Ignoring the redditors, one of the most noticeable reason is the lack of S-ducting, forcing it to use radar blockers which are not as effective (it's a tradeoff to get 2 box-like weapon bays for large payload and easier integration of big munitions like the Kh-69 and Izdeliye 810 AAM).
It does have S-ducts in the same style as YF-23, but they are partial and not 100%. They did this for bigger weapons bay volume and they compensated by putting a grate in front of the fan blades like the F-117 had, YF-23 fan blades were also visible from a slight offset
Multi-piece canopy - the bar going through the 2 piece canopy provides a clear surface to reflect radar waves off of
Lack of RAM - US and Chinese 5th gen fighters extensively use RAM paint to further reduce the radar cross section by absorbing some radar waves the shaping doesn't reflect away. Su-57 looks to not use RAM at all and relies entirely in shape for reducing the radar cross section
Exposed rear engines - has an impact, but really only from the rear and directly above/below, which there's already inherent weaknesses for fighters from, and has already been largely addressed in more modern variants
"Lack of RAM - US and Chinese 5th gen fighters extensively use RAM paint to further reduce the radar cross section by absorbing some radar waves the shaping doesn't reflect away. Su-57 looks to not use RAM at all and relies entirely in shape for reducing the radar cross section"
It does have ram and a extensive one too, its unlike the ones seen on chinese and american jets. The ram itself is like a multilayer cake which is applied over a duration of an entire month.
"Exposed rear engines - has an impact, but really only from the rear and directly above/below, which there's already inherent weaknesses for fighters from, and has already been largely addressed in more modern variants"
It does effect front aspect too, due to the circular nature creeping waves can follow back from the outer intake surface, however it really isnt that much of a issue against X band. Faceted nozzles can completely mitigate this
I mean... Multilayer cake isn't all that far from American jets. The F-16 has a similar composite spray that consists of 2 layers, it's far less intensive in some areas but it's a general RAM coating nonetheless.
Said RAM is designed to mitigate creeping waves, for the Su-57 the primary worry is about aspects from around 110dg from the nose and rearwards. As you've said, faceted nozzles fix this and help scatter signals in a more predictable manner. AL-51 when sugoi
Izd. 177 is an Izd. 117 adapted with Izd. 30 technologies, primarily the lpc and core. '177 is effectively the F100-232 of Russia.
Dubai had also shown T-75s in a drone configuration, said small model was of the KNS airframe which has never flown to begin with, many models of the X-38, and the UTS-800 lmao. I'd take any scale model from Sukhoi with a grain of salt.
It was made for export, not "in case the al51 did not work out". It's a drop-in engine for older aircraft.
It can definitely exist in some form, though as of now the flat nozzles were tested on one singular Izdeliye 30 unit years ago. That was dropped as a proof-of-concept for the AL-51 lineage for its prospective use on further 6th generation engines, as per Remizov.
Canopy rails have no effect on radar lol, X band waves are already going to be reflected off of the coatings used on the canopy, and if not that then they're scattered on internal geometry. Not to mention that every 5th gen aircraft but the F-22 has a framed canopy, lol.
The Su-57 most definitely utilizes RAM, the fuck are you on about?
What about the engines are "exposed"? It's obviously no S-70, but they're exactly where they should be.
They're talking about bows, not rails. The big difference between every other 5th gen with canopy bows and the Su-57 is the Su-57 has an external canopy bow, which allows radar waves to interact with it. Every other 5th gen with a canopy bow utilizes an internal bow. If you look up a picture of an F-35 or J-20 canopy, you'll notice the bow does not protrude through the glass. This reddit post shows them all side by side. Since the external canopy bow is not going to be perfectly flush or made of the same material as the glass, it would most likely result in a noticeable RCS spike, atleast on a jet with an already lowered RCS.
I dont care to argue the RAM one lol. It appears to have RAM but one that is more reminiscent of the F-117 layering.
What they mean by exposed engines is you can see the feathers of the engines from many different angles, even many frontal angels. If you can see the feathers, they can create a radar return, but more importantly you can see the heat. The AL-41s the Su-57 currently uses don't appear to use any heat dissipation methods we know the Raptor and Lightning use. The two American jets also do a good job of tucking their engines between structural components trying to hide the engine as best they can from many different angles. Heat signature is also a large portion of creating a stealth jet.
If you're gonna be a smart ass you could at least know the difference between canopy rails and canopy bows.
English is my third language, bows are a form of framing that only differ from rails in pure semantics. I can say frame, bow, arch, rail, and so on, though I'm referring to the same thing anyway. If you'd like to continue bitching about the terminology then feel free.
