Su-57 Stealth Fighter: News #6

limb wrote:

dino00 wrote:Moscow. December 7. Interfax - The "second stage" engine, which ensures the cruising supersonic speed of the Su-57 fighter, will be ready in 2022, the head of Rostec Sergey Chemezov told reporters.

“I hope that sometime in 2022 the engines will be ready,“ put on the wing, ”and within a few years we will launch their serial production,” Chemezov said.

https://www.militarynews.ru/story.asp?rid=1&nid=542823&lang=RU

The SU-57 in 2022 will still have the same engine.

I wonder if the US 6th gen fighter will be flying by that time, and if the WS15s on the J-20 will be ready.

Also why would the aircraft with the new engines need many more years for testing, when all their other systems will be the same? Isnt the izd.30 being flight tested right now?

You cant be serious, 6th gen? No one really has even mastered 5th gen yet, not even the US when they can even figure out how to create durable/reliable RAM coating, and all the problems related to the F-35.

Backman wrote:^ You probably mean that in gest but the US 6th gen doesn't even qualify as vaporware yet. The Euro FCAS and UK Tempest are at least 2-3 years ahead of the US 6th gen.

Lockeed&Martin said they are working on it since few years.

Tempest and FCAS are vaporware. Contracts are still not signed and wirk not even started. Germany and France will never agree. Germany even prefered to buy f-18 over Rafale because of jalousy (rafale better than typhoon). UK won't have the ressources to make such aircraft alone.

limb wrote:I wonder if the US 6th gen fighter will be flying by that time, and if the WS15s on the J-20 will be ready.

Also why would the aircraft with the new engines need many more years for testing, when all their other systems will be the same? Isnt the izd.30 being flight tested right now?

I wonder if Western 6G will be on par with Russian 5G... it seems US is just trying to correct all the blunders they did with F-22 and F-35, while Europeans find it more elegant to say they are designing the sixth generation than admitting they are 30 years late to the party

BTW, should this be the differences from T-50 to Su-57?

Sixth gen is the same BS as US hypersonic missiles. They will actually get those before they get the F-35 to work to spec.
The claim is that sixth gen will be the base of full sized AI piloted drones. Keep dreaming in Technicolor.

LMFS wrote:

limb wrote:I wonder if the US 6th gen fighter will be flying by that time, and if the WS15s on the J-20 will be ready.

Also why would the aircraft with the new engines need many more years for testing, when all their other systems will be the same? Isnt the izd.30 being flight tested right now?

I wonder if Western 6G will be on par with Russian 5G... it seems US is just trying to correct all the blunders they did with F-22 and F-35, while Europeans find it more elegant to say they are designing the sixth generation than admitting they are 30 years late to the party

BTW, should this be the differences from T-50 to Su-57?

Well the core of the 6gen fighter IMO will for it to be like 5th gen, but much faster( M2+ with supercruise), with more payload capacity, more automated, with several times more sensitive sensors, more jamming, and possible laser weapons.

Engines are the core of this, both for speed and powering avionics, and as you said, the F135 is the world's most advanced fighter engine and its mature, compared to the izd.30. If the americans figure out how to build a fighter with good performance around it(and also create more advanced F135 versions), it will have much superior kinematic performance than the 2nd stage Su-57

limb wrote:Well the core of the 6gen fighter IMO will  for it to be like 5th gen, but much faster( M2+ with supercruise), with more payload capacity, more automated, with several times more sensitive sensors, more jamming, and possible laser weapons.

So, a more modern 5G with some sci-fi claims that will not be implemented any time soon, to make the farce less obvious. Anyone knowing the state of the art sees right through their BS.

Engines are the core of this, both for speed and powering avionics, and as you said, the F135 is the world's most advanced fighter engine and its mature, compared to the izd.30. If the americans figure out how to build a fighter with good performance around it(and also create more advanced F135 versions), it will have much superior kinematic performance than the 2nd stage Su-57

The only shred of actual technological advantage supporting them is the adaptive engines. But:

> We don't know how far are they from real deployment
> An F-35 with an adaptive engine is just partially going to compensate for a crappy airframe in terms of poor thermal management and under-par supersonic performance. It will remove some of its current disadvantages rather than leave the rest of the pack far behind
> We don't know what the performance or even layout / technology of izd. 30 is, or how far Russia is along the design of three stream VCE, which they are developing too.

