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

[Engineer]

I'm not forgetting anything, nor am I dismissing the paper - it's an excellent source (it can't help that you're trying to make it say things it doesn't actually address). We were on the subject of *subsonic* L/D ratio - that VG wings can adapt their AR to flight condition is an advantage, not a drawback.

As you say, the reason why it isn't done on the J-20 is that the "actual requirements" simply don't call for such good subsonic endurance, so the aircraft is fine without (and in fact better able to satisfy other, more pressing needs that favour low weight).

We are on the subject of whether better alternatives to variable geometry wing (and variable geometry inlet) exist, not just subsonic lift-to-drag ratio. You disagree that there is, claiming there are benefits of variable geometry wing that can't replaced while referring to loitering endurance/range. I showed you the paper has addressed that and more through discussing transonic lift-to-drag characteristics. What isn't needed is the solution known as variable-geometry wing, specifically the high aspect-ratio part in achieving that endurance.

Again, all the benefits of relaxed stability could be applied to a VG wing configuration as well (do you think NATF & A/F-X would've been stable?), which would then perform even better at subsonic loiter than the conventional relaxed stability design - these are separate tools really that combine for added effect.

No such aircraft exists in the real world, so there is no proof that substantiates your claim.

Sure - if you realize that the shock structure it generates will closely match the flow field used for streamline tracing the geometry, and that this flow field is a bog-standard cone or isentropic spike flow, you know that pressure recovery performance will resemble a conventional intake with a fixed external compression cone or isentropic spike. The weight and RCS advantages intuitively follow from the removal of the diverter, so you don't necessarily need to know about the design method for that, but it does inform your judgement on the resources required to successfully implement this design and whether these are lacking in Russia or not.

There is resemblance. However, DSI behaves differently to an "intake with a fixed external compression cone or isentropic spike" because the bump and cowling must work in conjunction on a DSI. That is exactly why I told you "DSI is not a conic intake".

Doesn't matter how they addressed it - it is a more critical (due to being safety-relevant) challenge than DSI and they took it in their stride. You act as though seamlessly integrating TVC into the FCS for a function (artificial yaw stability, rather than just control and trim) which tolerates no failure is a trivial task.

TVC is a solution to the problem of yaw instability. The Russian weren't feeling bold as you portrayed them, but were merely applying an already existing solution.

LEVCONs are not canards.

Indeed, but LEVCON contributes to vortex, the downstream behavior of which would be known to the Russian due to their experience with canard on previous Flanker models.

 

[Gloire_bb]

SU-57 supposedly having better lift than the Flanker, and as a result a higher top speed is nonsense,, when you make lift you are creating drag,,, that's why the SU-57 has likely had its max top end lowered...

It's actually subsonic. No one can approach(much less surpass) raptor with its fixed inlets and sacrificed aerodynamics, however they try. It's a law of physics.
By signature of the POTUS, it isn't something you can deal with.

On a serious note, plane is clearly designed for much higher speeds. And apart from outrunning missiles there are simpler tactical things, like squeezing into launch window, altitude performance, and so on.
I.E. exactly type of things in which F-35 is just abysmal(below average 4th gen capability, to the point there is a doubt in its capability to get H-6 before launch)

It's practical what you never need your top speed and range is secondary to stealth, afterburning to safety blackjack(after releasing it's payload) is clearly grateful.

 

[ougoah]

Russia has been playing games with India, they took their money, and then held out on disclosure,, so lets put this ball back in Russia's court. Russia has promised something they can not and will not deliver,,, that's the main reason India hasn't been allowed near the actual data, nor been allowed to fly an aircraft they have partially funded..

Yes, I am aware of India's gymnastics on the Rafale deal, they probably could use a lesson in "getting things done", but nobody in this deal trust the other to do what they say,,,, "guess there really is "No honor among Thieves", and I'm just being facetious here, but really???

any way LockMart is ready to manufacture the F-16 in India, so we'll see how that turns out,,, I can't say I have any faith in that deal either??

Indian sentiment is against F-16 deal. Puts them a half generation behind when it eventuates. They'd be better off getting more rafales, mkis, and tejas. There's talk the US will allow India to manufacture their own F-35s. If that is true, India may very well go with that option. It will be a great addition to their airforce. Whether they can really finance it is another issue. If they want to destroy their budget with an arms race against China, while being a lapdog of the Americans, they can do that. Won't bother China all that much because Chinese policy is not expansion.

I also previously thought that India is a big investor into PAKFA program but apparently it wasn't all that much compared to the total cost of the project. Only a very small fraction but I can't recall. If India wants a custom built Su-57 for their FGFA, they'll need to pay much more for development and then still purchase the fighter. Russia may not let them manufacture or give them tech. May not. Who knows how desperate they will become though. Indians are applying pressure now their options are open and they are certainly giving Russians a headache.

