Kaveri & aero-engine discussion

[chetak]

http://www.aircraftinformation.info/art_gnat.htm

Primary armament on the Gnat consisted of two 30-mm Aden Mk 4 revolver-type cannon mounted in the outer portions of the air intakes with 115 rounds per gun. On most other aircraft this would have caused the engines to flameout from gas ingestion, but this never happened to the Gnat as the muzzles were carefully designed to deflect gases out to the sides of the intakes. A row of four circular holes on the outside of each barrel and triangular extensions of the intake in front of each muzzle kept gas from being sucked into the engine.

it simply means that the designers had found a clever way to keep the turbulent and disturbed airflow away from the engine intakes.

Such a simple and perhaps elegant solution is rarely possible these days.

It also means that the right and left guns were perhaps not interchangeable.

[shiv]

Is it anybody's argument that the missile exhaust/gunfire gasses are not highly turbulent and if ingested by the engine, it is this turbulent and highly disturbed airflow that is going to affect the engine much more than the content of the missile exhaust smoke/gunfire gas per se??
.

Don't know if there is any argument but every single reference to flame out after missile firing that I have seen speaks of plume ingestion and not turbulence or "ingestion" of turbulence. Will try and locate MiG 21 history in this regard. Not tonight though.

[shiv]

it simply means that the designers had found a clever way to keep the turbulent and disturbed airflow away from the engine intakes.

Such a simple and perhaps elegant solution is rarely possible these days.

It also means that the right and left guns were perhaps not interchangeable.

Would prefer to see a reference other than your post

[JayS]

rain will turn to steam ( not much different from smoke) quite early in the compressor stages itself.

Hmm. Food for thought. Ever wondered why Mil thrust of Mil engine is called dry thrust and AB thrust, wet thrust..?

No more on this from me in this thread. May be engine thread.

[chetak]

Smoke and rainwater are completely different issues wrt jet engines. Gun gases in particular are not just "smoke" but particulate matter that is at a high temperature and uncombusted propellant - like squirting explosive into the intake.

Plain smoke can be bad enough - all aircraft must avoid volcanic plumes that can be cool but 30000 feet high. Rain cloud is safe. Chalk and cheese

volcanic plume is not just smoke. It has a very very high particulate matter content. Google for a british airways(?) flight in which all four engines shut down in flight with the crew completely clueless and also unaware that they had flown through a volcanic eruption zone at night.

All frantic attempts to relight had failed and they here losing height. Stiff brit upper lips were not all that stiff on the flight deck that night. As they nosed down lower into much clearer air, they managed to relight their engines one by one until all four came back on line.

Heavy particulate matter content will do that to you.

Jet engines have a very high aspiration rate. The ratio of the mass flow through the engine as compared to the amount of gun gas injection they may have aspirated momentarily is small to negligible. Uncombusted propellant particles in the engine will just burn and not explode.

A sivakasi deepavalli cracker explodes because of the way it is tightly packaged. If you deconstruct it, empty out the "masala" and pile it up on the floor and set it alight, it just burns, it will no more explode.

You can set C4 on fire because it also just burns. A detonator is needed to make it show it's true colors and explosive capabilities.

Aircraft guns are fired for a few seconds and the gun gasses will start to disperse immediately thereafter because of the airflow so not all of it is aspirated into the engine intakes. What is problematic however is the disruption in the airflow. GTs are usually rugged beasts and don't mind a bit of rain or smoke but what they don't tolerate well is turbulent air hitting their compressor faces. Air Intake design is critical to ensure that the airflow to the compressor is as smooth as they can make it.

[chetak]

Hmm. Food for thought. Ever wondered why Mil thrust of Mil engine is called dry thrust and AB thrust, wet thrust..?

No more on this from me in this thread. May be engine thread.

Have you heard of water injection during take off?? There is actually lots to wonder about.

[chetak]

Is it anybody's argument that the missile exhaust/gunfire gasses are not highly turbulent and if ingested by the engine, it is this turbulent and highly disturbed airflow that is going to affect the engine much more than the content of the missile exhaust smoke/gunfire gas per se??
.

Don't know if there is any argument but every single reference to flame out after missile firing that I have seen speaks of plume ingestion and not turbulence or "ingestion" of turbulence. Will try and locate MiG 21 history in this regard. Not tonight though.

What's the difference between plume ingestion and "ingestion" of turbulence??

It is the plume that is causing the turbulence and it causes more turbulence as it blooms or grows bigger. Missiles often drop away before they ignite, no??

The plume exits the gun barrel at speeds comparable to the bullet. More often than not, the bullet is supersonic with all the attendant effects of shock waves et al. This causes the local turbulence or disruption of airflow in the region around the intake.

If the plume is ingested, it is the attendant turbulence that is also automatically and inescapably ingested.

Plume and turbulence are inseparable in your example.

[Rishi_Tri]

Is the river flowing on its own? Where can it be heard flowing?

