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DISCUSSION: THUNDER AND TEJAS

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The Indian Air Force (IAF) finally inducted its first batch of Tejas multi-role fighters last week. Produced by Hindustan Aeronautics Limited (HAL), the Tejas was under development for about 30 years, and it is the second homegrown fighter in the IAF’s history, the first being the HF-21 Marut. The Tejas is envisaged to replace the IAF’s legacy MiG-21bis fighters.

There is not much to add except the fact that the Tejas is a potent and fully capable lightweight fighter. In fact, it even got a bit of intriguing fanfare from Dawn News (a leading Pakistani newspaper), which stated that the HAL Tejas was “considered superior to counterparts like the JF-17.”

Sadly, Dawn did not add much to qualify the statement, which has fed into a lot of noise and one-sided chiding from South Asian enthusiasts. The following is not a conventional comparison, nor is there a conclusion of which one is better. Rather, Quwa’s position that is that the two platforms are broadly comparable, but excel over one another in context, i.e. specific areas.

The Tejas is already equipped with a helmet mounted display and sight (HMD/S) system in the form of the Elbit DASH. In fact, a fair assessment would also recognize that the Tejas’ radar, the Elbit EL/M-2032, is a credible and widely appreciated system. India also spent more time on airframe development, hence the reason why the Tejas entered service at a time when the Pakistan Air Force (PAF) is fielding three full JF-17 squadrons. In exchange for its development time, the Tejas enters the field with a fully digital fly-by-wire (FBW) flight system, a heavy use of composite materials, and a credible turbofan engine (i.e. GE404).

Today, the Tejas is the better equipped fighter. However, this does not mean that is the decisively superior platform. To suggest as much would be to claim that the PAF has capped all development of the JF-17, and as such, has no plans to configure the JF-17 with subsystems that are comparable to those on current and future Tejas variants. Moreover, the better unit does not mean its rival is not comparable, which is a far more important metric considering nothing remains static over the course of time.

The JF-17’s development was driven by necessity, but it was also encumbered by Pakistan’s problems. In terms of the former, the JF-17 was designed from the onset as a platform that would mainstream beyond visual range (BVR) air-to-air capability across the backbone of the PAF fighter fleet. It has achieved that objective thanks to the SD-10/A active radar-guided BVRAAM. Unfortunately, Pakistan’s problems – i.e. the economic mess thrown up by corruption and neglect – meant the JF-17 could not enter service with the ideal set of subsystems. For example, the JF-17 does not have a HMD/S system (but it will in the future).

Astute readers (especially those familiar with the JF-17) will notice that while the Tejas – inducted in 2016 – is fully equipped, the JF-17 – inducted in 2011 – is being improved via relatively frequent iterative cycles. In other words, the PAF is gradually adding modern subsystems – such as HMD/S – whilst also enabling the fighter to accrue real-world usage and experience (which will also feed back into the iterative cycle). It is also enabling an increasing number of PAF pilots and personnel operate within a modern air warfare environment, i.e. one built upon multi-role fighters, airborne early warning and control (AEW&C) aircraft, tactical data-link, etc. Lessons in these areas will feed into further development as well.

The advantages found in Tejas today – e.g. composite materials, HMD/S and others – will make it to the JF-17 Block-III, which will also incorporate systems found on planned Tejas versions, e.g. an active electronically scanned array (AESA) radar. Infrared search and track (IRST) and improved turbofan engines (e.g. RD-33MK) are also being considered. As long as it remains in production, there will always be more advanced JF-17 blocks, each incorporating the current system of its day.

Of course, it is not all promise with the JF-17. The Thunder does possess a few advantages as well, and these – ironically perhaps – are borne from the very problems that encumbered its development. Difficulties in finding funds and overseas vendors shaped the JF-17 into an affordable and accessible modern day fighter. If Pakistan can acquire the modern platform alongside its weapons and subsystems, then chances are, so can almost any other air force using fighter aircraft. Should Pakistan succeed in making HMD/S, 5th-gen within visual range air-to-air missiles (WVRAAM), modern EW/ECM suites, and AESA radars accessible for itself, then it will have made them accessible for many other air forces as well.