We both agree Su-57 is far from VLO and in that sense, it is not a something they promised ie a full fledged 5th gen in the American definition of the word, benchmarked off the raptor. Maybe it's got some tricks up its sleeves and India will see its capability. Or maybe it really is a glorified updated flanker with superior kinematic performance. The costs involved in getting that last 10% of VLO ability wasn't worth it or doable at this stage and they're banking on new technologies negating stealth advantages.

 

[Jeff Head]

I.E. exactly type of things in which F-35 is just abysmal(below average 4th gen capability, to the point there is a doubt in its capability to get H-6 before launch).

also @Air Force Brat

1st, the F-35C is absolutely NOT abysmal at getting to Mach speeds. It has a 43,000 lb thrust with afterburner and a stated top speed of Mach 1.6., or abysmal at getting to any attacking bird.

Getting to an H-6 or any other aggressive aircraft is a function of several things.

The stealth and speed of the attacker. (H-6 is not that good at either)

The sensors employed by the defender. The US Navy had its E-2D aircraft up near the carrier and out on any expected attack axis...and there is no naval aircraft AEW that is better...none.

THe sensors on the carriers themselves, particularly the new Ford class, but the Nimitz are strong too are not bad at all...but for finding and directing aircraft against attackers the AEW aircraft are the most critical.

Also, the E-2D has significant cooperative engagement capability...it can take control and launch an F-35 or F-18s weapons without those aircraft needing to go active.

FInally, the F-35 itself is amazingly data agile and a mini-AEW aircraft itself. It was built to take advantage of all of these strong capabilities.

So, with the F-35C (or the Super Hornets too) the US aircraft are going to have the absolute best chance in the world of getting at aggressor aircraft before they can launch. They are going to launch full of fuel and then top off as often as necessary to make sure that those out on the threat axis can get to where they need to be as fast as possible and a long as possible...and nobody does those types of things like the US Navy.

They have been exercising at it for many decades...and more importantly, designing their aircraft and sensors for it for just as long.

 

[Gloire_bb]

Well...
No amount of sensor fusion will help, if you are out of range.
And with f-35 you're out of range, because acceleration performance at supersonic speeds is known to be bad. 43'000 lbs of relatively high bypass ratio engine on a relatively full lady don't help much. Accidentally, f-35c accelerates the worst among them.
Same factor(being fatty) makes f-35 surprisingly bad at loitering for amount of fuel it carries, so even small mistakes in timings, intercept control and so on will send fighters looking for fuel.
Well, at least F-35 is stealthy.

Ultimately, all of this is about 4 AMRAAMs(or 2 Meteors and 2 amraams, if your country doesn't suffer from NIH syndrome).

H-6Ks have range, ew suite(certainly a reciever, but also ability to jam communications between C4 aircraft and loitering fighters), tactics, formations and lower altitudes to play with. Furthermore and most importantly, it's for attacker to decide when he will strike. Because even during CW carrier sigint was out-trolled many times(mimic strike assembly for ships to intercept - show scrambled interceptors a parrot - catch CSG with pants down).

While it's very cute what attackers are always assumed to be charging in a single group from the shorter route - F-35/F-18 equipped carrier is toothless at ranges where attackers are forced to act like this.(so strictly speaking, expect not just all sorts of maneuvering and fainting from attackers, but also j-20s and Flankers with LRAAMs making life interesting to CAP and E-2).
Otherwise - expect need to loiter at ranges, preventing stand- off, multiple groups ubder heavy EW cover, baiting, mistakes and so on.
In dealing with some of factors mentioned, f-35 is below most recent Fantoms.

But ultimately, it's all semantics. Fact is what main customer for "killer mode" f-35 is rumored to be JASDF. Because f-35 literally has no hope of intercepting archers, and otherwise they literally have no hope of going for missiles. Too much will get through anyways. And unhappy customer forced to develop 5th gen on his own and untill then deal with impossibility of protecting himself is kinda shameful. Frankly speaking, if not for traditional "best buddy", probably they should have bought Eurofighter.

US Navy designed different aircaft for this mission.
Neither Rhino nor Lighting II are amongst them.
And long retired F-14D is better than both by a huge margin.

 

[Air Force Brat]

Indian sentiment is against F-16 deal. Puts them a half generation behind when it eventuates. They'd be better off getting more rafales, mkis, and tejas. There's talk the US will allow India to manufacture their own F-35s. If that is true, India may very well go with that option. It will be a great addition to their airforce. Whether they can really finance it is another issue. If they want to destroy their budget with an arms race against China, while being a lapdog of the Americans, they can do that. Won't bother China all that much because Chinese policy is not expansion.

