Kaveri & Aero-Engine: News & Discussion

[bala]

The entire blame for Kaveri engine is on the 1 exam wonder boys/girls of IAS. BARC/ISRO have independent PMO level access/authority. That is how they progressed and made things to work. However MOD is beholden to these IAS duffers who are loathed to think big. Every little thing is a chore in approval cycle. You want a test bench to test things, it goes through an entire rigmarole of procedures and justification cycle. MOD babus whisper things into mantriji which makes it worse since most mantriji are clueless themselves.

Even now, there are things that can be salvaged on the engine front. Give Bharat Forge's Baba Kalyani full authority to fashion a jet engine (special project) with GTRE / DMRL reporting to him. We need engines for lower things like trainers, jaguars, turbo props, etc. Cut out the MOD babus from engines completely. We don't need these blokes. Also involve HAL who know about practical things for an engine.

[A_Gupta]

Isn’t GTRE a part of DRDO? Does this have the same insulation or lack thereof from MoD babus as any other part of DRDO?
Isn’t the Kaveri engine program a GTRE project?

[Jay]

The entire blame for Kaveri engine is on the 1 exam wonder boys/girls of IAS.

At this point this seems incorrect. I do not believe in the story of "perceived helplessness" of the PMO or ministry in correcting the wrong and getting this program of national importance back on track. Either there is something happening that we are not privy to or the leadership is not competent in this area.

[A_Gupta]

Has the CAG report of 2011 named “Inordinate Delay in Fruition of Kaveri Engine” been discussed here on BRF?

[RCase]

There is a more fundamental problem in the induction of talent that has to do with the snail's pace progress in Jet Engines.

Societally, there has been a step-motherly, almost consolation prize attitude towards the following: Material Science/ Metallurgy, Chemical Engineering and Aeronautical Engineering. Do not mean any disrespect to those who have majored in these fields. As a thought exercise, let us find out how many JEE top 100 ranks opted for Metallurgy, Chemical, Aeronautical, Naval or Civil Engineering as their preferred choice - probably close to 0.

I can bet you that you can easily find an investment banker who is also among the top ranks of JEE. The malaise lays in the educational process that has (unfounded) biases, ending up with people getting slotted into areas with little or no aptitude for the specialization.

These fields need to be made 'cool' to attract and retain top notch talent.

[A_Gupta]

Delhi Defense Review, April 19, 2017 had this to say:

The key problems encountered by the Kaveri design, according to sources who have formerly been associated with the program, are:

* Unacceptable levels of fan-blade flutter risk – It seems that the Kaveri intake may need some redesign to reduce the chances of stall inducing self-excited vibrations (flutter) being experienced by the engine’s duct fan blades.

* Reheat oscillations – Kaveri prototypes currently experience significant combustion oscillation in their augmentors/afterburners. This also has an impact on specific fuel consumption during reheat.

* First stage low-pressure compressor blade vibration – The Kaveri’s first stage low-pressure compressor is also experiencing worrisome levels of rotor blade vibrations at the moment.

https://web.archive.org/web/20190302044 ... et-engine/

[uddu]

This is the current status of Kaveri engine.
1st Series produced Kaveri Delivered | Tejas Mk2 FF in 2026
Kaveri Derivative Engine (KDE) Industrial Maturity Roadmap
Prototype Phase (K9, K10 series)
Hand-built by GTRE with partial industrial inputs.
Objective: Demonstrate core, afterburner, and durability of modules.
Outcome: Validated ~46 kN dry thrust (KDE baseline).

D-Series (Deliverable Units)
Built by Indian industry partners (Godrej, HAL, MIDHANI, Tata, BHEL, etc.) with GTRE design authority.
D-1 (2025) →
First production-standard engine, fully modular.
Objective: Validate industrial tooling repeatability.
Tests: baseline thrust, material integrity, accelerated endurance.

D-2 & D-3 (2026) →
Incorporate fixes from D-1 runs.
Objective: 150-hour endurance test.
Tests: mission-cycle runs, HATF / INDIRA altitude testing.

D-4 & D-5 (2027) →
Near-final config engines.
Objective: Qualification trials (300–500 hr).
Tests: vibration, thermal cycling, bird ingestion, FOD, icing.

Q-Series (Qualification Engines)
Certified hardware for flight trials.

Q-1 & Q-2 (2028) →
To be flown on a Flying Test Bed (IL-76 / Tejas testbed).
Objective: Real-world performance validation.
Q-3+ (2029–30) →
Integrated with UCAV (Ghatak/Warrior).
Objective: Weaponized platform clearance.


Kaveri with After burner | KDE completes UCAV Cycle run
Typical UCAV Mission Cycle (Engine Perspective)

Engine Start & Taxi
Ground start (APU or external air start) → idle.
Low thrust requirement, but must ensure reliable ignition and stable idle.
Take-off & Initial Climb
Full Military Thrust / Afterburner (if equipped) for a short duration.
High acceleration demand, similar to fighters, but UCAVs often optimize for low-observable climbs (moderate throttle).

Cruise / Transit Phase

Long endurance at mid-part throttle (typically 60–70% of military power).
Efficient fuel burn is critical → engine operates at optimum TSFC region.
This phase is longer in UCAVs than fighters.

Loiter / Surveillance

Engie cycles between low and mid-thrust.
Requires carefree throttle (no surge or stall when rapidly adjusting).
Heat management is critical for IR signature reduction.

Combat / Strike

Sudden throttle bursts (from cruise to near max military thrust).
Short afterburner bursts (if designed).
UCAVs need rapid thrust response for evasive maneuvers despite not being dogfighters.

Return Cruise

Back to fuel-efficient mid-power.
Engine thermal cycle repeats (important for fatigue testing).

Approach & Landing

Multiple throttle reductions, idle descent, then short thrust bursts for wave-off or correction.
Must maintain stable idle without flameout.

UCAV Mission Cycle Testing in ASEMT

When simulating UCAV missions in Accelerated Simulated Endurance Mission Test (ASEMT), the engine is stressed through:
Rapid throttle cycling → mimicking loiter → strike → loiter.
Thermal cycling → heating/cooling from thrust bursts.
High endurance runs at cruise power → tests TSFC efficiency.
IR suppression evaluation → nozzle + hot section coatings.

[bala]

This is the current status of Kaveri engine.

Thanks Uddu ji for the great update on Kaveri. I think we are way past CAG and flutter nonsense which is all old news. Many things were fixed in Kaveri and they are well documented.

The facilities for testing at altitude are missing and also things like bird-hit/environmental snow storm/hail/stones etc that pose hazards during real world flights. This requires a GE Ohio / Safran / Saturn type testing facility were things can be simulated and engine designers know the results of the test. Our IAS wonder babus don't want to sanction such facilities for test since they cost some thousands of crores, but India needs them desperately. ISRO has a test facility for rockets in Mahendragiri. The high altitude flight stuff requires modifying a four engine aircraft and wiring it up for testing 1 engine while flying on 3. This is another task which requires an aircraft and people willing to sell/modify such things. This is hugely tricky and we end up with Russia as the sole nation willing to do such a thing. I think the next best thing is ghatak type flying craft, since even if we loose the ghatak it is no big deal. Basically India is at stage wherein testing and certification are pending on Kaveri.