Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 31 Oct 2019 16:54

nam wrote:
If we concentrate on stealth, EW, terrain flying and ability to fly at 80-90K for BVR games, we would have done pretty well.


What is 80-90K?

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nam » 31 Oct 2019 17:32

brar_w wrote:
nam wrote:
If we concentrate on stealth, EW, terrain flying and ability to fly at 80-90K for BVR games, we would have done pretty well.


What is 80-90K?


Should be 80K feet. I believe F22 are capable of operating at 100K ft, so a AMCA capable of 80K ft would be a good achievement.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nam » 31 Oct 2019 17:44

JayS wrote:Sorry, but how exactly F35 (or any other aircraft for that matter) having or not having super cruise capability even relevant for AMCA..?? What matters is, whether it can manage to fulfil IAF SQRs without Super cruise or not. ADA says it does, more or less. So that should be the end of it.

F35 is designed to replace the teen fighters with equivalent combat load/range capability if not more (roughly speaking). It fulfills that part well enough, even without super cruise. That's exactly why the designer compromised on it.


At this time, USAF is the only airforce, which has experience operating a fighter with super cruise. Based on it's experience, USAF did not think, missing such a feature will effect operational capability of F35, which will form majority of it's force structure.

I am just hoping that the objective to get 4-5 sqd with supercruise is not a case of "better is the enemy of good enough", while we limit AMCA Mk1 at 2 sd.

We have seen this with LCA MK1, where the production cannot be accelerated because the order is not big enough.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 31 Oct 2019 17:49

nam wrote:
brar_w wrote:
What is 80-90K?


Should be 80K feet. I believe F22 are capable of operating at 100K ft, so a AMCA capable of 80K ft would be a good achievement.


And that does not sound absurd? :-?
Last edited by brar_w on 31 Oct 2019 17:55, edited 1 time in total.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby JayS » 31 Oct 2019 17:51

nam wrote:
brar_w wrote:
What is 80-90K?


Should be 80K feet. I believe F22 are capable of operating at 100K ft, so a AMCA capable of 80K ft would be a good achievement.


Where are you getting these figures..? That's way to high altitude. F-22's service ceiling is 65000ft as per wiki. And AMCA will not be able to achieve such altitude.

Brar can correct me but I don't think it was a design requirement for F22 for it to be able to fly at such altitude. I think its a by-product of its powerplant capability.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nam » 31 Oct 2019 18:30

brar_w wrote:
nam wrote:
Should be 80K feet. I believe F22 are capable of operating at 100K ft, so a AMCA capable of 80K ft would be a good achievement.


And that does not sound absurd? :-?


I read about 100k ft claim somewhere. I could be wrong. Mig31 which is heavier than F22 & 150KN wet thrust, is claimed at 90K ceiling.

I would guess, F22 with similar powered engine & being lighter might have 10k more? Granted there are other variable to achieve this and F22 might not be optimized to achieve such a height.

May be I am wrong.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby ArjunPandit » 31 Oct 2019 18:48

Pardon my ignorance, but 100 k ft will be 30 km and the density of atmosphere should be very low. Would the engine get enough air? Apart from sr 71 and mig 25/31 jet planes haven't flown above 85 k ft

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby JayS » 01 Nov 2019 00:21

Indranil wrote:I think it matters. Also, I believe it is a strawman to say internal volume means compromised aerodynamics. The internal volume of Su-35/PAKFA/F-22 is more than that of a F-35, is there a compromise in aerodynamics? Yes stealth shaping comes with compromise, but that is not as big a detriment. In other words, F-22/F-35/PAKFA/J-20 would not become significantly less draggy if they smoothened out their contours.

May, I ask the questions:

1. If the decision is made to make F-22 multirole today, can the airframe take it? Is it a matter of avionics upgrades, testing and qualification? If the decision is taken and the F-22 is made multirole today, will it be at par to the 4th gen multirole aircrafts? I know the answer to the last question for sure. No. the F-22 will be a far superior in A2A than any 4th gen aircraft in A2A. And it can do the strike roles pretty well too.
2. 2035 onwards, Most top air forces will operate 5th generation aircraft. What will an air-to-air fight look like between two 5th gen aircrafts in 1v1, or 2v2, or 4v4? Will it be BVR and done? Will aerodynamics matter?
3. If LM engineers were given a singular mandate. Design a shore-based conventional TO/landing multirole aircraft, would the result be a F-35A?


