LCA news and discussion

Rahul M · Post by **Rahul M** » 19 Aug 2009 23:15

krish, probably you are aware of that but the person you are talking to knows a thing or two about aeronautics, well enough to teach it at any rate.

KrishG · Post by **KrishG** » 19 Aug 2009 23:18

So, krishG, what IS the "external pressure" between LEO and GEO? Could u pls look that up in Wikipedia, which should save the exertion of thinking?

I was talking about engines in general and the effect of altitude on Isp. Where did LEO and GTO come into the question ?? Aren't engines used on the lower stages ??

Any continuing my argument, the stage mass-ratio of engines developed by ISRO are also below the NASA, ESA standards. That doesn't mean that ISRO is in the 70s.

Sanku · Post by **Sanku** » 19 Aug 2009 23:55

Is Narayanan, the AKN by any chance? (yes I know NNN != AKN)

enqyoob · Post by **enqyoob** » 20 Aug 2009 00:23

krish, the cryogenic engine (LH2-LOX) is used to go from LEO to GEO, mainly, except on the Space Shuttle where they run it all the way from the ground. This is why "vacuum Isp" is the relevant figure to quote, so you don't have to get confused about external pressure etc. The Isp figure for cryogenic LH2-LOX has gradually changed from 390 seconds for engines early on, to now over 450 seconds, and that is all because of engine design refinements. Probably cannot go much higher unless the engine combustion chambers can be made MUCH stronger without weight increase, allowing much higher chamber pressure and temperature.

IOW, it is no mean achievement to get above 400 seconds vacuum Isp and still not have the engine blow up within seconds. This is the ISRO achievement, and they did it by (YES!) suffering several blowups on the test stand. Usually the failure occurs either in the turbopumps, which have to pump out some incredibly high flow rate of propellants - at a pressure much higher than that inside the combustion chamber - and still be ultra-light (pump rpm exceeds 180,000 now on STS Main engine) or at the nozzle throat, where the entire exhaust has to go through, and the heat transfer is highest.

Why is all this relevant to GTRE? Well... ISRO solved the problems when under very nasty sanctions. They did the "R" and then went and did the "D" and blew up the engines and went back and did more "R" and "D" until they got it right, and they went for the state of the art, not for 1970s specs.

GTRE, meanwhile, has been, for whatever reason, stuck in the mud, operating for all we know, like a college Engine Club. One "high-altitude test" once in a decade (and that occurred after the DRDO ppl got deeply involved and forced this to occur) and then.. nothing much. When their director goes and

that they met the specs, one has to ask what the heck is the purpose of the organization, because the specs are for engines of the early 1970s.

See the full story on Wikipedia: It's time, maybe, to really analyze their claims.

The DRDO assigned the lead development responsibility to its Gas Turbine Research Establishment (GTRE), which had some experience in developing jet engines. It had developed the GTX37-14U afterburning turbojet, which first ran in 1977, and was the first jet engine to be designed entirely in India.[1] A turbofan derivative, the GTX37-14UB, followed. The GTRE returned to turbojet technology with the greatly redesigned, but unsatisfactory, GTX-35.

For the LCA programme, the GTRE would again take up a turbofan design which it designated the GTX-35VS "Kaveri" (named after the Kaveri River). Full-scale development was authorised in April 1989 in what was then expected to be a 93-month programme projected to cost 382 crores (nearly US$82 million at the time).

OK, so they had turbofan designs in the 1970s, and decided to go BACKWARDS to the very low bypass ratio (leaky turbojet). This is the first reason why I am so disappointed. There is no way that a turbojet can be a better solution for a transonic / Mach 1.6 fighter aircraft, which will spend most of its flying life at Mach 0.6 or so.

Development

The original plans called for 17 prototype test engines to be built. {so this was not a terribly stingy program..} The first test engine consisted of only the core module (named "Kabini"), while the third engine was the first example fitted with variable inlet guide vanes (IGV) on the first three compressor stages. The Kabini core engine first ran in March 1995. Test runs of the first complete prototype Kaveri began in 1996 and all five ground-test examples were in testing by 1998; the initial flight tests were planned for the end of 1999, with its first test flight in an LCA prototype to follow the next year.[2] However, progress in the Kaveri development programme was slowed by both political and technical difficulties.

Design

The Kaveri is a low-bypass-ratio (BPR) afterburning turbofan engine featuring a six-stage core high-pressure (HP) compressor with variable inlet guide vanes (IGVs), a three-stage low-pressure (LP) compressor with transonic blading, an annular combustion chamber, and cooled single-stage HP and LP turbines.

OK, so they used Variable Inlet Guide Vanes, which is to control the angle of attack reached by the compressor blades and allow a wider range of operation without the compressor stalling. They also throw in the term "transonic compressor". This means that the design does not shy away from having tip speeds greater than Mach 1, and in fact operates with shocks inside the rotor. Shocks are great ways of achieving large pressure ratios. But getting a transonic rotor designed, means some very careful calculations of shock interactions and shock-boundary layer interactions. Perfectly suited to the hordes of DOOs and PIGs around with engineering degrees, good math background and excellent computing skills (they sure don't want hands-on experiment skills!!!!) suited to careers in air-condishunned computer rooms onlee.

Excellent, I thought this meant that they were really pushing the limits on the pressure ratio for each stage. .. silly me!

Look at the specs - 3-stage low pressure compressor, 6-stage high pressure, so 9 stages total, to reach a total pressure ratio of 20! So average stage pressure ratio is 20^(1/9) < 1.4

This is ancient technology. There is nothing "banned" about designing compressor stages to achieve pressure ratios as high as 2.0 if you use this shock-in-rotor design idea. - it does not take any exotic materials. It just takes hard work, designing and calculating and validating and testing and refining until they get it right. So they COULD have got the pressure ratio to 25 with much fewer than 9 stages. Or they could have used the same weight to put in a couple of fan stages at the front and get the bypass ratio up.

The development model is fitted with an advanced convergent-divergent ("con-di") variable nozzle, but the GTRE hopes to fit production Tejas aircraft with an axisymmetric, multi-axis thrust-vectoring nozzle to further enhance the LCA's agility. The core Turbojet engine of the Kaveri is the Kabini, named after the Kabini River (which is a tributary of the Kaveri river).

The general arrangement of the Kaveri is very similar to other contemporary combat engines, such as the Eurojet EJ200, General Electric F414, and Snecma M88.

{See? This is pompous, deceptive rah-rah garbage. Translation: they think it LOOKS like those engines! }

At present, the peak turbine inlet temperature is designed to be a little lower than its peers, but this is to enable the engine to be flat-rated to very high ambient temperatures. Consequently, the bypass ratio that can be supported, even with a modest fan pressure ratio, is only about 0.16:1, which means the engine is a "'leaky' turbojet" like the F404.

I submit that this is total BS. Saudi Arabia, Egypt and Israel operate engines with much higher turbine inlet temperatures, and it is not any cooler in their deserts than it is in the Thar desert.

What the heck is this "flat-rating to very high ambient temperature" anyway? Can't IAF pilots be educated to realize that on a hot day you have to get up to higher speed before pulling back on the stick? Can't the load managers learn to include ambient temperature in their calculations of aircraft weight limits?

The Kaveri engine has been specifically designed for the demanding Indian operating environment, which ranges from hot desert to the highest mountain range in the world.

{Translation: It don't perform well in cold weather or hot, sea level or mountaintop. Do they have superior sand ingestion tolerance? Superior icing tolerance? What the heck does this claim mean? Maybe this is all about the "variable inlet guide vane"}

The GTRE's design envisions achieving a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1, which it believes will permit the Tejas to "supercruise" (cruise supersonically without the use of the afterburner). The Kaveri is a variable-cycle, flat-rated engine and has 13% higher thrust than the General Electric F404-GE-F2J3 engines equipping the LCA prototypes.

