The Defence Research and Development Organisation (DRDO) has achieved significant milestones in developing the Advanced Turbo Gas Generator (ATGG) engine, marking a critical advancement in India's indigenous propulsion technology capabilities.

The project represents a strategic convergence of design excellence, manufacturing innovation, and industry partnership, positioning India to reduce dependence on foreign propulsion systems whilst strengthening its defence manufacturing ecosystem.

Project Partnership And Manufacturing Framework

DRDO's Gas Turbine Research Establishment (GTRE) identified Azad Engineering Limited as its sole industry partner for manufacturing and full-scale assembly of the Advanced Turbo Gas Generator engine. This partnership, formalised in May 2024, grants Azad Engineering responsibility for complete end-to-end manufacturing, assembly, and integration of fully assembled engines for defence applications.

The Hyderabad-based precision engineering company represents a critical bridge between DRDO's design capabilities and production scalability, expanding its manufacturing portfolio beyond power generation and aviation sectors into integrated propulsion system production.​

The contract structure emphasises long-term collaboration, with Azad Engineering scheduled to commence deliveries of the first batch of fully integrated engines by early 2026. This timeline reflects both the technical maturity of the design and the production readiness of the manufacturing partner, indicating that the development phase has progressed beyond conceptual stages toward operational deployment.​

The ATGG employs a single-spool turbojet configuration, a design philosophy that prioritises compactness, manufacturing simplicity, and operational reliability. The engine architecture comprises four distinct functional sections, each optimised for specific performance objectives.

Proof of Concept Manufacturing Through Additive Techniques

A significant technological achievement within the ATGG development program involves the manufacturing of the Proof of Concept (PoC) engine utilising additive manufacturing methodologies. This approach represents a departure from traditional subtractive manufacturing paradigms, enabling rapid iteration cycles and novel component geometries impossible to achieve through conventional machining.​

The additive manufacturing approach deployed within DRDO's ecosystem employs laser-based Directed Energy Deposition (DED) technology. The DRDO-Industry-Academia Centre of Excellence (DIA-CoE) at IIT Hyderabad has developed an indigenously designed Large Area Additive Manufacturing (LAAM) system based on powder-based Directed Energy Deposition technology.

This system features a build volume of 1 metre by 1 metre by 3 metres, constituting one of India's largest metal additive manufacturing machines and demonstrating DRDO's capability to fabricate large aerospace components through additive processes.​

The LAAM system employs dual laser-powder delivery heads for enhanced thermal control and accelerated deposition rates, utilising laser and blown-powder based DED technology.

This technical infrastructure enables the production of complex geometries within engine components, supporting the fabrication of the ATGG PoC engine and validating manufacturing processes before scaling to full production quantities. The additive manufacturing approach facilitates rapid prototyping, supports topology optimisation strategies, and enables the production of functionally graded materials—all capabilities increasingly valuable for advanced propulsion systems.​

High-Speed Permanent Magnet Alternator Development And Testing

A crucial ancillary system integrated within the ATGG program involves development of a high-speed permanent magnet alternator (PMA) for electrical power generation. During 2024, DRDO completed development and testing of a prototype high-speed permanent magnet alternator designed to operate at the elevated rotational speeds characteristic of gas turbine engines.​

The permanent magnet alternator represents a technically demanding component requiring careful electromagnetic design, thermal management, and mechanical integrity considerations. High-speed alternators operating at tens of thousands of revolutions per minute demand sophisticated rotor dynamics analysis, advanced materials capable of withstanding centrifugal stresses, and precision bearing systems.

The permanent magnet configuration eliminates the requirement for excitation windings and external power supplies, reducing system complexity whilst improving efficiency and reliability—attributes particularly valuable for military applications demanding high availability and minimal maintenance.

Permanent magnet alternators leveraging rare-earth materials such as Neodymium-Iron-Boron (Nd-Fe-B) offer superior energy density, enabling more compact alternators with higher power density. DRDO's Defence Metallurgical Research Laboratory (DMRL) has previously developed high-energy rare-earth permanent magnet (REPM) components with energy products ranging from 18 to 35 megaoersted (MGOe), utilising domestic rare-earth mineral reserves. This foundational materials capability directly supports the alternator development program, enabling indigenisation of critical magnetic components.​

The 2024 prototype development and testing milestone validates the alternator's electromagnetic performance, mechanical robustness, and thermal management characteristics across representative operating conditions. Successful completion of this testing phase confirms the alternator's readiness for integration within the full ATGG engine system and provides essential data for production design refinement.

Engine Applications And Strategic Significance

The ATGG serves multiple strategic defence applications, with the Medium-Range Anti-Ship Missile (MRSAM) program identified as the primary near-term application. The engine's compact single-spool architecture and lightweight characteristics render it particularly suitable for cruise missile propulsion, where volumetric constraints, weight penalties, and thermal signatures present critical design drivers.​

Beyond anti-ship missile applications, the engine architecture demonstrates significant adaptability for derivative configurations spanning unmanned aerial vehicles (UAVs), target drones, trainer aircraft, and auxiliary power units.

The scalable turbojet core enables development of small turbofan and turboshaft variants through incorporation of additional stages or auxiliary systems, supporting a broad spectrum of defence platforms. This versatility amplifies the program's strategic value, enabling amortisation of development investments across multiple weapon systems and platforms.​

Manufacturing Capacity And Indigenous Technology Demonstration

Azad Engineering's selection as the sole production agency reflects DRDO's confidence in the company's precision manufacturing capabilities and capacity for scalable production. The expanded manufacturing infrastructure at Azad's Hyderabad facilities specifically accommodates end-to-end assembly of integrated turbojet engines, representing a significant capability enhancement within India's defence industrial base.​

The program underscores India's demonstrated proficiency in designing indigenous gas turbine engines incorporating cutting-edge technologies—a capability validated through preceding programs such as the Kaveri engine development initiative. Whilst the Kaveri program confronted significant challenges in achieving production-ready performance standards, the accumulated technological knowledge, materials science expertise, and design methodology have informed development of more focused, achievable propulsion systems such as the ATGG.​

Strategic Implications For National Autonomy

The ATGG development program exemplifies India's strategic commitment to "Atmanirbhar Bharat" (self-reliant India) by establishing indigenous capability in advanced propulsion technologies.

By combining DRDO's design and research capabilities with Azad Engineering's manufacturing expertise and leveraging cutting-edge additive manufacturing techniques, the program demonstrates an integrated approach to defence technology self-sufficiency.​

The development timeline, with initial deliveries projected for early 2026, represents an aggressive but achievable schedule reflecting the technical maturity of the design and the manufacturing readiness of the industry partner.

Successful execution of this program will establish India as a credible indigenous developer and manufacturer of modern turbojet engines, with significant implications for operational autonomy across multiple defence platforms.

The integration of high-speed permanent magnet alternators within the ATGG architecture addresses a critical subsystem requirement and validates DRDO's capability to develop complex electromechanical components utilising domestic materials and manufacturing expertise. The 2024 prototype development milestone reinforces confidence in technical execution and positions the program for successful transition to full-scale production.

IDN (With Agency Inputs)