Kaveri & Aero-Engine: News & Discussion

[SaiK]

may be it should be penny wise and pound foolish for weight reduction, after all this 45% composite by weight has been to waste basket. And the rest of the weight comes by way of additional metal support and copy book design that increases surface area.

imho, we could still rework on the airframe, increase the aerodynamic angles, and thus cut more surface area and weight.[perhaps tejas bk-2]. the electronics and its metal boxes must be converted to hard kevlars or light weight aluminum alloys as well. I am sure, there is something really wrong to quote 1 ton more.

I am sure, LCA team is not dumb enough to put the empty weight 1 ton more.. this ravi sharma guy is paid by franco-russkie operators as always. for every write up on lca, he gets his one year pay packet.

Every problem can be an oppty.. I think LCA can still reduce weight by designs. or the extra weight is because of GE engine.

[vina]

The article states that the LCA is overweight by ONE TON . I find that impossible to believe. That means that it is overweight by a range of 16 to 25%, based what the initial design weights were.

Yes, I think that is accurate... the LCA infoboards at the SG Air show all stated that Tejas Empty weight is 6.5 tons,(originally, it was 5.5 ton).

The rep also said the same thing... he didnt answer when asked about the apparent weight increase.

Hmm. That is interesting.. What did the extra 1 ton go for ? . Even the Tejas TDs were within that weight limit and they had done a weight reduction exercise to bring down the weight by a significant amount from that. Plus the LSPs will have no test instrumentation and every subsystem and component would have been weight budgeted. So what did the extra 1 ton empty weight go ? I wonder.

The Gripen's empty weight is 6620 Kg according to Wikipedia. So the LCA is in the Gripen's ball park and with the GE F404 IN 20, has better T:W ratio than the Gripen. But all the same, there were no complaints on "overweight" LCA until now. If that had been the case, DDM would have been bashing them all along and that would have been right there on the top of the list , along with 'overweight,delayed, no Kaveri.." etc.. Who knows maybe 6500 WAS the design weight and 5500 was DDM/ FUD.

[SaiK]

imho, given the political climate, saturn may be the ideal partner to boost the combustion science and go for those single crystals, and get the right thrust to weight ratio.

may be additional weight is not the empty weight, but with fully loaded with drop tanks and missiles. Engines should any way derate for 20% higher performance than the design specs. Something is really crappy about this weight business and after having known about the engine turbine complexities.

[Katare]

I think it was well known and discussed fact that LCA is over weight. Even the TD's were over weight for budgeted TD weights. Final weights are usually achieved at the end of the development cycles by gradually removing extra sturdy parts by lighter ones as the confidence in integrity of the design grows.

Now the quantum of over weight is uncertain, I have seen 300Kg to 800Kg figures over the year but 1 ton is astronomical at this stage. May be they are adding over weight component of Kaveri and LCA togather, which would actually make sense for calculating T:W ratio.

[SaiK]

anybody has read this one?
http://www.kcn.ru/tat_en/science/ans/jo ... 6_2_6.html

complete contents?

and this one?
http://www.iamot.org/conference/index.p ... r/view/258

[shiv]

Here is a question someone sent me on email. Could someone answer it? I did say i would post it on here because I am unable to answer it.

I had a small query about F414 engine and was wondering whether you could answer it?

There is this old article about F414 and at the end of the article it says:

http://www.globalsecurity.org/military/ ... s/f414.htm

'The final growth step - Step C - would produce an engine with 30 percent more thrust than the F414 - just under 29,000 pounds, or about 128 kilo- Newtons. This thrust level is nearly equal to the F110 Increased Performance Engine. To reach this impressive thrust level will demand further airflow growth from the fan, a modest temperature increase, a new two-stage low pressure turbine and a new afterburner'.

Has USA already come out with F414 engine Step C i.e. thrust of about 128 kilo-Newtons?

[rakall]

SHIV

what happened to your plan to vist GTRE?

Eagerly waiting -- so that you cn agte us some fresh & pure updates..

[maitya]

SHIV

what happened to your plan to vist GTRE?

Eagerly waiting -- so that you cn agte us some fresh & pure updates..

And has been long long overdue, if I may add - Shivji pls, any updates would be welcome!!

