Kaveri & Aero-Engine: News & Discussion

SaiK · Post by **SaiK** » 23 Mar 2014 18:12

page thru and point your likings here
http://search.dilbert.com/search?p=Q&sr ... omic&srt=6

Indranil · Post by **Indranil** » 23 Mar 2014 22:11

Chacko sahab,

That is is plain and simple wrong. If the reliability is not a problem, LCA would be a slow duck with the (current) Kaveri. It would need a longer takeoff run (like the Jaguar), but it would most certainly take off. I don't think there is any question about that.

How do civil airplanes take off with their power to weight ratio?

Austin · Post by **Austin** » 23 Mar 2014 22:23

I think what he means is Kaveri is not yet Flight Qualified to be integrated into LCA .... they need to get kaveri flying right and get the engine certified before they can think about mating with Tejas Airframe irrespective of changes needed in airframe for the engine.

chackojoseph · Post by **chackojoseph** » 24 Mar 2014 07:08

indranilroy,

I am only relaying a conversation, I do not subscribe to it. However, we should listen to all quarters.

Indranil · Post by **Indranil** » 24 Mar 2014 08:48

Surely. But in this case the observation is plain wrong. There is no grey area.

chackojoseph · Post by **chackojoseph** » 24 Mar 2014 08:59

Do you have information if it was certified flight worthy after Russia tests? AFIK Dr. Tamilmani hasn't said so.

member_28502 · Post by **member_28502** » 24 Mar 2014 09:01

since this is thread for Maha gurus and ati gurus
I tread with with great trepediation and ask few
kweschens ji sarkar

eej it poshible to solve Laplace istranshforms with out he knewledge of trigonometry or differential calculations?

if it ij not then

how can we make a jet engine with out even knowing how to make a rotary engine for our basic trainers?

let the private sector make small private parts for big engines to start with.

look at the history of the leading companies of the world
Prat and Whitney started with measuring gauges and precision tools rotary engines and then jet engines
Roll Royce the same way
first lets make a engine and aircraft like this

use it as UAV Rustam-e-hind ( rustam from behind)

as told to me by Chai Ram part time chai supplier For HAL

chackojoseph · Post by **chackojoseph** » 24 Mar 2014 09:12

Nijalingappa,

we have some experience based on Orpheus 703 engine.

member_28502 · Post by **member_28502** » 24 Mar 2014 09:22

Any knowledge in public sector is lot in translation from Russian designs or British designs...

I am talking about private sector.

MTAR started as a recondition out fit in Balanagar, The founders worked for me (reddy brothers of HMT SPM division taking pay from HMT and working in my shop and their shop after punching in at SPM division)
Godrej started with welding of steel structures then into ISRO jobs and DRDO jobs
L&T started with electrodes Eutectic Division now can weld submarines and you name it

Pvt sector has to sart private (small) parts and then allow them with tax incentives and firm orders no hanky pancky Director general of Military Scams
which abound and look at BEML scandal

here is how we cheat or leech public money in Defense procurement

notice anything sad here?

chackojoseph · Post by **chackojoseph** » 24 Mar 2014 09:35

You can explain "private parts for Big engines."

Private sector does contributes to kaveri engine.

member_28482 · Post by **member_28482** » 25 Mar 2014 16:47

When could we expect certification for Kaveri Engine

Is there any test going on P9 or P10.

Next year, the GTRE plans to show the engine’s performance first on an Il-76 plane and then as the second engine fitted on a twin-engined fighter like MiG-29. It would be tuned to certification standardshttp://www.thehindu.com/news/national/k ... 190724.ece

chackojoseph · Post by **chackojoseph** » 25 Mar 2014 19:12

The old schedule remains till someone say's it is changed. There is no indication that it will not go Russia for further trials.

putnanja · Post by **putnanja** » 08 Apr 2014 23:33

Cross-post from R&D thread.

Chat with Shri Tamilmani of CEMILAC on Tarmak FB page. Excerpts related to Kaveri:

We are not planning any new platform. Our focus is on resolving tech challenges on kavevri engine and prove it to be a successful Indian engine.
The solution for the few problems in kaveri are totally indian. However at times we seek an independent audit prior to testing on engine
Kaveri is in the testing phases for endurance and reliability with multiple prototypes for certification process. We hope to succeed in 2 years after completing the airworthiness tests.

Indranil · Post by **Indranil** » 02 May 2014 14:58

Tenders for the rotors and casings of the 25 ~~Ton~~ kN Hindustan Turbofan Engine (HTFE-25) are out. Looks like will have a 4-stage HPC.

NRao · Post by **NRao** » 02 May 2014 16:58

Pardon my ignorance, where would such an engine be used?

Also, would it reflect on the Kaveri at all?

vic · Post by **vic** » 02 May 2014 17:06

Indranil, Can you analyse, what sort of engine is HTFE-25? Something equivalent to AL-55 or Adour or Garrett etc?