The implication of this for some countries, such as Nigeria and potentially others, could be immense. Just consider Nigeria, which is one of Sub Saharan Africa’s top economies. That country does not have many foreign vendors willing to sell it sensitive equipment, and its funding constraints limit its ability to readily pursue the few existing avenues. However, with the JF-17 – which it is poised to begin inducting soon – the Nigerian Air Force (NAF) will possess a platform that is equipped with the same kind of air-to-air and air-to-surface weaponry found on any other current generation platform.

Furthermore, the NAF can ride upon the JF-17’s developmental work for the PAF, which would mean incorporating additional subsystems – such as HMD/S and a 5th-gen WVRAAM – without being beset with separate integration and expensive long-term support costs. With the exception of South Africa, Botswana and possibly other JF-17 users, no other country in Sub Saharan Africa would have a platform that has a development roadmap that is uniquely suited for countries with political and economic constraints.

Despite this, one might take a jab at the notion that the JF-17 would do best in certain environments, such as Sub Saharan Africa. Fair enough, but it does not change the reality that the JF-17 platform is meant to compete with the Tejas (and others), yet it has been developed without the luxury of free-flowing technology access or strong funding mechanisms. Yes, India is to be commended for having such capacities, but unlike a fighter plane, those traits are not easily transferrable to others. If the JF-17 is broadly comparable, but decisively more affordable and accessible, then it is a success. Whereas the Tejas would fare better in comparison to the JF-17 in the eyes of Bahrain or Jordan, the Tejas would have to compete against the likes of Saab and Korean Aerospace Industries (KAI) for those markets. The JF-17 on the other hand could present a compelling case for Nigeria, Namibia, Zambia, Azerbaijan, etc.

A lesson in the above is that it is easy to move goalposts as a means to determine ‘success’ or ‘superiority.’ In some respects, such as viability for countries clearly aligned with the U.S. or new/prospective NATO powers, the Tejas is the better option. Others, such as those looking for a modern multi-role system with minimal risk of third party regulatory hurdles (over avionics or engine), or a tighter budget, will prefer the JF-17. Simplistic comparisons do little to advance discussion and generate valuable knowledge, but nuanced case studies on specific areas could be helpful to determine the viability of one platform over another, albeit within specific cases.
http://quwa.org/2016/07/03/discussion-thunder-tejas/
 
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I'll try to keep my contrevesial statement short -
" Tejas is currently much better on paper and future prospects, but JF-17 is already flying with comparable to less capabilities. That makes JF-17 more successful as of now. If Tejas deliver what MK1 promises truly(i.e fullfils mission requirements) till 2019 and MK1A is inducted by then, Tejas will be a greater success.
 
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I'll try to keep my contrevesial statement short -
" Tejas is currently much better on paper and future prospects, but JF-17 is already flying with comparable to less capabilities. That makes JF-17 more successful as of now. If Tejas deliver what MK1 promises truly(i.e fullfils mission requirements) till 2019 and MK1A is inducted by then, Tejas will be a greater success.
Tejas hals also flown for about 3000 hours
 
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If India is looking for a comparison with a plane that was built with one thought alone. Sanctions, with little input from western technologies, then India has already lost the battle and reeks of mediocrity.
 
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"Flying" is not exactly a parameter.

I guess, head to head, Tejas scores in all parameters compared to jf17...except DSI.

Tejas hals also flown for about 3000 hours

Flying was more of a phrase, what i meant was operational experience. Most of those 3000 hours have been under controlled environment.

The program will be a success when the IAF feels confident enough to send them on actual missions ( which i feel the IAF is still not, IAF is a spoiled brat used to better options). They (MK1) are currently deployed at Bangalore and are not expected to be deployed at front lines before 2020.

OTOH JF17 has good mission experience (thanks to lack of options for PAF)(IAF would never have accepted a plane with config of JF17 blk1), anti-insurgency , point defence etc. In that sense the LCA is not flying yet.
 
