Kaveri & Aero-Engine: News & Discussion

[NRao]

Much water has flowed under the bridge and we are where we were when it all started?

Livefist :: August 2010 :: Kaveri's Compressor Blades + The Indian Single Crystal Effort

1) That presentation (to be clear, from : India's Defence Metallurgical Research Lab (DMRL) in Hyderabad) is from 2010 (there could be newer versions out there)
2) It does not claim that the Kaveri has SCB, it very well could have if that were a fact
3) It states, like a few posters here have, that India does have access to SC technology

Now, why this technology has not reached the Kaveri is beyond me. It has been talked about umpteen times on BR but without any conclusion. All I am saying is that MY FEEL is that all the latest technologies have not reached the Kaveri - why I do not know.

But, here is an interesting diagram, we now have a basic idea of temp/pressure/alloys in a Kaveri (it may have changed):

[vina]

Singha sir,
In another forum (keypublishing forum) there is a post of one Mr.Harry which includes an image of SC blade casting. Not sure if I'm allowed to post the link of that thread here.
This tech was given to HAL koraput for manufacturing turbine blades for AL31FP.

Do post that link. But B.Harry died a while ago. Even if HAL Koraput has been given that, it probably came with such kind of restrictions and clauses that it cannot be used for other programs and has end use restrictions rendering it essentially useless beyond the SU-30 program.

[NRao]

One more thing. The Kaveri did get some assistance from Central Institute of Aviation Motors (CIAM) of Russia.

Indian brains, some Russian help - not outright (I wonder why not. if they could help with nuclear efforts, why not engines), Ge and few others declining to help, Snecma willing but reluctant.

So, it seems to me that they have reached some sort of technical limit on the Kaveri. The limitation I suspect means redesign, which means not-for-LCA redesign.

I feel that the Kaveri-LCA has to be trashed - it will not work. Kaveri has to be redesigned - I suspect it will be larger than this engine and then they will have to fit a AMCA around the larger engine.

IF they want to retain this size, then it will take eons - time + funds.

Again, it is speculation on my part, but speculation based on data points I have read. But, then I could be totally wrong too.

[vina]

But, here is an interesting diagram, we now have a basic idea of temp/pressure/alloys in a Kaveri (it may have changed):

Well, that diagram looks like what that would ultimately LIKE to achieve and not what it is at present. With a overall pressure ratio of 30 and turbine entry temp of the order of 2200 C , you are looking at only single crystal blades and absolutely cutting edge cooling schemes and thermal barrier coatings in the high pressure turbine.

And yeah. That engine will be at par with the EJ200 + and GE414 and M-88-3/4in terms of technology levels. I dont think we are there now.

[NRao]

But, here is an interesting diagram, we now have a basic idea of temp/pressure/alloys in a Kaveri (it may have changed):

Well, that diagram looks like what that would ultimately LIKE to achieve and not what it is at present. With a overall pressure ratio of 30 and turbine entry temp of the order of 2200 C , you are looking at only single crystal blades and absolutely cutting edge cooling schemes and thermal barrier coatings in the high pressure turbine.

And yeah. That engine will be at par with the EJ200 + and GE414 and M-88-3/4in terms of technology levels. I dont think we are there now.

We seem to have something to start with.

I think you are the best at guestimating what could possible be off from that diagram. Work backwards. Take a swipe.



Q: If they were to rework the dimensions of this engine, retaining pretty much the rest of it (alloys, etc), will it produce the wet thrust they are looking for? Or can it produce it?

[vina]

I think the "directionally solidified" stuff came from DMRL based on the techfocus article below

http://drdo.gov.in/drdo/pub/techfocus/2 ... il2011.pdf

Thanks. Hmmm. Some pretty solid and good work by DMRL. They have got the manufacturing and fabrication of directionally solidified blades in place and in addition to the Kaveri, seem to have got that into the Jaguar's Adour MK811 as well! Now, that is really going to squeeze the testimonials of RR out of one of the most lucrative annuity revenue streams. Ouch!