SaiK · Post by **SaiK** » 02 May 2014 18:44

can someone pl extract those zips into significant details as text here? having troubles downloading. tia

Indranil · Post by **Indranil** » 02 May 2014 20:07

Not much is known about the engine. I could start guessing about it from about 2 years back. HAL acknowledged it about 1 year back. Initially it will be developed for military trainers (read IJT, Hawks) when they come in for re-engining, UAVs (back-up for Ghatak?). There was news that they are developing variants for the military transports (turbofan version of Saras?) and civil versions for business jets. The prototype for the low-bypass engine was to fly in 2016. But we have to wait and see when the high bypass engine comes out.

Vic, it is somewhere between the Adour and Garrett. Looks more similar to the Garett in dimensions. Maitya sir can elaborate more (though there is not much to go on now).

My perception is that Kaveri will gain next to none from this project, other than the setup of indigenous industries to fabricate some parts.

vina · Post by **vina** » 02 May 2014 21:53

25 Ton Hindustan Turbofan Engine (HTFE-25)

Something wrong here. This is something like 250 KN. More commercial jet aircraft like RB211 engine. Dont tell me that HAL is planning to go against CFM, PW & RR to supply engines for B747 kind of planes!

vic · Post by **vic** » 02 May 2014 22:42

I think HAL should go in for an engine which can be drop in replacement of Adour engine, something like F125.

Indranil · Post by **Indranil** » 03 May 2014 08:38

vina wrote:
25 Ton Hindustan Turbofan Engine (HTFE-25)
Something wrong here. This is something like 250 KN. More commercial jet aircraft like RB211 engine. Dont tell me that HAL is planning to go against CFM, PW & RR to supply engines for B747 kind of planes!

Thank you for pointing it out. No, it is not a 250 kN engine. It will produce 25 kN.

vic · Post by **vic** » 03 May 2014 09:45

There were some googled reports I came across which mentioned HTFE as 20-30kn engine. Budget for it's development was stated to be only Rs. 400 crores. I wonder what happened to ToT we got for paying Rs. 3500 crores for AL-55 engine R&D which is also 17-25 kn engine but is late, overweight, poor SFC, poor MTBF and the deal provides for NIL manufacturing.

SaiK · Post by **SaiK** » 04 May 2014 21:01

http://www.convertunits.com/from/kilo+n ... o/kiloton+[long,+UK]
250kN->25ton is right not?

Austin · Post by **Austin** » 04 May 2014 21:43

It must be 25 kN , 25T is a huge engine that powers wide body aircraft.

As a reference the PS-90A-76 Engine we use on newer IL-76 AWACS each has thrust of 14.5 T

Right now we need to build atleast one good engine for any type of fighter that can see wide service in IAF , Kaveri was the closest we got to building one but considering it has yet to be flight certified and much less would never see any wide service in IAF Tejas Fleet we have to wait for another decade to get our first indigenous engine which can see wide spread usage

SaiK · Post by **SaiK** » 05 May 2014 00:23

are we talking weight or thrust or a ratio we need?

Yugandhar · Post by **Yugandhar** » 10 May 2014 09:25

IMO This is a move in the right direction to find synergies internally

http://www.thehindu.com/todays-paper/tp ... 995146.ece

Public sector behemoths Hindustan Aeronautics Ltd. (HAL) and Bharat Heavy Electricals Ltd. (BHEL), along with the Defence Research and Development Organisation (DRDO), are exploring a joint venture to design, develop, and manufacture gas turbines for many critical uses in the country.

Teams from these agencies are working on the details of such a venture, which can create a large, vital Indian capability for gas turbines.

They are also crafting a technology road map in this area, assessing infrastructure and expertise available in the country as well as identifying a suitable technology to acquire or develop for the country, persons close to the development told The Hindu .

Gas turbines are used across civil and military sectors, such as in large passenger aircraft, fighter aircraft and ships, besides industrial and power sectors.

chackojoseph · Post by **chackojoseph** » 10 May 2014 10:20

DRDO for research and HAL for critical parts. Hopefully, BHEL will be able to compete with global giants. Indian Railways is another potential customer with positive attitude for the type.

vic · Post by **vic** » 10 May 2014 11:34

Yugandhar wrote:IMO This is a move in the right direction to find synergies internally

http://www.thehindu.com/todays-paper/tp ... 995146.ece

Public sector behemoths Hindustan Aeronautics Ltd. (HAL) and Bharat Heavy Electricals Ltd. (BHEL), along with the Defence Research and Development Organisation (DRDO), are exploring a joint venture to design, develop, and manufacture gas turbines for many critical uses in the country.

Teams from these agencies are working on the details of such a venture, which can create a large, vital Indian capability for gas turbines.

They are also crafting a technology road map in this area, assessing infrastructure and expertise available in the country as well as identifying a suitable technology to acquire or develop for the country, persons close to the development told The Hindu .

Gas turbines are used across civil and military sectors, such as in large passenger aircraft, fighter aircraft and ships, besides industrial and power sectors.