[shiv]

SHIV

what happened to your plan to vist GTRE?

Eagerly waiting -- so that you cn agte us some fresh & pure updates..

And has been long long overdue, if I may add - Shivji pls, any updates would be welcome!!

[Neshant]

LCA should have been a 2 engine plane from the start like the tornado or Eurofighter.

achieving the performance specs would have been a lot easier and more resources could be focused on long range weapons and sensors.

[KSubramanian]

^^^^^
I think this idea was raised in the forum before. The following points were put forth:

There would be too many changes required to the design

2 engines to control for the FADEC & FCS

multiple points of failure

2 engine variant aircraft is the MCA

[Neela]

LCA should have been a 2 engine plane from the start like the tornado or Eurofighter.

achieving the performance specs would have been a lot easier and more resources could be focused on long range weapons and sensors.

1. LCA today is what (if not more) it was originally meant for.
2 . Development would not have been incremental. Learning curve could have
been haphazard....esp when the sanctions kicked in.

achieving the performance specs would have been a lot easier and more resources could be focused on long range weapons and sensors

Weapons and everything else comes later....a reliable aircraft is a pre-requisite for weapons. Walk before we learn to run.


What is needed is the smooth transfer of the LSPs to IAF.
With that through, it will be a platform from which several variants for th IAF and Navy are developed. Each of them will bring in knowledge ....and that will establish a true fighter aircraft development knowledge base. This then will be the ground from which the MCA will be developed.

[Sanku]

All the blame to GTRE/ADA/IAF and related whining aside -- GTRE et al KNEW in 1991 (I say this from personal experience) that the MAIN and probably the ONLY problem they foresaw with the program was in one phrase "single crystal blades" everything else they knew or knew they could learn.

Today the same problem is the main villain yet very little can be done -- the matter is outside the hands. It is important to remember that in every other respect the program is already more than there.

This says a lot about our Mil-Ind complex (good things) that they had a good grasp on the future.

[sunilUpa]

So a problem identified in 1991 is yet to be resolved and our mil-ind complex has good grasp on future?

[Singha]

SC blade manuf was supposed to be done in HAL Koraput under MKI deal. but I believe either
India backed out of it later to reduce cost or the Rus pulled it off the table or both and the
extent to which AL31FP parts would be made in India got reduced.

this was the white horse that was supposed to "teach" us SC secrets when it was signed
many moons ago.

[Tanaji]

SC blade manufacture is one of the zealously guarded secrets of engine design. We never had expertise, and probably had to start from scratch, right from metallurgical expertise. Should we have manufactured it in 17 years? Who knows how much funding was dedicated to this activity? Might be the designers said "this is too hard, lets solve it later" and made the engine with the program managers saying dedicating 30% of money for 5% gain is not good RoI (just pulling numbers out of the hat)

So, its a bit premature saying Mil/Ind is clueless when we dont know how much money and resources were thrown at it.

[Sanku]

So a problem identified in 1991 is yet to be resolved and our mil-ind complex has good grasp on future?

Precisely (no sarcasm)

Unfortunately making SC blades is a area which impinges on Kaveri but is also in its own a full field of metallurgical engineering independent of engine design. AFAIK the entire exercise in Indian context was restricted more or less to GTRE. Kaveri can only meet specs if we could create SC technology. Else where this entire field was mature before decisions on using this technology for engines was decided.

Thus it was very clear that a very ambitious gamble was being made; in many ways this is similar to the Cryo story.

As Tanaji said would just throwing money on it sufficed? Who knows? What I KNOW is that all possible effort was made by GTRE under the compulsions it works under to work on this field from day 1; the constraints being the usual hiring problems (for meta experts) the fact that GTRE itself was running on a budget for Kaveri; tech denials etc etc.

SC is today -- THE SECRET SAUCE -- for all main engine manufacturers; to part with it is to sign ones own death sentence. Only some like Soviet Union would have done it (where the motives were not commercial/IP protection) I suppose thats what GoI is trying to do with JV. If not the entire secret sauce at least hire the cooks to set up a kitchen for us.

Should this have been done earlier -- guess so but I don't think any body was ready -- and I still have my doubts that the JV for Kaveri will actually fructify.

In many ways this IS the last frontier.

