Russian Su-57 Aircraft Thread (PAK-FA and IAF FGFA)

[Engineer]

That must be why the definitive Su-57 engine is already flying in one of the prototypes while the WS-15 is nowhere to be seen.

The Russian are far more reckless and okay things that will never pass ground tests in China. The 117 engine catching fire many times and eventually costing one Su-57 prototype is one such example.

A DSI is not a magic replacement for any and every other type of intake, nor is the theory behind it incredibly complicated - so the fact that the Su-57 doesn't have one can easily be (and probably is) down to other factors.

Theory of flight isn't incredibly complicated either, yet only a handful of countries can design then mass produce fighter aircraft. Theory isn't the issue, putting theory into practice is, and the Russian have not demonstrated the ability to put DSI into practice.

What it does is provide shaping inherently well suited to stealth at performance competitive with more traditional (fixed) intake types. For a LO aircraft this saves a bunch of weight, because you get away with far less RAM/RAS to take care of cavities and other "hot spots" which are inevitable with conventional solutions. That's all there is to it though - it neither performs better (weight saving apart) than a traditional intake nor is it impossible to achieve similar levels of RCS reduction with a traditional intake (see F-22).

If the Su-57 doesn't have a DSI, the most likely reason is that it isn't in fact the best solution for the requirements which the Su-57 is designed to fulfill - which are not necessarily the same as those the J-20 is intended to meet. It's a bit surprising in an aircraft clearly aimed a certain level of low observability, but different aims lead to different solutions - it's not as though Russia is ignorant of the technology involved (Tupolev envisaged DSIs on a mid-1990s concept for a stealthy Tu-22M-sized bomber).

Ever wondered why you never see DSIs on supersonic transport concepts? They don't need to be stealthy, so a big part of the weight saving doesn't accrue, and variable intakes are better able to provide the high efficiency over a wide Mach number range which is so important for long range supersonic cruise. Horses for courses.

An intake is not just a tube. There are extra ducting for taking on/dumping air, and for variable intakes like those on the Su-57 there are even ramps and hydraulic actuators. These not only produce radar returns, but are also weight penalties. DSI get rid of them, thereby reducing weight as well as RCS. Fact is, in real-world application, traditional intakes no longer have advantages in comparison to a DSI.

The Russian wanted a quick solution for their 5-th generation fighter, so they heavily modified the Flanker design and called it a day. The Su-57 is essentially a 30 year-old design. There is no innovation. Even the highly touted LEVCON exists on previous Flanker models as canard. Such conservative approach shows that the Russian aren't confident in being able to get new technologies working. In comparison, the J-20 is truly a generation leap over the J-10. Saying Russia is now behind China is simply calling a spade a spade.

 

[Tirdent]

Deino, would it be possible to move the off-topic posts to the Russian military or Su-57 threads? I don't want to take this discussion further away from the real subject (Su-35), but at the same time some of the claims here can't just go unchallenged for the record.

The Russian are far more reckless and okay things that will never pass ground tests in China. The 117 engine catching fire many times and eventually costing one Su-57 prototype is one such example.

Many times? T-50-5 was NOT lost to an engine failure, going by the location of the fire damage, and the incident at MAKS 2011 was a compressor stall, something that happens occasionally even on mature designs (airliners.net has plenty of photos). Even if it was though, sh*t happens with new engines - the Eurofighter consortium lost a prototype to a double (!) engine failure. Doesn't change the fact that the EJ200 is easily one of the finest fighter engines built to date.

On the other hand, how about putting an engine into operational service which is apparently too unreliable to use in a single-engine fighter (and for a time even grounded the twin engine design). Or letting the fare-paying public beta-test a regional jet which had door pressure issues, had not proven a capability to operate safely in heavy rain and which did not have a certified production line established.

Sorry, but your claim is totally lacking in both facts and objectivity.

Theory of flight isn't incredibly complicated either, yet only a handful of countries can design then mass produce fighter aircraft. Theory isn't the issue, putting theory into practice is, and the Russian have not demonstrated the ability to put DSI into practice.