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In my point of view jf17 is only behind in one area and that is HMD with 5th gen HOBS wvr missiles. These things are game changer in wvr fight. I wish if block 2 could have these addition. other wise jf17 is at equal state with tejus. Any way block 3 will include all these upgrades. But for these we will have to wait untill 2018 approx. BTW it seems jf17 overall weapon package is superior to tejus at present.
 
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I congratulate India on finally getting the Tejas inducted, better late than never. Its always better to have your own machines than imports.

I have also said that Tejas is a good looking fighter, but I still think JF17 is better ( but i could be biased :) )
 
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Hi dear @Quwa
I must confess that your article is well written and very balanced-very rare to find such piece written by pakistani authors. But I would like to add couple of things that i felt you missed in your article.Kindly bear with me,as i will be a little rigorous mathematically.
Firstly,keeping everything aside,Tejas as a platform is superior to JF-17 thanks to two factors that I will explain mathematically-
1)Wing Loading:
Wing Loading is a very important factor in a lot of aircraft performance parameters. This is nothing but mass of the aircraft divided by itz wing surface area.A lower wing loading is prefered over higher wing loading as it vastly improves a lot of things ranging from min stall velocity,turning radius,take off distance to name a few.And i will prove all my points based on hard mathematics,i will try to not use advanced mathematics so that most can follow-pre requisite: Free body diagram analysis
amar_flt_dyn.jpg

(a) Effect of wing loading on turning radius: (kindly refer to my page above right side)
A lower wing loading(represented by Wl) will have lower turning radius vis-a-vis an aircraft higher wing loading- keeping everything constant
(b)Effect of wing loading on velocity required for take off: (on the left hand side of my page above)
Velocity is directly proportional to the square root of the wing loading,hence a lower wing loading will result into lower velocity with which an aircraft can take off- or land.This is specifically evident if we compare the take off and landing runs of both LCA and thunder-former's take off run is shorter by at least 200m!
I would like to point out that I have taken Thrust to be along V and L to be perpendicular to it,where "gamma" as usual denote flight path angle .Dotted line indicated local horizontal and vertical.

2)Second factor that makes LCA superior to JF-17 is "RELAXED STATIC STABILITY" in pitch plane. This helps LCA achieve higher pitch rates as compared to JF-17. Just for the benefit of readers I want to point out that a conventional flight must be simultaneously "balanced or trimmed at a particular alpha" and "stable".However due to requirement of higher maneuverability,modern fighter jets have inbuilt instability and that i achieved by placing CG aft of aerodynamic centre. This has a lot of advantages apart from providing excellent pitch rates and i will list them here-
(a) An unstable aircraft requires lesser hinge torque to displace the control surfaces.This in turns results in smaller actuators that can do our job.
(b)An unstable aircraft requires smaller net control surface area for producing moments.This in turns translates into smaller drag produced by control surfaces.
But this makes the design of control appreciably much more complex vis-a-vis an aircraft with stable design.Because now the aircraft wont return to itz equilibrium trim state when disturbed,so control surfaces must be "actively" used to constantly keep the aircraft in trim state. Thankfully RSS is almost always used by FBW system,because it is almost impossible to fly an unstable aircraft manually- which entails- balancing or trimming at a particular angle and stability.The pilot will just go mad! Hence a computer actively controls the stabilators to constantly trim the aircraft at a particular alpha as commanded by the pilot.This is also known as "artificial stability" in american literature because although the aircraft isnt stable,it "appears" stable thanks to behind the scene action of a computer- that makes it stable to fly for pilots!

The only area where JF-17 is ahead is operational deployment in force structure of PAF.This would have enabled them to frame their combat policies and deployment including thunder.This will take couple of years in IAF with LCA.We must also accept the fact that when thunder was inducted into forces,it could hardly fire BVR,a2a refueling,carry a designator pod,EW suite etc,However the IAF didnt give the IOC unless it could do all of it. SO,I tend to think that PAF inducted a fighter that couldnt perform any of these whereas IAF chose otherwise.

I would like @Oscar and @JamD to add their points to expand this discussion- ofcourse based on rigorous mathematics.
 
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Main advantage of jf 17 is that we can upgrade it on time. Due to modular built we can integrate large variety of systems. It is difficult with tejas seeking whole of avionic package is from israel and airframe designed from french and engine from US. It is baffling that why didn't they just buy gripen.
 