{Simple question: Is this true? DOES the present Kaveri engine actually demonstrate 13% more thrust than the GEF404? At what weight, and thrust-to-weight ratio?}

Plans also already exist for derivatives of the Kaveri, including a non-afterburning version for an advanced jet trainer, and a high-bypass-ratio turbofan based on the Kabini core.[3] Another concept being considered is an enlarged version of the Tejas with two engines fitted with fully vectoring nozzles, which might make the vertical tail redundant (the Tejas has no horizontal tail).[1]

This is all grandiose hope-raising. Yeah, I have PLANS to convert it to single stage sea level to LEO with Air Liquefaction and Thermal Compression and Parallel Hydrogen Injection, and with a Variable Cycle SCRAMJET mode tossed in. But right now I have a bullock-cart engine.

An indigenous Full-Authority Digital Engine Control (FADEC) unit, called Kaveri Digital Engine Control Unit (KADECU) has been developed by the Defence Avionics Research Establishment (DARE), Bangalore. The Combat Vehicles Research and Development Establishment (CVRDE) of Avadi was responsible for the design and development of the Tejas aircraft-mounted accessory gear box (AMAGB) and the power take-off (PTO) shaft.

OK, congratulations to them. In Malloo lore, this is equivalent to saying:

Got the stick and the prod to control the elephant, now all I need is the elephant

But I am being mean there - Engine Controls for a high angle of attack fighter is a tough subject, and I hope their box works.

Problems

Little information has been publicly released to date concerning the nature of the Kaveri's technical challenges, but it is known that the Kaveri has had a tendency to "throw" turbine blades, which required securing blades from SNECMA (as well as digital engine control systems).[4]

That is another sign of laziness. If the blades had a tendency to "throw" the solution is to fix that problem, keep the machine balanced, etc. etc. Not go buy blades from someone else. And... er.. if they had just developed the ultimate engine control box, what was the need to buy the SNECMA box?

Continuing development snags with the Kaveri resulted in the 2003 decision to procure the uprated F404-GE-IN20 engine for the eight pre-production Limited Series Production (LSP) aircraft and two naval prototypes. The ADA awarded General Electric a US$105 million contract in February 2004 for development engineering and production of 17 F404-IN20 engines, delivery of which is to begin in 2006.

In other words, the present Kaveri is NOT better than the F404.

In mid-2004, the Kaveri failed its high-altitude tests in Russia, ending the last hopes of introducing it with the first production Tejas aircraft.[5] This unfortunate development led the Indian Ministry of Defence (MoD) to order 40 more IN20 engines in 2005 for the first 20 production aircraft, and to openly appeal for international participation in completing development of the Kaveri. In February 2006, the ADA awarded a contract to SNECMA for technical assistance in working out the Kaveri's problems.[6] At that time, the DRDO had hoped to have the Kaveri engine ready for use on the Tejas by 2009-10.

OK, FIVE YEARS LATER, what's the hangup? Still failing high-altitude tests? WHY? Where are the research solutions for this?

Scientific Advisor to Defence Minister M Natarajan said nearly 90 to 93 per cent of the expected performance had been realised

OK, Rahul, so take the specs and multiply by 0.90.

DRDO has reportedly been able to develop single crystal blades, which represent a major technological achievement for engine development. Production and integrating this technology into the engine is expected to take some more time.

No comment. We've been through that discussion already.

Kaveri has already undergone 1,700 hours of tests and has been sent twice to Russia to undergo high-altitude tests for which India has no facility. The engine is also being tested to power the next generation of Unmanned Aerial Vehicles.[8]

With, say, 5 working models, what does 1700 hours of testing mean? In 12 years? This does not sound like a hard-working test program, does it? If they said that all 17 prototypes had been tested to destruction, I would have more respect for the program. Here it just shows gross lack of seriousness.

Before an engine is installed on a production airplane, don't you think at least one single engine should be shown to last for more than, say, 3000 hours at typical mission profile operating conditions?

In September 2008, it was announced that the Kaveri would not be ready in time for the Tejas, and that an in-production powerplant would have to selected.[9] Development of the Kaveri by the GRTE would continue for other future applications.

It was announced in November 2008 that the Kaveri engine will be installed on LCA by December 2009,[10] apparently for tests only.

{So we are back to a "research" organization that does no research.}

John Snow · Post by **John Snow** » 20 Aug 2009 00:29

There are some gurus in BRF with whom you dont mess with, except on political discourse in which nothing is a calculated move.

N guru in one such, I mention all the gurus here I might be banned.

Rahul M · Post by **Rahul M** » 20 Aug 2009 00:42

OK, Rahul, so take the specs and multiply by 0.90.

the quoted figure was the 0.9 multiplied to the spec, if you had actually read the post !

KrishG · Post by **KrishG** » 20 Aug 2009 00:57

Om Namo Narayanaya !!

China's WS-10 -
http://www.china-defense-mashup.com/?p=1145

If the specs are to be believed, then it's got to be admitted that the Chinese have done a good job.

NRao · Post by **NRao** » 20 Aug 2009 02:27

KrishG wrote:Om Namo Narayanaya !!

China's WS-10 -
http://www.china-defense-mashup.com/?p=1145

If the specs are to be believed, then it's got to be admitted that the Chinese have done a good job.

I am sure. BUT, are they proposing it for the LCA?

suryag · Post by **suryag** » 20 Aug 2009 02:31

{So we are back to a "research" organization that does no research.}

No they are involved in "re search". N^3ji while there is no doubt about the data and conclusions you presented I feel we are autopsying the outcome rather than focusing on the drive behind the projects. To start of ISRO was in a do/die situation when it came to cryogenic engines and things started moving on that front IIRC during 1992-93. We should probably also take into consideration the fact that ISRO did have atleast 40%(% is debatable) of know-how transferred to it from GlavKosmos. Added to this ISRO had already built up considerable infrastructure for testing of engines in the form of LPSC, Mahendragiri. ISRO also had good success in Vikas engines which I am told bore resemblance with France's Viking engines, so when they started development of Cryo technologies in 1993 they had the following

1. testing infrastructure
2. Working Liquid engine designs
3. Strong backing of the govt. to develop the technology
4. No third party offering equivalent or superior technology
5. A stream of labs to do research on supporting technologies
6. ISRO has IIRC a secretary overseeing the activites of DOS. This provides a single window interface between ISRO and GOI

Please compare this with the mandate given to GTRE when they started development of Kaveri
1. No testing infrastructure
2. No prior working design that was validate across a full flight path
3. Number of third parties offering better designs
4. Lack of intentions from govt to realise a product, it was conceived to be a research project right from the beginning and in case, during the course if there was a windfall the engine would be in Tejas
5. Only one lab to do everything.
6. GTRE comes under DRDO and is one of 56 labs(??)
7. Lack of synergy between HAL and GTRE for whatever reasons

IMO, GTRE vs ISRO is like comparison of a startup and a matured company, it is only so much that a startup can do given the budget and staffing.

Given all the above GTRE still cannot escape the blame for its poor output after so many decades, however, the bigger share of blame lies with GOI.

I am frankly tired of waiting for GTRE to come up with something and frankly there is a big need to revamp GTRE.

BTW, in telugu we have "pani leni mangalodu prathi mangalavaram pili gundu goriginattu"(loosely translated means a barber on his day-off(tuesday) tonsured a cat's head) akin to our discussion on Kaveri due to the lack of news on Tejas

Very Very OT as a kid i heard that ISRO busses were stoned in Sullurpeta by common public after an ASLV went into the sea

enqyoob · Post by **enqyoob** » 20 Aug 2009 03:08

This is a good template for comparison. Of course, I must remember that praise for ISRO/ nonpraise for GTRE should not be based on the chance working of one engine vs. troubles with the other. OTOH, ISRO's engine has worked several times now and is considered a functional product.

Let's see

1. testing infrastructure
2. Working Liquid engine designs
3. Strong backing of the govt. to develop the technology
4. No third party offering equivalent or superior technology
5. A stream of labs to do research on supporting technologies
6. ISRO has IIRC a secretary overseeing the activites of DOS. This provides a single window interface between ISRO and GOI

Please compare this with the mandate given to GTRE when they started development of Kaveri

1. No testing infrastructure

Why is that so? The Bangalore HAL engine factory had at least 2 working test cells as far back as 1977. With an $82M development budget, surely about $2M of that could have been devoted to building/ improving/acquiring a few test cells, incl. one with a low vacuum capability?
How else did ISRO happen to get engine thrust stands to develop the space engine?