From all indications I see, we are not there yet in terms of indigenous single crystal in terms of manufacturing and fabrication. We are probably close to the top of the hump and will take some time to go over it. The directionally solidified blade the DMRL claims is equivalent (CM -XXX) to is the latest alloy from the specialist I quoted.

But think of it. Once that single crystal blade of a current generation is in place, we can give the Russians the birdie for the Mig 29 and SU 30 engines and the French for the M2K and Rafale engines and also the GE 404 engines as well probably, like we seem to be doing for the Jaguar's Adour and what the Jugaad after market guys were doing for the Industrial Avon! No wonder RR, the Russians and GE and the others are not going to give it to us on free terms, that will see a very lucrative revenue stream dry up forever! This thing is literally a gold mine.

Into the breach men! Let us get this over the hump and be done with it.

how were the jet engines of the 70s and 80s achieve such high thrust without single crystal blades? Were they inefficient or were they huge?

Inefficient AND huge. What took a far larger number of stages and more fuel burn and a bigger engine is now done by a much smaller number of stages, with dramatically less fuel burn and a smaller engine. Sort of like what happened in automobiles. Today's power / cubic centimeter displacement (bhp/cc) is vastly higher than say 3 decades ago. What needed a V8 some 30 years ago is now done by a 4 cylinder of much smaller displacement and obviously using far less fuel and a smaller engine to boot.

Q: If they were to rework the dimensions of this engine, retaining pretty much the rest of it (alloys, etc), will it produce the wet thrust they are looking for? Or can it produce it?

What is the point in putting in a V8 engine of 4.8L displacement from 1975 producing some 160 hp in a Honda Accord in 2012, when a 4 cylinder 2.4 liter engine in a current Accord produces close to 200 hp and is around a third of the weight and gives some 15 miles per gallon more and not to mention runs for 300,000 miles without any problems while a V8 circa 1975 will go Kaput in less than 80K miles?

[vic]

Kaveri today cannot match the specification of M53 (Mirag 2000's) engine which was considered dated for the era 1967-70 when it was designed. We are just 40 years behind

[Sagar G]

Kaveri today cannot match the specification of M53 (Mirag 2000's) engine which was considered dated for the era 1967-70 when it was designed. We are just 40 years behind

So ???

[NRao]

What is the point in putting in a V8 engine of 4.8L displacement from 1975 producing some 160 hp in a Honda Accord in 2012, when a 4 cylinder 2.4 liter engine in a current Accord produces close to 200 hp and is around a third of the weight and gives some 15 miles per gallon more and not to mention runs for 300,000 miles without any problems while a V8 circa 1975 will go Kaput in less than 80K miles?

(((Errr...... the point is this 4 cylinder is of no use AT ALL - outside of consideration for a UAV right now.

The 4 cylinder from Honda at least lasts 80K miles.)))

But, I take it a redesigned engine will produce the desired thrustS, albeit inefficiently.

IF true then it all boils down to materials I would like to think. And, IF that is true, then they have a very long way to go IF they want to retain the current dimensions.


We heard a lot from Western sources about Indian inability to absorb newer technologies. This may be an example of that situation - wherein Russia has provided enough to kick start the effort on SCB, but India is unable for what reason to push it over the hump.

[Sagar G]

We heard a lot from Western sources about Indian inability to absorb newer technologies. This may be an example of that situation - wherein Russia has provided enough to kick start the effort on SCB, but India is unable for what reason to push it over the hump.

That's pure BS from goras, it's an excuse for refusing to share technology and by subscribing to such views you are only falling into there trap. It's just a small part of the larger plan to keep the brown man downtrodden. About alleged Russian transfer of SCB tech to India I haven't seen any authentic info about this in open source and neither any insider info about it to gauge how much tech we have been provided and what pound of flesh did Russia extract for that so unless and until we don't get the details of this alleged tech transfer it would be only wise to not form any kind of assumptions about it.

[SaiK]

aah ha!
http://www.business-standard.com/india/ ... er/497740/

“We are abandoning the plan for co-development with Snecma."

GOOD.

But, why go global? I think I have successfully persuaded to get off from snecma, if the above is true. Who says public spells don't work!?