[Rakesh]

FANTASTIC!!!!!

prasannasimha-ji, would you happen to know if this is the Snecma-GTRE venture? Can you provide any more info other for us jingos? I am waiting on the Rolls Royce-GTRE venture as well.

Kaveri is our LAST hurdle. We master this (even if RR and Snecma still have the golden key i.e. hot section) and India will have arrived. The Jet Engine Technology Joint Working Group (JETJWG) with the US will become an afterthought. Sad, but what to do.

On the bright side, *certified* Kaveri88 (via Snecma) and *certified* Kaveri200 (via Rolls Royce) will pave way for Tejas Mk1A and Tejas Mk2 without a doubt. AMCA will follow suit.

Fly Baby, Just PLEASE FLY!!!! And Touch the Sky with Glory! The prayers & best wishes of every Indian is with you. Jai Hind!!!

तस्मादज्ञानसम्भूतं हृत्स्थं ज्ञानासिनात्मन: |
छित्त्वैनं संशयं योगमातिष्ठोत्तिष्ठ भारत

asmād ajñāna-sambhūtaṁ hṛit-sthaṁ jñānāsinātmanaḥ
chhittvainaṁ sanśhayaṁ yogam ātiṣhṭhottiṣhṭha bhārata

Therefore, with the sword of knowledge, cut asunder the doubts
that have arisen in your heart. O scion of Bharat, establish yourself
in karm yog. Arise, stand up, and take action!

[shiv]

Plume and turbulence are inseparable in your example.

Particulate matter sir, exists in smoke and missile plumes which can cause enough damage to prevent relighting
http://aviationweek.com/awin/compressor ... elicopters

[Vivek K]

Great news, can the paanwalla bribe the chaiwalla to get some more news!

[prasannasimha]

Unfortunately silence of the Lambs

[dinesh_kimar]

^ river in South India flowing better.

- More thrust obtained from engine ?

- I wish Sjha or Siddique sahib come out with some news / white paper at end of year on such small things as thrust/ weight / reliability / future plans.

[tsarkar]

Is it anybody's argument that the missile exhaust/gunfire gasses are not highly turbulent and if ingested by the engine, it is this turbulent and highly disturbed airflow that is going to affect the engine much more than the content of the missile exhaust smoke/gunfire gas per se??
.

Don't know if there is any argument but every single reference to flame out after missile firing that I have seen speaks of plume ingestion and not turbulence or "ingestion" of turbulence. Will try and locate MiG 21 history in this regard. Not tonight though.

This is one of the reasons why air launched missile incorporate smokeless propellants


Aircraft under development are extensively tested using CFD as well as operational testing for smoke ingestion.

Gun cartridges generate a lot of smoke, and A-10 is prone engine flameouts when cannon was fired. Solution was engine ingitors automatically turning on when gun is fired.

Also check out the windshield wipers.

http://www.thedrive.com/the-war-zone/13 ... nd-a-curse

If I remember the Nachiketa CoI finding from memory, the cause of ingestion was slow speed and high altitude (with less air density). If air density or airspeed was higher, this would not have created a problem. Otherwise MiG-27 ingest a lot of gases when firing guns.

https://www.flickr.com/photos/torqueavi ... 954060903/

[JayS]

Don't know if there is any argument but every single reference to flame out after missile firing that I have seen speaks of plume ingestion and not turbulence or "ingestion" of turbulence. Will try and locate MiG 21 history in this regard. Not tonight though.

This is one of the reasons why air launched missile incorporate smokeless propellants


Aircraft under development are extensively tested using CFD as well as operational testing for smoke ingestion.

Gun cartridges generate a lot of smoke, and A-10 is prone engine flameouts when cannon was fired. Solution was engine ingitors automatically turning on when gun is fired.

Also check out the windshield wipers.

http://www.thedrive.com/the-war-zone/13 ... nd-a-curse

If I remember the Nachiketa CoI finding from memory, the cause of ingestion was slow speed and high altitude (with less air density). If air density or airspeed was higher, this would not have created a problem. Otherwise MiG-27 ingest a lot of gases when firing guns.

https://www.flickr.com/photos/torqueavi ... 954060903/

For Missile exhaust ingestion, smokeless or smoke shouldnt matter. Its the hot gases which makes the engine stall. And as such the exhaust of missile would hardly have any particulate matter in it.

Here is a paper from ADA folks trying to understand missile exhaust, which would be used to study its impact when ingestied by engine, impact on aircraft surface etc etc.

https://www.google.co.in/url?sa=t&sourc ... YoYbHRzm4n

[nam]

Once Kaveri completes all the test, who is going to produce the engines? HAL?

[Indranil]

The smokeless propellant is used to hide the trail of the missile. Makes it more difficult to acquire and track.

[Karan M]

Also metal particulates interfere with datalink. Issue faced by trishul and hence its propellant was changed late into the program.