[maitya]

Singhaji, SC blades were actually produced by the DMRL couple of years back - the report was also posted in BRF (negi??) - but that was as in laboratory production and not for mass-scale production required for serial-engine-manufacture.
I thought *one* of the help that was being sought in those JVs were just that.

[NRao]

LCA should have been a 2 engine plane from the start like the tornado or Eurofighter.

achieving the performance specs would have been a lot easier and more resources could be focused on long range weapons and sensors.

The LCA was started in the early 80s to compete with the F-16C in particular. That was the goal. F-16C? TSP!!

[negi]

Singhaji, SC blades were actually produced by the DMRL couple of years back - the report was also posted in BRF (negi??)

Ahem... sir It wasn't me .

[NRao]

Aug 5, 2005:
http://www.drdo.org/pub/nl/oct05/president_dmrl.htm

President witnessed the various stages of casting viz., injection die, assembling, cluster preparation, dipping area, cleaning and de-waxing process, directional solidification furnaces and finally the components of Tejas (LCA). He appreciated the single crystal blades and the whole process of Investment Casting and emphasised on self-reliance in all sectors, especially for the national defence.

?????????

Aeronautics - A DRDO perspective
5 February 2007
M. Natarajan

Bangalore: A hearty welcome to you all to Aero India 2007, the international seminar on "Aerospace Technologies - Challenges and Opportunities" organised by the Defence Research and Development Organisation in association with the Aeronautical Society of India.
Aeronautics industry in India has been registering an exponential growth. In addition to the government sector, a number of private air Transport operators and industries are contributing to the growth. DRDO has taken a conscious decision to remain focussed and to work on the development of defence systems and related technologies.

Aeronautics-related development budget is the largest in DRDO, close to Rs.10,000 crore (about $2 billion)and expected to grow to Rs.25,000 crore (about $5 billion) or more in the next 10 years. We have allocations for programmes related to the Light Combat Aircraft (LCA), the Kaveri Engine, electronic warfare systems, multi sensor airborne surveillance platform, Unmanned Air Vehicles (UAV) and missiles. Thus we have major thrust areas in manned aircraft, unmanned aerial systems, airborne systems and air armaments.

While meeting user perspectives and requirements remain the major objective in the DRDO's aeronautical programmes, we are equally conscious of the need to do research on emerging technologies, drawing on talents and skills from academia and industry and augmenting our own human resources besides building requisite infrastructure for research and development.

The Indian Light Combat Aircraft — Tejas — incorporates many new avionics and glass and display systems. It is clearly a leap from the HF 24 base the country had as its maiden design. The Tejas has completed nearly 600 flights without any incident and we have orders in hand for 20 LCAs for the Initial Operational Clearance (IOC) besides eight being built as part of the development phase. It is clearly a significant milestone and the order symbolises faith in DRDO by decision makers. With this strength on our side, there are now prospects for international collaborations for design and development of future aerospace vehicles and systems and we are looking forward to meaningful discussions with leading aircraft designers and manufacturers at the Aero India show.

The LCA is already evolving into its variants — the LCA Naval Version and LCA Trainer, with the potential to become an advanced jet trainer beyond Hawk. The naval version will have about 70 per cent parts in common with the LCA Air Force trainer. It shall meet with specific requirements of the nose drop for improved cockpit vision, LEVECON for improved aerodynamics, strength enhancement to airframe and carriage for resisting arrestor gear loads, a fuel dumping system and capability to operate from aircraft carriers. We see opportunities to build an MCA and eventually an UCAV as a continuation for our efforts in this direction. I believe a succession of LCA-based platforms is what we need to preserve and keep improving avionics, EW systems and sensors such as multi mode radar and weapons package towards meeting the country's defence needs well over the next 25 to 30 years.

We have ambitious plans on the UAV platforms, thanks to significant achievements under the Lakshya and Nishant programmes at the Aeronautical Development Establishment. We have taken action already to develop a medium and long endurance UAV to be jointly developed with the Indian industry partner. In fact we have already requested "Expression of Interest" from Indian industries to partner with us. We have hopes that the Indian industries would cater to the needs of services for mini-UAVs. We will support all our manned and unmanned aircraft programmes with engineering simulation facilities and ground rigs to fix all problems on the ground.