Major aero-engine development facilities are being set up in Chitradurga, where a 5,600-acre hub of strategic industry will house R&D, testing and production units of the DRDO, Department of Space (DoS) and Department of Atomic Energy (DAE).

These will include an official altitude test facility for aero engines, which US defence major Boeing is providing as an offset in India’s Rs 22,800 crore ($4.12 billion) purchase of ten C-17 Globemaster III transport aircraft. So far, GTRE has had to do all its testing in Russia.

I hope the global participation is only for drawing board [chinese model]. MoD expecting some firang companies to trade off technology is high hopes. Man.. what are they thinking?

I think we need to keep harping on GTRE reorganization and role up their sleeves and start working on their backyard more than expecting a spoon feed. 15-20 more years to deliver goods if done indigenous, then it is time for GTRE men to split up, and work given to other orgs who can do it in 5 years.

[NRao]

aah ha!
We are abandoning the plan for co-development with Snecma

Aah ha indeed. May explain why the MMRCA deal is being so slow too. And what would happen to the M2K upgrades I wonder.

“To develop a more powerful Kaveri engine quickly and to become self-reliant in engine design, we need a foreign partner which can bring in core technologies. Otherwise the next cycle of engine development could take another 15-20 years,” admits Ramnarayan, frankly.

The DRDO is struggling to develop the nickel and cobalt superalloys for the Kaveri turbine, where temperatures of 1,600 degrees centigrade warp normal metals.

Shaping the alloys into engine parts is an equal challenge. GTRE has learned how to make “directionally solidified” turbine blades; but it has not mastered the making of “single-crystal blades”, which are now standard.

Need help with a few alloys AND SCB at the very least.

Older article:

Feb, 2012 :: Kaveri turbofan programme seeks extension

Negotiations [with SNECMA] on technology sharing and intellectual property have taken the better part of the two years

The joint effort, in effect, calls an end to the Kaveri K9 programme as it stands.

DRDO sources confirm that Snecma will transfer several key technologies as part of the joint engine programme, which include single crystal blades, bladed disk and EBPVD (electron beam plasma vapour deposit coating), all critical areas that the Kaveri engine has failed to find solutions to within the country, though not for lack of trying. Programme managers believe single crystal blade technology will be a major solution to one of the Kaveri's biggest problems — deformation of blades during testing as a result of high ambient temperatures. This has proved to be a severe limiting factor, considering that structurally solidified blades have structural integrity that comes nowhere close to single crystal structures. According to sources, it is negotiations over the modalities for single crystal blade technology that has taken so long,

Almost the entire work force that has been dedicated so far to the Kaveri will be diverted to the K10 effort with Snecma. Scientists foresee challenges in absorbing the technology, but are confident that they will achieve goals once the contract is signed and the effort flagged off. A senior GTRE scientist says, "We have the will and the base technologies. We understand fully well what our shortcomings are, and are eager to deliver a full performance engine to the customer. Gone is the time when we can stay in the lab indefinitely saying we will come up with certain technologies by ourselves. The French will help us cut down on development time. And we will both deliver an engine that will power Indian aircraft. Everybody wins."

[SaiK]

I do not believe in GTRE senior scientists assertion. I think they are doing a CYA. I understand the technology here is complex and extremely safety critical, but it must not be over emphasized to side track the objectives laid for GTRE. I a sense, it is a CYA to their failures to deliver to specs.

Their funding needs to be bumped, management team reorganized, and fresh ideas and engineers on merit take up prestigious jobs, and paid well. Instead of paying the firang companies, pay the hard core workers.

It can be done in 5 years, if done correct.

[NRao]

Casual reading on "nickel and cobalt superalloys" lead to noticing there are some 4-5 alloys of these metals alone in relation to an air craft engine!!!! Then comes casting these alloys.

It should take 1-2 years to select a partner. Another couple to transfer techs and start work. And, another two to build the first true Kaveri for the AMCA. Six years out. Till then the design work on the AMCA would be frozen.