[ramana]

Also metal particulates interfere with datalink. Issue faced by trishul and hence its propellant was changed late into the program.

So how do they get that ISP without mass flow? I thought instead is Al which ionizes in the hot exhaust use a different metal?

[ramana]

Yes.
HAL Jet engine division

[shiv]

Doesn't Al burn brightly and leave a residue of oxide? That said - is there any propellant other than H2 + O2 that burns to produce 100% gases and no solid particulate matter? There is no such propellant that I could find on searching the net.

There is no such thing as a propellant that leaves NO solid residue. Any number of references on the Net show that "smokeless" propellants leave "very little" residue. Very little is not zero. All guns that use smokeless propellant need less frequent cleaning of residue - but that cleaning is required nevertheless

The point I want to make is that apart from hot gases, particulate matter can choke up jet engines. Volcanic ash at 40,000 feet - which is cool still causes engines to fail.

I had posted a link earlier that points out that the propensity for an engine to flame out on gas ingestion may vary. A brand new or recently serviced engine may continue running while ingesting some gas, but an older engine or one that is due for servicing may flame out. Missile and gun exhausts are bad for engines and hardly innocuous.

About particulate matter
https://play.google.com/store/books/det ... fAC&rdot=1

The primary cause of engine thrust loss in the volcanic ash ingestion events in Indonesia in 1982 and at Redoubt was the accumulation of melted and resolidified ash on the stage 1 turbine nozzle guide vanes. These deposits reduced the effective flow area causing an increase in the compressor operating line and compressor surge. Compressor airfoil erosion contributed to the loss of surge margin. Turbofan engines tested operating at high combustor discharge temperatures, and exposed to high concentrations of sand/dust with low melting point, exhibit symptoms and conditions similar to those of engines exposed to volcanic ash. Operation at low-thrust level while in an ash cloud significantly reduces the rate of engine performance degradation.

[NRao]

Does this count?

Solid-propellant rocket

Minimum-signature (smokeless) propellants Edit

One of the most active areas of solid propellant research is the development of high-energy, minimum-signature propellant using C6H6N6(NO2)6 CL-20 nitroamine (China Lake compound #20), which has 14% higher energy per mass and 20% higher energy density than HMX. The new propellant has been successfully developed and tested in tactical rocket motors. The propellant is non-polluting: acid-free, solid particulates-free, and lead-free. It is also smokeless and has only a faint shock diamond pattern that is visible in the otherwise transparent exhaust. Without the bright flame and dense smoke trail produced by the burning of aluminized propellants, these smokeless propellants all but eliminate the risk of giving away the positions from which the missiles are fired. The new CL-20 propellant is shock-insensitive (hazard class 1.3) as opposed to current HMX smokeless propellants which are highly detonable (hazard class 1.1). CL-20 is considered a major breakthrough in solid rocket propellant technology but has yet to see widespread use because costs remain high.[22]

[shiv]

Does this count?

This is all OT, but since you ask probably not

That claim leads to a dead link (reference no 22)
The language sounds like a promotional/advert type message about research work

From the little I know of chemistry and physics. 100% smokeless is achievable only when water is the end product but even C02 or other gases will do. Anything that burns produces some products - and 100% burning should produce 100 % gases alone for "no particulate matter". To my knowledge this has never been achieved. Smokeless is always "very little residue". "Smokeless" is a bogey - a marketing term. The actual chemistry is what matters. That is what I need to see.

A word search leads to a desi paper which says of the compound you asked about having a "faint smoke trail". Not smokeless
http://euroasiapub.org/wp-content/uploa ... 4530-1.pdf

But let me get to the point about gun testing and the Tejas. Gun plumes are dangerous to aircraft engines not because of "turbulence onlee" or "hot gases onlee" or "particulate matter onlee". It is a combination of one or more of all three that pose a danger. That is why it is preferable to minimize - or preferably avoid, all gun gas ingestion.

The Tejas has a gun port below and behind the right intake and is apparently well away but a live video of gun firing trials shows how huge the plume is. In case a Tejas is banking to the right and descending - following a target below and to the right - there could be a possibility of gas ingestion. This of course is my speculation based on visual size of plume and site of gun port. I am sure the designers know this, but they will surely test for it.
https://www.youtube.com/watch?v=4KbZDuBKcEs

[JayS]

X posting from LCA thread

Doesn't Al burn brightly and leave a residue of oxide? That said - is there any propellant other than H2 + O2 that burns to produce 100% gases and no solid particulate matter? There is no such propellant that I could find on searching the net.

There is no such thing as a propellant that leaves NO solid residue. Any number of references on the Net show that "smokeless" propellants leave "very little" residue. Very little is not zero. All guns that use smokeless propellant need less frequent cleaning of residue - but that cleaning is required nevertheless

The point I want to make is that apart from hot gases, particulate matter can choke up jet engines. Volcanic ash at 40,000 feet - which is cool still causes engines to fail.