I have been suggesting tie up of Bhel, Hal and Gtre for developing turbine engines for ten years on brf.

Indranil · Post by **Indranil** » 12 Jun 2014 22:18

The HTFE-25 engine from HAL is coming along nicely. Lots of tenders have been floated out for the manufacturing of many HPC parts: rotors, blades, shaft, casing, gears etc.

merlin · Post by **merlin** » 13 Jun 2014 10:17

indranilroy wrote:The HTFE-25 engine from HAL is coming along nicely. Lots of tenders have been floated out for the manufacturing of many HPC parts: rotors, blades, shaft, casing, gears etc.

Strange. HAL should be able to do those, isn't it? Those are not hot section parts.

Indranil · Post by **Indranil** » 13 Jun 2014 10:44

This is the hot section. My guess, is this is just for the prototypes. Building parts for just 2 engines would not be financially feasible.

shiv · Post by **shiv** » 21 Jun 2014 06:13

Very interesting article by one of my favorite out-of-box thinkers in the latest issue of "Vayu" - Prof Prodyut Das about Kaveri.

Need to scan or obtain the article for all to read.

He says
1. India did not have the essential test rigs for engine development and still does not have them. Even Egypt in 1964 had a modified An 12 as flying test bed.

2. We should stop worrying about Blisk/single crystal etc and look at little details like improving airflow around individual blades etc.

I have not yet re read the article in detail - will post later. Maybe will post scans.

Overall he praises Kaveri if it has reached 90% of its thrust and suggests the ways forward

shiv · Post by **shiv** » 21 Jun 2014 07:19

Ah! Here it is
http://profprodyutdas.blogspot.in/

The Kaveri Turbofan Project- an “open source” assessment

If reports that the Kaveri has reached 90% of its Full Military power are true it represents a considerable achievement for the Engineers concerned. It also indicates no foreign collaboration is required to complete this project. The above numerator is unfortunately tarnished by the denominator of several decades of development with no engine flight cleared and a realistic date of completion is uncertain. Jet Engines development presupposes certain facilities as sine quo non: a) Test rigs for combustion chamber development b) Test rigs for testing the compressor spools together at rated conditions, c) test rigs for testing the turbine blading for cooling, thermal and mechanical loads simultaneously and finally d) a flight test bed to test the engine in the air. Item d) is still not available in the country and there are reasons to believe that items a), b, c) were not available at the time of taking up the project and may not in fact be satisfactorily available even now. Recall that Egypt, developing the E300 engine under the guidance of Ferdinand Brandner, with much poorer traditions and resources, had a flying test bed , a modified AN12, in 1964,.

The lack of these basic test rigs and their exploitation would have had a significant effect on the programme. The present “problems” with the engine – lack of performance, unreliability and overweight can be traced directly to the lack of the above test rigs and indicates a lack of top leadership at the front line of problems. It was “disconnected thinking”, in 1987, to so confidently say that our engine would be “flat rated”. The basic tools needed for the job was nowhere there. The relatively low total running hours (< 2000hrs for the entire programme spread over about ten engines) would mean that the infantile “measles and mumps” kind of problems have not yet been exposed. If the engine hours are correct, it was surely premature to have air tested the engine in 2003 when it, quite expectedly, failed. “A part of the learning process” is not an adequate explanation for this kind of repeated self induced “failure”. The failure delayed the project and should not have been done at that point of time. I recall a former Director, in discussing the Kaveri pressure ratio, admitting privately “Yes. We did over reach ourselves”. He was being modest! The fault, dear Brutus, is in our stars! Pratt & Whitney (P&W) was not allowed to do Jet Engine work because of the War. GE was clearly ahead. Immediately after, in 1945 itself, P&W set up a Turbine Laboratory (WTL). Note that they named this critical survival asset after their Chief Engineer Andrew Wilgoos and not after Rentschler, their Founder & Chairman!) WTL was fully integrated into P&Ws mission to be a prime player rivaling GE and had the skill and resources of P&W on tap. We set up GTRE but it was a completely different entity vis a vis HAL in terms of aims, service conditions and critical performance parameters. Yet GTRE was supposed to depend on HAL. We do things right but don’t or cannot do the right things! Even given the best of intentions results would be what they are.