I also previously thought that India is a big investor into PAKFA program but apparently it wasn't all that much compared to the total cost of the project. Only a very small fraction but I can't recall. If India wants a custom built Su-57 for their FGFA, they'll need to pay much more for development and then still purchase the fighter. Russia may not let them manufacture or give them tech. May not. Who knows how desperate they will become though. Indians are applying pressure now their options are open and they are certainly giving Russians a headache.

We both agree Su-57 is far from VLO and in that sense, it is not a something they promised ie a full fledged 5th gen in the American definition of the word, benchmarked off the raptor. Maybe it's got some tricks up its sleeves and India will see its capability. Or maybe it really is a glorified updated flanker with superior kinematic performance. The costs involved in getting that last 10% of VLO ability wasn't worth it or doable at this stage and they're banking on new technologies negating stealth advantages.

Jeff responded to several of your statements, and I liked your post, because you are at least open to thinking,,, so

#1. The Indians are not now, even able to purchase an F-35, much less build it, so I said they were very interested in the F-35, because the F-35 is very stealthy and has the top ranked combat capability, particularly in BVR, but it is also incredible WVR, in spite of all the negativity, the F-35 is very agile and it has the most incredible HMS on the planet,, yes that helmet requires some tweaking, but the F-35 will launch its weapons at an extremely high off bore sight angle, so no need to maneuver behind your opponent for a kill, all you have to do is look at him, and pull the trigger!

#2. Those F-16IN Block 70/72 Super Vipers will likely come out on top of each of the aircraft you have named as an instead of,,, the Indians have declined to buy more Rafales?? and Lockheed is entirely open to moving all F-16 production to India, in order to free up manufacturing capability for the F-35...so Indians seem to like "snarky kool" high zoot aircraft, hence the attraction to the SU-57, but that aircraft and the Russians have been a disappointment to the Indians.. The F-16IN Super Viper will likely have conformal fuel tanks and very advanced avionics, it is a 4.5 + generation aircraft, and it will be very capable..

so what India decides to do is wide open at this juncture, but the Block 70/72 Super Vipers are a very high tech and capable,, it would be a tremendous mistake to underestimate these very powerful aircraft, and it would allow India the ability to be the sole exporter of these very capable aircraft and that would indeed help them re-coup their investment...

I do believe at some point, if this deal went well, that India might be accorded the privledge of buying the F-35, they have had lots of problems with Russian aircraft requiring a great deal more maintenance at a much higher expense that quoted,,, but to some extent, many of us have had that situation,,,the US currently fighting a war to keep enough F-18s airworthy to be a force at all?? sad huh, but tactics like Schumers and Nancy will keep us back on our heels for a long time... very sad!

 

[ougoah]

I'm sure F-16IN will be the most capable viper ever but the Indians are ambitious and will want to spend the billions on eurocanards, FGFA, or their AMCA. If F-35 is permitted, that is another option. F-16 no matter how capable will be at least half a gen behind the ones coming out of Russia and China when F-16IN does get into IAF. I just can't see IAF pouring all their funds into F-16 instead of the other options. MKI offers range and payload advantage and can receive upgrades too.

I'm pretty sure IAF will eventually get Su-57 or some variant. They will not want to annoy Russia that much and let's not suppose Su-57 will definitely be any worse than F-16 or even F-35. Yeah I get F-35 is good. You don't need to sell it to me. I've never "underestimated" either F-16 or F-35.

 

[Jura The idiot]

... NIH syndrome).

...

LOL! NIHS

 

[Tirdent]

We are on the subject of whether better alternatives to variable geometry wing (and variable geometry inlet) exist, not just subsonic lift-to-drag ratio. You disagree that there is, claiming there are benefits of variable geometry wing that can't replaced while referring to loitering endurance/range. I showed you the paper has addressed that and more through discussing transonic lift-to-drag characteristics. What isn't needed is the solution known as variable-geometry wing, specifically the high aspect-ratio part in achieving that endurance.

Well, define "better" - that's conditional on the intended task. Better for the requirements of a pure air superiority fighter? Sure, a light-weight low-AR wing in conjunction with relaxed stability is best. For an aircraft with high demands on defensive patrol endurance? An unstable VG wing will look increasingly favourable the higher your loiter requirements go, until there eventually comes the tipping point beyond which fuel savings out-weigh the empty weight gain.

No such aircraft exists in the real world, so there is no proof that substantiates your claim.

No real-world example required.

Relaxed stability decreases trim drag - what the aspect ratio of the base wing has doesn't fundamentally alter that effect. Even long-range airliners with their very high AR wings generally have a trim tank in the horizontal stabilizer to move their centre of gravity aft in cruise to take advantage of it (though for safety/certification reasons they again never become genuinely unstable - only "less stable"). Just because it doesn't exist doesn't mean it could not be done if there was the requirement for it (ask the USN how happy they are about NATF & A/F-X getting the axe in favour of short-legged Super Hornets, though).