I had posted a link earlier that points out that the propensity for an engine to flame out on gas ingestion may vary. A brand new or recently serviced engine may continue running while ingesting some gas, but an older engine or one that is due for servicing may flame out. Missile and gun exhausts are bad for engines and hardly innocuous.

About particulate matter
https://play.google.com/store/books/det ... fAC&rdot=1

The primary cause of engine thrust loss in the volcanic ash ingestion events in Indonesia in 1982 and at Redoubt was the accumulation of melted and resolidified ash on the stage 1 turbine nozzle guide vanes. These deposits reduced the effective flow area causing an increase in the compressor operating line and compressor surge. Compressor airfoil erosion contributed to the loss of surge margin. Turbofan engines tested operating at high combustor discharge temperatures, and exposed to high concentrations of sand/dust with low melting point, exhibit symptoms and conditions similar to those of engines exposed to volcanic ash. Operation at low-thrust level while in an ash cloud significantly reduces the rate of engine performance degradation.

Nothing is particulate free 100% by that standard Shiv. Not even normal Air. Engines can certainly stand some amount of particulate matter. They cannot be supersensitive because in daily life they have to withstand air which is not "100%" particulate matter free. Also when we talk about particles things like size, composition, velocity, mechanical properties matter. OEMs do test engines with significant amount of sand of various type thrown in it. Because they have to operate in sandy environment of areas like middile east. Here is a video of Sand Ingestion test. GE has Sand ingestion test facility. I am sure other OEMs too have it.

https://youtu.be/IMIkk-ZqUzM

But of coarse the threshold is to a certain limit and Volcanic erruption presents extreme situation. So engines cannot withstand that situation always. But the particulate density of even a smoky missile exhaust or that of Gun exhaust should be well below the threshold. Similar argument can be made with respect to turbulence (in fact turbulence would the last thing I would think of). Due to low probability of any noticeable damage happening due to solid particles and turbulence, it can be safely ignored. Impact of hot gas and vibration or even shock waves due to bullets or present in shock diamond have far more significant. So those are crucial factors and are considered generally. Others can be safely neglected.

If you see any generic compressor map you will realise that engines operate very close to the surge line. Its relatively easy to throw it off balance and make it surge. But as I said earlier, modern engines are much more resilient now, especially with FADEC in place and Military engines especially have good stall margin now a days. So sensitivity of engines to hot gas ingestion is far less now compared to engines from 60s or 70s.

[shiv]

Nothing is particulate free 100% by that standard Shiv. Not even normal Air. Engines can certainly stand some amount of particulate matter. They cannot be supersensitive because in daily life they have to withstand air which is not "100%" particulate matter free. Also when we talk about particles things like size, composition, velocity, mechanical properties matter. OEMs do test engines with significant amount of sand of various type thrown in it. Because they have to operate in sandy environment of areas like middile east. Here is a video of Sand Ingestion test. GE has Sand ingestion test facility. I am sure other OEMs too have it.

Remember the news item from a couple of months ago - I think it was Indigo airlines
http://www.thehindu.com/business/Indust ... 781399.ece

Pratt & Whitney has informed the Directorate General of Civil Aviation that Indian climatic conditions are primarily responsible for snags encountered in its engines fitted in Airbus A320 new engine option planes.

The American aircraft engine manufacturer has said that weather conditions unique to India such as high humidity, heat and saltiness due to the ocean were causing problems to A320neo plane engines, sources said.

Yes the environment and "normal air" are also a problem - compared with crystal clear temperate latitude air. Other manufacturers too - includingthe Russians have cited special problems in India

This in fact leads to a greater propensity for flame-out in engines that may have run a full cycle and may be just due for overhaul. The balance may be tipped by a "little gas ingestion"

So the fact that engines must run reliably in rough conditions does not mean that it is in any way "OK" to allow "a little" gas ingestion from guns or missile plumes. As far as possible they have to be avoided. I think these factors become important in strange ways. We do know that the GSh 23 itself has finite life and must be discarded after X rounds (2500?) . The same way - it is possible that if "a little" gas ingestion is allowed safely the engine itself will have to undergo inspections after a specified number of gun firings to make sure that limits are not crossed. I think you know this and I know this. But on BRF with people moaning and complaining about delays I think it is necessary to point out the complexities of testing and safety.

If an engine require overhaul more frequently because of gun firing - the manufacturer is going to blame HAL and HAL may blame the air force. This sort of rubbish has happened time and time again and then we will have BRF geniuses saying "Air Force must learn from America"

[prasannasimha]

The Kaveri will be tested around 2020-2021 on the Tejas as per some Chaiwalla reports.