[Singha]

AMCA design work need not be frozen because both for 90knx2 and 125knx2 there are solid alternatives from foreign vendors and for sale. but yes the engine bay design should be done carefully so that adaptor structures can be used to accomodate atleast 2 choices for the chosen size of the AMCA...a little subpar having to fit the bigger choice but can be tuned down later. Cheen is using AL31 in J-20 when its obvious the engine bay can accomodate a bigger engine of the foxhound mould.

we better get the AMCA project going seriously of we are ever to master the VLO thing, internal bays, aesa radar, DASS etc.

[SaiK]

from kat thread:

MMRCA deal: Negotiations between defence ministry, Dassault run into fresh hurdle.
The French, it appears, are unwilling to transfer cutting edge technology such as that of the electronically scanned AESA radar while citing lack of maturity of the Indian defence industry to absorb such critical technologies as an excuse.

There is a strong lobby of small and medium French enterprises which is against industrial offsets and sees it as a threat to the competiveness of the French defence industry. Early last year, Patrick Colas des Francs, chief executive of Coges, the trade show organizer for the Eurosatory land systems exhibition reportedly said, “Offsets are a threat to small and medium-sized companies. This is a real problem.” "Offset deals not only take production work away from French subcontractors and suppliers, but also provide accelerated access to knowledge and skills that allows companies in the client country to compete in world markets," he said.
.

Assumption here is that throwing more money will solve the problem or bring the solution substantially faster. It's wrong! Often repeated mistake, money is but one of the many resources needed for success. Experience, design data, supplier base, infra and baseline needs time and good management more than they need money. DRDO has never been short of money, it has almost never been denied additional time and money by GOI. Anyhow the DRDO budgets and western budgets are not comparable because they follow completely different accounting. If DRDO budgets were to be calculated using proper GAAP methods they’ll be several times more than what they are on the paper. .....xyz

well said, and well shown by France et al.. this lesson must be learned by DRDO (especially GTRE) and GoI. One can't just pay money and get IPR-ed products with technology transfer. It would be every other person in the country of seller of technology's dead body sometimes.. These rights are basis for capitalism. It is a joke that GoI and GTRE charter on seeking technology. shame in many sense.

[vina]

AMCA design work need not be frozen because both for 90knx2 and 125knx2 there are solid alternatives from foreign vendors and for sale. but yes the engine bay design should be done carefully so that adaptor structures .

They should choose one of the two sizes upfront. Cant do both. The 90KN is a Eurofighter/Rafale sized bird while the 125KN+ is an F-15/Su-30 sized bird.

What they should do is to design the plane around NATO standards so that they can access the largest , most competitive and most sophisticated supplier and buyer ecosystem around. All the buses, electronics, interfaces , armaments etc should be fully compliant with whatever relevant IEEE and NATO standards, so that no one gets a lock on our choices and crimps our flexibility.

Even the PAK-FA indian version should be fully NATO compliant and weapon interfaces and buses and maitenance and servicing stuff should be fully as per global stds. Going the Russian way will be a repeat of the Mig21 to Mig 29 story repeated again.

[maitya]

But, here is an interesting diagram, we now have a basic idea of temp/pressure/alloys in a Kaveri (it may have changed):

Well, that diagram looks like what that would ultimately LIKE to achieve and not what it is at present. With a overall pressure ratio of 30 and turbine entry temp of the order of 2200 C , you are looking at only single crystal blades and absolutely cutting edge cooling schemes and thermal barrier coatings in the high pressure turbine.

And yeah. That engine will be at par with the EJ200 + and GE414 and M-88-3/4in terms of technology levels. I dont think we are there now.

Vinaji, this has been discussed a few times before, that diagram is a bit misleading (maybe pre-meditated as well) - 2200dec C temp is what is attained in the combustor and not the Turbine Inlet/Entry Temp - no turbine blade exists (yet) which can handle that high temperature (except maybe the ceramic ones, but then there are no military turbine engines, that I know of, uses ceramic blades).

Also as moi, Geethji and Katareji had pointed out earlier here - from moi (and here - from Geethji and here - from Katareji), to prevent melting of the turbine blades, the tertiary/dilution zone of a combuster allows the "cold" air (approx 2/3 of the volume of compressor-generated "cold air")bypassed from the combustor primary zone (PZ) and the secondary/intermediate zone, to mix and bring down the temp of the combusted gas to an acceptable/tolerable level of the turbine blades - before it hits the turbine.