Regarding impact on aerodynamics - Higher internal volume - due to IWB and higher internal volume requirement due to S-duct and so on - basically affects the wave drag. Think of the aircraft as an equivalent sear-hawk body. Higher the inner volume for given length, thicker is the SH body and higher is the wave drag.

A paragraph from this paper - Inventing the F-35 Joint Strike Fighter
The development of
stealth and long range air-to-air missiles had changed the nature of air combat, so that the emphasis was on
achieving “first look, first shot” and reducing the need to dogfight at close range. For these reasons, the two AIM 9
missiles were removed and the aircraft was designed to carry two 2000 lb bombs in the internal weapons bays, in
addition to the 2 AIM 120 missiles. This increased the aircraft’s frontal area and wave drag. The Air Force variant
was derived, as before, by removing the lift fan and thrust vectoring nozzles and substituting a fuel tank and
conventional cruise nozzle

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Indranil » 01 Nov 2019 00:29

Brar sahab,

I am not quoting your entire reply to my previous comments. It is quite elaborate and I urge readers to read it (at the end of the last page). I will use the crux of your replies.

I think you evaded the main the thrust of my questions. The question is “Does the stealth vs. aerodynamics compromise mandate that a fifth generation fighter be sub (or at best at) par to fourth generation aircraft in aerodynamics? I strongly believe that the answer is no. People try to justify otherwise citing the F-35 which is wrong in my opinion. Your rebuttal to making F-22 a truly multirole aircraft is also based along the same lines. If F-22 was being designed today, its bays would have been suitably designed to carry the bombs and missiles required. That would not have affected its shape (and hence its aerodynamic prowess) significantly.

Now, let me argue that if designers were given the sole task of designing a CTOL (or even a CATOBAR) multirole aircraft, the design would go differently from the F35. Aircrafts are designed around engines. And the F35 program was designed to use the same engine for all three variants, including the STOVL variant. This (almost) mandated a single engine fighter. The drive train for the lift fan is a design marvel (and a maintenance headache) in itself. If that had to accommodate power from two engines, it would have been a nightmare. But, there is only so much power that one can derive out a single low bypass engine, and the 119 is up there! So that limits the thrust available. But, then on the other variants, you also have to live with this power and yet provide the extraordinary hangtimes on internal fuel!

Now, let us consider the case where the designers can design more freely, i.e. without the single engine requirement. If every other 5th generation aircraft design is a sign, then the optimum choice is for two engines. Because it allows you to provide the thrust required to carry all that internal fuel and ammunitions. Then you can go for an aircraft with higher empty weight (i.e. length). That has huge ripple effects on the design freedoms. The most conservative of 5th generation designs are looking for 220 kNs of thrust. And almost all of them look like the F-22. There is a reason!

If history is any indicator, countermeasures have rarely been behind by more than a decade. I expect the same for countermeasures for long range A2A missiles of today. I don’t believe in the “my long range missiles will do the job for me, and I will never have to see my enemy” philosophy. From what I gather from my chat circles, most people don’t agree either.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Indranil » 01 Nov 2019 00:33

JayS wrote:Regarding impact on aerodynamics - Higher internal volume - due to IWB and higher internal volume - basically affects the wave drag. Think of the aircraft as an equivalent sear-hawk body. Higher the inner volume for given length, thicker is the SH body and higher is the wave drag.

I think I understand that :| I think I have answered your question in the above comment.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby JayS » 01 Nov 2019 02:38

The argument that 5th generation requirements enforce suboptimal aerodynamics is a 4th Gen vs 5th Gen aircraft comparison. Question is if for identical requirement, if one designs a 4th gen aircraft and one 5th Gen aircraft, for same combat configurations which one will have lesser drag.? Do you think they will be equally good..??

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 01 Nov 2019 02:41

Yes and a great way to do that (for purely comparative purposes) is to use DI levels for known 4th gen. types.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Indranil » 01 Nov 2019 03:14

JayS wrote:The argument that 5th generation requirements enforce suboptimal aerodynamics is a 4th Gen vs 5th Gen aircraft comparison. Question is if for identical requirement, if one designs a 4th gen aircraft and one 5th Gen aircraft, for same combat configurations which one will have lesser drag.? Do you think they will be equally good..??