As far as what ails just think about this - there are only 7 scientists b as new recruits and over 70 scientists G. New recruitment has verily stalled and only the old timers are slogging with no new recruits getting approved. This just goes to show the constraints whereas even the MRE food section of DRDO has over 50 scientists working. That is the reality. Getting alloys made to specification is easier said than done.Guess what the cahs injection to the project is ? Take any other jet engine maker and see the funding . The GTRE heads have to sit in Delhi begging for funds from some Babu and even this is cut and delayed and yet everyone wants a world class engine.
Incidentally the Kaveri at present meets 95% of its design mandate and the push for the last 5% is where all this is going on.

Those in Bangalore can go and see Adhamya Chethana on National College grounds

[prasannasimha]

By test beds I meant flying test beds

[chetak]

The Kaveri will be tested around 2020-2021 on the Tejas as per some Chaiwalla reports.

As far as what ails just think about this - there are only 7 scientists b as new recruits and over 70 scientists G. New recruitment has verily stalled and only the old timers are slogging with no new recruits getting approved. This just goes to show the constraints whereas even the MRE food section of DRDO has over 50 scientists working. That is the reality. Getting alloys made to specification is easier said than done.Guess what the cahs injection to the project is ? Take any other jet engine maker and see the funding . The GTRE heads have to sit in Delhi begging for funds from some Babu and even this is cut and delayed and yet everyone wants a world class engine.
Incidentally the Kaveri at present meets 95% of its design mandate and the push for the last 5% is where all this is going on.

Those in Bangalore can go and see Adhamya Chethana on National College grounds

many "recruits" are seduced away by foreign companies after a couple of years in the DRDP or PSUs. So much for dedicated staff. Everybody wants to get ahead and why not??.

How the hell do you wind up with 70 Sc Gs in one unit?? How many more are "outstanding" scientists?? This is not just one but almost every DRDO lab.

so, long story short, no engine, full promotion, no tension, full pension, right??

Its the story of every lab and PSU in India.

I am sure that there is a lesson in there deep inside, somewhere, for all of us.

If results were not a big problem, funding would never be the issue.

some alloys you can make, some you can buy, some you cannot make and some you cannot buy. More importantly, don't use pusher type propellers where ordinary everyday type tractor propellers would have worked better, ESPECIALLY when you have an very steep learning curve to deal with.

Big boys take all this into consideration before they start a tough journey.

In the end, its always no tension, full pension.

To truly succeed, one needs relentless, dedicated drive and also hunger and fear gnawing away at the vitals, sometimes one more than the other.

There are the new beginnings of such unheard of characteristics in some aviation PSUs, nowhere else.

These guys bulldoze their way through problems by innovative methods,selfless team work and co opting certification agencies very very early in the design cycle and the end result is foremost in their sights. Its slowly catching on.

Pity, we neither had the amreki hire and fire nor the ruski gulags.

Just like One MODI and and a whole lot of faceless, useless bjp, with the aam aadmi asking vociferously why no second rung leadership is available.

so after decades of effort, it does not matter that 5-6 % is left to complete because the tough part is yet to come and some chaiwallah says wait another 3-4 years and then after that GOK how long before it can actually be put into a fuselage or even hung on a wing??

some lab took more than 24 years to develop a basic UAV and an absolutely stunned foreign audience at some conference just could not believe their ears at the time line disclosed by a famous lab director whose farewell took a full three days of breakfast to dinner celebrations to see him off.

I wonder, at times, if hire and fire or a gulag at the end of the dark tunnel would not have been a better way for us to go.

[NRao]

The Kaveri will be tested around 2020-2021 on the Tejas as per some Chaiwalla reports.

The French, I thought I read, were planning on a 2019 or so trisl. So, I'd this a pure GTRE effort, without any help from outside?

we neither had the amreki hire and fire

The US has multiple efforts, at various levels, going in non compete parallel. AFRL, as an example, funds promising kids at Masters level and has jobs + funds waiting once they graduate. DARPA has s thread of their own. NASA. All in addition to the well known culprits like GE and P&W. Most of the research efforts fail. Thus the risk is huge.

[chetak]

Nothing is particulate free 100% by that standard Shiv. Not even normal Air. Engines can certainly stand some amount of particulate matter. They cannot be supersensitive because in daily life they have to withstand air which is not "100%" particulate matter free. Also when we talk about particles things like size, composition, velocity, mechanical properties matter. OEMs do test engines with significant amount of sand of various type thrown in it. Because they have to operate in sandy environment of areas like middile east. Here is a video of Sand Ingestion test. GE has Sand ingestion test facility. I am sure other OEMs too have it.

Remember the news item from a couple of months ago - I think it was Indigo airlines
http://www.thehindu.com/business/Indust ... 781399.ece

Pratt & Whitney has informed the Directorate General of Civil Aviation that Indian climatic conditions are primarily responsible for snags encountered in its engines fitted in Airbus A320 new engine option planes.

The American aircraft engine manufacturer has said that weather conditions unique to India such as high humidity, heat and saltiness due to the ocean were causing problems to A320neo plane engines, sources said.