2. No prior working design that was validate across a full flight path
Nope, this was completely the other way. There were hundreds of working engines, both commercial and military, available to the Indian defence establishment for validation testing/ reverse engineering. Compare to the case of ISRO, where the US was blocking even the delivery of the 3 or 4 Russian cryogenic engines, let alone any formal tech transfer. Space engines were/are closely guarded, and there are very few of those built, compared to aircraft jet engines.

3. Number of third parties offering better designs
True, but this should have been a fire on the tail to get there, with the answers well-known, hey? Also, WERE there so many offers? If so, wouldn't the obvious course have been to design the LCA to fit, say, the Russian engine that has been in production in India for a long time?

4. Lack of intentions from govt to realise a product, it was conceived to be a research project right from the beginning and in case, during the course if there was a windfall the engine would be in Tejas

This, if true, was primarily because of lack of confidence in GTRE's ability to deliver anything, a well-founded lack, obviously. But an $82M development project in 1992, when the Indian financial position was at Paki level of bankruptcy, was a major national investment. I don't see this as a lack of intent on the part of GOI. What it appears to be, is what I said before:
GTRE did not expect the LCA to reach a flying-airframe status. They expected the rest of the LCA team to have their level of motivation / seriousness.

5. Only one lab to do everything.
Why? Per the guru(s) who volunteered their experience to me, this was precisely because GTRE WOULD NOT BRING ANY OTHER EXPERTISE IN. Specifically, the engine factory guys were not brought in, even to BUILD the prototypes!!!!!

6. GTRE comes under DRDO and is one of 56 labs(??)
Compare that to the above. So they had 55 other labs, plus all the universities, plus the engine factories, plus the airline engine expertise, all to call on in order to break through. Compare to ISRO's situation. Even in terms of phoren technology, I know that for many years (maybe still..) PIGs were prohibited from working on NASA's rocket engine and orbital codes - precisely to obstruct ISRO. No such restriction existed AFAIK on gas turbine compressor / fan or combustor codes.

7. Lack of synergy between HAL and GTRE for whatever reasons.
Since it was GTRE that was mandated to develop engines, not HAL, the fault for this must be placed squarely on GTRE. HAL may not be exactly the shining example of self-motivation etc. etc., but in this case it was clearly not HAL's fault. If they would not cooperate, GTRE should have screamed and got the DRDO/ADA / Prime Minister's Office to dump on HAL.

Instead, per most ppl who have reported here on dealings with GTRE, the latter sat around completely complacent that the LCA would never fly. So in 2009 we find ourselves looking at ridiculous excuses like "we chose a low Turbine Inlet Temperature because we wanted to Flat-Rate the Thrust for high ambient temperature".

Even at this late stage, the govt, should take jet engine DEVELOPMENT away from GTRE. And they should give the mandate for RESEARCH on jet engines to some other entity. The GTRE building that I remember from long ago, would make a nice centrally located and appropriate named cafeteria / Officers' & Babus' Mess.

Finally, I cannot speak for others, but I am NOT beating this drum because of lack of news on the LCA. I am raising the flag to point out the sheer falsehood of the claims published over the past 40 years by GTRE, and the fact that continuing along this path will be a complete disaster for the Indian aerospace establishment, and for Indian defence. People seem to agree with my estimate of the total cost / market size of the engine market, IF the LCA and MRCA are really be produced in the numbers needed to make a big difference to Indian conventional deterrence.

The dismal failure to recognize the importance of engine technology, can only be compared to the dismal failure to go aggressively into Renewable Energy decades ago. Both are errors that conspire to enslave India. Breaking out is needed in both. So it just happens that nothing much else is coming out on the LCA, so they haven't kicked me off this thread and forced me to use some other forum to make noise.

John Snow · Post by **John Snow** » 20 Aug 2009 03:10

They were expressing solidarity with ISRO that things do fall some times.

PS: Most of them must have been organized from their HQ in Bejing.

negi · Post by **negi** » 20 Aug 2009 03:49

PIGs..

...heck..

abhiti · Post by **abhiti** » 20 Aug 2009 07:54

Rahul M wrote:
Kaveri: 65000/(1100*9.8 ) = 6
F414: 98000/(1060*9.8 ) = 9.43
RD33: 81000/(1055*9.8 ) = 7.8
just a nitpick, that would be around 6.8 instead of 6.

Well it all depends on what figure you choose for thrust. If you choose 72 KN i.e. 90% of 80KN then Kaveri comes to 72% of F414 and 87% of RD33. Did someone note we are comparing it to F414 not F404. F404-GE-F2J3 specs are 81.5KN-3911mm-889mm-1061kg. The calc for F404: 81500/(1061*9.

= 7.838. So it is essentially 87% of F404 as well. But if the figure is at 65KN then Kaveri is at 78% of F404 and RD33. Also how come Russian RD33 seem to match American F404 in engine technology? How come no one approached Russians on help with GTRE engine? It is because Russians are known to fudge there numbers! This essentially the reason CCS decided that further investment in GTRE effort is merited.

enqyoob · Post by **enqyoob** » 20 Aug 2009 07:59

It is because Russians are known to fudge there numbers!

Well... could be, but the Russian engine, built in India, powers aircraft that are in use with the IAF, hey, so why not get the real data from those? The issue of fudging does not arise because one does not have to depend on the Russian specs.

abhiti · Post by **abhiti** » 20 Aug 2009 08:00

narayanan wrote:
It is because Russians are known to fudge there numbers!
Well... could be, but the Russian engine, built in India, powers aircraft that are in use with the IAF, hey, so why not get the real data from those? The issue of fudging does not arise because one does not have to depend on the Russian specs.

RFI for engine development for LCA was sent to SNECMA and GE, not to Russians. Why? It is because HAL does know real figures! But I have access to internet figures only.

enqyoob · Post by **enqyoob** » 20 Aug 2009 08:16

Ah, yes, but the flaw in your argument is that planes powered by the Russian engine FLY in the IAF. If the Russian engine were, say, as bad as the Kaveri, the Su-30MKI would be drawn by bullocks, hey?

Alternatively, could the Kaveri be a candidate to improve the Su-30MKIs? Have the RFIs come out to do this, I wonder?

RFI for engine development for LCA was sent to SNECMA and GE, not to Russians. Why?

One could argue that this is because the GTRE/ADA types are more interested in the trips to Paris and US than in getting the best deal for India. If there were good technology transfer from the engine factories in India, to the GTRE program, then it would make sense to get samples of the newest US and Oiropean engines.

abhiti · Post by **abhiti** » 20 Aug 2009 08:43

narayanan wrote:Ah, yes, but the flaw in your argument is that planes powered by the Russian engine FLY in the IAF. If the Russian engine were, say, as bad as the Kaveri, the Su-30MKI would be drawn by bullocks, hey? Alternatively, could the Kaveri be a candidate to improve the Su-30MKIs? Have the RFIs come out to do this, I wonder?

Su 30 is a great aircraft because Russians know their limitations on engine technology and design their aircraft based on that. Btw Chinese also designed J-10 around larger engine instead of LCA designers who based it on smaller engine assuming home developed engine will match performance of western technology. It may not be because they are smarter but simply the reality of embargo which is turning out to be blessing in disguise.

AL-31: 122KN-4990mm-1280mm-1570kg (Russian standard), 1800 kg (French standard!) i.e. T/W 6.9
F100: 129KN-4851mm-1181mm-1696kg i.e. T/W 7.76

If Kaveri reached 90% of its AB thrust then it will be comparable in T/W with AL-31. This makes me suspect Kaveri is likely to be at 65KN thrust than 72KN. But it will still put it within 15% of AL-31 T/W and I suspect even true T/W of RD33 engine.