What makes fighter design difficult is primarily knowing what constitutes a good fighter aircraft and what doesn't - i.e. well-defined specifications and systems integration. Also, far more countries have the ability to build a decent fighter than you might imagine, but unless they have a good-size home market, a historical export market presence or a political imperative for independence, doing so generally doesn't make sense. Switzerland is an example.

A DSI intake is rather different in that regard - it is a passive system without actively controlled bleeds or moving ramps to schedule, the "secret sauce" is thus all in the shaping. Deriving a working geometry requires a solid understanding of supersonic cone flow theory and good windtunnel/CFD capability for fine tuning off-design operation. Russia has both in spades and was apparently mooting the idea as early as 20 years ago.

If it hasn't shown up on a flying aircraft despite this that's probably because it didn't earn its way aboard based on performance specifications required.

An intake is not just a tube. There are extra ducting for taking on/dumping air, and for variable intakes like those on the Su-57 there are even ramps and hydraulic actuators. These not only produce radar returns, but are also weight penalties. DSI get rid of them, thereby reducing weight as well as RCS. Fact is, in real-world application, traditional intakes no longer have advantages in comparison to a DSI.

Sure they do - weight and radar signature are most certainly not the only relevant aspects of intake design, pressure recovery is arguably at least as important as either. A DSI is comparable to a well-designed *fixed* intake of conventional type in this regard, but it doesn't match a movable ramp intake with respect to wide Mach number range of efficient performance. Again, if DSI intakes were superior to other solutions in any and every way, why do we not see them on aircraft concepts which depend critically on good supersonic pressure recovery but for which stealth is irrelevant?

Obviously, if design priorities favour certain aspects of intake performance, conventional designs continue to be preferable.

The Russian wanted a quick solution for their 5-th generation fighter, so they heavily modified the Flanker design and called it a day. The Su-57 is essentially a 30 year-old design. There is no innovation. Even the highly touted LEVCON exists on previous Flanker models as canard. Such conservative approach shows that the Russian aren't confident in being able to get new technologies working. In comparison, the J-20 is truly a generation leap over the J-10. Saying Russia is now behind China is simply calling a spade a spade.

Where to start? With all due respect, that paragraph is just nonsense. Facts and objectivity, please.

Can we settle for equivocation? There are aspects of aviation where the Russians are ahead, and aspects of aviation where the Chinese are ahead. While the Russians are doing exceptionally well with their limited funding, if trends continue the Chinese will manage to get ahead of the Russians categorically through greater spending.

That said, there is no need to be defensive when delta (rate of change) is on your side.

I'm not that interested in "fairness" or keeping score, Russia urgently needs to get its ecnonomy going, stop its waste of development resources and improve military leadership if it is to keep pace with China in future. However, Equation & Engineer's point in this specific case just doesn't hold water.

Russia is living on borrowed time right now, they are drawing on the Soviet Union's incredible military development experience and infrastructure, but with their anaemic economy and new technologies emerging, this will not carry them much further. There's so much inefficiency, needless duplication of effort, pork barrelling and just plain lack of vision in the military leadership going on that they could be doing a lot better than they are. Just a couple of examples:

- Continuing to push the hopeless passenger variants of the Tu-204 and Il-96 over more competitive military and cargo derivatives
- Killing the very forward-thinking An-70 in favour of the inadequate and obsolete Il-76MD90 (yes, Ukraine, but why not buy them out of the project?)
- In connection with both items above, not selecting the vastly superior Il-96 as the next generation AWACS and tanker platform
- Building both the Ka-52 and Mi-28 instead of telling Mil to get their posterior in gear and shape up the Mi-38 transport
- Not building the MiG Skat UCAV, rather than variations of the increasingly obsolete MiG-29 (which has too unfavourable a cost/capability ratio compared to the Flanker)
- As cool as it looks, not cancelling the Su-34 in favour of more Su-35s and/or Su-30SMs as well as a thorough avionics and smart weapons upgrade for the Tu-160 & Tu-22M
- Totally missing the boat on the UAV trend (the Altius-M and Orion-E are competent designs, but with better leadership they could have been here so much earlier)

And that's just aviation, space and navy aren't faring any better. There are a couple of projects which demonstrate they haven't quite lost their mojo, such as the MS-21, various missiles, liquid rocket engines, the PD-14 & Izd. 30 jet engines as well as the nuclear submarine programme (though here again there is this Status-6 boondoggle), but on the whole Russia clearly has to up its game, and do so fast! In China, there is a lot of similar duplication going on of course and in many areas they're still playing catch-up to boot, but unlike the Russians they at least have the financial resources to afford it without jeopardizing their overall competitiveness.