Yes the environment and "normal air" are also a problem - compared with crystal clear temperate latitude air. Other manufacturers too - includingthe Russians have cited special problems in India

This in fact leads to a greater propensity for flame-out in engines that may have run a full cycle and may be just due for overhaul. The balance may be tipped by a "little gas ingestion"

So the fact that engines must run reliably in rough conditions does not mean that it is in any way "OK" to allow "a little" gas ingestion from guns or missile plumes. As far as possible they have to be avoided. I think these factors become important in strange ways. We do know that the GSh 23 itself has finite life and must be discarded after X rounds (2500?) . The same way - it is possible that if "a little" gas ingestion is allowed safely the engine itself will have to undergo inspections after a specified number of gun firings to make sure that limits are not crossed. I think you know this and I know this. But on BRF with people moaning and complaining about delays I think it is necessary to point out the complexities of testing and safety.

If an engine require overhaul more frequently because of gun firing - the manufacturer is going to blame HAL and HAL may blame the air force. This sort of rubbish has happened time and time again and then we will have BRF geniuses saying "Air Force must learn from America"

never ever heard of an engine that requires overhaul more frequently because of gun firing but I have heard of airframes that add extra time to the airframe hours whenever an armament related sortie is flown.

Incidently, P&W is lying through their "unable to solve the problem" teeth.

high humidity, heat and saltiness due to the ocean were causing problems

is not a unique Indian problem and it never ever was.

This is truly high quality amreki BS

How come other manufacturers haven't ever reported such unique conditions which would have resulted in a lot of engine testing in such "unique" Indian conditions??

[shiv]

How come other manufacturers haven't ever reported such unique conditions which would have resulted in a lot of engine testing in such "unique" Indian conditions??

They have - but this is about the air force. I have heard (literally) that wear and tear of IAF engines is higher because of smoke and dust. But I am unable to provide a source - will try and locate one.

[shiv]

OK here is one ref - but from WW2
https://books.google.co.in/books?id=Uxj ... nt&f=false

"..abrasive dust ground down the engines..

Another - but generic - not specific to India. But this is what low flying aircraft of IAF face day in and day out in the North Indian summer
http://blog.covingtonaircraft.com/2011/ ... -overhaul/

Life for an engine operating primarily in dry, dusty conditions, near salt water, in varied climates or any combination of these is subject to extra wear.

What this means is that the TBO (Time Between Overhaul) for engines operating in these conditions will have to change and the spares that need to be kept in reserve may be different.

[shiv]

never ever heard of an engine that requires overhaul more frequently because of gun firing but I have heard of airframes that add extra time to the airframe hours whenever an armament related sortie is flown.

This is because gun gases are prevented from entering engines by rigorous testing. Air Marshal Rajkumar in his chapter in the MiG 21 history book says that K-13 missile firing was always done only after turning on the engine relight switch.

[JayS]

The Kaveri will be tested around 2020-2021 on the Tejas as per some Chaiwalla reports.

The French, I thought I read, were planning on a 2019 or so trisl.

you have set yourself for disappointment by taking all those reports of Kaveri flying in 2 yrs, French help, GE JV in India at face value. Ain't happening that soon. Ground reality hasn't changed significantly.

The other day I was looking for something in old LCA posts. I stumbled upon a post by Shiv from 2011 about Kaveri, after AI-11. If one don't see the dates the same post could have easily been passed of as post after AI-17. It mentioned French help for Kaveri and Kaveri to fly on LCA in 2-3 yrs.

[JayS]

Nothing is particulate free 100% by that standard Shiv. Not even normal Air. Engines can certainly stand some amount of particulate matter. They cannot be supersensitive because in daily life they have to withstand air which is not "100%" particulate matter free. Also when we talk about particles things like size, composition, velocity, mechanical properties matter. OEMs do test engines with significant amount of sand of various type thrown in it. Because they have to operate in sandy environment of areas like middile east. Here is a video of Sand Ingestion test. GE has Sand ingestion test facility. I am sure other OEMs too have it.

Remember the news item from a couple of months ago - I think it was Indigo airlines
http://www.thehindu.com/business/Indust ... 781399.ece

Pratt & Whitney has informed the Directorate General of Civil Aviation that Indian climatic conditions are primarily responsible for snags encountered in its engines fitted in Airbus A320 new engine option planes.

The American aircraft engine manufacturer has said that weather conditions unique to India such as high humidity, heat and saltiness due to the ocean were causing problems to A320neo plane engines, sources said.

Yes the environment and "normal air" are also a problem - compared with crystal clear temperate latitude air. Other manufacturers too - includingthe Russians have cited special problems in India

This in fact leads to a greater propensity for flame-out in engines that may have run a full cycle and may be just due for overhaul. The balance may be tipped by a "little gas ingestion"

So the fact that engines must run reliably in rough conditions does not mean that it is in any way "OK" to allow "a little" gas ingestion from guns or missile plumes. As far as possible they have to be avoided. I think these factors become important in strange ways. We do know that the GSh 23 itself has finite life and must be discarded after X rounds (2500?) . The same way - it is possible that if "a little" gas ingestion is allowed safely the engine itself will have to undergo inspections after a specified number of gun firings to make sure that limits are not crossed. I think you know this and I know this. But on BRF with people moaning and complaining about delays I think it is necessary to point out the complexities of testing and safety.