The Good news is that an engine that is giving 90% of its cold thrust cannot be all that bad. The engineers who can achieve that also cannot be bad. What has been lacking has been the leadership over several “generations” of higher management. We will come to this point later. The Kaveri does not want more technology. It needs more care and analysis. Jet engines, though inherently simple, are extremely sensitive to detail as the following examples will illustrate. “Point one millimetre” (‘four thou’ if you are that old!) is the general unspecified tolerance in aerospace machinery. It is the average thickness of human hair. If the gap between the rotating blades and the casing varies by this “point one “ millimeter in a Kaveri sized engine it means a difference in the turbine tip/casing flow area of about the size of a 20mm hole. Imagine the differences in flows if you are dealing with pressures of around 20 bars! If the clearance is that amount too little, you will soon get very expensive sounds, blades being shed and possibly an engine fire. The tip clearance is a decider for TBOs. The current technique is to remotely sense the tip clearance and heat or cool the casing locally to keep the clearance constant. No wonder the grudgingly respected Chinese engineers still manage to stir fry their new engines with some regularity! The same “thickness” or (thinness, if you will!) in the engine casing will vary the weight of the engine by approximately 5-8 kg and an increase or decrease in engine length by about ten millimeter will affect engine weight by about 4 to 5 kgs due to casing and shaft weights. Of course a 0.1 mm variation in blade profile is unthinkable. I cite these figures to show the “gearing” between cause and effect in Jet engine development and the need to go over details, components and results with a fine comb -and an engineering Sherlock Holmes by your side!

However creditable the performance of the “troops” the present situation reflects on the higher direction of the programme. There are two management issues involved. The first was to undertake the project without having the physical resources ready. Everything is always wanted yesterday. It appears the then leaders, (assuming they knew clearly what was involved) either wanted to “make someone happy” or wanted the project “at any cost”. Honesty about the situation-so disdained by the “clever”- is an essential requirement –and a mark of leadership. In 1962 Lt. Gen Kaul, by acceding to political pressure gave us the Himalayan Blunder .Nine years later Sam Manekshaw by stubbornly (but charmingly!) refusing to move until he was ready, delivered Bangladesh! The second area of failure of Leadership was a failure of knowledge. There was a lack perhaps of a holistic view of what the engine was supposed to do. They apparently wanted an engine “just like the F404” rather than thinking more systemically about an adequate engine which would do the job. By these two fatal lacunae-one physical and the other mental- GTRE fell into “mission impossible” mode.

Rebooting our mindset
Let us look at the above in a bit more detail. Modern Western Military engines are, perhaps surprisingly, strongly injected with technologies developed for competing in the civilian markets. It makes sense for the West to use these thoroughly proven technologies in their military programmes- it helps to amortize costs! An opposite corollary was the USSR where Technology Development was always led by Military requirements and USSR civil engines were the dregs in terms of Sfc and TBO! For a civilian engine a TBO of 4000 hrs is “essential”. The plane flies fourteen hours per day. One cannot yank the engine off the pylon every 6 weeks as a R29B style of 550 hour TBO would entail. Every gram of fuel saved per hour is of consequence given the huge number of hours flown per year. This entails engines having compression ratio s of 20:1 to 30:1 with current research exploring 70:1. (Want to play catch up with the Technology, any one!) One could go on but the drift is that before we follow someone’s lead we have to stop and think of our task and the cloth we have for our coat. What are these?

a) Slash the engine ‘to begin with’ TBO to around 400-500 hours .Insist the Air Force declare what is their attrition rate for single engine close support fighters. I know we lost about 30 Hunters out of 96 active in the six squadrons in the nine years between inductions to just before the ’65 war. Very few if any of these could have approached 1000 hours. It would be interesting to have a histogram of the number of engine hours of all the MiG 21s at the time of their write off. If this figure is pretty low as I suspect it to be, there is no need to make a 2000 TBO or 4000hr technical life an immediate target. A 250 hrs TB0 (Incoming! Incoming! Duck! Duck!) would last a couple of years on a fighter airframe. Reduction of TBO time will significantly reduce the development task without affecting the operational efficiency. The ‘problem” of low TBO-replacing engines- can be ameliorated by designing for easy installation and removal. In the Mig 15 two men could do it in one hour! Engines are more “plumbed” nowadays but that is where the challenge of good engineering comes in! Incidentally, an Indian Engine built with Indian materials in Indian factories would be formidably competitive against all comers even with these low TBOs and TTLs.

b) Do we really need 20:1 CRs (compression ratio) given the engine becomes heavier and more surge prone as we jack up the CR? Higher CRs mean more stages and the compressor and combustor casings being open ended pressure vessels, mostly in heavy alloys add much to the weight. Remember that a 0.1 mm thicker casing will add 8 kg to the weight! We know the benefits of high compression ratios are subjected to diminishing returns. The Orpheus with a CR of 6:1had a sfc 1.03, the R 25 had a CR of 12:1 and had a sfc of 0.9 and an engine with 20:1 CR will have an sfc of around 0.8. This “high compression ratio” led improvement in sfc does not pay in our typical low duration sorties. For an IAF standard fighter sortie the weight of engine plus fuel required (for the same level of technology in other areas) disfavours the high compression engine. Also because the compressor passage areas are fixed, the resistance to compressor flows at part throttle (where the wretched engine will be spending most of its life, anyway!) the proneness to surging will cause problems. Finally to remember is that high CRs in themselves are a partial contributor to the sfc figures. Burners, combustor and turbine blade technology being the others.

