GTRE (DRDO) Successfully Tests Kaveri Dry Engine (KDE) with Unrestricted Throttle Capability
India’s long-standing quest for aerospace self-reliance has entered a new phase with the successful transformation of the indigenous Kaveri jet engine program. Once a stalled initiative struggling to meet the requirements of manned fighters, the Kaveri Derivative Engine (KDE) has now been repurposed as the propulsion system for the Ghatak stealth unmanned combat aerial vehicle (UCAV)—a move that marks a critical step toward indigenous defence technology development.
Milestone Achievement: Unrestricted Throttle Test Success
The Gas Turbine Research Establishment (GTRE), under the Defence Research and Development Organisation (DRDO), recently achieved a major breakthrough by conducting a successful performance test of the Kaveri Dry Engine (KDE) with unrestricted throttle movement. This test confirmed that the engine could maintain smooth operation across the entire throttle range, without performance degradation or instability, an essential requirement for reliable thrust control during combat missions.
The KDE, a non-afterburning version of the Kaveri turbofan engine, is designed to deliver approximately 46 to 49 kN of thrust, with ground trials indicating outputs nearing 50 kN. Stable combustion across the throttle spectrum and advanced fuel delivery mechanisms ensure operational efficiency under diverse flight scenarios.
The UCAV Rebirth: A New Role for Kaveri
Unlike the original Kaveri, which was developed for India’s Light Combat Aircraft (LCA) Tejas with an afterburner requirement of 85 kN thrust, the new derivative serves as the heart of India’s stealth UCAV platform. The absence of afterburners allows the engine to be lighter, more fuel-efficient, and stealthier—attributes critical for deep-penetration missions.
The Ghatak UCAV, sanctioned in 2018, is expected to cruise at speeds close to Mach 0.9, with a service ceiling of up to 13,000 meters (approximately 40,000 feet) and endurance of around two hours on internal fuel. It is projected to have a maximum take-off weight of 13 tonnes, an operational range exceeding 1,000 kilometres, and the ability to carry precision-guided munitions for strategic strikes.
GTRE Director SV Ramana Murthy explained that the UCAV’s reduced thrust requirements and stealth-oriented design allowed engineers to adapt the Kaveri core, achieving 75% commonality with the original variant while implementing advanced compressors, improved turbine blades, and materials resistant to high temperature and stress.
Addressing Past Challenges with New Technologies
The Kaveri’s earlier hurdles in achieving desired thrust, reliability, and performance were overcome by incorporating lessons from global aerospace collaborations. GTRE leveraged interactions with Safran (France) and NPO Saturn (Russia), gaining access to advanced aerodynamic designs, compressor configurations, and high-temperature alloys without compromising strategic independence.
The upgraded KDE incorporates state-of-the-art digital control systems, enabling superior fuel management and engine monitoring, crucial for unmanned platforms operating in complex combat theatres.
A Cost-Effective Development Journey
Since its inception in 1983, India’s investment in the Kaveri program has been approximately $239 million (₹2,000 crore)—a fraction of the cost compared to other global aerospace programs. For context, the development of the Eurofighter’s EJ200 and Rafale’s M88 engines required around $1.6 billion each, while the F-35’s F135 engine development crossed $6.7 billion. Even China’s WS-15, meant for its stealth fighters, saw investments exceeding $42 billion.
This modest investment underscores the importance of targeted, sustained research and development and reflects India’s approach to balancing strategic autonomy with resource efficiency.
Future Pathways: Fifth and Sixth Generation Engines
The success of KDE has opened doors for next-generation propulsion initiatives. GTRE is now working on a 120 kN thrust engine tailored for fifth-generation fighter jets, with ambitions of enhancing thrust-to-weight ratios, fuel efficiency, and engine life beyond 2,000 operational hours.
Looking further ahead, the organisation is spearheading the sixth-generation propulsion program for the Advanced Medium Combat Aircraft (AMCA) MK-2, aiming for turbine entry temperatures of 2,100 Kelvin, putting India on par with advanced engines globally. These efforts also include technology collaborations with Safran, Rolls-Royce, and General Electric, focusing on joint development and future-proof designs.
Infrastructure and Collaboration: A Strong Foundation
GTRE’s 130 kN Twin Engine Test Bed Facility at Rajankunte, Bangalore, expected to be fully operational by October 2025, represents another cornerstone in India’s aerospace ambitions. The facility will support endurance and high-stress testing for larger engines, further accelerating indigenous development efforts.
According to K Rajalakshmi Menon, Director General of Aeronautical Systems at DRDO, India has reached a stage where international aerospace firms recognize the country’s capability to participate in advanced engine development programs. “Equal partnership, technological maturity, and strategic intent position India as a credible collaborator in global aerospace ventures,” she noted.
Strategic Independence through Indigenous Innovation
As KDE approaches certification for the Ghatak UCAV, and derivative technologies expand into naval and ground platforms, the programme exemplifies how persistence in research, coupled with strategic partnerships, yields long-term benefits.
India’s journey from technological setbacks to breakthroughs reflects a broader national goal: reducing dependence on foreign suppliers and building a self-reliant defence ecosystem capable of meeting future combat challenges.
The Kaveri program’s revival is not just a story of engineering resilience—it is a blueprint for how sustained innovation, strategic vision, and international collaboration can propel India into the front ranks of aerospace technology development.