RFI for engine development for LCA was sent to SNECMA and GE, not to Russians. Why?
One could argue that this is because the GTRE/ADA types are more interested in the trips to Paris and US than in getting the best deal for India. If there were good technology transfer from the engine factories in India, to the GTRE program, then it would make sense to get samples of the newest US and Oiropean engines.

Well then why not just exclude Mig35 from MRCA too...afterall $12b buys more trips than $300m. There is more to it than babus wanting to take trips.

Raj Malhotra · Post by **Raj Malhotra** » 20 Aug 2009 12:33

Not to mention that a paanwala told me that 70-80% of the components of the assembled kaveri are imported

KrishG · Post by **KrishG** » 20 Aug 2009 14:39

Raj Malhotra wrote:Not to mention that a paanwala told me that 70-80% of the components of the assembled kaveri are imported

LINK GTRE

vina · Post by **vina** » 20 Aug 2009 15:35

Not to mention that a paanwala told me that 70-80% of the components of the assembled kaveri are imported

paanwala is right. Sncema (it is I think) supplies made and supplied many of the components that went into the Kaveri like blisks, blades etc. No point in establishing manufacturing facilities for those kind of things. More important to get the design and validation right. That is the right way to go, rather than the ass backwards way things were done in the name of "indigenization" in India. Ie, getting licensed manufacturing, but nothing about the design and R&D.

Manufacturing we can always build up later once we have a working engine in place. The bulk of the expense is in setting up the manufacturing infra /upgrading HAL engine division to build those things. That comes in much later when the engine is proven.

vina · Post by **vina** » 20 Aug 2009 16:41

narayanan wrote: For the LCA programme, the GTRE would again take up a turbofan design which it designated the GTX-35VS "Kaveri" (named after the Kaveri River). Full-scale development was authorised in April 1989 in what was then expected to be a 93-month programme projected to cost 382 crores (nearly US$82 million at the time).

OK, so they had turbofan designs in the 1970s, and decided to go BACKWARDS to the very low bypass ratio (leaky turbojet). This is the first reason why I am so disappointed. There is no way that a turbojet can be a better solution for a transonic / Mach 1.6 fighter aircraft, which will spend most of its flying life at Mach 0.6 or so.

Diyar Enqyoob-ud- din -e-Gas-Turbiney,

Mullah's sojourn in the Binor Madrassa has dulled all sense of phassion which be-sharm kaffir wimmin flaunt in the billi walk (and maybe not passion

). Now all the goray kaffirs are screaming on and on , especially the AL-Amreeki and now Al-Prittanis and Al-Roosies also ciam something called Sooper Crrueeyse . All such things I am sure are haraam for you. However, Yindoos, being Kaffirs , their Ayer Phorce also will want Sooper Crrueyes in the YellCeeYea no ?

So this boor mujahid submits that Al-GTRE was ahead of the curve saar!. This leaky thing (unmentionable things again ) that you zikr to , is well suited phor Sooper Crueeyse no , with such low pye-pass and everything ?. In such things , lower is better onree no ?. Why even the latest PW-119 in Al-F-Bayees, has lower pye pass onree and a thrust to weight of around 9 no ?

.. "transonic compressor". .. Shocks.. DOOs and PIGs ..
Excellent, I thought this meant that they were really pushing the limits on the pressure ratio for each stage. .. silly me!

Look at the specs - 3-stage low pressure compressor, 6-stage high pressure, so 9 stages total, to reach a total pressure ratio of 20! So average stage pressure ratio is 20^(1/9) < 1.4

Tauba Tabua. It is Shocking that you use nacheez and filthy terms like Doo and Pig in a phamily phorum. No sharam onree.

be flat-rated to very high ambient temperatures.

What the heck is this "flat-rating to very high ambient temperature" anyway?

Saar. Yindoos wear dhotis which are "flat rated" for high temperachurs. How? .Dhotis have natural ventilation , aka (convection air cooled) and the Kaveri also uses similar technology. We give more hawa and ventilation in the core hot areas , by higher air flow , just like the dhoti wearers! What works for dhotis works for engine also no ?. Point is flat rating is not just for hot but also for high. Just like a Yindoo wearing a dhoti is guaranteed certain amount of coolness and walking speed in very high garmi and unchayee, so to will the Kaveri give guaranteed performance , allowing take offs at very high altitudes at Leh and forward air fields even during peak summers.

Now dont give solutions like.. lengthen air field, lengthen take off run, take off with less load etc.. That is the air phorce decision and have other costs and crimps operational flexibility (you probably cant build such lengths in the mountains and what if the runway is bombed and you have to take off in a short run , eh I ask you?)

The Kaveri engine has been specifically designed for the demanding Indian operating environment, which ranges from hot desert to the highest mountain range in the world.
{Translation: It don't perform well in cold weather or hot, sea level or mountaintop. Do they have superior sand ingestion tolerance? Superior icing tolerance? What the heck does this claim mean? Maybe this is all about the "variable inlet guide vane"}

Sigh.. You don't appreciate the advantages of wearing a dhoti /lungi and natural ventilation. What to do, you tubes wearing maadurn generation.

The GTRE's design envisions achieving a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1, which it believes will permit the Tejas to "supercruise" (cruise supersonically without the use of the afterburner). The Kaveri is a variable-cycle, flat-rated engine and has 13% higher thrust than the General Electric F404-GE-F2J3 engines equipping the LCA prototypes.

{Simple question: Is this true? DOES the present Kaveri engine actually demonstrate 13% more thrust than the GEF404? At what weight, and thrust-to-weight ratio?}

Diyar al Gas Turbiney. Pliss to go back to phirst pooch. With 27:1 pressure ration and such low pye pass, will easily do this Nacheez Sooper Cruyeese easily no ?

Point is we are materials nood at this time. Time to swallow this 100% indigenous fetish and the part of MAKING it fully in India. Tap into the global ecosystem/supply chain of the industry and get all the materials and components from Vilayat . Then we can get such numbers in a reasonable time. The manufacturing and indigenous materials part (the harder part really) can come later once we have the engine designed and proven to perform as desired.

As of today, the GE F404 is underpowered . We have moved on to IN20 and now F414 / EJ200 because the LCA has been eating too much halwa and slurping Amballapuzha Payasam , Ada Pradaman and Pazha Pradaman and put on some nice haunches like Tamil phillum heroines. So what phor this 13% comparison. We need 95 to 100KN, instead of the 80KN earlier. A good 20% more max power. Even of the Kaveri can replace 404, it is not good enough.

Plans also already exist for derivatives of the Kaveri, including a non-afterburning version for an advanced jet trainer, and a high-bypass-ratio turbofan based on the Kabini core.[3] Another concept being considered is an enlarged version of the Tejas with two engines fitted with fully vectoring nozzles, which might make the vertical tail redundant (the Tejas has no horizontal tail).[1]

This is all grandiose hope-raising. Yeah, I have PLANS to convert it to single stage sea level to LEO with Air Liquefaction and Thermal Compression and Parallel Hydrogen Injection, and with a Variable Cycle SCRAMJET mode tossed in. But right now I have a bullock-cart engine.

Here the Mullah is fully right. This I fully agree with you is just passing hot air from the orifice in the rear.

Problems

Little information has been publicly released to date concerning the nature of the Kaveri's technical challenges, but it is known that the Kaveri has had a tendency to "throw" turbine blades, which required securing blades from SNECMA (as well as digital engine control systems).[4]

That is another sign of laziness. If the blades had a tendency to "throw" the solution is to fix that problem, keep the machine balanced, etc. etc. Not go buy blades from someone else. And... er.. if they had just developed the ultimate engine control box, what was the need to buy the SNECMA box?

Saar, the K9 (aka bitch) version throwing it's teeth has been fixed.. some 3 order vibration or something which they could find only in Jurmany vilayat onree because we dont have such test facility in our Mulk and also relight problems at CIAM because no high altitude test facility at Mulk and also compressor stages stalling.. All fixed onree... Everything fine.

Point is ,such testing cycles get lengthened because we have to get sign off from babu, sanction, phoren exchange, RBI clearance, pack MTR packed food, rice, dhal, masala, shop for winter clothing (balls freeze in vilayat and cant eat haraam food in Al-Jurmany and Al-roos) etc onree.

