India’s indigenous Kaveri turbofan program is entering a crucial validation phase with planned flight testing on an LCA TEJAS prototype, integrating a “hollow reheat” afterburner module.

This interim configuration does not initiate full afterburning but instead validates plumbing geometry, airflow distribution, temperature rise, and integration clearances within the aircraft’s wet section tunings.

The objective is to derisk the complex transition to a genuine reheat-capable Kaveri by maturing thermal margins, nozzle actuation, and fuel-control integration logic before committing to a fully igniting AB combustion phase.

By proving the airflow stability and compatibility of the metallic linings, ducts, and afterburner flame holder regions, GTRE and HAL are ensuring that subsequent Kaveri afterburner maturation will face reduced risks of thermal runaway, hot-spot formation, and instability once kerosene injection and ignition occur in trial stages.

The hollow AB effort forms part of a staged roadmap whereby the current 83 kN thrust-class target for a reheat-enabled Kaveri can be assessed step by step within TEJAS’s airframe envelope. Testing configuration will initially emphasise dry-to-hollow AB transitions, FADEC command acceptance, and nozzle throat control under load, thereby collecting key envelope data on engine-airframe harmonics.

This staged integration reduces both technical risk and safety concerns, offering the test team real-world aero-thermal data before moving to ignited reheat operations in later prototypes or dedicated demonstrators. Such flight trials will also benchmark clearance parameters against air induction distortions in the TEJAS’ intakes, providing valuable baselines for both fighter-class and future UCAV applications.

Parallel to the TEJAS flight-integration activity, the Kaveri dry engine derivative, being refined in cooperation with France’s Safran and DRDO’s GTRE, is intended for emerging indigenous UCAV programs such as Ghatak/IUCAV.

This dry variant, dispensing with the reheat section, targets 46–52 kN thrust output with greater emphasis on low specific fuel consumption, IR signature reduction via cooled exhaust mixers, and reduced thermal load consistent with stealth UCAV mission requirements.

While the wet variant’s maturity path is linked to manned fighter applications, the dry Kaveri path overlaps with stealth-configured autonomous combat systems, where compactness, endurance, and signature control outweigh raw thrust augmentation.

Component improvements underway include single-crystal turbine blades, higher OPR compressors, FADEC refinements, and indigenous thermal barrier coatings, all derived from prior Kaveri core learnings but implemented within a stealth-optimised architecture.

Together, these twin work-streams—hollow AB validation on TEJAS and dry engine advancement for UCAV—define a dual-track propulsion strategy: de-risking afterburner integration for eventual fighter compatibility while ensuring a robust dry-core engine family to power unmanned combat vehicles.

This approach reflects a pragmatic compromise after decades of difficulty, leveraging indigenous experience with external advisory infusion, providing India with a propulsion base more independent of foreign supply chains while gradually bridging the gap from demonstrator-level cores to operational propulsion systems.

IDN (With Agency Inputs)