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The Indian Air Force (IAF) finally inducted its first batch of Tejas multi-role fighters last week. Produced by Hindustan Aeronautics Limited (HAL), the Tejas was under development for about 30 years, and it is the second homegrown fighter in the IAF’s history, the first being the HF-21 Marut. The Tejas is envisaged to replace the IAF’s legacy MiG-21bis fighters.

There is not much to add except the fact that the Tejas is a potent and fully capable lightweight fighter. In fact, it even got a bit of intriguing fanfare from Dawn News (a leading Pakistani newspaper), which stated that the HAL Tejas was “considered superior to counterparts like the JF-17.”

Sadly, Dawn did not add much to qualify the statement, which has fed into a lot of noise and one-sided chiding from South Asian enthusiasts. The following is not a conventional comparison, nor is there a conclusion of which one is better. Rather, Quwa’s position that is that the two platforms are broadly comparable, but excel over one another in context, i.e. specific areas.

The Tejas is already equipped with a helmet mounted display and sight (HMD/S) system in the form of the Elbit DASH. In fact, a fair assessment would also recognize that the Tejas’ radar, the Elbit EL/M-2032, is a credible and widely appreciated system. India also spent more time on airframe development, hence the reason why the Tejas entered service at a time when the Pakistan Air Force (PAF) is fielding three full JF-17 squadrons. In exchange for its development time, the Tejas enters the field with a fully digital fly-by-wire (FBW) flight system, a heavy use of composite materials, and a credible turbofan engine (i.e. GE404).

Today, the Tejas is the better equipped fighter. However, this does not mean that is the decisively superior platform. To suggest as much would be to claim that the PAF has capped all development of the JF-17, and as such, has no plans to configure the JF-17 with subsystems that are comparable to those on current and future Tejas variants. Moreover, the better unit does not mean its rival is not comparable, which is a far more important metric considering nothing remains static over the course of time.

The JF-17’s development was driven by necessity, but it was also encumbered by Pakistan’s problems. In terms of the former, the JF-17 was designed from the onset as a platform that would mainstream beyond visual range (BVR) air-to-air capability across the backbone of the PAF fighter fleet. It has achieved that objective thanks to the SD-10/A active radar-guided BVRAAM. Unfortunately, Pakistan’s problems – i.e. the economic mess thrown up by corruption and neglect – meant the JF-17 could not enter service with the ideal set of subsystems. For example, the JF-17 does not have a HMD/S system (but it will in the future).

Astute readers (especially those familiar with the JF-17) will notice that while the Tejas – inducted in 2016 – is fully equipped, the JF-17 – inducted in 2011 – is being improved via relatively frequent iterative cycles. In other words, the PAF is gradually adding modern subsystems – such as HMD/S – whilst also enabling the fighter to accrue real-world usage and experience (which will also feed back into the iterative cycle). It is also enabling an increasing number of PAF pilots and personnel operate within a modern air warfare environment, i.e. one built upon multi-role fighters, airborne early warning and control (AEW&C) aircraft, tactical data-link, etc. Lessons in these areas will feed into further development as well.

The advantages found in Tejas today – e.g. composite materials, HMD/S and others – will make it to the JF-17 Block-III, which will also incorporate systems found on planned Tejas versions, e.g. an active electronically scanned array (AESA) radar. Infrared search and track (IRST) and improved turbofan engines (e.g. RD-33MK) are also being considered. As long as it remains in production, there will always be more advanced JF-17 blocks, each incorporating the current system of its day.

Of course, it is not all promise with the JF-17. The Thunder does possess a few advantages as well, and these – ironically perhaps – are borne from the very problems that encumbered its development. Difficulties in finding funds and overseas vendors shaped the JF-17 into an affordable and accessible modern day fighter. If Pakistan can acquire the modern platform alongside its weapons and subsystems, then chances are, so can almost any other air force using fighter aircraft. Should Pakistan succeed in making HMD/S, 5th-gen within visual range air-to-air missiles (WVRAAM), modern EW/ECM suites, and AESA radars accessible for itself, then it will have made them accessible for many other air forces as well.