c) Are we worrying too much about smoke and NOx? Western “standards” are again derived from already existing and already proven and available low risk “Civilian” technology which we do not have. A short combustor means a lighter engine because the shaft and casing becomes shorter. Shorter combustors will require focused research on getting the spray pattern “tighter” in the spread of droplet size. How much work has been done in this area before we set our targets?

d) Western aircraft design philosophy believes that VG intakes don’t make sense below M1.3. Our designers follow the same track. This, I believe, is a “frozen” thought from the ‘60s and the days of electromechanical sensors and actuators. Given developments in sensor technology and computer controls we should look at new variable geometry intake configurations to maximize pressure recovery. Even if we can save the equivalent of one or two stages on the compressor it would help in reducing the length of compressor, ergo a lighter engine.

e) Also to be examined is the total thrust /fuel flow requirement profile and optimize the engine’s weight and fuel consumption in relation to the task. A typical LCA type engine will have the following profile. A/B thrust approx 2⅟2-3 minutes, Full military 6 minutes, 60% thrust 20 minutes, 45% thrust 25 minutes, and flight idle about 5 minutes. The figures are illustrative but the idea that we must reduce the Total fuel burn/sortie rather than optimize for a rarely used “best” figure. The intake, the engine and the afterburner together have to be seen as a system which will give optimum performance in the 0.6-o.8M at low level with all other conditions being seen as “special” cases for the system.

f) A consequent question to the point made above is given that relatively small duration of operation of the max. Installed thrust how much of the thrust should come from the engine and how much from the A/B? The Tyumanskii/Gavrilov R 25 of the MiG 21bis is an example of alternative thinking. The dry thrust is 59kN, with A/b it is 69kN but with a “boosted” a/b it gives 97kN (from Russian sources!) which thrust wise would be ample even for the LCA! The use of the boosted A/b reduced engine life at the rate of one hour per three minutes but it works! Anyway as said before a “totally Indian engine” will be cheaper.

There are several more such issues but the point I am trying to make is that we have to see the task not as an engine “just like” something else, as I suspect, had been done. Let us move from mere Information to Knowledge and, hopefully, from Knowledge to Wisdom! GTRE hamstrung itself by trying a “drop fit” replacement for the F404. The saner approach would have been to have a dialogue with ADA so that ADA would be prepared to “rebore” (Not, please, literally as one irate reader seemed to think!) the LCA airframe to accept the slightly different engine. We must therefore come to a state of mind where we read the book and then throw it away to chart our own course. So what needs to be done?

If you have ten hours to chop a tree…
Spend nine sharpening your axe! Build up and “sophisticate” our test rigs so that the key problems can be solved in detail. For example the test rig for the turbine blade should not only be able to handle a mass flow of around 5kg/sec @ 1400⁰ C- for a cascade of four or five blades but also will be able to simulate the creep loads on the blade whilst a separate air source will supply cooling air through the internal passages. Similarly for the compressor test rigs it is necessary to have rigs powerful enough to test the two spools together irrespective of what may be the practice in other countries. A short combustion chamber will need research on droplet uniformity, spray pattern, burner types and configurations. Turbulence and uniformity of temperature at Turbine entry are other areas to study. The test rigs help to break down the problem before synthesizing the solution. These test rigs are the axes for the problem and in future we must emphasize test rigs and their roles in any project. Normally the evolution, design, fabrication, and operation of productive test rigs will require the same quality of ingenuity and good engineering as the engine itself.

The obvious thing to do-don’t!
Perhaps there is a need to review the Jet engine programme as a “National” programme rather than a DRDO baby. No single organization can do the job alone. In England Bristol Engines starting Jet development from scratch but let Lucas focus on the critical fuel systems and combustion. Team work has to be enforced by getting GTRE back to what it really was set up to do and HAL has to be forced to pick up “GTRE’s baby” and bring it up to some state of civil behaviour. It is possible that a team of HAL ‘s best designers and fitters from Koraput and Engine Division are transferred to lead the Kaveri programme. Unfortunately, whilst administratively such action is possible it won’t work in peacetime. Internal priorities would change; the organizations concerned would become creative. We would see tribal warfare the Pathans would relish! As things stand GTRE must find a way out from the difficulties it has created for itself!

