in continuously, for years, before returns materialize.
That's a fundamentally different challenge than assembling, say, an automobile, where components and supply chains already exist off the shelf.
A jet engine has to be designed, tested, and manufactured almost entirely from first principles, inside the country attempting to build it.
That's precisely why India needs a domestic partner with genuinely deep pockets, willing to absorb years of expenditure before the AMCA program itself starts generating returns.
Reliance, whatever else it's known for, has exactly that kind of balance sheet.
The Trust Deficit Driving This Urgency
Why now, though? Why is India suddenly moving on three engine fronts simultaneously?
One widely discussed theory, raised by defence commentators including Major Arya, points to growing disillusionment with American engine suppliers.
Delays in supplying GE F404 engines have repeatedly slowed India's own Tejas Light Combat Aircraft program in recent years.
Air force veterans, Arya notes from his own conversations with former senior officers, have grown wary of depending on any single foreign supplier for something this strategically critical.
By contrast, he points out, the Indian Navy became largely self-reliant years earlier, having invested early and consistently in domestic shipbuilding companies.
The Air Force, on this reading, is now trying to close a similar gap — later, and with a narrower window to do it in.
That reading isn't the only explanation on offer, and India's engine push long predates any single supply delay.
But it helps explain why three separate efforts are accelerating at once, rather than one program simply taking its time.
Three Engine Ecosystems, Building at Once
Reliance and Rolls-Royce aren't India's only fighter engine conversation happening right now.
A separate track involves French engine maker Safran, which builds the engines powering the Rafale.
Defence Minister Rajnath Singh confirmed India is moving forward with Safran to begin manufacturing fighter jet engines domestically, though full technical details are still emerging.
Alongside both foreign partnerships sits a third, fully domestic effort: Kaveri 2.0, India's own indigenous engine program.
The original Kaveri engine famously lacked sufficient thrust to power a fighter jet on its own. The 2.0 version is specifically being developed to close that thrust gap.
Put together, that's genuinely three parallel fighter-engine pathways: Reliance–Rolls-Royce, a Safran partnership, and India's own Kaveri program.
Not every path needs to succeed for India to end up with a viable engine. But having three genuine attempts running simultaneously is a meaningfully different posture than relying on a single supplier.
That redundancy itself may be the point.
The One-Way Engines Nobody Talks About
Fighter jets aren't the only things that need engines. Cruise missiles, loitering munitions, and drones all need their own dedicated propulsion.
On July 22, DRDO's Gas Turbine Research Establishment delivered exactly that: India's first indigenous expendable turbojet engine, in the 350 kg thrust class.
"Expendable" means exactly what it sounds like — these engines fire once, and don't come home.
"Expendable" is the key word. These engines are built for one-way missions. Fire once, and that's it — there's no returning, no reuse.
GTRE designed the engine; Hyderabad-based Azad Engineering manufactured and assembled it, under an industry partnership with DRDO.
The engine generates roughly 3.43 kN of thrust — a fraction of what a fighter jet engine produces, but genuinely sufficient for its intended job.
It's designed for compact propulsion across missiles and unmanned expendable aerial platforms, built to be cheap, durable, and precision-engineered despite never coming back.
For comparison, India's long-range attack cruise missile already uses a similarly styled 450 kg-class small turbofan engine.
Jet engine technology at any scale is mastered by only a handful of nations. Even at this smaller, expendable class, that milestone matters.
A Small Startup Just Cracked Something Rare
The third story is arguably the most technically striking, and it didn't come from a defence giant at all.
D-Propulse, a startup incubated at IIT Madras, successfully demonstrated India's first indigenous 5 kN air-breathing rotating detonation engine.
The hot-fire test, conducted at a DRDO facility in Hyderabad, produced a stable 5 kN thrust, validating the engine at Technology Readiness Level 5.
That's a meaningful threshold. TRL-5 means the technology has moved beyond a lab curiosity, into validation under realistic operational conditions.
D-Propulse founder Saurav Jha called it the first successful demonstration of an indigenous rotating detonation engine at this thrust class in India.
The company's chairman is Dr. Vijay Kumar Saraswat, DRDO's former chief and a past NITI Aayog member — a genuinely heavyweight name lending credibility to a young startup.