Add to that the fact that the bullshitting US have their BS level in overdrive trying to scare off China and Russia, and we have a SDI-type farce in play where current US weapons systems are crap but next ones are going to be all-mighty alien tech they are going to pull out of their rears and completely destroy any military argument their opponents may have. Interestingly, only retarded Western fanboys believe this, I am more than sure Russians and Chinese are laughing hard at this latest, sad attempt by a declining country to take ancient nations like them for idiots.

I found this to be of some interest:

Russia Is Using Augmented Reality To Produce Its Su-57 Fighter

https://www.thedrive.com/the-war-zone/38083/russia-is-using-augmented-reality-to-produce-its-su-57-fighter

You guys seen/heard the sound the Su-57's engines/intakes make, now? Some are suggesting it's the result of the radar deflection plate.
Most noticeable at:
- 0:20
- 1:38

Daniel_Admassu wrote:I found this to be of some interest:

Russia Is Using Augmented Reality To Produce Its Su-57 Fighter

https://www.thedrive.com/the-war-zone/38083/russia-is-using-augmented-reality-to-produce-its-su-57-fighter

Comments are a great example of Western retardation, poor idiots

LMFS wrote:

Daniel_Admassu wrote:I found this to be of some interest:

Russia Is Using Augmented Reality To Produce Its Su-57 Fighter

https://www.thedrive.com/the-war-zone/38083/russia-is-using-augmented-reality-to-produce-its-su-57-fighter

Comments are a great example of Western retardation, poor idiots

The Drive is literally the propaganda bullhorn for the F-35, and according to the readers of that site: The Su-57 is more expensive and with more flaws than the F-35 program.

The fact that the flaws of the F-35 program (which amounts to several dozen) is glossed over, yet the Su-57 literally called junk by their limp-wristed, pencil-necked, slack-jawed neckbeard editors (who are probably getting kickbacks form Lockheed Martin) is all you need to know about their editorial staff.

magnumcromagnon wrote:

LMFS wrote:

Daniel_Admassu wrote:I found this to be of some interest:

Russia Is Using Augmented Reality To Produce Its Su-57 Fighter

https://www.thedrive.com/the-war-zone/38083/russia-is-using-augmented-reality-to-produce-its-su-57-fighter

Comments are a great example of Western retardation, poor idiots

The Drive is literally the propaganda bullhorn for the F-35, and according to the readers of that site: The Su-57 is more expensive and with more flaws than the F-35 program.

The fact that the flaws of the F-35 program (which amounts to several dozen) is glossed over, yet the Su-57 literally called junk by their limp-wristed, pencil-necked, slack-jawed neckbeard editors (who are probably getting kickbacks form Lockheed Martin) is all you need to know about their editorial staff.

That is quite correct. The site is especially driven in its acclamation of anything the US MIC bakes. They are all the F-35 this and the F-35 that. Whenever they have to mention new Russian hardware it has to end with the usual 'vapourware' reminder. This particular article seems to tone it down for a change.

Well tbf that author seems unbiased compared to the regular western BS, but yeah the commentators are just circlejerking jingoistic russophobic boomers.

There is one criticism about the AR vision misaligning the bolt positions though which idk how valid it is.

limb wrote:Well tbf that author seems unbiased compared to the regular western BS, but yeah the commentators are just circlejerking jingoistic russophobic boomers.

There is one criticism about the AR vision misaligning the bolt positions though which idk how valid it is.

Dynamic AR comes inevitably with some alignment error at the level of the current processing limits. If the observer is standing perfectly still I am sure the computer won't have any issues aligning every bolt and rivet to the projection. But what good will that be as the whole point is to inspect and help with the assembly live. In that regard I think the tech is adequate.

Daniel_Admassu wrote:

limb wrote:Well tbf that author seems unbiased compared to the regular western BS, but yeah the commentators are just circlejerking jingoistic russophobic boomers.

There is one criticism about the AR vision misaligning the bolt positions though which idk how valid it is.

Dynamic AR comes inevitably with some alignment error at the level of the current processing limits. If the observer is standing perfectly still I am sure the computer won't have any issues aligning every bolt and rivet to the projection. But what good will that be as the whole point is to inspect and help with the assembly live. In that regard I think the tech is adequate.

It has nothing to do with it. The view is misaligned because the device was calibrated to match the view through the eyes, not the camera. It's like when you have different perspective through your left and right eyes, because there is some distance between them. Same thing applies here.