However, you can perfect only when doing. Now the next stage is to go ahead and finish testing and fly the engine . And knowing Yindoos, I can tell you very clearly. NO NEWS IS GOOD NEWS. If things are going badly, you will hear it immediately, old Yindian saying

The ADA awarded General Electric a US$105 million contract in February 2004 for development engineering and production of 17 F404-IN20 engines, delivery of which is to begin in 2006.

In other words, the present Kaveri is NOT better than the F404.

See previous pooch about Ada Pradhaman and Pazha Pradaman and high fat payasams.

In mid-2004, the Kaveri failed its high-altitude tests in Russia,
....
OK, FIVE YEARS LATER, what's the hangup? Still failing high-altitude tests? WHY? Where are the research solutions for this?

See pooch about packing MTR food and masalas and shopping for winter clothing.

With, say, 5 working models, what does 1700 hours of testing mean? In 12 years? This does not sound like a hard-working test program, does it? If they said that all 17 prototypes had been tested to destruction, I would have more respect for the program. Here it just shows gross lack of seriousness.

Before an engine is installed on a production airplane, don't you think at least one single engine should be shown to last for more than, say, 3000 hours at typical mission profile operating conditions?

Diyar Mullah. You need to run a working engine onree no. Only no Yin Jin is fully working !. So there are you are.
A lot of Yin Jins self destructed .. Some blew up on the bench (as per earlier reports of "setbacks"), K9 bitches threw teeth , all sorts of nautanki and drama has happened!.

{So we are back to a "research" organization that does no research.}

Ok. This is where I get serious. You are right in that there are structural problems as the orgs are right now.
The bad blood between GTRE and HAL are rooted in history and goes back to decades. HAL has been the dog in the manger all along and since they control a large budget via the manufacturing, they have absolutely no interest in any fundamental research either.

See, in the Soviet model we copied, the design org (Mikoyan, Sukhoi )etc are SEPARATE from the building orgs (Irkuts, KNAAPO, RSK) etc. The latter just assemble do some small modificiations while the fundamental design and R&D are with the design orgs. The traditional western model is each individual company (McDonne, General Dyn, Lockheed, Grumman , Hawker, BAE , Dassault etc) being more market led the manufacturing was LINKED and integral to the design.

Now in India, we adopted the worst of both worlds. In Soviet land, the DESIGN orgs had the power, prestiged budget. In India, we got it ass backwards. HAL got the money and power (because they handled large manufacturing, workforce and infra and could be used to dole out pelf and patronage and were prestige show cases) and being a assembly /manufacturing shop after Marut was killed , it basically killed all R&D as well.

The LCA program has basically resurrected design expertise in India, sort of like a Pheonix from the ashes. What has been achieved is basically very very creditable. If GTRE has a working engine which is 5 years short of reaching latest F414 /EJ200/M88 performance levels (which can be done if we tap into the global material base since we are Nuke Kosher and are also near Munna/Allie), that is a great achievement.

Going forward we need to do the following.

1)Break up HAL into three companies Aircraft Company , Avionics Company and Engine Company.
2) Merge the Engine Company with GTRE
3) Grant entry for the private sector and other competent PSUs and create a credible competitor for each of the Aircraft, Avionics and Engine Companies
4) Use the MRCA project to do this. The MRCA should ABSOLUTELY NOT go to the Russians PRECISELY for that reason. We will have CLONE of the Sovietized HAL , even if the contract goes to the private sector. Get a western plane in and get the airframe made by someone like Tata/L&T , the Avionics by a host of IT/Vity guys and the Engine by say even BHEL /L&T/Someone Else who is willing to invest
5) No 4 will be a swift kick to the nuts of HAL and wake them up .
6) With that base we will have a truly COMPETITVE ecosystem for aerospace (both civil and military) in India and that is when we will see something different and better results than in the past.

What we will REALLY end up doing.
1) HAL will be the "designated" agency for the MRCA offsets and will continue to be the hide bound uncompetitive monolith with terrible performance as it continues (think LCA radar), with it getting work even if it has no competency in any area.

2) Mantris/ Babus will be loath to let go of all the cash flow and controlt that comes with having a gignatic ops with little competition. They will fight tooth and nail against letting in either private competition or other competent PSU competition.

3) We will fix the LCA with foreign help, maybe get the Arjun in service etc. But the system will be fundamentally flawed and structurally bad and we will muddle along as always.

4) Chipanda with no distraction of the "middle path" and full focus and clarity of purpose (which anyways is the strength of the soviet command and control) will wield the whip, apply size 12 motivators, starve the peasants but still pour wealth on the Military Industrial Complex and will whiz forward with the intent of catching up with Unkil.

nash · Post by **nash** » 20 Aug 2009 17:05

my 180 degree pranaam to vina ji

enqyoob · Post by **enqyoob** » 20 Aug 2009 18:54

Bismillah!

V r having beebals hu KNOW onlee!

Mullah Vinatullah, can u pls explain seriously about the "flat-rating"? I cannot see at all how having a T-i-T lower than what is really needed, serves you better on a hot day at high density altitude. I would think that you need the highest possible temperature precisely under that condition, so that the hill at the end of the runway doesn't start looking like Mt. Gopalankutty?

If you had higher pie-bass, u could use some of the spare hawa to cool things, but there the "leaky turbojet" choice leaves very little. So still very confused. I fiyar that if I go and moon GTRE on this point, I may get the swift kick on the musharraf when someone explains this point to me reaal slowly.

As 4 Super Tom Cruise, I haven't thought about that enough to agree or disagree on need for very low bypass. I guess it depends on whether one knows how to mix the bypass flow with minimal losses downstream?

Gagan · Post by **Gagan** » 20 Aug 2009 20:14

vina wrote:4) Use the MRCA project to do this. The MRCA should ABSOLUTELY NOT go to the Russians PRECISELY for that reason. We will have CLONE of the Sovietized HAL , even if the contract goes to the private sector. Get a western plane in and get the airframe made by someone like Tata/L&T , the Avionics by a host of IT/Vity guys and the Engine by say even BHEL /L&T/Someone Else who is willing to invest
5) No 4 will be a swift kick to the nuts of HAL and wake them up .

Saar, if you so much as threaten to do that, the private sector in yindia will poach HAL dry. Where do you think all those halal and dhoti wearing, cost-effective experts in TATA and L&T are going to come from? In addition to the massa engine manufacturers, now basing in Bangalore in rightful earnest, you will have Indian pvt companies trying to poach HAL babooze and "R" and "Dee" folks.

HAL will not fight - they can't, they will simply give up and surrender, or employ the unemployable, since they assemble onree.

Rahul M · Post by **Rahul M** » 20 Aug 2009 21:42

........But if the figure is at 65KN then Kaveri is at 78% of F404 and RD33. .....

why are you insisting on discussing this mythical 65 kn figure which doesn't exist anywhere in real life ?
you arrived at 65 kN by a mistaken calculation. kindly give it a rest. you do not need to justify an honest mistake.

Rahul M · Post by **Rahul M** » 20 Aug 2009 21:59

I couldn't find off hand but am I right in thinking that the f119 i.e the F-22's engine has a bypass ratio of around 0.25 ?? (not sure if the figure was at all released !!

)

KrishG · Post by **KrishG** » 20 Aug 2009 22:29

abhiti wrote: It is because Russians are known to fudge there numbers! This essentially the reason CCS decided that further investment in GTRE effort is merited.

I found an interesting article in a Russian Newspaper saying that in Aero India-2009 Russia's Ivchenko Progress offered to develop a 95 kN engine AL-9500F, with GTRE if required for LCA-Mk 2.

The deal most probably went the same way GTRE-Sncema went although the article doesn't offer any more info on the subject.

http://babelfish.yahoo.com/translate_ur ... =Translate

Willy · Post by **Willy** » 20 Aug 2009 23:12

Guys guys guys.After all this back and forth where do we really stand? Has the Kaveri been scrapped now that we are going in for either the American or European engine for the LCA-MKII or will the kaveri continue to be developed side by side with a foreign partner?