If I was in charge of Russian aerospace & defence, I'd look very long and very hard at Sweden's approach to efficient R&D and procurement - they need to make every single Ruble count going forward!

 

[Engineer]

Many times? T-50-5 was NOT lost to an engine failure, going by the location of the fire damage, and the incident at MAKS 2011 was a compressor stall, something that happens occasionally even on mature designs (airliners.net has plenty of photos). Even if it was though, sh*t happens with new engines - the Eurofighter consortium lost a prototype to a double (!) engine failure. Doesn't change the fact that the EJ200 is easily one of the finest fighter engines built to date.

On the other hand, how about putting an engine into operational service which is apparently too unreliable to use in a single-engine fighter (and for a time even grounded the twin engine design). Or letting the fare-paying public beta-test a regional jet which had door pressure issues, had not proven a capability to operate safely in heavy rain and which did not have a certified production line established.

Sorry, but your claim is totally lacking in both facts and objectivity.

LOL! T-50-5 WAS lost to engine fire. That is a fact. MAKS2011 should have served as a warning. Russia should have done what China did by responsibly grounding all flights until the root problem is resolved, but Russia did not heed the warning and ultimately paid the price. Cannibalizing another prototype to restore an essentially written-off airframe was a desperate attempt at maintaining a "zero airframe lost" test-flight campaign. This shows Russia is placing utmost importance in propping up a fragile image of an aviation power while putting everything else, even safety, secondary. It is Russia that has lost objectivity.

What makes fighter design difficult is primarily knowing what constitutes a good fighter aircraft and what doesn't - i.e. well-defined specifications and systems integration. Also, far more countries have the ability to build a decent fighter than you might imagine, but unless they have a good-size home market, a historical export market presence or a political imperative for independence, doing so generally doesn't make sense. Switzerland is an example.

And what makes DSI design difficult is primarily knowing what constitutes as a good design and what isn't. Thanks for reinforcing my point that something that is "simple" in theory doesn't make it simple in application.

A DSI intake is rather different in that regard - it is a passive system without actively controlled bleeds or moving ramps to schedule, the "secret sauce" is thus all in the shaping. Deriving a working geometry requires a solid understanding of supersonic cone flow theory and good windtunnel/CFD capability for fine tuning off-design operation. Russia has both in spades and was apparently mooting the idea as early as 20 years ago.

Mooting an idea isn't the same as putting it into application. Get real! Also, DSI is not conic intake.

If it hasn't shown up on a flying aircraft despite this that's probably because it didn't earn its way aboard based on performance specifications required.

DSI earns its way abroad flying 5-th generation fighter in both US and China, so your argument doesn't work.

Sure they do - weight and radar signature are most certainly not the only relevant aspects of intake design, pressure recovery is arguably at least as important as either. A DSI is comparable to a well-designed *fixed* intake of conventional type in this regard, but it doesn't match a movable ramp intake with respect to wide Mach number range of efficient performance. Again, if DSI intakes were superior to other solutions in any and every way, why do we not see them on aircraft concepts which depend critically on good supersonic pressure recovery but for which stealth is irrelevant?

Obviously, if design priorities favour certain aspects of intake performance, conventional designs continue to be preferable.

DSI is also comparable to variable intake (your so called movable ramp intake), and actually has better pressure recovery in the flight envelope that the aircraft flies most often in. Indeed, J-10B receives DSI which replaces the three-shock variable inlet system found on J-10A because DSI is superior. Both US and China use DSI on their 5-th generation fighters, which is enough proof of DSI's superiority. Aerodynamics work the same over Russia as it does over US and China, so Russia's lack of result in DSI only means Russia is lagging behind.

Where to start? With all due respect, that paragraph is just nonsense. Facts and objectivity, please.

The fact that Su-57 being a heavily modified variant of Flanker is bare for all to see. You should heed your own advice by seeing facts and display some objectivity.