Pitting a fixed high-AR wing with relaxed stability against a stable VG wing configuration is a contrived, intentionally biased comparison - there's no reason to apply relaxed stability to one but not the other.

There is resemblance. However, DSI behaves differently to an "intake with a fixed external compression cone or isentropic spike" because the bump and cowling must work in conjunction on a DSI. That is exactly why I told you "DSI is not a conic intake".

As DSI for fighter applications is a purely external compression intake, beyond triggering the terminating normal shock (which is about as easy as it gets) the cowl *contributes* basically nothing to pressure recovery though. The challenge is in designing it such that it *detracts* as little as possible from the theoretical optimum achievable with the chosen shock system and centers on managing and optimizing the boundary layer diversion. This is a bit harder to do than with a traditional intake (where the diverter and bleed take care of it) and accounts for the characteristic forward-swept shape to allow for BL air to spill overboard even downstream of the lip, but there's little scope here for improved pressure recovery over a well-designed conventional counterpart.

BTW, your earlier point about increasingly complex shock systems worsening inlet drag due to friction from higher wetted area at low speed & cowl drag due to larger flow turning angle at high Mach affects ALL external compression inlets - including DSI. Designing for shallower initial shock angles and greater total intake flow turning angle will result a longer, larger bump and a higher cowl projected frontal area - another effect which familiarity with the design method will make clear.

TVC is a solution to the problem of yaw instability. The Russian weren't feeling bold as you portrayed them, but were merely applying an already existing solution.

Again, you are trivializing a very significant challenge - what kind of solution to that problem would not have been "already existing" in some way or other? Ion thrusters?

Indeed, but LEVCON contributes to vortex, the downstream behavior of which would be known to the Russian due to their experience with canard on previous Flanker models.

Bit of an oversimplification, but fair enough - what about this:

"Indeed, but a conical shock system contributes to pressure recovery and the downstream behaviour is known to the Russians from earlier intakes with conical centre-bodies."

No further off the mark than what you said. I still don't see how designing a suitable cowl to both match the shocks (they already have that t-shirt) and accommodate BL diversion without a diverter & bleed (the only truly novel aspect) would defeat them.

 

[Air Force Brat]

Well...
No amount of sensor fusion will help, if you are out of range.
And with f-35 you're out of range, because acceleration performance at supersonic speeds is known to be bad. 43'000 lbs of relatively high bypass ratio engine on a relatively full lady don't help much. Accidentally, f-35c accelerates the worst among them.
Same factor(being fatty) makes f-35 surprisingly bad at loitering for amount of fuel it carries, so even small mistakes in timings, intercept control and so on will send fighters looking for fuel.
Well, at least F-35 is stealthy.

Ultimately, all of this is about 4 AMRAAMs(or 2 Meteors and 2 amraams, if your country doesn't suffer from NIH syndrome).

H-6Ks have range, ew suite(certainly a reciever, but also ability to jam communications between C4 aircraft and loitering fighters), tactics, formations and lower altitudes to play with. Furthermore and most importantly, it's for attacker to decide when he will strike. Because even during CW carrier sigint was out-trolled many times(mimic strike assembly for ships to intercept - show scrambled interceptors a parrot - catch CSG with pants down).

While it's very cute what attackers are always assumed to be charging in a single group from the shorter route - F-35/F-18 equipped carrier is toothless at ranges where attackers are forced to act like this.(so strictly speaking, expect not just all sorts of maneuvering and fainting from attackers, but also j-20s and Flankers with LRAAMs making life interesting to CAP and E-2).
Otherwise - expect need to loiter at ranges, preventing stand- off, multiple groups ubder heavy EW cover, baiting, mistakes and so on.
In dealing with some of factors mentioned, f-35 is below most recent Fantoms.

But ultimately, it's all semantics. Fact is what main customer for "killer mode" f-35 is rumored to be JASDF. Because f-35 literally has no hope of intercepting archers, and otherwise they literally have no hope of going for missiles. Too much will get through anyways. And unhappy customer forced to develop 5th gen on his own and untill then deal with impossibility of protecting himself is kinda shameful. Frankly speaking, if not for traditional "best buddy", probably they should have bought Eurofighter.

US Navy designed different aircaft for this mission.
Neither Rhino nor Lighting II are amongst them.
And long retired F-14D is better than both by a huge margin.

Its NOT semantics, there is hard data to back up the effectiveness and adaptability of the F-35, and while the F-14 was a very neat airplane, it had lots of issues that resulted in its early retirement, but hey, if you wanta write fiction here on SDF??? you be my guest,??? me I'm gonna stick with the 3rd US Five Gen in production and active duty service.

the USAF, USMC, and the NAVY are all very happy with their airplanes, as are the many, many foreign customers, they my friend are putting their MONEY! where their MOUTH is!!

you know friend, people don't have to buy airplanes that don't work anymore, and the F-35 is selling like "ice-water in Hell!"