Define the mission and I can give a better answer. For example, if it is long air patrols, a fifth gen fighter with more internal fuel and internal A2A missiles is likely to have lower drag. Similarly, if the strike distance is high and the strike package is small, the fifth generation fighter has lower drag.

You will accuse me of moving the goalposts to the sweet spot of the 5th generation fighters. Okay, so let us put the goalposts at the sweet spot of the 4th generation aircraft. Let's choose missions that 4th generation fighters can complete on internal fuel only. For these roles, the fifth generation aircraft has more drag than the 4th gen counterpart because it pays the price of higher internal volume and hence empty weight. But that doesn't mean that the 5th generation fighter has to compromise on maueverability or too speed. 5th generation aircraft have higher TWR, a luxury that F35 did not have, thanks to its one engine design. PAKFA has more internal volume in both its fuel tanks and bomb bays. It did not compromise on maneuverability neither on top speed (albeit it has moving intakes). AFAIK, the SQR for AMCA does not allow any compromise for these either.

It is about design goals and constraints. F35 was designed with the constraints of a single engine and goal to complement the F22s. That's not the constraints and goals of other countries.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 01 Nov 2019 03:29

Is there any word on the size and dimensions of the strike weapons the AMCA would be able to carry? The AMCA and others have similar constraints on their designs. The PAKFA and F-22 are large and heavy aircraft and not in the medium weight class. The biggest constraint on the KF-X and the AMCA will be propulsion especially in the early 2030's. Weight, size and IWB flexibility will have to be traded for things like performance and supercruise.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Indranil » 01 Nov 2019 03:34

Nothing official yet. But you can guess from the AMCA design iteration over the last decade. It has progressively grown larger and heavier.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nachiket » 01 Nov 2019 03:43

brar_w wrote:The biggest constraint on the KF-X and the AMCA will be propulsion especially in the early 2030's. Weight, size and IWB flexibility will have to be traded for things like performance and supercruise.

It also depends on whether the projected empty weight and MTOW specs can be met. The KF-X has relatively ambitious specs of only ~12 tonnes empty and 25 tonnes MTOW with 2 F-414's. That is not a bad T:W ratio if they can achieve it. In fact it would be much better than that of the F-35A. Of course the F-35 will score much better on internal volume and lower fuel consumption thanks to the single engine setup.

The AMCA's projected specs at least from wiki are more conservative with 17 tonnes empty and 31 tonnes MTOW (wiki figures). It will need the higher thrust F-414 derivative if one materializes to achieve the expected performance parameters. The wiki figures might be utter crap though.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 01 Nov 2019 03:47

nachiket wrote:It also depends on whether the projected empty weight and MTOW specs can be met. The KF-X has relatively ambitious specs of only ~12 tonnes empty and 25 tonnes MTOW with 2 F-414's. That is not a bad T:W ratio if they can achieve it. In fact it would be much better than that of the F-35A. Of course the F-35 will score much better on internal volume and lower fuel consumption thanks to the single engine setup.


F-35A does not have a supercruise requirement and the key metric is thrust minus drag (dry thrust). KFX with those F-414's will be limited in its speed. I think once it matures, you will see that reflected in its performance envelope.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nachiket » 01 Nov 2019 04:08

brar_w wrote:F-35A does not have a supercruise requirement and the key metric is thrust minus drag (dry thrust). KFX with those F-414's will be limited in its speed. I think once it matures, you will see that reflected in its performance envelope.

Well a combined dry thrust of ~120kN might be enough for supercruise if they can achieve their weight targets and how much drag reduction they can accomplish without compromising stealth.

For the AMCA, it will not be enough, which they have acknowledged, hence the need for the 110kN engine specified. What is left unsaid is the Dry thrust value envisaged for this engine. Wet thrust value of 110kN by itself is meaningless as far as supercruise is concerned.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby VinodTK » 01 Nov 2019 04:11

Indranil wrote:Nothing official yet. But you can guess from the AMCA design iteration over the last decade. It has progressively grown larger and heavier.


The powers be should get away from genaric sizing (LCA, MCA) naming approach. Develop and build an aircraft that can cover Yunnan, Guangxi, and Guangdong provinces in China (flying out of the eastern air basis). Such reach and capability has a huge psycological advantage.