Virupaksha · Post by **Virupaksha** » 20 Aug 2009 23:45

Willy wrote:Guys guys guys.After all this back and forth where do we really stand? Has the Kaveri been scrapped now that we are going in for either the American or European engine for the LCA-MKII or will the kaveri continue to be developed side by side with a foreign partner?

There is a saying, after hearing the whole of ramayana, he asked how is rama related to sita?

The short answer for your question is nowhere

Nothing has been decided yet, except that kaveri and LCA have been completely decoupled.

enqyoob · Post by **enqyoob** » 21 Aug 2009 00:08

vinaji:

AFAIK, supercruise just means that you have enough thrust to go supersonic without afterburner. This again just means that you have a high enough thrust-to-weight ratio that you can afford to size the engine to produce enough dry thrust, and low enough TSFC to make the mission viable.

By suitable sizing of the inlet and diffuser and nozzle, it shouldn't matter what bypass the engine has. But it is true that exhaust velocity must be high enough to fly supersonic, so that does mean a fairly low bypass ratio - or sufficiently high pressure ratio and temperature.

So this choice of very very low bypass is because the pressure ratio and temperature are not high enough. Supercruise is a bit far away, given the "transonic drag growth" of the LCA and the fact that the Kaveri is nowhere near getting to the needed T/W ratio.

But I see your point.

Reminds me of the movie "Mouse on the Moon". Both US and SU poured money into this tiny nation, in the name of winning hearts and minds in the 3rd World, and encouraging Space Research.

The King got the Aid purportedly for a human mission to the Moon, but in fact the project objective was to have all-gold plumbing in the Palace toilets.

Unfortunately, the mad professor who was head of the nation's Scientific Establishment had other idea, and actually flew a Moon rocket and landed there, causing both US and SU to get in a desperate race to beat them.

Likewise, the specs may have been set to induce the phoren log to provide 3rd World Educational Aid.

enqyoob · Post by **enqyoob** » 21 Aug 2009 03:20

vinaji:

F-119:
Dry thrust 26000lbf, weight 3900 lbf. So T/W DRY = 6.67 This is why it can supercruise. IOW, its DRY T/W is better than Kaveri's WET T/W.

Bypass ratio: 0.45 which is not at all small, for a fighter engine!

Wet thrust ~35000lbf ( both thrust figures are probably bogus)
Wet (afterburning) TSFC ~ 1.94 per hour. (probably bogus, but it's anyway lower than the 2.2 usually quoted for wet TSFC)

High turbine stages 1
High compressor stages 6
low pressure turbine stages 1
low compressor stages 3

So, our dear K-9 also has 6+3 stages. Unfortunately there are some very large differences.

F119: Counter-rotating shafts. This means that most of the swirl energy put into the flow by the low pressure compressor is recovered by the high pressure compressor, and same for the turbine, allowing very high turbine stage pressure ratio, thus minimizing number of turbine stages. They probably save having a stator stage at the end of the low pressure compressor as well.

The turbine stress must be really something, and so they have these "integral blade-disc" etc. But these are the reasons the thrust/weight ratio is so good, and they get supercruise.

enqyoob · Post by **enqyoob** » 21 Aug 2009 06:31

vinaji: On the F-35's engine, the bypass ratio is smaller (0.2) but remember that this is also a shaft-power engine - it drives the huge lift fan, so you can think of it as a variable-cycle engine, which operates at very LARGE bypass ratio at takeoff and landing, then becomes a turbojet for high speed flight.

Pratt & Whitney F135-PW-100 Augmented Turbofan

* Type: Dual shaft turbofan with low bypass ratio and afterburning
* Bypass Ratio: 0.2:1
* Low Pressure Compressor: Three stage fan
* High Pressure Compressor: 6 stage axial flow compressor
* Burner: Annular, through flow "floatwall" combustor
* Turbine: Dual spool counter-rotating, single stage axial high pressure turbine, single stage axial low pressure turbine
* Exhaust: Converging afterburning jet pipe, variable area divergent secondary nozzle, with 3 bearing swivel arrangement.
* Thrust Rating: 40,000 lbs. thrust class with afterburner
* Maximum military power (no afterburner): Approximately 30,000 lbs. of thrust
* Weight: 3,750 lbs.
* Thrust/weight: 10.5:1
* Air mass flow: Approximately 200 lbs/sec
* Overall Pressure Ratio: Approximately 30:1
* Maximum Turbine Inlet Temperature: 2,800 F+ ("+" is right, it must be waaay "+")
* Specific Fuel Consumption: .70 lb/lbt/hr (dry), 2.0 lb/lbt/hr (with afterburner)

*******************************

Compare to the F-100-229 and you can see some of the evolution in the F-119.

4. 1. General characteristics

* Type: Afterburning turbofan
* Length: 191 in (4,851 mm)
* Diameter: 46.5 in (1,181 mm)
* Dry weight: 3,740 lb (1,696 kg)

Components

* Compressor: Axial compressor with 3 fan and 10 compressor stages
* Bypass ratio: 0.36:1
* Turbine: 2 low-pressure and 2 high-pressure stages
{On the F119, by going to the counter-rotating shafts, they managed to cut down on number of stages drastically (2 turbine stages vs. 4), without changing the engine diameter, while increasing the thrust. Hence the large improvement in T/W, and large reduction number of parts. Counter-rotating shafts are notoriously prone to instability (resonances) so this was not an easy thing to do, and matching the rotation speeds and getting the right blade angles etc. was probably not easy either}

Performance

* Maximum Thrust:
o 17,800 lbf (79.1 kN) military thrust
o 29,160 lbf (129.6 kN) with afterburner
* Overall pressure ratio: 32:1
* Specific fuel consumption:
o Military thrust: 0.76 lb/(lbf·h) (77.5 kg/(kN·h))
o Full afterburner: 1.94 lb/(lbf·h) (197.8 kg/(kN·h))
* Thrust-to-weight ratio: 7.8:1 (76.0 N/kg)

abhiti · Post by **abhiti** » 21 Aug 2009 07:38

narayanan wrote:{So we are back to a "research" organization that does no research.}

Well now I know why you being so

at GTRE. It does seem to suggest what I saw at another govt research company - a bunch of novices trying to build a complex system. Novices survive on key words and want to just work on latest hype funda. Anytime someone even learnt to spell it they will just jump ship to private company with 3 times more mullah! What happens to the project? Welcome the next trainee!

enqyoob · Post by **enqyoob** » 21 Aug 2009 08:07

Do u?

vina · Post by **vina** » 21 Aug 2009 10:36

AFAIK, supercruise just means that you have enough thrust to go supersonic without afterburner. This again just means that you have a high enough thrust-to-weight ratio that you can afford to size the engine to produce enough dry thrust, and low enough TSFC to make the mission viable.

By suitable sizing of the inlet and diffuser and nozzle, it shouldn't matter what bypass the engine has. But it is true that exhaust velocity must be high enough to fly supersonic, so that does mean a fairly low bypass ratio - or sufficiently high pressure ratio and temperature.

Saar. I hardly remember anything in detail from Yin Gineering. I just remember "conclusions" like "Induction Motors are constant RPM motors and have piss poor speed control' and the number 1440..

So all I remember is "conclusion" --> Low Bye Pass is Good for sustained high mach numbers.

Now.. all i do is follow phassion and trends and try to go ahead of the trends and see how to match upcoming demand with a product/service that will satisfy it . aka. YumBeeYea giri.

Since I used YumBeeYea skills and successfully "upsold and cross sold" and created value by finding new uses for existing applications and hence was value accretive net-net and was perceived by customer as high value .. (aka, I sold the low by pass as the best solution for the new Phassion trend, aka Sooper Cryuuze).