Globally, only a small handful of countries are seriously pursuing this exact propulsion technology: India, the United States, Russia, and China.
A Chennai-incubated startup just placed India firmly inside that short list.
Why a Rotating Detonation Engine Is Different
Most jet engines rely on conventional combustion — fuel burning in a steady, controlled flame.
A rotating detonation engine works fundamentally differently. Instead of a steady flame, it uses detonation waves that rotate continuously around a combustion chamber.
This process, called pressure-gain combustion, is inherently more thermodynamically efficient than the constant-pressure combustion used in traditional gas turbines.
In practical terms, that means more thrust generated from less fuel, using a simpler design with fewer moving parts.
D-Propulse's version also integrates an aerospike nozzle — a design that maintains efficiency across a much wider range of altitudes than conventional bell-shaped nozzles.
Aerospike designs are notoriously difficult to engineer well. Successfully integrating one here is itself a meaningful technical achievement.
The immediate target application is supersonic cruise missiles, particularly tactical missiles carrying 100 to 200 kg warheads.
Cheaper, smaller, faster, and more fuel-efficient than conventional propulsion cycles — exactly the profile modern militaries increasingly want for mass-producible precision weapons.
The Hard Engineering Problems Still Being Solved
None of this came easily. Getting a rotating detonation engine from lab experiment to flight-capable prototype involved genuinely difficult engineering hurdles.
Maintaining stable detonation waves is the first challenge. The combustion has to behave nearly identically every single cycle for the engine to work reliably.
Extreme noise and vibration is a second. A continuous detonation process inevitably shakes the entire structure around it.
Reliable ignition and sustained operation is a third, alongside handling genuinely intense thermal loads generated inside the chamber.
Fuel injection and mixing design matters enormously too — precisely timed and distributed, much like the fuel injection systems used in diesel engines, but operating under far more extreme conditions.
Specific technical variables — combustor diameter, annular flow channel geometry, injector placement, ignition sequencing, nozzle geometry — all had to be solved together, not in isolation.
D-Propulse's own roadmap reflects how much work remains. The company is targeting a flight-ready engine by December 2027, not immediately.
TRL-5 is real progress. It is not the same as a weapon system ready for deployment.
What Self-Reliance Actually Requires Here
Step back, and a pattern emerges across all three stories.
None of them is a finished product. All three are explicitly framed around Atmanirbhar Bharat — India's push for self-reliance in critical defence technology.
And all three point toward the same underlying argument: India needs to own its entire engine ecosystem, not just assemble engines designed elsewhere.
That means Indian companies investing directly in engine research and development, not simply licensing finished foreign technology.
It means owning manufacturing capability outright, rather than relying on a supply chain that can be delayed, restricted, or withdrawn due to another country's decision.
Fighter jets, cruise missiles, loitering munitions, drones — every one of these platforms needs a domestically secured engine supply to be genuinely strategically independent.
That's a considerably larger ambition than any single AMCA engine deal, however significant that deal turns out to be on its own.
Whether India actually achieves it will depend on outcomes still years away — but for the first time in decades, multiple credible paths are being pursued at once.
Manohar Insight
What strikes me most here is the range of players involved.
A conglomerate the size of Reliance. A decades-old DRDO laboratory. And a startup barely a year old, incubated inside a university.
That spread is worth noticing. Engine self-reliance has historically been treated as a job only large state institutions could attempt.
Seeing a private, IIT-incubated startup independently reach a real propulsion milestone suggests that assumption is genuinely shifting.
None of these three stories guarantees success on its own. A strategic intent can quietly stall. A TRL-5 prototype can take years longer than planned to reach flight readiness.
But having three genuinely different institutions at three different scales, pursuing three different engine classes simultaneously, is a meaningfully different posture from what India has had before.
It also means fewer eggs sit in any single basket — a lesson recent supply delays seem to have made unmistakably clear.
The real story here isn't any one engine. It's that India finally stopped waiting on just one path to build them.
Join the Signal
With three separate engine programs now underway — a corporate partnership, a DRDO delivery, and a startup breakthrough — which do you think is most likely to actually reach India's fighter jets and missiles first? Share your take in the comments.
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