India’s drive for self‑reliance in defence technology has received a significant boost with Hindustan Aeronautics Limited achieving a crucial milestone in the development of its indigenous HTFE‑25 turbofan engine.

The engine core has successfully reached 99.5 per cent of its designed speed during testing, a breakthrough that comes after years of delays and criticism surrounding the project.

The HTFE‑25 is India’s first indigenous turbofan engine for aircraft applications. Work began in 2013 at HAL’s Aero Engine Research and Development Centre in Bangalore, with the aim of reducing dependence on foreign engine technology for military and future aviation platforms. The latest test result has renewed interest in the program as India seeks to build capability in one of the most complex areas of aerospace engineering.

The Hindustan Turbofan Engine‑25 is a 25 kilonewton thrust‑class engine designed for smaller aircraft platforms.

It is a low‑bypass, twin‑spool turbofan featuring a three‑stage low‑pressure compressor, a five‑stage high‑pressure compressor, and air‑cooled turbine blades. Its design makes it suitable for military trainer aircraft, advanced trainers, light business jets, heavy unmanned aerial vehicles, and future unmanned combat platforms.

HAL has stated that the engine can power aircraft weighing up to around five tonnes in a single‑engine configuration. In a twin‑engine setup, it could support aircraft weighing close to nine tonnes.

Potential applications include the HJT‑36 Sitara trainer aircraft and the Combat Air Teaming System unmanned combat platform.

The latest achievement relates to the engine’s core, which is considered the most technically demanding part of a turbofan engine. The core includes the high‑pressure compressor, combustor, and high‑pressure turbine.

Reaching 99.5 per cent of design speed demonstrates that the engine core can operate under extreme conditions involving high temperatures, pressure, and mechanical stress. Engineers regard this stage as critical because it validates the durability and performance of the engine’s most vital systems.

HAL has incorporated advanced manufacturing methods in the HTFE‑25 program, including 3D‑printed components made from titanium‑aluminium‑vanadium alloy. These components reduce weight, improve strength, and enhance the thrust‑to‑weight ratio. The engine has a reported thrust‑to‑weight ratio of around 5.56 and is designed to support operations at altitudes of nearly eleven kilometres.

The development journey has been long. The core engine was first successfully tested in December 2015, and by 2019 more than 300 tests had been completed. Progress slowed in subsequent years, and by mid‑2024 the full technology demonstrator engine had achieved only about 55 per cent of its design speed. This slow pace led to questions about the program’s viability.

HAL later improved its testing and design capabilities to accelerate development. In December 2023, the company opened a new design and testing facility covering nearly 10,000 square metres. This expansion increased testing capacity and streamlined the development process.

Importantly, HAL has funded much of the engine’s development through its internal corporate resources, rather than relying entirely on direct support from the Indian Air Force or Ministry of Defence. This independence has given the company greater flexibility in research and testing.

Aircraft engines remain among the most difficult defence technologies to master, with only a handful of countries having successfully developed advanced jet engines. India has long depended on foreign suppliers for military aircraft propulsion.

HAL aims to make the HTFE‑25 ready for production by 2030. If successful, the engine could support India’s trainer aircraft, drone programs, and future aviation projects while reducing reliance on imported technologies.

This milestone is important because it demonstrates that India’s indigenous HTFE‑25 turbofan engine has reached a stage where its most complex and technically demanding component—the core—can operate at nearly full design speed under extreme conditions of heat, pressure, and mechanical stress. 

Achieving 99.5 per cent of the design speed validates the durability and reliability of the high‑pressure compressor, combustor, and turbine, which are the heart of any modern jet engine. It signals that HAL has overcome some of the toughest engineering challenges in aerospace propulsion, bringing India closer to reducing dependence on imported engines and establishing a self‑sustaining ecosystem for future trainer aircraft, drones, and combat platforms. This breakthrough also strengthens India’s broader defence manufacturing ambitions and enhances its strategic autonomy in aviation technology.

The HTFE‑25 forms part of India’s wider effort to strengthen indigenous defence manufacturing, alongside home‑grown systems such as missiles, aircraft platforms, and unmanned technologies. The latest test achievement is a vital step in building a domestic aircraft engine ecosystem and represents a turning point in India’s aerospace journey.

India’s ‘failed’ jet engine project turns around: How HAL’s HTFE-25 hit a major milestone

Agencies