What ails thee Knight?
Over the decades our betters have replaced in our Engineering colleges “practice based” engineering with “science based” engineering-even at the undergraduate level! Consequently GTRE, as with other scientific research establishments in India, has unquestioningly adopted the rather large assumption that possession of an engineering degree confers the abilities of an engineer to the holder. The natural consequence of this assumption is that the more the degree the more the “qualification” of the person to take engineering decisions -never mind that one of the most esteemed and successful engineering leaders in the country, who has unfailingly delivered, Mr. E Sreedharan of Pamban Bridge, Delhi Metro et al ( the list be long!) is a “mere” B.E. The reality is that Engineering is a practioner’s art and the “qualification”- irrespective of its degree -is merely a license to enter the area. Possibly, as in education, in selecting “leaders”, possessions of qualifications have outweighed other parameters. The result is a lack of engineering leaders who enjoy being “at the front”. I could cite several examples (looking back, quite amusing!) of the effect of lack senior “engineering leadership at the “frontline” .That will have to wait. However I will give an “unrelated” example. Rommel won his battles often with inferior forces, because he had much more direct knowledge of the tactical situation “real time” and was personally judging the situation with his great experience and technical skills-apparently he was an IC engine “nut”-rather than relying on what some inexperienced Feldwebel thought of the situation. This undistorted, experienced, assessment of realties came from being right at the front when his opponents were at their HQ way back from the action. How many “Top” Scientist work side by side with the fitters? The administrative problem is that passionate engineers often tend to be “enfants terrible” of the organization and are often ACR’d ( quite validly, depending on your priorities!) “Not quite mature” or “good but simple minded”! The net result of all this is that GTRE probably has excellent administrators- and they are also needed -but it does not have excellent practical engineers who can calmly “think things through” and yet have the authority to get thing s done.

There be hope yet…
Despite the clouds above the situation is ripe for rapid rectification which should enable us to have- without foreign collaboration- a flight cleared engine within a predictable and short time scale Foreign collaboration, if available, may not hurt but I believe the here the demand for collaboration is a bureaucratic “failsafe” decision; no one can be blamed. It is this lack of “the right stuff” – people who will work on the engine rather than eat their dinner-which is why we are where we are at present. Instead of commercial collaboration what we can do is however is to get retired engine designers over as a Teacher or a guide. The Chinese not only regularly had Hooker over as an honoured Guest they also had Ferdinand Brandner over as a Professor in their top University. I don’t think Brandner simply taught the prescribed course! The other reason for rejecting foreign collaboration for the Kaveri is the nature of the present need. The answer to the Kaveri’s performance problems cannot be yet more technology-there is no magic in Technology- but more care and thought and listening to what the engine is trying to tell us- yes it talks! Assuming the basic design (barring, apparently the A/B) was sound, what is needed is a hundred small improvements - improving the surface finish of the compressor casing bore or the blades, working on cleaning up flows near the roots, stressing the components down to closer margins, tightening technology processes and so on rather than introducing “blisks” or “shrouded blading” or SCBs which everyone seems to talk about. We put in certain Technology. It was put in to do a job. Why is it not then doing it? It is here that GTRE is, by its charter, subtly handicapped. Being a R&D set up it does not have those seasoned practiced people whose hands can “read “the engine even with their eyes closed. A R&D organization, anywhere on the Globe will not have the skills common in a production unit.

Cutting your coat
We need to:

i) Enter into a dialogue with the customer about TBO, engine change procedures, TTL et al.
ii) Back off from trying to build something “same as the GE F XYZ”. It is not necessary or even the best solution. The Airframe boys should be ready to rebore their fuselage. Everyone does it all the time.
iii) Flog the engines on the test beds even if they are developing no more thrust than kerosene stove. If 550 hrs TBO is technical target one would expect 5500 hours on a batch of ten engines anyway. That way at least the infantile mechanical problems are exposed and can be corrected.
iv) Prioritize the acquisition of more than one flying test bed. Do you know Harry Folland’s last design was a large test bed to test the 2000 hp class Bristol engines that were supposed to be coming up in the 40s. A large simple multi engine aircraft an enlarged Canberra using the AL31 would be a lovely project for “people building”.

If we were to do it again
In future the task has to be bifurcated with GTRE contributing by providing experimental data and HAL Engine plant doing all the nitty gritty mechanical detail design stuff in which HAL is arguably, by far and away is better placed to do. Let me illustrate by one example: The Kaveri accessories drives gear box. HAL Helicopter Division has years of experience designing and making lightweight gear boxes for helicopters. For reasons possibly of “unease with HAL”, ADA gave the contract to CVRDE, a sister organization but with no aerospace collaboration and no direct access to the technology. My bet is that HAL Helicopter Division would have given a better gearbox in shorter time simply because the HAL’s supply chains of know how, information, machinery and process technology and human resources were shorter than CVRDE. With every “license manufacture” agreement comes a wealth of information- materials, processes, heat treatments, machining methods, testing methods and parameters, even how and where to mark the part no and how to store the part. Over the years, at HAL this “know how” has been subconsciously processed into Know why. To CVRDE it would be new territory. The difference may or may not have been much but “look after the days and the years will look after themselves”. This is why RAE and it’s cousins at AMES or Zhukovsky do not design engines and aircraft.

What are the areas on which DRDO/GTRE is particularly well equipped to focus on and what will be necessary for us to develop for a future Indian Engine programme?