So I will give you a YumBeeYea answer and dont laugh, it is a logically correct answer. Just like back in the late 60s and 70s, bell bottoms were the rage ( I am sure you walked around in the Madrassa wearing one.. come on , admit it, no shame there.. such things happen) , and the bell bottoms are making a come back in 2010, it is just back to the future no ?, So what has all this got to do with Gas Turbines.. If you look at it, the only successful super cruiser EVER is a 60s plane called the Concorde.. It actually super cruised across the Atlantic..with around 120 passengers + lugggage. That is far far better than Al-F- Bayees can EVER hope to do. Just look at the Bristol Engines in the Concorde and check out the vintage of the specs and by pass compared to civil engines of today.
So fast forward to 2006 or so, Dubai and Gelf were rolling in cash, and party was looking to continue forever and here was a new company that promised a Mach 1.6 or so biz jet..Like I said, back to bell bottoms.. they wanted a Concorde like performance but for 12 to 15 people onree thank you (chi-chi Sheik cant rub shoulders and bottoms with commoners after all). So what is the Yin Jin they choose ?. Is it any of the new fangled high bypass modern turbo fans with equivalent thrust ?. No sir.. No sir. They go ALL the way back to the vintage JT8D low by pass engines, while putting out a statement that confirmed the Only thing I remember ..." Low by pass engines are best suited for sustained high mach numbers!.

I know that you being a scientist will sniff at the common sense YumBeeYea answer. Okay, so will actually need to put pen on paper and think. Will do that and post over the weekend.

negi · Post by **negi** » 21 Aug 2009 10:57

Vina saar but supercruise is an attribute of the platform/AC and not just the engine , the engine most of the times is designed around the airframe and not vice versa. F-22 and F-35 are a classic case for the same . The high sweep angle ,internal weapons bays,blended wing design along with a complementary engine enable the F-22 to supercruise.

As you said LBP TF are meant for sustained high Mach numbers (i.e supersonic regime) ; look around how many aircraft today were designed ground up for supercruise and even out of those which claim to have achieved it with uprated engines how long can they sustain it with a substantial weapons load when compared to the raptor ?

If GTRE indeed designed the Kaveri around Tejas which imo was never meant to supercruise the assumption that low BP ratio was chosen for supercruise does not hold.Infact GTRE's decision to opt for a LBP design imho was a natural selection just like other design houses i.e. first get a core turbo jet working and then graduate to turbo fans by first designing a low BP turbofan (from my limited open source oracalite gyaan I understand that for a given engine diameter the compressors will need to achieve a higher pressure ratio> high T.i.T > high performance turbine(SCB) in order to drive the FAN as well as the compressor for a higher BP ratio engine vis a vis a vanilla turbo jet or a low BP turbo fan to maintain designed thrust numbers at service altitude

)

enqyoob · Post by **enqyoob** » 21 Aug 2009 16:20

vina saar:

negi is 500% halal. The only way the ell cee yay can SuperTomCruise is after delivering all the weapons, and on the way home. This is true of most a/c. The eph baaees carries a lot of its mitthais inside the fuselage. So it is very questionable indeed where the ell-cee-yay was supposed to be going with this SuperTomCruise, if it ever was a requirement.

I think it's like abhiti says: someone pulled a buzzword from the news and says:

Oh, Eph-baees claims Super Tom Cruise? We are having Super Tom Cruise also onlee, since 1963!

They must have been real novices since they had not heard of Air Liquefaction. Maybe the Saras engine will have this.

Same as

flat-rated thrust - ONLY injin specifically dejigned phor Indian condishuns!

As for the JT8D example, you are absolutely right in that Air Dubai would choose that for their indi-genius Hawai Carpet - e- Dawood. The JT8D has a feature that is far more important than "lo pye bass". It is called "Age". You can buy it from junkyards with no fear of Eye-Taar etc. etc. When ppl want an engine to test in, say, a new test facility to see if they can send it into compressor stall and possibly blow it up, do they choose an Eph -eksau unnees??? Nooooo! They choose JT8D! Been there, done that (it didn't blow up, but the stall event at 12:30AM was indeed interesting..)

In fact, let us look carefully at the JT8D as a candidate for the Kaveri -666 Advanced GTRE Turbofan of 2013.

The Pratt & Whitney JT8D is a low-bypass (0.96 to 1) turbofan jet engine, introduced by Pratt & Whitney in February 1964 with the inaugural flight of Boeing's 727.

JT8D:
Thrust 12,250 to 17,400 pounds-force (62 to 77 kN) Hey! Right there! Kaveri: 73KN with afterburner!

* Type: Turbofan
* Length: 120.0 - 154.1 in
* Diameter: 49.2 in
* Dry weight:

Components

* Compressor: Axial flow, 2-stage fan, 6-stage LP, 7-stage HP
* Turbine: 3-stage

Performance

* Maximum Thrust: 21,700 lbf
* Overall pressure ratio: 16:1
* Power-to-weight ratio:
*********************************************************
And it has another thing in common with the K-9:

* 22 August 1985 – British Airtours Flight 28M - an engine failed during take-off from Manchester Airport, the fire spreading into the cabin, resulting in 55 fatalities aboard the Boeing 737-236 Advanced. The uncontained engine failure was later traced to an incorrectly repaired combustor causing the turbine disc to shatter and puncture the wing fuel tanks. [1]
* 06 July 1996, An engine explosion happened on an MD-88, Delta Air Lines Flight 1288, just prior to take-off at Pensacola, Florida, U.S.A. A loose turbine blade penetrated the rear of fuselage (close to the point to where the engines are mounted), decapitating two passengers in seats 37A and 37C.
* 15 April 2008, a DC9-51 operated by Hewa Bora Airways crashed and burned at Goma following an engine fire

BUT.. against, that, consider the success record since 1964:

* JT8D-5, operating on the McDonnell Douglas DC-9-10 Aircraft
* JT8D-7, operating on the Boeing 727-100 and some 727-200 aircraft
* JT8D-9, operating on the Boeing 737-100 and 737-200, McDonnell Douglas DC-9-30 and the Sud Aviation Caravelle (10B, 10R, 11R, and 12 models only) aircraft
* JT8D-9A, which is another version of the JTD8-9, operating on the Boeing 737-100, 737-200, 727-200 and McDonnell Douglas DC-9-30 aircraft
* JT8D-11, operating on the Boeing 727-200 and McDonnell Douglas DC-9-40 aircraft
* JT8D-15, operating on the Boeing 727-200 and 737-200 aircraft, Dassault Mercure and McDonnell Douglas DC-9-30, -40 and -50 aircraft
* JT8D-17, operating on the McDonnell Douglas YC-15, Boeing 727-200 aircraft and 737-200 aircraft
* JT8D-17R & S, operating on the Boeing 727-200 Advanced aircraft and McDonnell Douglas DC-9-50 aircraft
* JT8D-209, used on some McDonnell Douglas MD-81s
* JT8D-217A/C, used to power the McDonnell Douglas MD-81/MD-82/MD-88 and MD-87
* JT8D-219, used to power the McDonnell Douglas MD-82/MD-83 and MD-88 and are being fitted to the USAF's E-8C J-STARS Aircraft

AFAIK, every time you get on a B737 flight in India, whether IA or JetAir, u r trusting ur life to 2 JT8Ds, both probably older than urself. Listen carefully to the engine noise - you won't hear that on planes anywhere in the US or Oirope any more.

Finally, "LO-PIEBASS" on the JT8D is still around 1, which is higher than on most fighter engines. On Kaveri it is 0.1 something. Big difference.

More than 14,000 JT8D engines have been produced, totaling more than one-half billion hours of service with more than 350 operators making it the most popular of all low-bypass turbofan engines ever produced.

Look at the size of the Injin market, more to the point, look at the experience base that goes into actually developing world-beating engines.

vina · Post by **vina** » 21 Aug 2009 16:55

narayanan wrote:vina saar:

negi is 500% halal. The only way the ell cee yay can SuperTomCruise is after delivering all the weapons, and on the way home. This is true of most a/c. The eph baaees carries a lot of its mitthais inside the fuselage. So it is very questionable indeed where the ell-cee-yay was supposed to be going with this SuperTomCruise, if it ever was a requirement.

negi ullah has forgotten reading combrehensions lessons from the Madrassa. Fatwa on him to be given 100 stripes and to re-read the posts.
I never suggested that LCA /Super Cruise was a requirement. Just putting things in perspective that in a high mach number sustained flight the engine characterestics would be towards low by pass and not high bypass.