If PLAAF ever touches any of the key centers in India; IAF should be able to respond. Plus such a capability will put the PLA rocket force into a permanent standby mode.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Indranil » 01 Nov 2019 04:18

brar_w wrote:
F-35A does not have a supercruise requirement and the key metric is thrust minus drag (dry thrust). KFX with those F-414's will be limited in its speed. I think once it matures, you will see that reflected in its performance envelope.

That's a very valid statement. That F35A's performance numbers are real. The KFX's and AMCA's capabilities are on the drawing board. We don't know what will happen when the rubber hits the tarmac. But at least for both of them super cruise is a design goal. For F35A, it was not.

Who knows what will be compromised on the AMCA/KFX. Will supercruise and maneuverability be compromised for internal volume or vice versa. In India's case, the land mass is not that huge and the air fights will be at our doorsteps or just beyond. Design goals and tradeoffs may be different from those of the F35.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nachiket » 01 Nov 2019 04:35

Indranil wrote:Who knows what will be compromised on the AMCA/KFX. Will supercruise and maneuverability be compromised for internal volume or vice versa. In India's case, the land mass is not that huge and the air fights will be at our doorsteps or just beyond. Design goals and tradeoffs may be different from those of the F35.

Whatever the compromises made (and there will surely be a few) important thing is for successive IAF leaderships to stick with them and understand that there can be no do-overs even if the threat perceptions start to change later. Have to avoid an Arjun like situation where design choices made intentionally to fulfill certain requirements were later on termed as drawbacks when the requirements changed.

Secondly, design compromises cannot be on the basis of requirements alone unfortunately but on a realistic assessment of current technological capability and what can be feasibly achieved in the very near future. Especially in terms of engine performance. And I'm not even talking about our own ability to develop a suitable engine, but that of GE. How much more dry thrust can they promise to coax out of the 414 even in the EPE variant? It cannot be a lot. Best to assume that is the absolute max available to us (without any expectation of an indigenous engine project that can somehow improve on that). If supercruise is difficult to achieve with that, might as well scrap that requirement altogether.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Kartik » 01 Nov 2019 04:38

Indranil wrote:I sometimes wonder if India, South Korea and Japan join hands to develop their fifth generation aircrafts. All three countries are aligned and all three have mediocre experience in designing aircrafts and engines. All three don't have the funds to do it alone, but joining forces may result in a great product. The timelines of these programs are also aligned.

I don't think anybody can argue that the F414 EE is the back up for all three aircrafts. I don't think there is any alternative today.


South Korea and Japan in one program is next to impossible. They don't like each other much.

India and South Korea could've been partners on a 5th gen program. The KF-X and AMCA are both going to be somewhat similar jets, similarly sized, possibly similar ballpark weights, with 2 F-414s (at least for the first AMCA batch). However, back when South Korea was scouting for partners, India was wedded to the PAK-FA program and had invested $230 million on its FGFA Preliminary Design Phase.

IMO, the Indian establishment also didn't seem to have that much faith back then in India leading a 5th gen program (given that the LCA hadn't yet entered service and built up a solid reputation). Things seemed to have changed now, with leadership putting faith in the industry's ability to deliver. Back then it was thought that HAL/ADA would be junior partners and Russia would basically just "teach" them what to do and we'd customize an existing model, the way the MKI program did on the Su-30. We would then assemble them here, with Russia having some workshare and the rest being local. Now that the Su-57 is clearly out of the picture, the focus has shifted over to the AMCA and there seems to be some urgency building up.

Till even a couple of years ago, South Korea was clearly the more junior partner of the two in terms of real experience, given that the T-50/FA-50 were mostly LM designed but South Korean built. LCA established India's aerospace industry and their knowledge base. But since then the South Koreans have moved much more swiftly, using Israeli experience to work on an AESA radar, whereas we built our own in the meantime. They've involved more South Korean private industries as well, much more so than on the T-50/FA-50.

But in more ways than one, there were real hurdles to any partnership. The timelines for induction of the jets are different. India had the Tejas Mk1A and then the Tejas Mk2/MWF program in the mould of the Gripen E to work on immediately, for replacing over 200 fighters. Whereas South Korea never really developed the FA-50 to anywhere near the Tejas Mk1 or Mk1A level. Forget a F-414 engined FA-50 Mk2 or whatever, they're seeing even modest requirements (like a targeting pod or IFR) being dictated by export nations. Clearly the ROKAF doesn't see much value in going down the FA-50 path.