The Defence Avionics Research Establishment (DARE) is the lead laboratory spearheading research and development in airborne electronic warfare and mission avionics, very significantly contributing to self reliance in these critical technology areas. DARE has successfully equipped aircraft fleet of Indian Air Force and Indian Navy with Radar Warning Receivers and EW suite. The public sector unit M/S Bharat Electronics manufactures the TEMPEST, TRANQUIL and TARANG Systems. Mission computers for SU 30 MKI, Jaguar and MIG 27 and of course LCA have been successfully developed and are being used. A Core Avionics Computer has been developed as part of MiG 27 upgrades as also a similar system for Jaguar. A supersonic electronic pod as a high accuracy direction finding system for SU 30 MKI aircraft has been developed. Digital radio frequency memory with a built-in ECM jammer has also been developed against radar threats. Programs on the anvil include development of advanced EW systems for LCA and futuristic MCA.

We are also developing the Airborne Early Warning and Control System with the Centre for Airborne Systems as the lead laboratory. The original proposal envisaged an executive Jet based platform. During the last 2 years, changing scenario as well experience gained through AWACS being procured has resulted in additional insights into the operational requirements. After detailed and thorough analysis, a baseline configuration has been evolved and finalised. The scope of AEW&C programme is to deliver two fully qualified systems to the IAF as part of Phase I. Additional 6-8 systems are contemplated as part of Phase II of this programme.

As far as Kaveri engine (to power LCA) is concerned we have worked on the gas turbine engine technology and this has enabled GTRE to develop Kaveri engine and in realizing the dry thrust, re-heat thrust almost 90-93 per cent of the expected performance. Our current plan is to leverage the hard earned knowledge and invite risk sharing partnership in completing the development and certification processes. Efforts are being made to formalise this partnership programme as early as possible with leading engine houses that have responded. In parallel, we are also working on the marine version of the Kaveri engine and have made substantial progress in this.

One of our DRDO labs, namely the ADRDE is involved in development of parachutes, arrester barriers, floatation systems, balloons and other arial delivery systems. Our current and long term plans include private sector participation in development and production of these items.

The Centre for Military Airworthiness and Certification (CEMILAC) is in charge of seeing through certification of products and processes under all our programs. The centre has developed tremendous expertise in the complex methodology of certification on par with international organisations.

We have identified key technology areas in aeronautics. We will stay focused on emerging technologies such as newer materials for single crystal blade, electro optic sensors and active electronically scanned array radar, long range precision guidance systems, ring laser gyros and MEMS based sensors and navigation systems, BVR missiles, stealth and Supercruise. We will invest in significant training programmes that focus on refreshing and enhancing design skills of our young scientists. We sincerely believe all these measures will get the requisite governmental support.

The aerospace seminar, undoubtedly, is the best forum to share our vision and experience and learn from those with record of achievements and accomplishments and seek professional alliances on topics of mutual interests and business pursuits.

May I, therefore, wish the deliberations over the next three days to be productive and purposeful for all the participants. I particularly give my best wishes to young scientists, who are here in numbers to seize the opportunity to meet with the challenges of the future with innovative and creative ideas and efforts and user in a growth in aerospace technology and products akin to the growth in our automotive industry.

(Speech delivered by M. Natarajan, Scientific Advisor to the Defence Minister)

[Neela]

The programme on Discovery showed something very similar to this.


The commentator did mention that drilling holes through the angled blade (running from top to the base in the pic )for cooling was very difficult.


Added later:
Link URL:
http://www.grc.nasa.gov/WWW/5000/images/blades.jpg

[John Snow]

That is gun drilling in a variable thickness curving blade. CNC with ultra sound or xray machine to monitor the progress is must ( at least initial set up) or it must be done in EDM.
**
added later
If it is investment casting then appropriate material (wax) inserts could be placed when poured these will melt away and the bore is made for the cooling ducts, which can be reamed later.

[ramana]

Dont go to the CNC machines or "experts" will nuke you!

[Neela]

This link
Mech Engg Magazine has lots of information.

The investment that is required is mind blowing. Like Sanku said, this does look like the final frontier.

Excerpts:

Thus, turbine airfoils subjected to the hottest gas flows take the form of elaborate superalloy investment castings to accommodate the intricate internal passages and surface hole patterns necessary to channel and direct cooling air (bled from the compressor) within and over exterior surfaces of the superalloy airfoil structure.