Look at the camera placement on hololens. Of course the recorded image and 3d projections won't match.

ult wrote:

Daniel_Admassu wrote:

limb wrote:Well tbf that author seems unbiased compared to the regular western BS, but yeah the commentators are just circlejerking jingoistic russophobic boomers.

There is one criticism about the AR vision misaligning the bolt positions though which idk how valid it is.

Dynamic AR comes inevitably with some alignment error at the level of the current processing limits. If the observer is standing perfectly still I am sure the computer won't have any issues aligning every bolt and rivet to the projection. But what good will that be as the whole point is to inspect and help with the assembly live. In that regard I think the tech is adequate.

It has nothing to do with it. The view is misaligned because the device was calibrated to match the view through the eyes, not the camera. It's like when you have different perspective through your left and right eyes, because there is some distance between them. Same thing applies here.

Look at the camera placement on hololens. Of course the recorded image and 3d projections won't match.

I think the presentation is a recording of the final overlay of the camera vision and the 3d model projection and not the headset recording. It had something connected with my graduate dissertation and used to read a few things about the field and upto until at least 2017 projection misalignment was a persistent issue even with high end dynamic AR headsets. The problem had been with lack of real time processing power of live imagery, in particular in depth perception of 2d cameras. Some high end sets included multi band data from IR sensors for 3d perception. But it has been a while since I read on the subject and don't know what is up these days.

ult wrote:

Daniel_Admassu wrote:

limb wrote:Well tbf that author seems unbiased compared to the regular western BS, but yeah the commentators are just circlejerking jingoistic russophobic boomers.

There is one criticism about the AR vision misaligning the bolt positions though which idk how valid it is.

Dynamic AR comes inevitably with some alignment error at the level of the current processing limits. If the observer is standing perfectly still I am sure the computer won't have any issues aligning every bolt and rivet to the projection. But what good will that be as the whole point is to inspect and help with the assembly live. In that regard I think the tech is adequate.

It has nothing to do with it. The view is misaligned because the device was calibrated to match the view through the eyes, not the camera. It's like when you have different perspective through your left and right eyes, because there is some distance between them. Same thing applies here.

Look at the camera placement on hololens. Of course the recorded image and 3d projections won't match.

The Drive being the usual retards. It's Russian must be something wrong with it.

https://defence-blog.com/news/microsoft-hololens-helping-russian-engineers-build-su-57-fighter-jet.html

Is this true?

LMFS wrote:The first is the plane, the second the CoG. If the plane with anhedral is higher than the CoG it contributes to stability.

I'm not sure if you have watched the video that I have posted, but wings placed well above the center of gravity, swept wings or dihedral wings tend to increase the roll restoring force making the plane more stable in the longitudinal axis.
On the other hand, anhedral wings have the opposite effect compared to dihedral and hence they are reducing stability in longitudinal axis.
The anhedral angle is often used for high mounted wings to "relax" the inherited stability of the high mounted swept wings so that the aircraft can be more easily maneuvered, and the other role anhedral wings play is in increasing the "Dutch roll" stability.
To much roll restoring force is increasing the Dutch roll tendencies because of disparity in directional and rolling stability and anhedral wing is used for more balanced ratio.

LMFS wrote:Good find again. An initial analysis would say you have two elements there, the LEVCON which acts most of the time as a LE flap, and the chine which would be a reduced size LERX. But the video proves the type of optimization that could be expected of Sukhoi-TsAGI but needed proof, that is, that there is a synergy between both and the vortexes can be transferred from one to the other, it appears to be a highly dynamical process. Agree on the rest of your comments and that was the bottom line of my argument too, that the use of the LEVCONS allows to keep the flow over the lifting body attached with a much smaller use of high-drag causing LERX. Probably this is going to help big time in supersonic flight and maybe also with excess power and acceleration in general. Remember we did not find that video you referred about Bodgan explaining the superior performance of Su-57 vs -27, but I do remember him saying how much attention the pilot needs to have to avoid going supersonic without even noticing. Him being used to pilot the -35, the difference needs to be more than marginal, and the thrust difference between those engines (izd. 117 vs 117S) is not really big.

I think the fact that it is not an additional LE to take care of in terms of RCS, as canards normally, is a nice advantage for a VLO plane. In terms of aero I am also not sure because I understand the close coupled, elevated canard provides more energy to the boundary layer similarly to how a LE slot would beat a normal LE flap. But probably the LEVCON is less draggy at reduced deflection angles and most of the vortexes as we see happen actually at the chines, which would be there nevertheless. So in fact this is a very clever design for a supercruising plane, as far as I manage to grasp.