I did write a couple of lines on my brilliant YumBeeYea skills in marketing a dog to do new tricks by addressing future requirements and creating lot of 'value'.

Point is the future is not very high by pass ratios if the high sustained super cruise beyond mach 1 is a requirement (which will be as engine thrust to weight increase) and it will be back to bell bottom like 70s kind of fighter engine characterestics in terms of operating cycles.

As for the JT8D example, you are absolutely right in that Air Dubai would choose that for their indi-genius Hawai Carpet - e- Dawood. The JT8D has a feature that is far more important than "lo pye bass". It is called "Age".

This aint no Hawai Carpet-e-Dawood Pindigenous stuff.

I am talking of These Guys, who seem pretty competent and who know what they are doing.

And it aint your grandpa's JT8D either. Check it out here

It caught my eye because they sold the initial "pre order" of 40 jets in the Gelf and usual Sheik suspects and the Saudi Al-Waleed ordered one after he booked an A380.

AFAIK, every time you get on a B737 flight in India, whether IA or JetAir, u r trusting ur life to 2 JT8Ds, both probably older than urself. Listen carefully to the engine noise - you won't hear that on planes anywhere in the US or Oirope any more.

The only place you will hear that kind of engine whine in India is on an IAF IL-76. You know better than this. Fuel costs in India are easily among the highest in the world. All the private airlines use the latest jets with uptodate engines. The private guys' fleets are very new and have very low average year.Much lower than most AmirKhan and Oieropean airline. Even the much maligned indian airlines has a technologically decent fleet. The old B737s with those kind of engines were given off to one subsidiary called Alliance Air long ago..and I think are most probably scrapped. IA got on to A320 long ago and even the remaining A310s have been retired (A310s have high by pass engines)

Finally, "LO-PIEBASS" on the JT8D is still around 1, which is higher than on most fighter engines. On Kaveri it is 0.1 something. Big difference.

Ah, but you have to keep the use in mind isn't it. For fighter engine 0.4 is high, 0.6 like SU30 is on the top end. While in a civil engine /transport engine which is subsonic 6 is what is the current numbers going upto 9 pie bass in phyoochur.

So Kaveri is on the lower end , closer to to a pure jet .. Something like a GE 404 will be something like 0.3 or so I guess.

But what I am willing to bet is this. While everyone knows the wet thrust of the PW 119 and the one of the F-35, see if you can get some numbers on the dry thrust anywhere which is reliable. Then do the ratio of dry to wet thrust. I am willing to take a bet that it will be lesser than engines of earlier vintage like F100 an F110 , especially if all the ballyhooed stories of Sooper Cryueeze so heavily advertized are in anyway way true.

Anyway, will post on the dhoti/hawa/flat rating ityadi later..BTW, note that the JT8D link I have posted has been flat rated to 19600lbs or so from it's full rating of 21k oddlbs.

enqyoob · Post by **enqyoob** » 21 Aug 2009 17:19

I am beginning to c what the "flat-rating" is. Its a number that one advertises that should be valid most days, as opposed to the Top Rated value which is known to only the Ayatollahs. That would make sense, but in the case of the K-9, if the secret number is high, well... they seem to be keeping it VERY secret incl. from the IAF. Or maybe the underground injin factory is coming up (I mean down) even as we chew the cud here, someplace deep under the dakoo ravines of Madhya Pradesh, to crank out 1,000,000,000 of the SuperCruise K-10s with the 3500K Turbine Inlet Temperatures and the single integrated compressor-turbine-combustor combo BLISK. I hope!

On the modernity of the injuns, vina, pls do check on what powers Jet Air 9W401 and 405 every din between Mumbai and Malloostan. The noise of that engine has not changed since the 1980s when it used to be ICXXX doing the STOL at Wellington Island. This is something that has been worrying me for decades. This is the only flight (correction - maybe I heard something like it on a scary flight between Madrid and Valencia where they lost my baggage) where I can hear the burners coming on one by one, and they sound just like an old gas furnace with too much rust on the burner gas outlets (IOW, broadband combustion noise with some very-long-time-scale, large-amplitude unsteadiness dominates over any fan/ turbine compressor tones). Those planes are not exactly new either, unless I can describe myself as a kindergartner. I reason that if I become pest-e-sha'eed on the matrubhoomi, I get the Award Travel to Houristan, so I just go to sleep.

My fear is that you are assuming that high fuel prices dictate engine modernization in the matrubhoomi. Jet fuel prices are VERY heavily subsidized by guvrmand (all over the duniya) while engine modernization capital costs are real.

As for JT8D, OK, so P&W must be offering a modernized version of the old pig to Havaii Carbet -e- Dawood, because it won't get the execs into jail under ITAR.

This is what I was suggesting as a quick growth path for GTRE (actually for its replacement which may have some intention of doing work):

1. Buy some of these ancient engines (or as modern as u can go without triggering Technology Control regimes or paying high prices). Preferably from the desert storage dumps, or from Oshkosh Air Show or Moscow Auctions. You can probably get them cheaper than a new set of just bearings. If the engine is old, and the plane hasn't been in a crash, at least you should be able to get a smooth-running shaft that is quite straight, which is no mean achievement if you try to make one new.

2. Put these in test cells (OK, MAKE the test cells) and test over the whole range, using the tests to get data on the engines AND the facilities and the people running the instrumentation.

3. Take them apart and build engines with indi-genius components gradually replacing/ improving all components, and improve reliability and performance, while always having a few working TEST models.
Call them Tapti -1, 2.... upto 1,700,000.

4. Use these data sets for CFD validations, dynamics predictions, material predictions, reliability predictions, everything. Publish widely, challenge universities to come up with improvements.

5. Build the "test hours" to hundreds of thousands.

Without this pace of development and experience and iteration, there is no hope. With it, there is no reason why India shouldn't have world-beating domestically produced engines within a decade. Right now, the situation is:

a. No test experience because no engine
b. No test cells because no testing needs due to no engine
c. No experienced personnel because no test experience due to no engine
d. No engine due to no experience and no testing.

This does not seem to offer an Evolution Path to Technology Dominance, hey? (any hope 4 me in the happy world of Customer Pleasing, hain?)

Finally, the point about "SuperCruise" proven by this new advanced JT8D is that any old pig engine can be used for supercruise, as long as the payload fraction and range are reduced and the plane does not carry external stores and the fuselage is so narrow you can't raise your head in the window seats (like Concorde, incidentally). Bypass ratio can be quite high if you can fit it into the plane, or even put it outside like on an SR-71. This is why the supersonic biz-jet is so attractive - compare that thing shown on the Aerion website to (a) Lockheed F-104 and (b) Northrop Tigershark. It's basically a fighter with no external stores, and no canopy bubble. The development risk is reduced because the basic design has crashed enough times as a fighter and killed enough pilots to have provided plenty of data.

I don't see that there is any "futuristic migration" to low bypass ratio, especially to save fuel. On the contrary, any Concorde-2 for instance will have a much higher bypass ratio. This is because the T-i-T can be raised and the core pressure ratio can be over 50 these days, though something around 30 may be optimal for Mach 2 at 50K feet).

Interesting point about the JT8D meeting noise requirements - so is this why I hear only combustion noise on Indian airliner jet engines? Superior fan noise suppression? I tend to doubt that...

Also, the good news is that the JT8D shows something else - you can take a basic engine outline and keep advancing it from 12000 lbs to 21,000 lbs, like the story of George Washington's Original Axe (handle has been upgraded 20 times, blade 17 times and it is now a carbon composite handle with a titanium ceramic alloy blade with integrated ND fiber Laser cutter).

This still requires going to better bypass ratio on the Kaveri design.

Sanku · Post by **Sanku** » 21 Aug 2009 17:20

Oiii I really want to read the posts, but it is impossible to read it with all the Pinglish. Please please please talk in normal forum language.

-----

Oh and test cells? If GTRE could get test cells in the first place we wouldnt be having this discussion.

And no it has nothing to do with GTRE not wanting to work...