As an example, one 1999 study done for the U.S. Department of Energy found that for a nominal $6,000, 13.6 kg single-crystal blade, a 90 percent yield would raise the cost to $7,000, while a 20 percent yield would shoot unit costs up to $30,000 each. Much work has been going on in the casting industry to increase yields for these large turbine blades and vanes, using liquid aluminum or tin cooling, or inert gas jet cooling, to increase the efficiency of the critical one-dimensional transient heat transfer process that controls single crystal solidification

I am no expert on this. But the complexity of the task requires years of sustained investment and work to get to a stage where we can make a single engine, let alone variants

[SaiK]

rolls royce does a water jet guided laser cutting for their latest SC blades [not an urban legend].. especially, these holes are interesting in the sense, they follow the curvature the blades as well. Not sure, how the jet pattern is established for following the blade curves - secrets!.

They also claim their SC blades perform higher due to such micron holes, since it drastly improves the cooling of the blades to keep it around 1700*K.

[Neshant]

would not holes just weaken a structure.

[Anujan]

would not holes just weaken a structure.

No, depends on many factors. (a) Depends on the direction of stress. Imagine a rod and a cylinder, along the longitudinal axis, they have the same strength this is not true along the perpendicular axis. Similarly, I would expect the blades to undergo stress in an axis parallel to the holes and not perpendicular to the holes. So the holes do not compromise on the strength much.
(b) Materials have very different properties at higher temperatures than lower temperatures. Usually their tensile strength and bulk modulus is higher at lower temperatures (you can imagine them "softening" at high temperatures. This is not exactly the case, the crystal bonds weaken at higher temperatures, which makes it easy for them to snap). If for example the holes compromise strength by 5% but keep the temperature of the blade down by say 25%, it might be well worth drilling holes.

This hole business has an analog in conventional things like knives and swords. If, for example you look at knives meant for stabbing, there is a longitudinal groove in them that make them lighter without compromising strength (take our very own Kukri for example. The groove does not weaken the knife). Knives meant for slashing on the other hand dont have the grooves.

[SaiK]

following the lines of spinster's ideas above[added later section], wonder if we could avoid drilling by the crystal growth over say stent like tubes arranged in the pattern of the desired holes required, part of the jig.

[bala]

Another important point is that each blade is different and has slightly differing curvature. The blades are numbered and inserted in order for the final assembly. Besides temperature gradients, the blades are also subjected to pressure gradients.

I hope GTRE has also mastered high pressure/temp hoses that are used for connecting auxilliary systems. This is one area where major engine failures occur.

[John Snow]

would not holes just weaken a structure.

As long as the dia to pitch is maintained with in tearing and shear stresses its ok.
since the blade is deflecting the jet stream (on a curved surface) you will have mostly torque (torision stress) some bending stress nad couple ( the blade it self is fixed in one end and free on one end hence analogus to a contilever.

also the hole are in varying thickness there fore they should not distrub the static balance (of mass) as it may cause undue vibration and force rotating in excess of 30,000 rpm (at minimum)

[SaiK]

I am thinking GTRE would jump to BLISKs.

btw, http://www.manufacturingtalk.com/news/nvi/nvi102.html

Single Crystal with BLISK assemblies!!!

http://www.pilotfriend.com/aero_engines ... istory.htm

[asbchakri]

Guys wasnt SNECMA awarded a contract in Feb 2006 to help the Kaveri Engine programme. I just want to know in which areas were they supposed to help and what is the status of that. I havent heard much on that area.

[K Mehta]

x-posting from lca thread
Modified Kaveri Engine to Propel Indian Navy Ships
The Gas Turbine Research Establishment, Bangalore of Defence Research and Development Organisation which has been indigenously developing Kaveri engine for propelling the Indian Light Combat Aircraft (Tejas), has now come up with a modified marine version, as a spin off during research, to develop shaft power for propelling Indian Naval ship.