 

[Tirdent]

LOL! T-50-5 WAS lost to engine fire. That is a fact.

How about a source then?

This shows Russia is placing utmost importance in propping up a fragile image of an aviation power while putting everything else, even safety, secondary.

Just in case anybody thought I was making stuff up regarding Chinese safety culture with the ARJ21:

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And does the early WS-10 saga really bear recapping? Compared to that, Russia's handling of the T-50-5 fire actually demonstrates remarkable candour and confidence that competent observers will be able to judge the implications for themselves. But we digress, this argument of yours was not founded in fact from the start.

And what makes DSI design difficult is primarily knowing what constitutes as a good design and what isn't. Thanks for reinforcing my point that something that is "simple" in theory doesn't make it simple in application.

This was pretty clearly NOT my point. That you have failed to understand it should give you pause.

Also, DSI is not conic intake.

I didn't say it was. Going by your failure to recognize this, you appear not to be all that familiar with the specifics of DSI intakes. Maybe you should reconsider making such bold claims about them.

DSI earns its way abroad flying 5-th generation fighter in both US and China, so your argument doesn't work.

I take it you consider the F-22 not to be American, not 5th generation and not flying? Whose argument is it exactly which isn't working here?

Not to mention the fact that at least some of Boeing's published 6th generation fighter concepts don't have DSI (even though the X-32 did).

DSI is also comparable to variable intake (your so called movable ramp intake), and actually has better pressure recovery in the flight envelope that the aircraft flies most often in.

The USAF (who by 2016 should have known a thing or two about the F-35's DSIs, I suspect...) disagrees:

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If DSI was the be-all-end-all, what "inlet aerodynamic performance" would there be to regain to "4th generation" levels?

Indeed, the DSI replaces the three-shock variable inlet system found on J-10A because DSI is superior.

Perhaps the J-10A intake was in fact a non-optimal rush-job to accommodate the eleventh hour engine swap to the AL-31F (I mean, look at all those braces!), so it doesn't actually perform very well? Also, define "superior" - maybe the PLAAF simply considers the operational utility of speeds beyond Mach 2.0 not worth the cost and maintenance burden of the moving parts and actuators in a variable intake?

Good enough at lower cost can easily amount to "superior" for the job at hand - an intake is a means to an end. A number of aircraft types with variable intakes actually had their ramps deactivated in the field after a few years of operational experience for that reason (F-14D, Tornado GR.4).

Aerodynamics work the same over Russia as it does over US and China, so Russia's lack of result in DSI only means Russia is lagging behind.

And China never built a swing-wing aircraft - doesn't mean they couldn't if they thought the benefits were worthwhile. Again, probably a matter of priorities rather than ability.

 

[ougoah]

I don't doubt Russia can come out with DSI intakes. Even if they used some industrial espionage, it is definitely well within their abilities. The fact they choose not to use it, only shows DSI is not suitable for the purposes of their fighter. It does not show they can't do it (of course it will not go onto a prototype for testing if they abandoned the idea in the planning phase and even if they did test it, they won't be publishing photos). DSI offers some advantages over fourth gen intakes so PLAAF opted for them on their LO fighters. Makes sense knowing what those advantages are. Their main "interceptor" is the flanker type which has the speed factor covered.

 

[Engineer]

How about a source then?

Just in case anybody thought I was making stuff up regarding Chinese safety culture with the ARJ21:

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And does the early WS-10 saga really bear recapping? Compared to that, Russia's handling of the T-50-5 fire actually demonstrates remarkable candour and confidence that competent observers will be able to judge the implications for themselves. But we digress, this argument was not founded in fact from the start.

Red herring isn't going to disprove that a prototype is lost as result of Russia's recklessness. Red herring only shows you have no argument.

This prototype is a write-off by many competent observers. What Russia displayed here is not candour and confidence but deceit and recklessness. It is deceit because Russia tells everyone no airframe was lost despite the T-50-5 was rebuilt out of another prototype - one prototype is still lost no matter how it is counted. It is reckless because Russia is using experimental engines on an experimental aircraft. Furthermore, the Su-57 prototype at MAK2011 being one of a few prototypes, serviced by specialists from the factory, specially pampered to wow international observers, still developed engine problems. It is a sign that the aircraft was immature for an airshow but Russian okay'ed the aircraft to go anyway - recklessness.