1) Carbon fibre fan casings: TETs, engine efficiencies and thrust are in symbiosis. Given modern TETs a pure jet is no longer efficient and some degree of bypass is inescapable. The fan shroud operating at relatively low pressures and temperatures is an ideal case for (carbon) composites. DRDOs appropriate unit should develop expertise on fabricating and proving fan shrouds of approximate 900mm dia. and capable of handling pressures of 2-5 bars.
2) Short Length combustors: Excellence in combustion is a key to fuel efficiencies and light weights. GTRE must focus on a target of the shortest combustor length. Dual spray nozzles optimized for cruise and max thrust as used in modern civilian engines may be explored if found imperative.
3) Compressor Aerofoils: The R11 achieved a 9:1 compression ratio using just six stages with consequent savings in weight. Could this be “the starting block” for a new development programme aimed at high pr. rise per stage with stable operations?
4) Carbon fibre fans capable of sustaining bird hits.
5) Turbine cooling technology: GTRE must further improve its capability to simulate actual working conditions faced by turbine blades.
6) Production technology for precision cast “ready to use” turbine blades.
7) Expansible thermal coatings to minimize “heat losses” through compressor casings.
8) Technology for “milling” combustor surfaces to very close limits.
9) Fan gearing systems. The future engines will all be geared so that the fan drive turbine can run at its happiest speed. This will give us useful freedom in fan design.
10) Blisks. The Centrifugal Compressors, carved from an aluminum “cheese”, was an early form of Blisk. If HAL has the Goblin compressors process sheets these could be the starting point for our “Blisk” programme. Why not give HAL the contract?
It is tempting to suggest that the actual bench testing should be done by a different and independent group. Honda used to test all their engines at a different and independent test site. This is merely good Industrial practice and should be worth replicating here.
The flying test bed is of course an imperative. “Outsourcing” this function is simply not on. Apart from the problem of logistics there is also the subtle question of security of the engine itself when abroad. Countries adopt or build their own special aircraft for acting as a flying test bed. It is just a pipedream that if a few airworthy C119G airframes were available today one could toy with the idea of an interim test bed for the Kaveri! The old thing was configurationally ideal for a test bed. Of course an “enlarged” Canberra (ref “The Haft of the Spear” Vayu) would be another option. These would be simple aeroplanes capable of being designed, built and maintained by simple people and would need a simple budget!
With such a list of activities to do GTRE would be busy and happy. I am reminded of the fact that TsAGI “discovered” that the tailed delta configuration was the best layout for the supersonic combat role and such was the quality and reliability of its findings that both Mikoyan and Sukhoi OKBs were not too proud to rely on Ts AGI data for the MiG 21 and Su9 aircraft plan forms. Perhaps the proud traditions of high quality fundamental research continue till today; the similarity of aerodynamic layout of the Su 27 and the MiG 29 is no coincidence.

Give unto Caesar….
We must give unto HAL that the logical house for development of actual engines is HAL Engine Division. The reason is that they are organized, experienced and their supply chains are shorter. What then will they do? For my money they should engage in the development of three “core” engines using not tomorrow’s technology, not today’s technology but yesterday’s technology. By yesterday’s technology I mean technology that has been in production at HAL BLR or KPT for the last five years at least and we are all exposed to it thoroughly. The three cores will be of sizes 10kN, 25 kN and 60kN. They should all be single shaft turbojets and the stress will be on timeliness, reliability and technology security above all the other necessary aims. It is a sedulous myth that advanced features “teach”. If advanced features are a cause of such delay as enabling the proposer (s) to retire without delivering, then “advanced features” is de facto an accessory to a swindle. Maximum stress will be put on using Midhani materials. The Orpheus, the work of a Master, has a few interesting features which could be replicated. The shaft is a thin walled large diameter tube; it easily permits the insertion of the second spool’s shaft as was done in the case of the Pegasus which gave three times the thrust even in its earliest version (despite VTOL configuration!). We can expect more. The second Orpheus feature I find desirable is that it has a limited number of stages (7+1) on a short shaft and so can use just two bearings thus avoiding the third bearing and jointed shaft with its attendant proneness to whirling vibrations and ,who knows, blade shedding. In fact starting point for the 25 kN could well be the Orpheus since large quantities of partly used engines must be with ED Sulur (?) following the retirement of the Kiran! The purpose of these core engines is they will over time form a family of fan and “leaky” engines for a variety of military and civil applications ranging from 10kN to 250 kN. They will incorporate the certificated advanced technology GTRE will no doubt develop. In fact GTRE’s contribution will be essential to the success of the programme. A side effect of the development of these small “cores” is that any of the Embraer’s can be rigged up as a 3 engine flying test bed either DC10 or Lockheed Tri star style or even in place of the AEW pack and the tail arrangement changed to a twin fin arrangement-good project with a “bite” for our young engineers in collaboration with Embraer.
In a lighter vein, GTRE should quietly examine its press statements carefully before clutching in the “tongue”. Talks about Marine Kaveri are allowable but to talk of a Kaveri powered locomotive is to betray “Ivory Tower” disconnection. Not only will the engine choke in the Indian dust but also the power would be so enormous the train length would exceed the loop line (siding!) length used by the Railways. Marine and Power versions are completely different animals using different materials and operating in different ambient conditions. These derivatives will in no way help the Aircraft Engine programme and recalls Northkote Parkinsons’s story about how a big Government funded project to make a hyper rocket fuel failed miserably but said the Chief of the project at a press conference “I am afraid we have failed to have a useful rocket fuel but fortunately we find it is an excellent paint remover!” The UACV Kaveri idea is much better and on the right track.