The implication of this for some countries, such as Nigeria and potentially others, could be immense. Just consider Nigeria, which is one of Sub Saharan Africa’s top economies. That country does not have many foreign vendors willing to sell it sensitive equipment, and its funding constraints limit its ability to readily pursue the few existing avenues. However, with the JF-17 – which it is poised to begin inducting soon – the Nigerian Air Force (NAF) will possess a platform that is equipped with the same kind of air-to-air and air-to-surface weaponry found on any other current generation platform.

Furthermore, the NAF can ride upon the JF-17’s developmental work for the PAF, which would mean incorporating additional subsystems – such as HMD/S and a 5th-gen WVRAAM – without being beset with separate integration and expensive long-term support costs. With the exception of South Africa, Botswana and possibly other JF-17 users, no other country in Sub Saharan Africa would have a platform that has a development roadmap that is uniquely suited for countries with political and economic constraints.

Despite this, one might take a jab at the notion that the JF-17 would do best in certain environments, such as Sub Saharan Africa. Fair enough, but it does not change the reality that the JF-17 platform is meant to compete with the Tejas (and others), yet it has been developed without the luxury of free-flowing technology access or strong funding mechanisms. Yes, India is to be commended for having such capacities, but unlike a fighter plane, those traits are not easily transferrable to others. If the JF-17 is broadly comparable, but decisively more affordable and accessible, then it is a success. Whereas the Tejas would fare better in comparison to the JF-17 in the eyes of Bahrain or Jordan, the Tejas would have to compete against the likes of Saab and Korean Aerospace Industries (KAI) for those markets. The JF-17 on the other hand could present a compelling case for Nigeria, Namibia, Zambia, Azerbaijan, etc.

A lesson in the above is that it is easy to move goalposts as a means to determine ‘success’ or ‘superiority.’ In some respects, such as viability for countries clearly aligned with the U.S. or new/prospective NATO powers, the Tejas is the better option. Others, such as those looking for a modern multi-role system with minimal risk of third party regulatory hurdles (over avionics or engine), or a tighter budget, will prefer the JF-17. Simplistic comparisons do little to advance discussion and generate valuable knowledge, but nuanced case studies on specific areas could be helpful to determine the viability of one platform over another, albeit within specific cases.
http://quwa.org/2016/07/03/discussion-thunder-tejas/
A good well written informative and unbiased comparison of JF-17 and Tejas. I enjoyed reading it. Thanks.
 
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I would like @Oscar and @JamD to add their points to expand this discussion- ofcourse based on rigorous mathematics.

For everyone else.. Gentleman, for note; please do not be intimated by such "rigorous mathematics" .

Ill skip the screenshots of equations that technically mean nothing because they show no results and since I am no longer into engineering and prefer making good money in business, I have no time for "rigorous mathematics" nor are these even required since we are not trying to drown people in mathematics and instead want to ensure that everyone can understand without such "rigorous" and frankly unneeded mathematics for this topic. @JamD

Ill leave that to well established people like actual pilots with degrees in aerospace. Please understand that regardless of posted equations; the basic laws of aerodynamics that have been established over 50 years cannot change. People have been making Delta winged fighters for over 60 years now, and if their low wing loading offered such massive advantage.. everyone would have made pure Delta fighters today. The most you need to know about low wing loading is highlighted in blue. @Bilal Khan 777 .

From ACdre Kaiser Tufail's blog:

Delta Wing Aerodynamics

Sweep angle of the wing leading edge helps delay drag rise with increase in speed. In a swept wing, the velocity of the airflow normal to the leading edge is reduced by a factor of the cosine of the sweep angle, with a corresponding delay in drag rise. High sweep angles are, however, associated with the problem of wing-tip stalling which results due to the airflow drifting span-wise across the wing, causing the tips to stall before the rest of the wing. The result is usually a violent pitch up followed by a spin. Wing fences and notches are a stop-gap solution as they generate a vortex over the wing which virtually arrests the span-wise airflow.