The highest TET that I've heard of are for F119, which is IIRC, around 1823K (or 1550deg centigrade) or thereabouts (maybe 1600deg C, as a higher ballpark). To handle even higher temp (approx around 1900deg C or a little more) you would need Ceramic Matrix Composite (CMC) technology, which is basically at a R&D stage worldwide (again IIRC).

By contrast, the TET for kaveri is around 1426deg C.

And I think it's worth mentioning in this context that, world-wide engine development (well more precisely, the engine metallurgy devleopment) history tells us every 100-150deg C increase in TET (beyond 1300deg C) has taken approx a decade of solid R&D by the advanced nations.
Pls refer to Pg 5 (Fig. 1.5) of the ebook The Superalloys - Fundamentals and Applications, Roger C Reed for a better understanding of the evolutionary path of the TET vs turbine metallurgy.
The path is DS -> Monocrystalline (SCB) 1st Gen -> Monocrystalline (SCB) 2nd Gen (usage of Rhenium) with internal blade cooling and TBC (1st gen) -> SCB with internal blade cooling and TBC (2nd Gen).

Long way for us to go before we start talking about 1600 deg C TET.

Also pls note 2200deg centigrade is very close to the stoichiometric temperature of "perfect" air-fuel mixture - very hard to attain in the real-world scenarios (but that's besides the point though).

[SaiK]

GE 414-EPE at 120 kN wet is all crap then? It is about the size and weight of Kaveri.

[Singha]

its a project funded under a technology demo program, not a fielded and ordered product.
I am sure GEAE can do it if either of USN or a large external client like IAF wants it.

[suryag]

Gurus here a doubt. If the dry thrust achieved is almost equal to the desired values does that mean the compression ratio(19 or 21 to be upped to 25 or 30) has been sorted out?

[vina]

If the dry thrust achieved is almost equal to the desired values does that mean the compression ratio(19 or 21 to be upped to 25 or 30) has been sorted out?

Nah.. You cant increase compression ratio, without increasing the TET. All that is inter related. Key bottleneck is TET.

All this means is that the kaveri is currently performing close to it's design goals as initially defined (a few bugs remain to be sorted out). Trouble is the LCA program has moved the goal posts and the current Kaveri cannot be used on the LCA.

[keshavchandra]

In human science we learned that there are only two ways to motivate a being;one is by money and another is by position and power.
for the defence R&D part in india done by the psu, it is must to have the same options to motivate the researcher. Like on every induction of any researched product, then whole research team must have a share on the current and even future cost of the product inducted in the defence services. After this you 'll see the change on any runing projects without any dilay and the enhanced level of researched outcome.

[member_20292]

We heard a lot from Western sources about Indian inability to absorb newer technologies. This may be an example of that situation - wherein Russia has provided enough to kick start the effort on SCB, but India is unable for what reason to push it over the hump.

Folks; I have in the past worked with people who
1. Have won Nobel prizes.
2. Have been in HP RnD for 25 years , doing material science work.

And I am a material scientist myself. The ex head of DMRL was my Professor at my alma mater.

And I say; go soft on those fellows at DMRL

a. Material Science does not attract funding and thus people. Folks from my undergrad insti, a top 10 engg insti, 5 years out of college, and exactly 3 are still in mat science and all of them have PhDs. the remaining 37 are in MBA/ Software/business.
b. Material Science is an old science. It takes time to develop, since a lot of the low hanging fruit have been done.
c. The efforts of even good work done in the lab (similar to what I have done in the past) result in companies like Solyndra (bust after 10 years) A 123 systems (bust after 7 years) ....and these were the market leaders with the best, world leading technology.

Those were the BEST companies in the materials field...the leading lights. If the best companies are unable to commercialize their technology in material science to satisfactory levels...where do institutions like DMRL stand a chance.?..with low funding, and thus low talent levels, unsupportive customers, and bureaucratic delays.

Please Google "The Valley of Death" in relation to technology commercialization.