Since you brought up safety culture, Russia is continuing a "fine" Soviet tradiation of recklessness which simply has no comparison. Let me remind you of the

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, the

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, and let's not forget

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. In Russia, people dying from faulty engineering is just a way of life.

This was pretty clearly NOT my point. That you have failed to understand it should give you pause.

I frankly do not care about your point, because it is not based on fact to begin with.

I didn't say it was. Going by your failure to recognize this, you appear not to be all that familiar with the specifics of DSI intakes. Maybe you should reconsider making such bold claims about them.

I am pretty familiar with DSI specifics, but judging by your projection, it is you who are not familiar. The fact that you used "moving ramp intake" instead of the technical term "variable geometry inlet" in your previous post is a good indication of your patchy knowledge in this subject.

I take it you consider the F-22 not to be American, not 5th generation and not flying? Whose argument is it exactly which isn't working here?

The F-35 is American, a 5-th generation fighter, and has DSI. Once again, it is your argument that isn't working here.

Not to mention the fact that at least some of Boeing's published 6th generation fighter concepts don't have DSI (even though the X-32 did).

The USAF (who by 2016 should have known a thing or two about the F-35's DSIs, I suspect...) disagrees:

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If DSI was the be-all-end-all, what "inlet aerodynamic performance" would there be to regian to "4th generation" levels?

Is DSI being used in top-of-the-line US fighter? Is DSI is being used in top-of-the-line Chinese fighters? The answer to both questions is yes. Clearly, more than one country think DSI is superior, and their actions are much louder than your spin with concept drawings.

Perhaps the J-10A intake was in fact a non-optimal rush-job to accommodate the eleventh hour engine swap to the AL-31F (I mean, look at all those braces!), so it doesn't actually perform very well? Also, define "superior" - maybe the PLAAF simply considers the operational utility of speeds beyond Mach 2.0 not worth the cost and maintenance burden of the moving parts and actuators in a variable intake?

Good enough at lower cost can easily amount to "superior" for the job at hand - an intake is a means to an end. A number of aircraft types with variable intakes actually had their ramps deactivated in the field after a few years of operational experience for that reason (F-14D, Tornado GR.4).

Your hypothetical questions are irrelevant. What relevant is that both US and China chose DSI for its latest fighters, proving there are good merits for using DSI. Russia couldn't have not known, so the only reason left is Russia's inability to implement one.

And China never built a swing-wing aircraft - doesn't mean they couldn't if they thought the benefits were worthwhile. Again, probably a matter of priorities rather than ability.

Actually, China couldn't build one. By the time China can, swing-wing is obsoleted.

 

[Tirdent]

Thanks Deino for moving the posts!

This prototype is a write-off by many competent observers. What Russia displayed here is not candour and confidence but deceit and recklessness. It is deceit because Russia tells everyone no airframe was lost despite the T-50-5 was rebuilt out of another prototype - one prototype is still lost no matter how it is counted. It is reckless because Russia is using experimental engines on an experimental aircraft. Furthermore, the Su-57 prototype at MAK2011 being one of a few prototypes, serviced by specialists from the factory, specially pampered to wow international observers, still developed engine problems. It is a sign that the aircraft was immature for an airshow but Russian okay'ed the aircraft to go anyway - recklessness.

As I pointed out earlier, the fire damage is located a good distance forward of the engines. But then the Su-57 looks like a heavily modified Flanker variant to you, so plainly your eyesight must leave a lot to be desired.

I'm also not sure why you are so hysterical about it being a write-off. Any serious observer can see that, and equally conclude that it's not the end of the world either. Losing a prototype, while clearly undesirable, is not that uncommon even among recent fighter projects.

Since you brought up safety culture, Russia is continuing a "fine" Soviet tradiation of recklessness which simply has no comparison. Let me remind you of the Nedelin catastrophe where engineers were burnt alive by a rocket fire, the N1 program where untested rockets were launched and exploded to see how things go, and let's not forget how first Cosmosnaut Vladimir Komarov cursed sloppy Soviet engineering before dying in a fiery crash. In Russia, people dying from faulty engineering is just a way of life.