Nil desperandum!
The Kaveri is in no way worse off than the LCA programme. What is needed, as with the LCA, is not more technology but more care and attention to detail. That will transform both projects if not into outstanding stupor mundi (wonder of the world) products as so tiresomely claimed but at least in to serviceable and affordable equipment. I take this opportunity to thank Shri Ashok Baweja, (Chairman HAL2004-2009) for suggesting during a casual conversation why I did not do a piece on the Kaveri. This piece had its genesis in his suggestion and is by way of thanks for the same.

kittigadu · Post by **kittigadu** » 21 Jun 2014 10:17

Excellent piece sir.

We need to first master the more mundane things, clearances, vibrations, hot component heat transfer, cooling circuit design, controls, etc, rather than hanker over blisks and composite fans and single crystal turbine blades. Only way this can be achieved is build compressor rigs, lots of cores and turbofans. Clearance technology for example is an art, needs good bearing design and vibration control, careful matching of rotor and stator thermal characteristics, whether in the compressor or turbine. Modern engines also have active clearance control systems for the turbine, where cold air from the fan is blown on the casings. All these are details, which give bang for the buck, and can only be achieved by extensive testing. So build multiple cores, multiple compression rigs and turbofans. Analyse all the test data, tinker with each build to perfect it. Even experienced jet engine makers build atleast 3-4 cores and about 10 turbofans in a new centerline engine program.

Blisks and composite fans and sc turbine blades and ceramic metal composite hot path components are good to have things, but they should be technology insertion programs running independently of the engine program.

China is already doing it and by what i have heard, by the end of this decade they will have a turbofan equivalent to cfm56 technology. No reason we cannot do the same, now with a supportive leader like Modiji in place.

The notion of foreign collaboration on jet engines is a non starter. The US goverment ITAR covering export regulations is on the web. One can look through the relevant sections to see how zealous it is in guarding hot section technology. GE and Snecma have been allies for about 40 years, but guard heir hot section technology from each other.

Pratyush · Post by **Pratyush** » 21 Jun 2014 10:41

This is well and good, but the real proof will rest in our ability do this on the ground. May be all that which is suggested by Prof Das. Could be used as a basis of a national GT development program. Which will target the following products.

1) Turbofan for civilian jets.
2) Turboprops, for regional transporters.
3) Military grade jet engines for the next generation aircraft's.

A start if made now, which is leveraging the learning derived from Kaveri ought to give the above, in the next 10 to 15 years.

kittigadu · Post by **kittigadu** » 21 Jun 2014 11:02

Kaveri technology can be leveraged to build gas turbines of the 30-70 mw range for power generation, units to pump gas etc. Ge has lm2500 products. Solar turbines has Titan family, all aeroderivative engines.

This will have two uses, one to gain more experience, by putting machines on the field, and can generate some returns to fund technology programs.

India's growing economy will have a good market.

Best bet is for government to transfer technology to multiple private entities.

Indranil · Post by **Indranil** » 24 Jun 2014 10:20

Okay. Here is the information about HTFE-25 from recent HAL tenders.

The Hindustan Turbo Fan Engine-25 (HTFE-25) is a twin spool, low bypass, nonafterburning, mixed flow turbofan engine in 25 KN class being designed & developed by Hindustan Aeronautics Limited (HAL).

Tender for manufacturing its gearbox is also out. I think that they are going to start testing this thing in about a year's time.

Pratyush · Post by **Pratyush** » 24 Jun 2014 12:18

IR,

For a project of this nature, what would be the ideal length of testing period.

Austin · Post by **Austin** » 24 Jun 2014 12:26

Next Generation Engine Work Points to Future U.S. Fighter Designs

brar_w · Post by **brar_w** » 24 Jun 2014 12:41

Austin wrote:Next Generation Engine Work Points to Future U.S. Fighter Designs

Key takeaways

With adaptive engine technology already set to hit the TRL-6 milestone before the end of the year, a production engine could be ready by 2021 if necessary.

and further clarity on a pretty well known fact (that the F-120 was a VC engine)

The first variable-cycle fighter engine was the early-1990s-era General Electric YF120 engine that lost to what became the Pratt & Whitney F119 that powers the Lockheed Martin F-22 Raptor. “The YF120 engine was an adaptive-cycle engine focused in a totally different area,” McCormick said. “The ADVENT and AETD are primarily focused on fuel efficiency, certainly there is additional thrust capability for the AETD as well as significant improvements in thermal management. But the YF120 engine it was an adaptive cycle engine focused very much on the supercruise requirement of the aircraft.”