Technology development is not easy, let alone commercialization, in any field. And then we come to the choice of field, and in this case material science, with large amount of capital investment required in every simple experiment done in the lab, it is NOT EASY.

[merlin]

[quote="vina"
All this means is that the kaveri is currently performing close to it's design goals as initially defined (a few bugs remain to be sorted out). Trouble is the LCA program has moved the goal posts and the current Kaveri cannot be used on the LCA.[/quote]

No.

Maybe for dry thrust. But for wet thrust, initial design goal was and remains 80kN. It it still short by about 10kN or so. Then comes reliability, longevity, etc., etc.

[tsarkar]

In my opinion, there should be a National Engine Initiative, not restricted to GTRE but thrown open to everyone.

Just like in Artillery,

1. L&T, Bharat Forge, Punj Lloyd were able to import & indigenize with higher ToT than ever achieved by any PSU
2. Tata went a step further, imported, indigenized with higher ToT, and implemented their R&D on top
3. Seeing the above, OFB woke up and utilized the ToT from Bofors available 26 years ago that it never used because it was scared of political implications. The head of OFB claims he took 16 months instead of 60 months. Someone should tell him he wasted 26x12=312 months http://articles.economictimes.indiatime ... -factories
4. BEML initiates another scam tying up with the politically connected Indian promoted Czech product (though the product has merits of its own).
5. DRDO starts its own artillery project that now looks redundant, in light of 1, 2 & 3. DRDO efforts should focus on enhancing work already done in 1, 2 & 3 rather than start from scratch.

Drawing analogy to the engine program, the RFP means that Technology has to be imported. Instead of a single track import, multiple tracks should be initiated.

The fixed salary PSU employee doesn’t care whether he absorbs ToT or not. He cares more about punching out at 5:29 pm. Private companies will inherently fare better in this matter since their Return on Investment in the engine technology is at stake.

[Yagnasri]

One small doubt - Is Kaveri ok for a long term use even at this level of performence? That is how many hours it got was run without getting burn or melted??? If it can be used safely then we can think of putting it to use in some new version of HF-24 or something like that. We can even thinkfor developmeent of some old verision Bomber like thing provided Engine is ok.

There seems to be two ways of doing things - Once a Engine is ok make a AC. If AC design is ok then go for Engine. I think we need to have some Engine with make use of Engine so that we can use of it may not be in LCA but may be in something else. What happend to the talk of using it for ships??? We do not hear it now. Can it be used or parts of it used for any other old fights.

We had a threat design your AC may be we need to discuss this there. I do not know.

[SaiK]

One thing about design is chasing after materials. The other thing about the design is the design itself. Rolls Royce demonstrated the later by having blades that cools down faster by the design. SC blades are one heckuva advancement, but at the same time the internal cooling designs helped them achieve. [laser/air/water jet drilled micro holes on the blades].

Ceramic coatings further reduce high temp effects on the exotic alloys, thus allowing the blades to function without losing its shape. [somethings that A5 shield did may also be considered here.. depends on bonding and mean time between coats]

SC blades with internal cooling designs are the key, along with the coatings.. is the winner - from my reads.

[Singha]

kaveri being run either in a flying testbed like IL76 or in a tejas will provide much valuable data bank on all aspects. these data banks built over decades is what never for sale and helps the big boys quickly zero in on the 10% soln and eliminate 90% of the space ....while newbies like us have to explore 100% and figure it out.

for one thing it will provide the reliability and mtbf data. WS10 was a fail in that.

[SaiK]

See, what perplexes me is the blades that goes into any jet engine (especially coming off from a r&d lab), must have been tested out for conditions per spec. Now, the blade failures are too late to be realized.. The fact is that, either the test facilities are ignoring certain actualities/realities in the design or the failure is entirely in different sphere. One never know with our DDM and babu setup, which can ruin any good lab job.

RE: blades warping (higher TET)

[pentaiah]

Dr. Kasturi DMRL

[srin]

A noob question ...

Not talking about AMCA engine, rather engine for LCA.

With the technology we already have, would it be more feasible to develop an F125 class engine and have two of them power the LCA, rather than a single F404 class engine ? Would two engines increase fuel consumption compared to a single engine of double the thrust ?

