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.

[Rakesh]

https://x.com/AjayshreeSamby3/status/20 ... 92704?s=20 ---> CSIR‑NAL, has signed an NDA with Russia's United Engine Corporation to collaborate on developing aircraft engines for CSIR‑NAL’s aerospace programs at Wings India 2026.

[A_Gupta]

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.

True. But the narrow set of skills tested in the JEE doesn’t predict lab/experimental/practical ability - I.e., you don’t need the top rankers.

[Rakesh]

Will start a new thread on the new JV between GTRE & the chosen foreign OEM. For now posting this here...


GTRE–DRDO Kickstart “Desi High Thrust Engine”
https://alphadefense.in/index.php/2026/ ... rtnership/
29 Jan 2026

[Rakesh]

GTRE Seeking Partners To Make A New Indigenous Jet Engine

The DRDO’s GTRE has issued an EoI seeking a Development‑cum‑Production Partner—governmental or private—to build an Indigenous Advanced High‑Thrust Aero Engine, addressing India’s strategic shortfall. The 3D‑designed engine comprises 11 sub‑systems, 34 assemblies, 125 subassemblies and 2,500 components (23,000 parts total). The partner must produce 18 test engines in 10 years and 200 in production. After Kaveri’s slow progress, gaps in superalloys, test facilities and precision manufacturing left India reliant on foreign engines for Tejas and risk AMCA delays; GTRE’s move aims to cut imports and secure autonomy, though timelines and technical risks remain high.

[maitya]

Writing after a while ...
Frankly this constant rudali wrt Single Crystal blade (and vane) manufacturing capability, is quite depressing - especially so, even after almost constantly writing on this topic for decade+.
DMRL developed SCB has been exhibited, in each AI, from around AI 2003 onwards (here's one such example, from AI13), without any fail ... pls refer to the archives (and look for Shivji's post, if they have still survived).
Also refer to this old post of mine - this will explain why SCB is not at all a technical problem.

However we never developed this lab-level-technology (which is good for technical demonstration), to mass-manufacturing level - actually, not possible without adequate funding and a full-fledged mass-manufacturing program to justify that effort (again provided multiple examples on this very point, spanning years).
Of course, good luck, explaining such nuances to the Baboons - after all a degree in Medieval History will never equip one to such type of critical thinking.

Single crystal blades:
India:
https://www.ptcil.com/PDF/Investors/pre ... m-GTRE.pdf

What they are:
https://www.asme.org/wwwasmeorg/media/r ... -blade.pdf

A_Gupta-ji, this is old news, have been discussed in quite a bit of details here ...
Anyway, following are the point that most misses here, wrt this:

... Post-Cast Operations including machining, grinding, brazing, vacuum heat treatment, thermal barrier coating, and powder vapour deposition, of Single Crystal ‘Ready-to-Fit’ Turbine Blades ...

1) So SX casting of the blades (and vanes) will be done by somebody else (most probably DMRL) - PTC industry will then take this already-casted SX blades (and vanes) and perform these "post-cast operations", before handing them over to GTRE to "join it" (another huge technologically complex endeavor) to the turbine disc.
These 2 posts (here and here) will provide some glimpse on just one of the hugely complex technological steps involved in casting (actually pre-casting) of SX blades/vanes. And I didn't even go into that actual casting technology itself.
(those interested, may pls search "LAB" and "HAB in my old posts - will give a good glimpse one of myriad technological hurdles of casting involved)

2) Wrt this post-cast operations, for one step, say for vacuum heat treatment, just as an example, somebody (presumably DMRL, the original "SX superalloy metallurgy" designer of the SX being used) has to whisper in their ears, the exact post-cast-heat-treatment regime (heating-cooling-heating-cooling-heating... at different rates, and ofcourse upto different temp levels)

3) Does this make any of tasks less complex ... hell no, each is a technology in itself (refer to my earlier posts on each of these topics for eg the 6 part series on TBC). A casted-but-non-heat-treated turbine blade and vane will last maybe a few mins if added just like that in a modern TF turbine. And heat-treated but with no TBC ones will last - well, say an hour or two max.

4) Pls try and answer this question that I've asked (and answered) innumerable times now:
The raw-metal temp capability of 1st Gen SX of M88-2s HPT blades/vanes would be slightly inferior/very similar to that of DS ones in Kaveri/Kabini - ~1050/1060deg C levels. But then how come M88 achieves 1580deg C TeT while Kaveri "languishes" at 1455deg C - and AL-31FP at 1380deg C.
For hints, since have answered this innumerable times in the past, pls dig around my old posts .

5) So what is missing in these news items - film-cooling architecture design and laser drilling technology, that is absolutely vital to be finally able to "manufacture" a turbine blade/vane. Currently must be with GTRE ...

[Rakesh]

Writing after a while ...

Saar, please do not disappear like this on us.

[A_Gupta]

^^^ Thanks!

Of course, good luck, explaining such nuances to the Baboons - after all a degree in Medieval History will never equip one to such type of critical thinking.

Isn't all of DRDO subject to the same Baboons, not just GTRE? So what accounts for some successes and other not-so-sucessful ventures?

[A_Gupta]

The 2011 audit of the Kaveri program included:

Audit scrutiny revealed that in so far as turbo fan technology of engines, GTRE had only a very limited experience of the GTX engine behind it. At the time of sanctioning of the project, GTRE had to nearly double its sanctioned strength of trained manpower to cope with the target. Even today, the institute is beset by shortages in the scientific and technical branch personnel which are affecting the progress of the project. Owing to inadequate planning, many elements of the project viz. Flight Test Bed Trials and altitude testing were not conceptualised /included in the initial project proposal and were added later only at the insistence of the IAF.