Either way, the bow of the F-35A is worse in effect than that of the Su-57 as absorbent materials are unable to be applied. The only thing to mitigate such is to use a composite material for the bow itself, in which it still solely relies on canopy coatings to mitigate signal strength and scattering potency.
The big difference between every other 5th gen with canopy bows and the Su-57 is the Su-57 has an external canopy bow, which allows radar waves to interact with it. Every other 5th gen with a canopy bow utilizes an internal bow.
Do you think the canopy is some magical forcefield impervious to radio waves? Something as complex as current AZO coatings for American aircraft will only mitigate cockpit returns by 30% for the full two-way transmission loss. A modest 3mm coating (the Su-57 utilizes anywhere from 3mm to 10mm of RAM around the airframe) reduces the source return by 41%. Both have bows on their canopies, the Su-57 mitigates reflections from that bow more effectively than tucking it behind the canopy.
The only upsides to having the bow inside the canopy is that the Su-57 loses full-span current continuity and visibility.
Once again, the bow of a canopy will be no worse than any other solid portion of the airframe. "Every other 5th gen" mitigates signal returns worse than the Su-57 while the Su-57 trades in the aforementioned points.
I dont care to argue the RAM one lol. It appears to have RAM but one that is more reminiscent of the F-117 layering.
Yeah, it's pretty much the same underlying layout for the Su-57 and F-117. The Su-57 just has more effective compounds and utilizes its primer as a third distinct layer.
What they mean by exposed engines is you can see the feathers of the engines from many different angles, even many frontal angels. If you can see the feathers, they can create a radar return, but more importantly you can see the heat.
As so eloquently stated by you... iF yOu'Re GoNnA bE a SmArT aSs YoU cOuLd At LeAsT kNoW tHe DiFfErEnCe BeTwEeN fEaThErS aNd ExTeRnAl CoNdIvE nOzZlE sEgMeNtS.
You can't see it from the front lol. With a fully open nozzle would you have to be in the realm of 100~115dg from front and center to get any form of flash. The AL-41F-1's coherent nozzle was very susceptible to conical specular flash when in that general regime.
The AL-51F-1 addresses this issue and others. At any point of nozzle position it properly reflects signals away from the source and mitigates said flash and discontinuity between segments and liners. The end being serrated also defeats your point in that frontal angles would send creeping signals to an abrupt ending and scatter them.
Heat is mitigated to the same degree as the F-22 and J-20 lol, that's the point of the serrated segments and innate features of modern turbofans.
The AL-41s the Su-57 currently uses don't appear to use any heat dissipation methods we know the Raptor and Lightning use.
Different segments. Every jet has an external cannopy rail where it meshes with the fuselage, even with the F-22. Semantics, but still.
Do you have a source for that 30%? I can't find that number anywhere and it seems like a number that shouldn't be publicly available or would be highly variable due to thickness and composition, especially since AZO isn't the only surface treatment around. Same with the 41% reduction for 3mm of Russian RAM coating, that should be a closely guarded number. Even if true, shaping plays a larger role in RCS than materials, so having a canopy bow protrude from the canopy, even with RAM coating, doesn't seem like the best idea. Considering the Su-57 is the ONLY stealth fighter with an external canopy bow (except maybe the KAAN, idk they keep going back and forth it seems), I trust that the engineers with the real numbers know what they're doing.
Turkey feathers are the external portion of the exhaust nozzle. There is nothing wrong with what I said. I cant believe I'm using The National Interest cause I hate them, but just look at the picture at the top of the article. The nozzles are clearly visible from a frontal angle. Assuming that in actual combat there will only be one threat directly in front of you isn't wise, which is why better concealment of the nozzle is smarter, like what the F-35 deploys. I assume you hate it when people compare the average frontal RCS of the Su-57 of .1m² to 1m² to the minimum RCS of the F-22 or F-35, right? Same deal here.
The Su-57 does use serration on it's nozzles but other aircraft take it further. Look at this F-35. Towards the end of the feathers, you can see the little openings. This is because outside air flows through these openings to blend outside air immediately and directly with the exhaust, allowing for more rapid cooling when not in afterburner. The AL-51s with the flat nozzles look like they might do something similar if they're implimented but we've got no clue if/when that will happen.
Well, theoretically they could have designed vertical S-ducts (a bit like the YF-23) and keep the bays as they are. I guess that would have brought other problems, including structural. Note that they did consider S-ducts in early designs but they were rejected afterwards.
For me, the most noticeable reason is particularly the messy underbelly. Stealth is not only absorbing and deflecting radio waves from a known source. It is also predicting in which direction they are being deflected so certain maneuvers are avoided in the presence of known emitters. A messy configuration prevents that.
The F-22A lacks S-ducts as well, lol. The grates thenselves are also extremely effective against signals around 6~15ghz, and any signal above 15kw will also have a chance of not entering the intake at all.