If an engine require overhaul more frequently because of gun firing - the manufacturer is going to blame HAL and HAL may blame the air force. This sort of rubbish has happened time and time again and then we will have BRF geniuses saying "Air Force must learn from America"

1. About this whether thing quoted by P&W. I have already called it out as BS even as it appeared in Media. Not because India doesn't offers some challenges in Operating conditions. It does. But because P&W should have considered it a priori, because neither those conditions have arisen recently out of the blue nor Jet engines have started flying in India in recent time only. To add to that I have also posted reports showing same/similar problems happening on another engine of same GTF family flying in Switzerland. So don't take whatever sorry excuses P&W is giving for their design flaws too seriously. But let me also add that its very usual to have such problems in any new engine (A320 NEO engine, on top, is not merely a new engine, or even merely first of this family, its the first of this GTF architecture in HBPR civil engine domain). Its usually takes a couple of years to iron out all such issues. Whats is disappointing to see is P&W not owning up the issues and blaming on some factors which it should have considered (and perhaps have considered for all we know but they still screwed up the design somewhat).

2. Impact of gas ingestion has been severe in old engines in many cases. The certification would always consider the most conservative cases. But over the decades the engine tech have improved by leaps and bounds and modern engines are not so much affected by gun gas ingestion or missile exhaust ingestion. But the certification requirements, design philosophies and SOPs remain, because those change only very slowly and lag considerably wrt the technical advancement. Thats how Aerospace industry is - ultra-conservative (which may sound counter-intuitive, especially for a sector which traditionally has been most cutting edge, technologically speaking). I do not think that such instances of gas ingestion have any significant impact on modern engines and their MRO plans. As such Military engines have much shorter inspection intervals as compared to Civil counterparts. Any possible impact may be easily detected in usual scheduled maintenance.

[shiv]

1. About this whether thing quoted by P&W. I have already called it out as BS even as it appeared in Media. Not because India doesn't offers some challenges in Operating conditions. It does. But because P&W should have considered it a priori, because neither those conditions have arisen recently out of the blue nor Jet engines have started flying in India in recent time only.

The problem I have with dismissing such an admission is that P&W is too big a company to bluff and get away without being chewed out by the vicious competition. There are others who will call their bluff. In fact along with the huge Indigo + P&W order there were a few smaller orders by other airlines of the same A 320 with CFM 56 I think. So P&W have made a candid admission of their fault in not anticipating a particular component failure caused by atmospheric conditions. A company of that size cannot simply bluff about a problem with its biggest single customer - Indigo

modern engines are not so much affected by gun gas ingestion or missile exhaust ingestion.

The statement that "modern engines are not so much affected" can only be a retrospective one that can come after much testing. I doubt if a single engine manufacturer would endorse the placement of a gun port where the engine can ingest gases based on the generalization that modern engines are much more tolerant to such ingestion. Note that in the quote above you have accused P&W of bluffing. Don't you think that any failure in an engine that happens to have ingested some gun/missile gas in a live fire exercise will simply be blamed by the manufacturer on gas ingestion to escape blame? Or do you believe they would say "OK - our engine failed - but it cannot be gas ingestion because our engines are certified tolerant"

No. No matter how "tolerant" engines are they cannot willy nilly be exposed to gas ingestion and everything possible must be done to avoid that knowing that some ingestion would be unavoidable in some flight regimes.

[Philip]

I think that the failure of Kaveri to arrive has been more of a management problem than technological.I know an industrialist who developed a blisk for it but has not recd. a single order for years and can't sell his invention becos of some paltry funding he recd.from the govt.

Technology is all around us globally.Whoever was in charge should've been given the freedom to identify a collaborator and the govt. to accept the scientific advice and released necessary funds.More than just Kaveri is the massive failure of various govt. in not setting up a dedicated aero-eengine establishment to develop a range of engines for all types of aircraft and helos.Where have our principal scientific advisors to the PM/Govt. been doing on this score?We're in no better shape engine wise since the HF -24 days and when looking at China's indigenous achievements must hang our heads in shame.

[chola]

Again, the Kaveri is a singular moon shot at a world class medium turbofan when our industry had never productionized a turbojet (or anything lower on the propulsion technology totem pole.) Our first indigenous turbojets being the GTX37/GTX-35 experimentals created during the Kaveri project.

Compared to the chini industry that progressed with the WP-6 turbojet for the J-6 to WP-7 for J-7 to WS-9 turbofan for JH-7 to WS-10 for J-11.