ROKAF has already started inducting F-35A and isn't thinking of a up-engined FA-50 variant to replace their F-5 and F-4s. Instead they've decided to put all their resources into the KF-X and use F-35 to fill in whatever gaps there are. IAF hasn't yet inducted any 5th gen jets and the feeling is that 4th gen jets will be sufficient for this decade, given our threat scenario.

Another problem with partnerships is negotiating workshare agreements and capability roadmaps that need to be funded. Eurofighter is a prime example of that.

I feel that now that the Su-57 derived FGFA is out of the picture, a public-private partnership should see the AMCA through. The private sector is far ahead today than it was when the LCA was being developed. There was and still is, nothing that the South Koreans could bring in that we didn't already have or couldn't develop on our own..IMO.

Japan is an all together different story. Their F-3 requirements are still not clear and there is AFAIK, not yet a commitment to develop.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Cybaru » 01 Nov 2019 04:43

Good points Kartik. It is time to get back to doing this alone and believing in ourselves.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Kartik » 01 Nov 2019 04:49

Indranil wrote:
brar_w wrote:
F-35A does not have a supercruise requirement and the key metric is thrust minus drag (dry thrust). KFX with those F-414's will be limited in its speed. I think once it matures, you will see that reflected in its performance envelope.

That's a very valid statement. That F35A's performance numbers are real. The KFX's and AMCA's capabilities are on the drawing board. We don't know what will happen when the rubber hits the tarmac. But at least for both of them super cruise is a design goal. For F35A, it was not.

Who knows what will be compromised on the AMCA/KFX. Will supercruise and maneuverability be compromised for internal volume or vice versa. In India's case, the land mass is not that huge and the air fights will be at our doorsteps or just beyond. Design goals and tradeoffs may be different from those of the F35.


As it stands today, the KF-X is sort of getting the worst of both 4th and 5th gens. There is no IWB planned as yet for the variant that will fly in the mid 2020s. So all weapons and drop tanks will be carried externally or semi-recessed; although the need for drop tanks will be minimal given that the space for the IWB will likely be used to house fuel tanks instead. But for missions where a 4th gen fighter may not have needed drop tanks, the KF-X will handicapped to always have a higher cross sectional area and higher wave drag.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 01 Nov 2019 04:51

Worth looking into the historical performance of those nations, their A&D industry, defense bureaucracy and armed forces expectations while working on joint programs and international cooperation etc. That is often the most important factor. How many Joint programs does a South Korea or Japan truly support at any given time? Depending upon how they are structured and how good the stakeholders are individually and together, JV's can be a drag on the overall program performance. One such example is the ESSM naval interceptor. The program (block II) was delayed 6 years because it took longer to get every partner to sign off on the capability and cost/work share agreements.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Indranil » 01 Nov 2019 05:02

There are some concerns that FGFA has been put aside today to make capital funds available for the new MRCA rather than the AMCA. Their are signals to the contrary, but you and me can be mere spectators in this question worth hundreds of billions of dollars.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Kartik » 01 Nov 2019 05:06

anyway the boat has sailed and South Korea is well into the development program now. There is so much of a mismatch between the IAF's anticipated AMCA delivery schedule (early 2030s) and the ROKAF's KF-X delivery schedule (2026) that it cannot be bridged now even if by some miracle all of the massively convoluted and bureaucratic negotiations on work-share, design authority and payments can be completed in a few months.

KF-X design is frozen and metal cutting started at the start of this year. AMCA design is for all intents and purposes sort of frozen, but not yet to the point where metal cutting can start and there is a distinct difference in the committed funding between these 2 programs. What is there to gain now by fusing these 2 programs into 1? IMO, nothing but a reduction in unit price due to larger production run.

Anyway, the world can make do with another 5th gen design too. Good for people like me who just love fighter jets and would love to see India's aerospace industry designing one of its own. The capability exists, the sustained funding is what is required. As it is, the F-35 has basically become the one and only Western 5th gen design. F-22 is for no one but the USA.
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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Kartik » 01 Nov 2019 05:07

Indranil wrote:There are some concerns that FGFA has been put aside today to make capital funds available for the new MRCA rather than the AMCA. Their are signals to the contrary, but you and me can be mere spectators in this question worth hundreds of billions of dollars.