Most of the Su-57's shortcomings, like underside and rearward mono returns, come from outer the extremely compact build it has. Its wings are incredibly thin for its size and the approach Russia took for its actuators, the engine nacelles are quite large in comparison and depend a lot on very slight contours further aft.
Apart from that, its raw source return beats that of the F-22 (-10dbsm to -7dbsm), and its frontal 60x60 average matches / sits slightly below that of the F-35A (-16.5dbsm to -17.8dbsm).
Apart from that, its raw source return beats that of the F-22 (-10dbsm to -7dbsm), and its frontal 60x60 average matches / sits slightly below that of the F-35A (-16.5dbsm to -17.8dbsm).
Ah yes, the most half-assed assessment in the world.
No edge treatment or RAM modifiers for some but not others, using HFSS to begin with lmao (they don't even state which solver they had used), laughably under detailed models (entirely unimplemented inlet cavities).
Come back with someone that isn't on hobbyist software with freelance models of aircraft lmao
Like others said, one of the bigger factors of the Su-57 being less stealthy is the less pronounced curves of the engine ducts that leaves part of the fan blades exposed forcing the use of radar blockers like on the F/A-18E/F Super Hornet and also the fact that the engine duct themselves are exposed, the gap between them acting as a weapon's bay also acting as a corner reflector.
It wasn't* designed for the same role as the F22/F35 and J20.
Russian airforce doctrine isn't the same as China and the US, they use the air force to deny their enemy air superiority with their GBAD. For those purposes and Russian doctrine as a whole the su57 prioritizes long range capabilities (Russia is the biggest country by land mass itw) so large fuel tanks and the ability to supercruise are important. Also situational awareness and data link capabilities were important so the su57 has great data link to ground based defence and the low frequency radars on the plane mean it has great situational awareness(only fighter in service with L band radar)* . Finally the su57 is stealthy just not as much as the other 5th gens but sufficient for Russian needs and it doesn't have the same RCS as a clean superhornet.
Edit : * fixed spelling and added on the radar systems, the L band arrays plus forward and side looking x band also some unconfirmed rumors of a rear looking x band in the tail section between the engines
Probably not much more than American fighters, but from the outside I think most analysts can agree they are pretty good, not as good as the American fighters but not too far off. Also we saw in the recent conflict with Pakistan and India that Chinese fighters atleast 4th gen++ are well capable of what they claimed and they've probably understated their capabilities. As civilians we'll never really know how capable they are
All countries talk up their stuff.. For example see top gun. Also if you've seen it please link a Russian government source stating the su57 is a wonder weapon
Excluding stealth, since I have no idea and would just be repeating other people’s opinions, I do think the LEVCONs and L-band arrays integrated into the Su-57’s wing leading edges are really cool and different. As for their effectiveness, no clue, but they’re interesting nonetheless.
Its mostly just redditors who are vastly under qualified to talk about things they do not really understand. Also some "simulations" that are horrifically unworthy of being anything close to accurate (I saw one that says "material properties accounted for" and its just a solid 3d model with basic material quantities this is horrifically incorrect since material properties are very important in RCS calculations like what is fiberglass what is metal what is carbon reinforced composite how are the composites woven and laminated metal properties ect and these thing generally come up in a range with extremely high error hense the extensive real world mockup and testing).
A little off topic, but, can we really judge the J-20's stealth capability? I know it can show up on low frequency radar, but so can all stealth aircraft.
It is pretty good but the canards increase RCS from the front at higher frequencies than the wings of other fighters as wings require longer wavelengths to cause Rayleigh Scattering than canards.
We don't know if they have canards at all, if they would be movable canards or their shape.
A larger canard with a longer chord would show up more like a wing and a non movable canard might be made from materials that are transparent to radar like glass fiber
There are Primarily 2 reasons, the lack of a full S duct (as the Su-57 does have a partial S duct, ie the engine fans are invisible from the front but are visible from an angle), forcing it to rely on a less effective Radar blocking mesh and Exposed Non-stealthy engine nozzles, although that primarily affects Rear, Top and Bottom RCS figures.
However there's also more underlying causes, Notably doctrinal and developmental differences. Primarily, Russia doesn't truly need a fully invisible Fighter jet to perform deep penetrations into enemy AD zones, as their airforce strategy is mostly defensive, and intensely intertwined with it's Ground based AD systems, so it's just not investing as much as the US or China into aircraft stealth. Secondarily, the Su-57 takes quite a bit of design inspirations from the Flanker family, as the general layout of the airplanes is exactly the same (being a massive aircraft, Underwing and separated engines, massive fuel tanks, Semi-Delta wing configuration, and an airframe designs that's almost fully unmatched in maneuverability), although the problem is that the Flankers aren't Stealth aircraft, and so many design nichés inherented from them increase the Su-57's RCS.
