India’s 73kN Kaveri Engine to Be Tested on Tejas Soon

For more than two decades, India’s quest to develop an indigenous fighter jet engine has remained one of the country’s most ambitious and technically demanding aerospace programs.

While nations such as the United States, Russia, France, and the United Kingdom mastered advanced military jet engine technology decades ago, India has spent the last 21 years striving to join this exclusive group of engine-producing nations.

Now, the long-awaited breakthrough appears closer than ever. The Gas Turbine Research Establishment (GTRE), under the Defence Research and Development Organisation (DRDO), is preparing for a milestone that could transform India’s aerospace industry.

For the first time, the indigenous Kaveri turbofan engine is expected to power a HAL Tejas fighter aircraft during flight trials by 2030, marking a significant step toward India’s goal of self-reliance in military aviation.

Kaveri Engine to Fly on Tejas Fighter

Instead of waiting for the final, more powerful version of the engine to be completed, GTRE has adopted a practical and phased approach. The organization plans to begin flight testing using the current afterburning Kaveri engine, which produces approximately 73 kilonewtons (kN) of thrust.

The engine will be integrated into an older Limited Series Production (LSP) Tejas Mk1 aircraft, which will serve as a dedicated flying testbed. This strategy allows engineers to collect invaluable real-world flight data while continuing to improve the engine for future variants.

Rather than delaying the program for several more years, India will begin validating the engine under actual flight conditions—an essential milestone in any fighter engine development program.

A Historic First for India’s Indigenous Fighter Engine

The upcoming flight campaign will represent far more than a routine engine test. It will mark the first time an Indian-designed fighter engine is evaluated aboard an operational fighter aircraft.

Until now, the Kaveri program has primarily relied on laboratory testing, ground test beds, and high-altitude simulation facilities. Flight testing will expose the engine to real aerodynamic, thermal, and operational conditions that simply cannot be replicated on the ground.

Successfully completing this phase would demonstrate that India has moved beyond experimental development and into practical aviation testing.

Tejas Was Originally Designed Around the Kaveri Engine

An interesting aspect of the program is that the Tejas Light Combat Aircraft (LCA) and the Kaveri engine were conceived together during the early stages of India’s indigenous fighter program.

The Tejas airframe was originally designed around the physical dimensions of the Kaveri engine. Although the aircraft eventually entered service with the General Electric F404 engine after delays in Kaveri’s development, the original design compatibility remains a major advantage.

Because of this, integrating the Kaveri into the Tejas requires relatively limited structural modifications compared to installing it on another aircraft platform. This compatibility reduces engineering complexity, lowers development costs, and shortens the timeline for flight testing.

What Will Be Tested During Flight Trials?

The initial flight trials will focus on validating the engine’s overall performance and reliability under operational conditions.

Engineers will evaluate:

• Throttle response
• Engine stability
• Thermal performance
• Fuel efficiency
• Vibration characteristics
• Engine-aircraft integration
• Reliability across different flight envelopes
• Performance during various altitude and speed conditions

The data collected during these flights will provide engineers with critical insights for further improvements before moving toward operational certification.

India’s Indigenous Engine Manufacturing Is Also Advancing

Progress is not limited to flight testing alone. India has also made important strides in indigenous engine manufacturing.

In September 2025, Godrej Aerospace delivered the first serial-production Kaveri derivative engine, designated D1, to GTRE. This marked an important transition from prototype development to limited serial production.

Building on that success, Godrej Aerospace is now preparing to deliver D2 and D3 engines during the first half of 2026.

The shift toward serial production demonstrates that India is gradually establishing the industrial ecosystem necessary to manufacture complex military jet engines domestically.

Extensive Ground Testing Before Certification

Before the engine is cleared for flight, the upcoming D2 and D3 engines will undergo an extensive testing program.

These evaluations will include:

• Long-duration endurance testing
• High-altitude performance validation
• Hot-weather operation
• Thermal stress evaluation
• Mechanical reliability testing
• Overall system validation

The results from these tests are expected to play a crucial role in achieving certification milestones and preparing the engine for future flight trials.

A More Powerful 85 kN Version Is Already Under Development

While the current 73 kN version will be used for initial flight testing, GTRE’s long-term objective is far more ambitious.

Engineers are simultaneously developing an upgraded afterburner that is expected to increase thrust output to approximately 84–85 kN.

If successful, this enhanced version would bring the Kaveri much closer to the performance levels required for modern fourth- and fifth-generation combat aircraft.

The upgraded engine could also serve as an important technology foundation for India’s future fighter programs, particularly the Advanced Medium Combat Aircraft (AMCA).

A Long Journey Filled with Challenges

The Kaveri engine program has experienced numerous technical challenges, delays, and redesigns since its inception more than two decades ago.

Developing a modern military turbofan engine is widely regarded as one of the most difficult engineering achievements in aerospace. Only a handful of countries possess the expertise to independently design, manufacture, and certify high-performance fighter engines.

Despite setbacks, India has continued investing in research, testing infrastructure, manufacturing capability, and indigenous technology development.

Today, the program appears to be entering a new and far more promising phase.

Conclusion

India’s decision to begin flight testing the indigenous Kaveri engine aboard the Tejas fighter represents a significant milestone in the country’s pursuit of aerospace self-reliance.

By adopting a phased development strategy, expanding domestic manufacturing through companies like Godrej Aerospace, and simultaneously developing a more powerful 85 kN variant, India is steadily closing the gap with the world’s leading jet engine manufacturers.

Although several challenges remain before the engine reaches full operational capability, the transition from laboratory testing to actual flight trials marks the most important achievement in the Kaveri program’s history.

If the planned milestones are successfully completed, the Kaveri engine could become one of the greatest technological successes in India’s aerospace sector, laying the foundation for future indigenous combat aircraft and reducing dependence on foreign engine suppliers for decades to come.