1) Russia =/= Soviet Union
2) Do you really want to discuss the Great Leap Forward and related policies and events? Intelsat 708? How many WS-10-related incidents aren't even well-known thanks to cover-ups?

I'd hate to prolong this toxic discussion which (let's be absolutely clear on that!) YOU originally kicked off, as unlike you apparently I don't actually enjoy slandering nations - I regret being suckered into doing so. You are precariously close to joining my ignore list and if you don't knock it off right now, you will.

I am pretty familiar with DSI specifics, but judging by your projection, it is you who are not familiar. The fact that you used "moving ramp intake" instead of the technical term "variable geometry inlet" in your previous post is a good indication of your patchy knowledge in this subject.

Well, if you're familiar I'm sure you can explain why I mentioned conical flow theory in this context. Also, there is no single "correct" term for variable intakes.

The F-35 is American, a 5-th generation fighter, and has DSI. Once again, it is your argument that isn't working here.

Hardly. Your point is that a DSI is the *only* viable solution for a 5th generation fighter, hence mine provides clear and unequivocal evidence to the contrary.

Is DSI being used in top-of-the-line US fighter?

Arguably no, since the F-22 is America's top of the line fighter...

Clearly, more than one country think DSI is superior, and their actions are much louder than your spin with concept drawings.

Superior for what they want their respective aircraft to do. For aircraft which have other requirements a different solution may be preferable, as the fact that DSIs are nowhere to be seen on even the most modern SST concepts demonstrates quite forcibly. Finally, what I'd say speaks loudest of all is that the USAF with its wealth of data on the DSIs of the F-35 by 2016, clearly considers pressure recovery on current 5th generation designs inferior to 4th generation variable intakes.

How are you in a position to challenge them on that conclusion?

Your hypothetical questions are irrelevant.

No more hypothetical than your assumption that it is performance improvement which led to a DSI replacing the 2D wedge intake on the J-10. Which is why they are actually very pertinent indeed, because your entire argument hinges on the premise that better pressure recovery is the *only* possible explanation. So by demonstrating that there are other perfectly plausible reasons (including real-world precedents), my supposedly irrelevant questions make your entire argument fall flat on its face.

Actually, China couldn't build one. By the time China can, swing-wing is obsoleted.

Aircraft which demand a combination of excellent field performance, Mach 2+ top speed at high altitude and efficient transonic cruise on the deck or long loiter at altitude have gone out of fashion, yes. If for whatever reason you wanted to design such an aircraft today though, odds are pretty good that you would still end up with VG wings (Lockheed NATF & A/F-X). Once again a question of priorities, rather than swing wings performing poorly as a solution.

Horses for courses and so on.

 

[Engineer]

As I pointed out earlier, the fire damage is located a good distance forward of the engines. But then the Su-57 looks like a heavily modified Flanker variant to you, so plainly your eyesight must leave a lot to be desired.

LOL! Engine fire located "good distance forward of the engines", I don't think you even know what you are talking about anymore. The Su-57 is a heavily modified Flanker variant. This is concurred by many people. Only the blind and the unwillings can't see this.

It is an indication that the Flanker is the technological limit of present day Russia.

I'm also not sure why you are so hysterical about it being a write-off. Any serious observer can see that, and equally conclude that it's not the end of the world either. Losing a prototype, while clearly undesirable, is not that uncommon even among recent fighter projects.

Losing a prototype isn't uncommon, and frankly it would have make no difference to me except you are the one who was trying to convince me that no prototype is lost. I merely corrected you with facts.

1) Russia =/= Soviet Union
2) Do you really want to discuss the Great Leap Forward and related policies and events? Intelsat 708? How many WS-10-related incidents aren't even well-known thanks to cover-ups?

I'd hate to prolong this toxic discussion which (let's be absolutely clear on that!) YOU originally kicked off, as unlike you apparently I don't actually enjoy slandering nations - I regret being suckered into doing so. You are precariously close to joining my ignore list and if you don't knock it off right now, you will.