Few days ago I have found very nice study about the "Influence of Canard Position on Aerodynamic Characteristics of Aircraft in Delaying Stall Conditions" : https://aip.scitation.org/doi/pdf/10.1063/1.5062792



It is interesting to see the vortex core visualisation in relation to the wing on different canard positions in both, the horizontal and vertical plane.
As we can see, the least amount of interaction is attributed to the long coupled canard position, like in the case of the EF2000, and that is the reason I have proposed the theory that the anhedral angle is used for better interaction of the wing tip vortex with the main wing.

Here is also a chart with the lift coefficient:



We can see that the lift coef. is almost the same for all configurations, including the no canard conf. till 20 deg. AoA. After that the lift is starting to increase for all canard configurations compared to no canard conf.
"The results showed that the addition of canard would be able to increase the lifting force coefficient up to 5 - 12.1 %. The canard position on the main wing affects to the vortex flow interaction, the value of lift coefficient, and maximum angle of attack. In the canard position on the upper side and adjacent to the main wing gives the best value against the maximum Cl value shift between 5 - 10 degrees which indicates a stall delay in the aircraft model."

It is interesting that similar results can be obtained with the use of LERX:





http://www.dl.begellhouse.com/journals/58618e1439159b1f,143d87610f727f67,0b49d4f31b5bdc82.html

"It is shown that the dynamics and stability of the vortex structures have a significant effect on the entire model aerodynamics, especially at high angles of attack. Analysis of the flow visualization shows that increasing vortex intensity, loss of stability, vortex breakdown, and displacement of the vortex breakdown point toward the leading edge of the streamlined surface are the general characteristics of the vortex structures at increasing angles of attack. Test numerical simulations are performed in order to determine the position of the vortex breakdown depending on the angle of attack for a delta wing. Analysis of the simulation results allows stating a preliminary principle of the vortex system control in order to obtain acceptable aerodynamic characteristics at high angles of attack. It is necessary to use engineering solutions aimed at delaying the vortex breakdown and increasing the distance between the vortices to reduce or eliminate their mutual interference. The simulation results are in satisfactory agreement with the experimental data obtained during the model tests in the T-102 wind tunnel at TsAGI. These results can be interpreted as input data for further investigations with the aim of controlling the vortex flow over maneuverable aircrafts"

This is exactly what is done by using the LEVCON's!

LEVCON's can increase the efficiency of the LERX at any AoA, not only at higher angles of attack, additionally increasing the lift coef. and can delay the vortex breakdown compared to the fixed LERX.
Not only that, LEVCON's can be used for directional stability/controlability [using differential deflection] and have a high AoA pitch down authority even if the TVC is having a malfunction.
I also tend to believe that the use of LEVCON had a big impact in size reduction of the vertical tail, and since the LEVCON has similar role as an LE flaps, it is interesting to note what role does the LE flaps have at high AoA.

https://www.nasa.gov/centers/dryden/pdf/88489main_H-2149.pdf

Leading-Edge Flap Effects

"Leading-edge flaps can have a significant influence in this forebody/LEX flow interaction and therefore high-angle-of-attack lateral-directional stability. By reducing wing separation at a given angle of attack, leading-edge flaps can reduce the effects of the upstream flow field (i.e. the forebody and LEX flow fields). In the case of F/A-18 development, the lateral instability that was observed in the region was alleviated by increasing the leading-edge flap deflection from 25° to 33°. The effect of the leading-edge flap deflection and noseboom on lateral-directional stability of the two models is shown in figure 29 for the NASA-2 16% (α = 40°) model and figure 30 for the NASA 6% model (α = 37°). In both cases the destabilizing effect of the boom was reduced by increasing the leading-edge flap deflection. As seen previously the effect was more pronounced on the NASA 6% model than on the NASA-2 16%. This delayed wing flow separation to a higher angle of attack, and lessened the unstable effects of the LEX vortices acting on the mostly separated flow over the wing surfaces. Since the forebody vortices interact favorably with the LEX and the noseboom disrupts the forebody flow field and attenuates the forebody vortices, the noseboom
is a destabilizing influence. However, with the leading-edge flap deflection increased to 33° this destabilizing influence is mitigated as shown in figure 30(b). The NASA-2 16% model showed much less sensitivity in lateral aerodynamics from this change in flap deflection.