Accepting the facts, the Ministry of Defence (Ministry) stated, in January 2009, manpower was an issue and that the depleting strength of skilled and expert manpower could not be replenished at the same rate.

Audit found that critical tests for components have not been carried out owing to the absence of facilities.

Now it is 2026 - are these issues behind India? Has the industrial eco-system of people's skills, experience, expertise, and industrial and laboratory infrastructure reached where it needs to be? What are the gaps?

[csaurabh]

The 2011 audit of the Kaveri program included:

Audit scrutiny revealed that in so far as turbo fan technology of engines, GTRE had only a very limited experience of the GTX engine behind it. At the time of sanctioning of the project, GTRE had to nearly double its sanctioned strength of trained manpower to cope with the target. Even today, the institute is beset by shortages in the scientific and technical branch personnel which are affecting the progress of the project. Owing to inadequate planning, many elements of the project viz. Flight Test Bed Trials and altitude testing were not conceptualised /included in the initial project proposal and were added later only at the insistence of the IAF.

Accepting the facts, the Ministry of Defence (Ministry) stated, in January 2009, manpower was an issue and that the depleting strength of skilled and expert manpower could not be replenished at the same rate.

Audit found that critical tests for components have not been carried out owing to the absence of facilities.

Now it is 2026 - are these issues behind India? Has the industrial eco-system of people's skills, experience, expertise, and industrial and laboratory infrastructure reached where it needs to be? What are the gaps?

I would argue that the manpower shortage issue is even bigger problem now that global aero giants have setup shop in Bangalore. Most of the manpower that could have been working at GTRE, NAL, etc. are working in Collins, Honeywell etc.

[williams]

The 2011 audit of the Kaveri program included:







Now it is 2026 - are these issues behind India? Has the industrial eco-system of people's skills, experience, expertise, and industrial and laboratory infrastructure reached where it needs to be? What are the gaps?

I would argue that the manpower shortage issue is even bigger problem now that global aero giants have setup shop in Bangalore. Most of the manpower that could have been working at GTRE, NAL, etc. are working in Collins, Honeywell etc.

Then we need to organize with better pay and benefits, management structure and challenging work environment to lure them.

[bala]

This from DRDO boss Sunil V Kamat on kaveri engine and where it will be deployed..

https://www.youtube.com/watch?v=u7vJQ50tgdM

[A_Gupta]

"The Indian Institute of Space Science and Technology (IIST) is a premier academic institution dedicated to the study and research of Space science and technology in India. It is located in Valiamala, Thiruvananthapuram, Kerala, and was established in 2007 to promote higher education and research in space sciences, technology, and engineering."

Does IIST produce output relevant to aeronautical engine engineering?

[Rakesh]

VIDEO: https://x.com/ANI/status/2018250672588939478?s=20 ---> On aero-engines, DRDO Chairman Samir V Kamat says, "An engine development is a long-drawn process. If you look at globally also, any engine development program takes between 10-13 years to reach maturity before it can be integrated with the platform. So, if the CCS gives a sanction this year, I would assume that by 2035-2036, the engine would be ready for integration. Then it would go through the acceptance trials. We will do the development trials of the engine much before with the platform but the final acceptance trials will start at 2035. The first two squadrons of AMCA will be delivered with a GE F414 engine. This will come only subsequently. AMCA delivery should start by 2034-2035."

^^^^^^^^^^^^

https://x.com/cvkrishnan/status/2018678 ... 12610?s=20 ---> If the CCS gives sanction for the Safran-GTRE JV this year, we can look at 2038 as the realistic timeline for a certified functioning engine be in production fighter aircraft. That’s the long gestation period for a jet engine development prototyping testing integration and certification.

[Kanoji]

But there was neither the vision nor the drive.

I think this is the crux of the issue in the Kaveri engine saga. I can contrast this with LCA program. From the initial days till its first flight it was headed by Dr Kota Harinarayana. I remember in one of his earliest interviews (to Flight Global - url given below) he mentioned that the LCA was first aircraft in Asia to be built from ground up. In the LCA program, every test rig had to be certified and each of it was a project by itself. This was the kind of challenge they were facing. I am guessing he had the vision, drive, patience and leadership to push things through. I can only hope and pray we get this kind of leader for the Kaveri program, going forward.

"We have developed numerous rigs - a dynamic avionics integration rig, iron bird for testing flight controls, environmental control system rig, fuel control system rig, and the like," he explains. Certification of each rig was a major project in itself, he says,

[ashthor]

If India Wants to Build a Jet Engine, It Should Know What China Endured
https://swarajyamag.com/commentary/if-i ... na-endured
06 Feb 2026

Beijing spent $42 billion, endured four decades of failure, and lost test pilots in the process, because there are no shortcuts to a jet engine.

Today, China fields fifth-generation stealth fighters powered entirely by domestically designed and manufactured engines. The journey from dependence to self-sufficiency cost more than $42 billion in direct investment, consumed four decades of continuous effort, and demanded a tolerance for catastrophic failure — including the deaths of test pilots and engineers — that few nations could sustain. For India, which faces its own jet engine gap with no indigenous powerplant for its fighters, the Chinese experience offers both inspiration and warning. Self-sufficiency is achievable. The price is higher than most democracies may be willing to pay.

[vera_k]

This does get to the crux of the matter.
Long as the IAF is seen as a defensive force, there is no need to develop an engine. Whether China occupies Taiwan or not, it has served as justification for developing tech even if not the state of the art.

[V_Raman]

is the achieved Kaveri thrust not even enough for empty LCA to take off/land/fly dry thrust mode? if it can, has it reached the state of reliability where it can be installed on an LCA for trials?