Using the core of the Kaveri engine, the scientists of GTRE have added Low Pressure Compressor & Turbine as a gas generator and designed a Free Power Turbine to generate shaft Power for the maritime application. The Kaveri Marine Gas Turbine (KMGT) as it has been named has been transported to Naval Dock Yard, Vishakapatnam and installed on to the Marine Gas Turbine test bed which is an Indian Navy Facility capable of testing the Gas Turbines upto 25 MW of shaft power through a reduction gearbox and a water brake dynamometer.

The Indian Navy has been involved in the development of the engine and participated and supporting the testing phase.

The engine has been tested to its potential of 12 MW at ISA SL 35°C condition which is the requirement of Indian Navy for propelling the SNF (Rajput) class of ships. This engine has been demonstrated to the Prime Minister Dr Manmohan Singh and others including the Scientific Advisor to Raksha Mantri Shri M. Natarajan, Vice Admiral B.S.Randhawa, Dr. D.Banerjee, CC (R&D).

With this development, India will become self-reliant in the technology of gas turbines for ship propulsion. This will put India in the elite club of Marine Gas Turbine designers e.g., USA, Russia, UK and Ukraine.

[K Mehta]

The success of KMGT would have interesting implications.
Question to gurus:
IF the KMGT succeeds, and the Kaveri for LCA doesnt, but spawns a number of marine engines which would power IN ships, would the investment made in it be worthwhile?
I agree that it would have failed the LCA programme but one of the main purposes was to create engine expertize in India, which it would have served.
Again Navy takes the lead in developing indigenous products.

[Sona R]

We can seek help of Rolls Royce in sorting out kaveri engine problem.

At present it is heavily dependent on civil aviation sector and it is outbid in military engine sector thanks to american armtwisting .

why not to rope rolls royce and solve the kaveri engine problem

[neerajb]

Wikipedia says:

Thrust:

Military thrust (throttled):11,687 lbf (52.0 kN)
Full afterburner:18,210 lbf (81.0 kN) [Goal: 20,200 lbf (90.0 kN)]

http://en.wikipedia.org/wiki/GTRE_GTX-35VS_Kaveri

After going through all the previous posts, it seems like the single crystal blades for the turbine are the stumbling block. But looking at the thrust figures, it is clear that the core part is working just fine and delievering what it was designed to do. Afterburner is the weak link here. In my opinion afterburner design should not be that difficult taking into consideration that GTRE successfully completed the core part.

Cheers....

[Singha]

fanboys tend to brag about their drilled brembo disc brakes too.

[chetak]

The success of KMGT would have interesting implications.
Question to gurus:
IF the KMGT succeeds, and the Kaveri for LCA doesnt, but spawns a number of marine engines which would power IN ships, would the investment made in it be worthwhile?
I agree that it would have failed the LCA programme but one of the main purposes was to create engine expertize in India, which it would have served.
Again Navy takes the lead in developing indigenous products.

HAL Engine Division may have considerable LM 2500 expertise.
They also have very considerable design expertise. 2+2 = .........
Sadly, the Kaveri does not seem to have too much growth potential so spawning
a number of marine GT types for different classes of ships is looking dim.
DRDO will always propose a " Don't raise the bridge but lower the river " type of solution.
We can still hope for the best.
The Navy may prefer to have one robust and dependable engine that it can use in different types of ships by using 1,2 or 4 numbers of GTs on each vessel.
Some of the very fast patrol vessels made by Goa shipyard may accept this GT without
too much of redesign.
There is good potential for use as a turbo generator for disaster management, floating dry docks etc.Good and compact design may make it air transportable. The power to weight ratio will be much better than a comparable DG considering the amount of electricity that can be produced.
Recovered exhaust heat may help in a small desalination plant.

[jahaju]

http://forums.bharat-rakshak.com/viewto ... 09#p515909

Dabhol Power Plant-
Sources said the gas turbine 2A failed in January after 2,841 firing hours and failure of the second turbine 2B had occured in January last year after 8,801 firing hours. A third major failure could have also taken place but was fortunately averted. During borescopic inspection on June 23, 2008, cracks were detected in compressor stage 15 static vane (S15) of gas turbine 3B after 5,248 hours of firing. GE has advised opening of casing leading to shutdown of about 45 days.

There are also frequent failure in liners, TPs and nozzles. In view of failure, GE has advised preventive borescopic inspection of each machine at an interval of 1,000 hours.

same company parentage, but with vastly different results.