[SaiK]

1?: No [technology gap is way too big here with what we have achieved so far]
2?: This is a big time thinking question - it all depends on the efficiency of the engines. You would need too much calc for this.

It requires some serious math calculation answer from a guru to tell that. If the thrust to deliver in the same engine takes lesser fuel compared to dual engine providing a similar thrust.

Anyways, try it yourself from wikis: http://en.wikipedia.org/wiki/Jet_engine#Thrust


jmt

[Indranil]

A noob question ...

Not talking about AMCA engine, rather engine for LCA.

With the technology we already have, would it be more feasible to develop an F125 class engine and have two of them power the LCA, rather than a single F404 class engine ? Would two engines increase fuel consumption compared to a single engine of double the thrust ?

Is building a F125 class of engine easier than building a F404 class of engine?

[Zynda]

The entire LCA airframe needs to be redesigned (enlarged) to accommodate 2 engines (even if they are two Kaveri turbines), which will definitely lead to increase in empty weight. Air intakes need to be redesigned to provide air flow for 2 engines instead of 1. Wing needs to be redesigned as well. Since the wing area may increase, the designers may decide to add a couple of more fuel tanks -> increase in Normal Take-Off weight. Dunno, if its worth the effort.

[GeorgeWelch]

The entire LCA airframe needs to be redesigned (enlarged) to accommodate 2 engines (even if they are two Kaveri turbines), which will definitely lead to increase in empty weight. Air intakes need to be redesigned to provide air flow for 2 engines instead of 1. Wing needs to be redesigned as well. Since the wing area may increase, the designers may decide to add a couple of more fuel tanks -> increase in Normal Take-Off weight.

Then it's no longer the LCA

[Indranil]

1?: No [technology gap is way too big here with what we have achieved so far]
2?: This is a big time thinking question - it all depends on the efficiency of the engines. You would need too much calc for this.

It requires some serious math calculation answer from a guru to tell that. If the thrust to deliver in the same engine takes lesser fuel compared to dual engine providing a similar thrust.

Anyways, try it yourself from wikis: http://en.wikipedia.org/wiki/Jet_engine#Thrust


jmt

No guru, and hence no great calculations. But here are my back of the envelop calculations. F125 is not going to cut it in terms total thrust required. Anyways here they are:

Code: Select all

             Thrust  Thrust   Weight    TWR   TWR     SFC    SFC    Dia   Length   Cross-sec  Volume  Inlet airflow
             (dry)    (wet)    (lbs)   (dry)  (wet)  (dry)  (wet)   (in)   (in)      area
F125IN        6230    9850    1360     4.58   7.24   0.775  1.91    23.3   140.2     426.17    59749      92.5
  X2         12460   19700    2720     4.58   7.24   0.775  1.91                     852.34   119498      185
F414         12500   22000    2445     5.11   9.0    0.810  1.74    35.0   154       961.62   148089      164

So, with 2 F125INs how would an LCA fare?
Weight: Minimal increase.
Performance (using Mk1s weight): TWR will greatly decrease in wet mode from 1.05 to 0.93.
Drag: (Most probably) decrease in wave drag due to smaller cross sectional area.
Internal volume: (Most probably) slightly increase
Range (with same amt. of fuel): Almost the same

[Indranil]

The entire LCA airframe needs to be redesigned (enlarged) to accommodate 2 engines (even if they are two Kaveri turbines), which will definitely lead to increase in empty weight. Air intakes need to be redesigned to provide air flow for 2 engines instead of 1. Wing needs to be redesigned as well. Since the wing area may increase, the designers may decide to add a couple of more fuel tanks -> increase in Normal Take-Off weight. Dunno, if its worth the effort.

Your suggestion is akin to what the AMCA is. His question was different. More like the Taiwanese IDF.

[Zynda]

Your suggestion is akin to what the AMCA is. His question was different. More like the Taiwanese IDF.

I am not suggesting sir. Just replying to the question posted earlier about adding an extra engine to LCA.

[SaiK]

slam dunk! good post indranilroy.