A large stabilisation is related to a deflected leading-edge flap as shown in figure 5.29. As can be seen, the lower part of the critical a-range is stabilized. A slat, as shown in the next figures 5.30 and 5.33 for two different configurations, has a different characteristic of stabilisation. In both cases lateral stability is improved over the whole tested high-a region."

What that does in practical terms?



We can see that the PAK FA is having about two times faster yaw rates than the Su-35S!
It also means that it can arrest yaw/roll rate more efficient, it can much sooner regain the lift over the wings and hence reduce the sinking rate when exiting Post Stall region, it can regain speed and altitude much sooner, it can have faster turn rates etc.

And just to put it to perspective, here is how F-22 is comparing to the Su-35S at certain Post Stall conditions



It is also interesting to note that the most modern Canards don't have the nose pointing capability of the classical layout plane such as F-18 for example let alone the controlability of the PAK FA!



We can see that the PAK FA is able to do a roll at AoA close to 90 deg., but what is interesting is the fact that the vortex burst is happening much sooner at the left side where the LEVCON is at its highest position [like in the case of the fixed LERX] compared to the right side where the LEVCON is deflected.

PeregrineFalcon wrote:
I'm not sure if you have watched the video that I have posted, but wings placed well above the center of gravity, swept wings or dihedral wings tend to increase the roll restoring force making the plane more stable in the longitudinal axis.
On the other hand, anhedral wings have the opposite effect compared to dihedral and hence they are reducing stability in longitudinal axis.
The anhedral angle is often used for high mounted wings to "relax" the inherited stability of the high mounted swept wings so that the aircraft can be more easily maneuvered, and the other role anhedral wings play is in increasing the "Dutch roll" stability.
To much roll restoring force is increasing the Dutch roll tendencies because of disparity in directional and rolling stability and anhedral wing is used for more balanced ratio.

Yeah you are right, I got that wrong.

Few days ago I have found very nice study about the "Influence of Canard Position on Aerodynamic Characteristics of Aircraft in Delaying Stall Conditions" : https://aip.scitation.org/doi/pdf/10.1063/1.5062792

Thanks for the link  

It is interesting to see the vortex core visualisation in relation to the wing on different canard positions in both, the horizontal and vertical plane.

It is quite striking that they simulate such AoAs with canard deflections that do not relate to real deployment of the control surfaces in actual current aircraft. After the onset of the maneuver, canards are kept at reduced AoA in order to help keep the airflow attached to the wing, not in the same angle as the wing. This very much affects the results of the simulations.

As we can see, the least amount of interaction is attributed to the long coupled canard position, like in the case of the EF2000, and that is the reason I have proposed the theory that the anhedral angle is used for better interaction of the wing tip vortex with the main wing.

I see no problem with your theory

We can see that the lift coef. is almost the same for all configurations, including the no canard conf. till 20 deg. AoA. After that the lift is starting to increase for all canard configurations compared to no canard conf.
"The results showed that the addition of canard would be able to increase the lifting force coefficient up to 5 - 12.1 %. The canard position on the main wing affects to the vortex flow interaction, the value of lift coefficient, and maximum angle of attack. In the canard position on the upper side and adjacent to the main wing gives the best value against the maximum Cl value shift between 5 - 10 degrees which indicates a stall delay in the aircraft model."

There was a study for the J-20 where they showed that canard + LERX had a synergistic effect improving the Cl of the plane, I think it was mainly due to vortex interaction. In that plane though, the canard in the same plane as the wing negatively effects lift during positive deflection.

It is interesting that similar results can be obtained with the use of LERX:

See above, the simulation is not realistic because LERX is fixed and works by creating vortexes while canards are mobile and they also keep airflow attached to the wing without the need to create draggy vortexes. Look this:



The canards are in this case used as a LE "slat", with the advantage that the airflow is more energized than it would be with a LE flap. That is the reason why I think they are superior in terms of lift augmentation even to a LEVCON like that in the Su-57, but I cannot prove it conclusively.

This is exactly what is done by using the LEVCON's!

LEVCON's can increase the efficiency of the LERX at any AoA, not only at higher angles of attack, additionally increasing the lift coef. and can delay the vortex breakdown compared to the fixed LERX.
Not only that, LEVCON's can be used for directional stability/controlability [using differential deflection] and have a high AoA pitch down authority even if the TVC is having a malfunction.
I also tend to believe that the use of LEVCON had a big impact in size reduction of the vertical tail, and since the LEVCON has similar role as an LE flaps, it is interesting to note what role does the LE flaps have at high AoA.