Of course- that is what I said when I wrote that the IAF seems happy with 4th or 4.5 gen designs for the 2020s. ROKAF is looking at 5th though the KF-X is only quasi 5th without internal carriage of weapons.

the FGFA funds will be used to actually acquire MMRCA 2.0 jets. AMCA is for the 2030s.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Cain Marko » 01 Nov 2019 09:14

Kartik wrote:
Cain Marko wrote:Where does the naval fighter fit in? IIRC the Navy was looking at a twin engined Desi design.


Indranil mentioned on the Navy LCA thread that the N-LCA Mk2 project is dead.

That was expected. Wonder what the twin engined design will look like....AMCA N?

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby chola » 01 Nov 2019 14:22

Kartik wrote:anyway the boat has sailed and South Korea is well into the development program now. There is so much of a mismatch between the IAF's anticipated AMCA delivery schedule (early 2030s) and the ROKAF's KF-X delivery schedule (2026) that it cannot be bridged now even if by some miracle all of the massively convoluted and bureaucratic negotiations on work-share, design authority and payments can be completed in a few months.

KF-X design is frozen and metal cutting started at the start of this year. AMCA design is for all intents and purposes sort of frozen, but not yet to the point where metal cutting can start and there is a distinct difference in the committed funding between these 2 programs. What is there to gain now by fusing these 2 programs into 1? IMO, nothing but a reduction in unit price due to larger production run.

Anyway, the world can make do with another 5th gen design too. Good for people like me who just love fighter jets and would love to see India's aerospace industry designing one of its own. The capability exists, the sustained funding is what is required. As it is, the F-35 has basically become the one and only Western 5th gen design. F-22 is for no one but the USA.


The 4.5/quasi 5th gen KFX is a valid path for an industry that only had a trainer (T/A-50) under its belt. The Koreans have a good measure of their ability. They design something that they know they can be successful with. They didn't tie the plane to an engine.

When we started on the LCA in the 1990s we tied it to us developing a cutting edge modern turbofan that even the Russians had a hard time with. De-coupling from the Kaveri, allowed the Tejas to develop more quickly.

The F-35 is not just a plane but a massive geo-political endeavor where the entire West plus Japan poured money and resource into one 5th gen aircraft to be shared but all the advanced democracies. That is why it is the one 5th gen aircraft of the West in this generation. It was deliberate.

The AMCA is more ambitious than the KFX but I do worry about the engine to support those exoectations. In a way, it could be a retread of the earlier problem we had with the LCA/Kaveri. The AMCA scientist's quote that "there is no engine" for the specs worked out worries me. We are again going for bleeding edge conditions on an engine we can't build yet.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby chola » 01 Nov 2019 14:29

Cain Marko wrote:
Kartik wrote:
Indranil mentioned on the Navy LCA thread that the N-LCA Mk2 project is dead.

That was expected. Wonder what the twin engined design will look like....AMCA N?


Hard to see what else it could be? Unless the navy wants something heavyweight (unlikely), it makes no sense to go clean-slate for a naval fighter with the same medium engines as the AMCA.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nam » 01 Nov 2019 15:46

Indranil wrote:There are some concerns that FGFA has been put aside today to make capital funds available for the new MRCA rather than the AMCA. Their are signals to the contrary, but you and me can be mere spectators in this question worth hundreds of billions of dollars.


This was also the case, when 114 Rafale was the flavor, until the anti-climax in 2016. Virtually everything was blocked to get Rafale in, with HAL also ready to "produce" at 3 times the cost.

India AWACS, AMCA design & FSED were also blocked to make way for Rafale.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Ganesh_S » 01 Nov 2019 23:21

Indranil wrote:
brar_w wrote:
F-35A does not have a supercruise requirement and the key metric is thrust minus drag (dry thrust). KFX with those F-414's will be limited in its speed. I think once it matures, you will see that reflected in its performance envelope.

That's a very valid statement. That F35A's performance numbers are real. The KFX's and AMCA's capabilities are on the drawing board. We don't know what will happen when the rubber hits the tarmac. But at least for both of them super cruise is a design goal. For F35A, it was not.

Who knows what will be compromised on the AMCA/KFX. Will supercruise and maneuverability be compromised for internal volume or vice versa. In India's case, the land mass is not that huge and the air fights will be at our doorsteps or just beyond. Design goals and tradeoffs may be different from those of the F35.