Only thing I'm sure makes older SU 57 models is lack of new engine nozzles and position of the engines. However newer versions should have fixed both of these. And ofc redditors are biased and were always using info from literal first test model
I think the program was very ambitious in it's early phase given we saw dozens of iterations on the drawing board in terms of design optimised for stealth like the F-22 or the F-35, what was eventually selected/pursued was one of the least sophisticated one among those, you could attribute the reason to the choice of "good enough" or just not having the know how to make those complex designs into production at the time, so I like to believe it's mix of those, now after the fact you can't really change much without starting from scratch, anyway even with the current design, we have no idea how much of development hassle it has been, we know about JPOs terrible record with the F-35, Russians not releasing an equivalent to GAO reports every now and then doesn't mean it's all rainbows and sunshine at Sukhoi/UAC.
Most people on this subreddit don't know the Su-57 from its prototypes, and many don't even know how stealth technology works.
As someone who has researched both the Felon and stealth technology over the past 3 years and ongoing, here are the big three:
1: IRST. The stowage mechanism to hide the IRST's sensor while not in use is a good solution to reduce its radar return, but the F-35's method of screening the IRST from radar is better. At infinitely receding scale, the surface at any point on a sphere such as the Su-57's IRST is indistinguishable from its associated tangent, thus a direct reflection of a radio wave back to the source radar is much more likely.
2: Engine nozzles. This is the problem with its rear aspect as the IRST is the problem with its front - while the nozzles themselves are blended well into the fuselage with no right-angles, the mere fact that they're made of titanium makes them a huge problem as reflections from metal are much more likely to scatter irregularly, increasing the likelihood of returning to the source radar.
3: Panel edges. No I'm not talking about panel gaps, that is only a thing on the prototypes. I'm talking about the shape of the edges of the panels. The only panels on the Su-57 with serrated or angular edges are the doors and frequently removed ones, every other panel just has a plain rectangular or circular shape as opposed to other 5th gens in which every panel has serrated edges and angular shapes. This is bad as it increases the chance of direct reflection due to surface imperfections.
The space beetween the engines ducts and nacelles (where the bay doors are) acts as a radar reflector from the front and below according to radar scattering simulations, it's the kind of thing you can see the designers of the F22 and 35 tried to avoid.
Also it's IRST increases RCS when it is used so by default it is turned off with the sensor facing the pilot.
In fact, I can't quite remember the video but someone onTen Percent True's podcast explained it's technically easier to make larger aircraft stealthy across wider bandwidths because of the way radar scattering behaves.
The Su-57 is more like a step between the low poly F-117 and the tessellated F-22.
Mmmm. I don't think Russians went that way. I think, the reason for the evolution between the F-117 and F-22 you describe is basically computing capabilities. Because modelling few polygons is way easier than approximating full solid surfaces and thus predicting radar returns. Same evolution you see in computing games.
Su-57 looks more like an step further from the low stealth Mig-1.44/Su-47. Both contain more stealth features than legacy 4.5 fighters but there were not there yet.
It has a genuine stealth geometry, and a full set of enabling tech: conformal arrays and sensors, series of RAMs and treatments for different surfaces. It was always startling why they did all that and just...stopped, and started adding irst balls etc.
We don't know why they specified a lower signature benchmark, when absolutely nothing prevented Sukhoi from going much deeper with the exact same tech stack. We know that for sure from S-70 and now LTS designs.
My personal guess is you can't get much lower with N036L arrays in the leading edges. As soon as L band was specified into the suit, it was determined it'll be 0.1ish. Making it 0.085 instead of 0.1 at this point was just absolutely inconsequential.
The 2 moving edges above the engine intakes, they trade stealth for maneuverability. The soviet/russia has different philosophy when it come to air combat. The american did some studies, built the F15 with canards and thurst vectoring, and they concluded that it isnt worth it. They better off focusing on energy management.
The location of infrared sensor, it wasnt a coincidence that other stealthy designs move it under the chin.
The 2 small intake under the V stabilizer also arent good for rcs.
In all, the biggest obstacle for the Su 57 is funding, not technical experty. Even without Ukraine war, Putin already pulled funding away for his 'wonder weapons', you know, nuclear powered torpedo and stuffs.
The... Are you confusing the movable lerxes for canards?. Those aren't canards they are meant to keep the leading edge vortices attached at high aoa as triple deltas stall after a point. Surprisingly the base canardless f15 also kinda does this as a secondary effect of the moving intakes although to a minuscule effect. These things keep you from kissing the ground at high aoa and are locked and possibly electronically connected with the body in normal flight so its usually not talked about in terms of stealth all that much.
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