Yes this is definitely interesting. I agree the LEVCON has a big impact in the size of the tails, since it allows to keep airflow attached to the lifting body at high AoA and therefore maintains the authority of the keels. Otherwise --> F-22

We can see that the PAK FA is having about two times faster yaw rates than the Su-35S!
It also means that it can arrest yaw/roll rate more efficient, it can much sooner regain the lift over the wings and hence reduce the sinking rate when exiting Post Stall region, it can regain speed and altitude much sooner, it can have faster turn rates etc.

I cannot judge that, no one is saying neither of the planes is trying to yaw as fast as possible. The Su-35 is equipped with LE flaps over the length of the wing. I agree though that the airflow management of the Su-57 with mobile LEVCONS + small LERX over the fuselage should be far superior to that of the Su-35 with big fixed LERX only.

It is also interesting to note that the most modern Canards don't have the nose pointing capability of the classical layout plane such as F-18 for example let alone the controlability of the PAK FA!

Eurocanards are single tail planes and therefore their high AoA handling is not on par with that of other twin keel designs. I don't have an opinion about J-20, have not researched enough.

We can see that the PAK FA is able to do a roll at AoA close to 90 deg., but what is interesting is the fact that the vortex burst is happening much sooner at the left side where the LEVCON is at its highest position [like in the case of the fixed LERX] compared to the right side where the LEVCON is deflected.

That is a complex maneuver to analyse. But in any case, the LEVCON should delay the onset of turbulent airflow regime at high AoA when deflected downwards, this is as expected.

Another users criticism regarding the aircraft's features.

Inlet: The SU-57 inlet is not the best design for signature reduction. There is zero debating here. In terms of what the intake is made of, we don’t know. But I am talking about the design itself. All those ramps, gaps, sharp corners, and radar blockers are just extra opportunities for radar waves be sent back to the enemy radar. I’m not saying the intake will cause the SU-57 to be seen on radar but instead that it has a larger RCS then say an intake from an F-35 or F-22 where there is nothing causing destructive interference. In other words the smoother the surface the less chances the radar signals will reflect back. What I am saying is that an inlet from something like an F-35/22 would have a lower RCS. What we do know is that the smoothest surfaces are the best at minimizing EM energy from being sent back to the receiver. The SU-57 has inlet ramps and gaps from those ramps. The radar blockers themselves would also cause some issues because the inlets are perpendicular.

LEVCONs: The LEVCONs are another discontinuity, not only that they actually move in flight and have sharp corners. They help with lift and probably marginally help in maneuverability? However, they add weight from hydraulics, actuators, and extra wiring, they certainly add to cost because of those extra components. Similarly they add cost into development since designers hade to design all those components and then test them under different lab and and in flight conditions. This is overly complicated and not necessary, in my opinion. That money and effort could have been used to reshape the IRST or add more serrated panels or whatever. I think the guys at Sukhoi are just obsessed with maneuverability and showing off how maneuverable their aircraft are.

IRST and other sensors: It doesn’t take a scientist to figure out the IRST and two 101-KSO sensors have zero effort or thought put into them. Sukhoi didn’t make any effort at all. The IRST has a 90 degree corner on the starboard side and a large gap aft of the IRST. Compare that to the careful and well thought out shape of the EOTS of the F-35 or the equivalent system on the J-20. The Americans and Chinese didn’t go through all that trouble for no reason.

Canopy: The Canopy is completely traditional and it’s shape is poor for RCS. The reason the F-22, F-35 and J-20 have trapezoid shaped canopies as well as a single piece canopy is because it, 1. Redirects radar waves and 2. Eliminates discontinuities by having one piece.

Serrations. Sadly the SU-57 has virtually no serrated panels besides the weapons bays, front landing gear, and a few panels for sensors up front. Again if we compare it with aircraft like the F-35, F-22 and J-20 which have probably thousands of serrated panels, it becomes clear the designers at Sukhoi were either lazy, didn’t want to spend the extra time and maybe marginal cost on serrations.

Currently agree probably with the DIRCM and 101ks-o bulbs. But not at a full agreement because the ThNDR DIRCM was to have the same 6 side polygon shape like the EOTs last time in 2012 and they are showing 2015 image of the F-35 having a double DIRCM bulb 100kw appearance assuming if the sapphire glass would be added. Would adding a sapphire glass for the 101ks-o help or would it add RCS?

...some of those criticisms are just ridiculous. from f-16.net or something?