On a swept wing, the torsional stresses during manoeuvring flight are enormous and indeed, dangerous at high Mach numbers. Greater structural strength can only be obtained by paying a greater weight penalty.

There is one way in which sharp sweep angles can be used without a lot of problems: delta wing. The shape is optimum for high speed flight. The extremely broad chord(average distance between leading and trailing edges) means that a low thickness-to-chord ratio needed for high speed flight can be achieved. The structure can be made rigid, has sufficient volume for fuel and, there are hardly any practical limits to the angle of sweep.

The low aspect ratio (square of the wingspan to wing area) of the delta wing gives excellent supersonic performance by presenting a smaller frontal area to the airflow. At lower speeds, however, the poor lift-drag ratio of the low aspect delta planform demands higher angles of incidence to generate the same amount of lift compared to a conventional wing. This causes greater induced drag resulting in speed bleed-off during manoeuvring flight; it also increases take-off and landing distances. It may be worth noting that the Mirage III/5/50 as well as the double-delta winged Draken, held the dubious distinction of having the lowest (read worst) aspect ratio of any fighter to date ie, 1.94 and 1.8 respectively, but this record has now been surpassed, surprisingly, by the very modern Tejas with a ratio of 1.75!

By its very shape, a delta wing has a large area which tends to give a relatively low wing loading (aircraft weight per unit area of lifting surface ie, the wings). This helps offset its poor sustained turn performance and enables it to turn tightly at low speeds – often below its normal landing speed – especially in descending manoeuvres in which it can trade height for energy.

Woes of Tailless Deltas

To date, only a few tailless delta fighters have been produced besides the Mirage III/5/50. These include the F-102 Delta Dagger, F-106 Delta Dart, J-35 Draken, J-37 Viggen, Mirage 2000 and Tejas.

In a tailless delta, lift augmentation devices like trailing edge flaps cannot be installed for want of space (though in the Viggen, these are cleverly placed on the large fixed canards). Also, upgoing elevons diminish wing lift which needs to be compensated by higher take-off and landing speeds, worsening short-field performance. Many a pilot who ended up in the arrester barrier has ruefully wished for a longer runway when confronted with a take-off emergency.

Two modern tailless delta fighters, the Mirage 2000 and Tejas feature relaxed static stability. A benefit of this design is that it confers an unstable nose-up moment which reduces the pitch-up required for take-off or during manoeuvres; the harm done to wing lift by upgoing elevons is, thus, minimised to a considerable extent. Leading edge flaps/slats on these fighters also add to the total lift when they automatically activate at slow speed, thus allowing lower take-off and landing speeds.


@amardeep mishra
Please do not try to take the path of the religious scholar by posting a lot of scripture in an attempt to drown out opposition.

Please show me a particular example of a fighter which employs a delta platform and is superior in a turning fighter to a conventional jet?
Moreover, just to glaze over the balance to the Tejas... you have oversimplified the concept into low wing loading and high wing loading when infact BOTH the Tejas and JF-17 are compound wings which varying wing loading at different sections not to mention that you have NOT provided ANY news article or otherwise to show that the JF-17 is unstable in pitch or not.

If low wing loading was such a miracle as you claim, every aircraft from the Su-30 to the F-22 would have chosen this path. The fact remains that only the Euro canards have chosen the delta and that too with the Canard to offset the associated woes of delta's along with offering a greater pitch movement.

P.S When taking pictures of your scribbles in notebooks, be kind enough to put at least some semblance of labels or explaining what conclusion( if any) you are trying to make as per your scribbles. It has been 6 years since I worked designing guidance systems and 8 since I graduated.. and there are many here for whom your notebook is nothing more than drawings.

When pitching an idea, please make it clear what you are trying to prove and how you have done so.
 
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Main advantage of jf 17 is that we can upgrade it on time. Due to modular built we can integrate large variety of systems. It is difficult with tejas seeking whole of avionic package is from israel and airframe designed from french and engine from US. It is baffling that why didn't they just buy gripen.

And you got nothing in debate
LCA LRU'S are Setup in India

As GE engine it comes. From plant in
Pune

Let make avionics integration aside because it's clear you have no knowledge about subject in hand.
 
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