Just a thought. If supercruise was a critical ASQR wouldn't it be better to have the design process around a realistically available engine and later evolve in other parameters as in MK1, MWF or the hornets?

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 01 Nov 2019 23:27

No single requirement parameter can be looked at in isolation. A larger engine would push the size towards a heavy fighter. That is obviously not an option unless the IAF commits to a significant change in direction. It would certainly be easier to design a high supercruiser with some of the larger or more modern engines for example. But is the IAF willing to go in for a AHCA as a 5GF? The same also applies to what the other requirements are for things like weapons payload, payload flexibility and how many internal sensors they want and what will be podded. All these requirements compete in one way or the other and sometimes if things are fixed (like weight and size for example) you just have to trade one for the other as you run out of options.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Ganesh_S » 01 Nov 2019 23:36

My point was assuming the design incorporates minimal drag and stealth wouldn't it be better to forgo mtow or range considerations to the extent that a later variant with higher thrust can solve these.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nachiket » 01 Nov 2019 23:49

Ganesh_S wrote:Just a thought. If supercruise was a critical ASQR wouldn't it be better to have the design process around a realistically available engine and later evolve in other parameters as in MK1, MWF or the hornets?

Did you read the news link posted previously by Vips, or my two posts pointing it out to fanne? This is exactly what they are doing. They have mentioned that the first 2 squadrons will fly with the F414-INS6 which is available today while subsequent ones will have a higher thrust engine. They also acknowledged that the INS6 powered variants will have performance limitations (like supercruise) which the IAF seems to be ok with.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Ganesh_S » 02 Nov 2019 00:00

nachiket wrote:
Ganesh_S wrote:Just a thought. If supercruise was a critical ASQR wouldn't it be better to have the design process around a realistically available engine and later evolve in other parameters as in MK1, MWF or the hornets?

Did you read the news link posted previously by Vips, or my two posts pointing it out to fanne? This is exactly what they are doing. They have mentioned that the first 2 squadrons will fly with the F414-INS6 which is available today while subsequent ones will have a higher thrust engine. They also acknowledged that the INS6 powered variants will have performance limitations (like supercruise) which the IAF seems to be ok with.


My apologies but my concern was to ensure supercruise assuming it to be a fundamental aspect of design and power and forgo payload or nomenclature aspects like light, medium or heavy by tradeoffs.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby brar_w » 02 Nov 2019 00:04

Ganesh_S wrote:fundamental aspect of design and power and forgo payload or nomenclature aspects like light, medium or heavy by tradeoffs..


These are not nomenclature aspects alone. Do you think the IAF, the primary customer, would not have provided a range for weight and size that it desires?

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby nachiket » 02 Nov 2019 00:16

The nomenclature by itself has little meaning and its definition keeps changing. The proposed LCA Mk2 with a single F414 is being called a Medium Weight Fighter now. And looking at its projected Payload and Internal fuel values that seems correct since the M2k is also considered a Medium category aircraft by the IAF. Meanwhile the AMCA which will have 2 F414's and a much higher empty weight and MTOW is also called a Medium aircraft. Basically anything smaller/lighter than a Su-30 and larger than a Mig-21 can be called Medium. But that obviously incorporates a very wide performance range.

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Re: Advanced Medium Combat Aircraft: News & Discussion - 30 August 2019

Postby Ganesh_S » 02 Nov 2019 00:54

brar_w wrote:
Ganesh_S wrote:fundamental aspect of design and power and forgo payload or nomenclature aspects like light, medium or heavy by tradeoffs..


These are not nomenclature aspects alone. Do you think the IAF, the primary customer, would not have provided a range for weight and size that it desires?


Sir pardon my layman ignorance and let me phrase it this way- if supposedly IAF has specified supercruise as a must have above all criteria set without compromising on stealth and there are two approaches to solving this both being a function of design and power.

1. Having a fundamental design (supercruise) for a given thrust with tradeoffs being addressed later.
2. Designing an aircraft without any tradeoffs except supercruise wherein the supercruise aspect is dealt later with a higher powered engine

Now my concern here is, as there is a diminishing return in both approaches which one of these is likely to lead towards an optimal design (or safer approach).
Last edited by Ganesh_S on 02 Nov 2019 01:09, edited 1 time in total.


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