The WS-10 was their tipping point and now they have an explosion of medium and heavy turbofan projects in both low and high bypass forms — WS-11, WS-13, WS-15, WS-18, WS-19, WS-20, WS-118, SF-A, CJ-1000 — across multiple organizations in a wide and deep industry with names like Shenyang Liming, Xian, Guizhou and ACAE.

We have only GTRE. This is not an industry like Cheen where subcomponents can be drawn. It is a singular organization with a singular jet engine project. It had done as well as can be expected under the circumstances.

[Abhibhushan]

Re heat and dust of India and Aero engines.

An annecdotal piece of info

In 1947 - 48 we had purchased the Hawkwers Tempest II as our main ground attack aircraft. The aircraft was powerful and effective for its role. It was powered by a radial engine that used a conceptually ‘new’ rotating sleeve valve. These engines worked well in Europe. Unfortunately, the sleeve valve technology could not survive in the Indian environment. Fine dust in the air of northern India started to jam these valves often. We had to admit defeat and junk the fleet of Tempest II by 1953/54.

[JayS]

1. About this whether thing quoted by P&W. I have already called it out as BS even as it appeared in Media. Not because India doesn't offers some challenges in Operating conditions. It does. But because P&W should have considered it a priori, because neither those conditions have arisen recently out of the blue nor Jet engines have started flying in India in recent time only.

The problem I have with dismissing such an admission is that P&W is too big a company to bluff and get away without being chewed out by the vicious competition. There are others who will call their bluff. In fact along with the huge Indigo + P&W order there were a few smaller orders by other airlines of the same A 320 with CFM 56 I think. So P&W have made a candid admission of their fault in not anticipating a particular component failure caused by atmospheric conditions. A company of that size cannot simply bluff about a problem with its biggest single customer - Indigo

Well, A320 NEO has more than more than 5700 orders and half of them are with PW GTF engines. Rest are LEAP 1A. CFM56 is older ones. Some airlines still buy original A320 config too. IndiGo order is 420 or so out of that.

I didnt feel the connotation of their statement was " candid addmission of their fault". It was more like blaming Indian conditions for failure. As I said, neither Indian conditions are new nor this is the first time jet engines are flying in India. What possibly can be the reason that PW failed to account for Indian conditions when there one of the biggest orders are from India...? And why would exact same failure would be seen in Europe if it was due to India specific conditions..?

As for other OEMs, they would probably do the same under similar conditions. The competitor engine Leap has its own issues. If they try to publically say anything against PW, PW can also give them in kind in next turn. Everyone has weak points. Second thing is its not that easy for a company to publically go against another in such matter. They will need a lot of technical data to back their statement. How will they get that when its proprietary to PW..? PW wont share anything obviously. There is no public investigation report also. (I recently got a taste of how unaware one OEM could be about some seemingly obvious thing from other OEM. Since we work with all three OEMs we know better).

I dont have problem with them saying the failures are due to India specific conditions but they have to accept "we failed to account for those conditions while designing". It cannot be "our design was alright. Its the Indian conditions which made it fail." Mission sheet for aircraft has many tens of missions of various range, payload and atmospheric conditions occuring world over. Some of them are specific to some countries. For example typically one set of mission would be there for Qatar for Hot day, which represents one of the worst conditions. Similarly very cold day mission would be there for some northen airport. There are thousands of operating points in such sheet typically. So if PW engine was expected to operate in india in large numbers, why India specific missions were not considered..? I would ask that question to PW.

Also saying something in media for saving face is not same as bluffing with customer. Even Indigo management would understand such tactics. They are not making much noise because PW is trying to compensate them with additional spare engines and perhaps even monetary compensations. Some airlines already have cancelled orders and convered to GE engine or delayed deliveries until PW can fix issues.

modern engines are not so much affected by gun gas ingestion or missile exhaust ingestion.

The statement that "modern engines are not so much affected" can only be a retrospective one that can come after much testing. I doubt if a single engine manufacturer would endorse the placement of a gun port where the engine can ingest gases based on the generalization that modern engines are much more tolerant to such ingestion. Note that in the quote above you have accused P&W of bluffing. Don't you think that any failure in an engine that happens to have ingested some gun/missile gas in a live fire exercise will simply be blamed by the manufacturer on gas ingestion to escape blame? Or do you believe they would say "OK - our engine failed - but it cannot be gas ingestion because our engines are certified tolerant"

No. No matter how "tolerant" engines are they cannot willy nilly be exposed to gas ingestion and everything possible must be done to avoid that knowing that some ingestion would be unavoidable in some flight regimes.

Guess you misunderstood me. When I say modern engine are far less sensitive, I dont mean we should put them under those operating conditions. I am just saying. An engine like F404 dont have to worry about it so much as some old engine like that might have had to. Designer would still obviously go as much conservative as possible if there is no significant cost associated with that particular design compromise and eliminate one headache. Less things to worry about. Dont fix whats not broken.