Don't blame me for your own despicability. I merely pointed out Russia is reckless, then you started red herring and proceeded to throw mud hoping for something to stick. I responded professionally, sticking with discussion about Russia's faulty engineering and provided further proof of Russia's reckless track record going all the way back to Soviet's time — something which you can't even deny. I literally laughed out loud when I read your threat about bringing Great Leap Forward into an engineering discussion. It is the exact type of low-grade response I expect from you.

Well, if you're familiar I'm sure you can explain why I mentioned conical flow theory in this context. Also, there is no single "correct" term for variable intakes.

No, variable geometry inlet is the technical term. Your knowledge is patchy, and it shows.

Hardly. Your point is that a DSI is the *only* viable solution for a 5th generation fighter, hence mine provides clear and unequivocal evidence to the contrary.

Nice try with strawman fallacy, and it is a strawman because I never made such point. I simply exposed your falsehood by pointing out that DSI is lighter, more stealthy, and has comparable performance with traditional inlet. You objected, so I cited how US and China use DSI on their top-of-the-line fighters. The fact remains that Russia does not have anything to show for with DSI, indicating the country is lagging behind.

Arguably no, since the F-22 is America's top of the line fighter...

F-35 is also America's top-of-the-line fighter. Furthermore, DSI first flew at end of 1996 whereas first F-22 rolled out in Spring of 1997. In short, DSI wasn't even available when F-22 was being designed. Your attempts at trying to present F-22 as some big revelation is nothing but a grasp at straws.

Superior for what they want their respective aircraft to do. For aircraft which have other requirements a different solution may be preferable, as the fact that DSIs are nowhere to be seen on even the most modern SST concepts demonstrates quite forcibly. Finally, what I'd say speaks loudest of all is that the USAF with its wealth of data on the DSIs of the F-35 by 2016, clearly considers pressure recovery on current 5th generation designs inferior to 4th generation variable intakes.

How are you in a position to challenge them on that conclusion?

US and China both use DSI on their top-of-the-line fighter. The airforce of two major powers put their money where their mouth is. That is a proof of DSI superiority. Your argument has nothing to stand on.

No more hypothetical than your assumption that it is performance improvement which led to a DSI replacing the 2D wedge intake on the J-10. Which is why they are actually very pertinent indeed, because your entire argument hinges on the premise that better pressure recovery is the *only* possible explanation. So by demonstrating that there are other perfectly plausible reasons (including real-world precedents), my supposedly irrelevant questions make your entire argument fall flat on its face.

An entire engineering branch, people with concrete data and much more knowledge than I, decided to replace J-10's variable inlet with DSI, so DSI having better performance is a fact and not an assumption. This real world example torpedoed your entire thesis on how variable geometry is better.

Aircraft which demand a combination of excellent field performance, Mach 2+ top speed at high altitude and efficient transonic cruise on the deck or long loiter at altitude have gone out of fashion, yes. If for whatever reason you wanted to design such an aircraft today though, odds are pretty good that you would still end up with VG wings (Lockheed NATF & A/F-X). Once again a question of priorities, rather than swing wings performing poorly as a solution.

Horses for courses and so on.

The development of LERX replaces the need for an adaptable wing geometry. DSI replacing archaic variable geometry inlet is similar. In both cases, fixed structure replaces complex movable mechanisms.

 

[Gloire_bb]

That is a proof of DSI superiority.

Depends on speeds you aim to achieve in combat conditions.

so DSI having better performance is a fact and not an assumption.

It isn't much of a secret, it's simply lighter and much less complex technically=service intensive.
At the same time, it works for performance envelope of j-10(and f-35, for the matter) just as well.
For f-22 it simply doesn't, available or not.
One mach too much.

It is an indication

...
Is this serious?

 

[Gloire_bb]

The development of LERX replaces the need for an adaptable wing geometry. DSI replacing archaic variable geometry inlet is similar. In both cases, fixed structure replaces complex movable mechanisms.

Tupolev played with LERX for parallel tu-160 design with fixed wing, but it simply was worse(couldn't get necessary specifications on some attack profiles).
And, as mentioned above, at least 4 aircraft manufacturers I know used swing wing on their projects after deploying lerx-equipped fighters.(Lockheed, Northrop, Sukhoi, MiG).