Sukhoi Su-57 flight testing, development & operations [2012-current]

[overscan (PaulMM)]

Probably 15900 kgf for AL-41F-1 and 17200 kgf for izd.30

Reading way too much precision into a Powerpoint graphic.

 

[overscan (PaulMM)]

Friend ,when we talk about MTOW ,again data from the Su-27SK's Flight Manual :

''Максимальная взлетная масса 33000 кг (при установке колеса КН-41 с шиной модели 017А и колеса КТ-156Д с шиной модели 2А).

Максимальная взлетная масса 28000 кг (при установке колеса КН-27 с шиной модели 016А и колеса КТ-156Д с шиной модели 2А).''

Suppose that MTOW of Su-57 is ≈35 tons,more or less that's it. We must count on every detail such as that Al-Li Alloy used in Su-57's structure is lighter then Al Alloys used in Su-27( V95 and Dural) .Of course Su-57 has composite and metallic skin. Even FWC-fuselage weapon compartments are strenghtened, they are made from very light Al-Li Alloy. As wrote before, engines are lighter by in total of 300kg ,then vertical stabilizers are much smaller and lighter. What about avionics and other el. equipment. Old mechanical radar N001 Myech is alone heavier then all eight AESA radars of N036 Byelka radar system ,I supose but it is very possible.Then we have that fiber optic wiring and of course digital quadraplex FBW vs old hydro-mechanical control system.Also all systems and subsystems in Su-57 are digital,in Su-27 analogue ( heavier of course). You mentioned fuel system with all components , yes but where is hydraulic control system etc.​

All of this can tell us that empty weight of both is in the same level,if, again if Su-57 is maybe even lighter on tarmac then Su-27?

All your posts are heavy on speculation and low on facts, and you keep ignoring people giving you contradictory evidence. For example, the good evidence that Al-Li is not heavily used as intended.

This is not a good combination for longevity on this forum.

 

[overscan (PaulMM)]

Somebody is still going to have to explain how "plasma ignition" improves the thrust values of any jet engine.

2013 Chinese paper on Plasma ignition says its lighter and performs better as an ignition device over a wider range of conditions than a conventional ignition system. That's all.

https://www.sciencedirect.com/science/article/pii/S2212540X13000382

 

[Squirrel]

Somebody is still going to have to explain how "plasma ignition" improves the thrust values of any jet engine. Once the fuel has been ignited in both the main and AB sections, it is self sustaining and 99% complete combustion. Better or more powerful ignition systems may be useful in initiating combustion in the far corners of the flight envelope for main combustor relight after flameout, and AB ignition in the upper left corner, but it doesn't make any more thrust once lit.

It seems that catch of using plasma ignition system is not in increasing thrust values but in reaction time between engine working modes.

 

[RadicalDisconnect]

Judging by this diagram,max static thrust in Full AB mode ( special regime) is between 15000kgf and 16000kgf.

View attachment 751343


Soruce: https://bmpd.livejournal.com/3221633.html

This is a presentation powerpoint chart where the engine model graphics are all spaced evenly from each other in both horizontal and vertical axis, and no mention of whether its to scale or not. Doubtful this can be used to calculate thrust figures from.

To continue the story about construction materials if I can. So we have that Al-Li Alloy V-1461(not 1441 as mentioned before, sorry ,RadicalDisconnect was right) with about 50% of the empty weight of the serial Su-57. As we know this metallic structure material is applied in complete structure of air intakes and centroplane,in that big upper cross section of the centroplane,leading edges of the wings and LEVCON's ,complete carrying inner and skin structure of the vertical stabilizers then in the inner and partially in the skin structure of the horizontal stabilizers.Also it is applied on the places where the wing hardpoints are and as structural carrying inner parts of the wings. Al-Li Alloy V-1641 is welded with Argon. As mentioned before, Al-Li Alloy V-1641 is easily to identify by its yellow color.

And Sukhoi specifically said that their attempts at incorporating the 1461 Al-Li alloy did not work. It could not withstand impact riveting, and had unexpected failure mechanics with particular issue of plastic deformation, and Sukhoi also consider the test samples from VIAM to be cherry-picked. Sukhoi went into this in detail in their 85th anniversary book, and how after a dramatic failure with static testing of T-50-7 with the 1461 Al-Li alloy, Mikhail Strelets decided to abandon it and go back to alloys like B-95, with the conversion happening in phases so that it doesn’t disrupt production of prototypes, and by the time serial aircraft were made, the 1461 alloy is only in some non-load bearing parts. In fact this was reported by insiders back in 2016, and now Sukhoi’s own published account confirms it.

 

[flateric]

If you watched that reportage, you could see that they have models / mock-ups of practically every Western/ NATO aircraft and even space assets . Sergey Nesterov said in one moment that they had and tested the B-2A model ten years before it became operational at all!

I can see bunch of models having poorly reproduced OMLs of prototypes. Regarding B-2 model tested 'ten years before IOC' - it is an utterly BS.

 

[RadicalDisconnect]

That is not correct, Su-27 was primarily designed to be air superiority fighter like the F-15C, and its weight is in line with its intended role.
171000 kg number is actually the amount of lift in kg Su-27 can generate below Mach 0,85 and at 9G, which is simply huge!
And of course, the plane is capable of pulling 9G at weight going over 19000kg.
For example, at 3000 m altitude, the plane can sustain 9G’s at 900 km/h IAS, weighing 20000 kg.

Source? Because in the Su-27SK manual, 171,000 kg was specifically listed as "overload" (перегрузка) for conditions of under Mach 0.85, and even the formula was given. Of course the aircraft is capable of somewhat more but only as a safety margin, because all aircraft have some safety margin designed in.

Su-57 has smaller wings with longer cord length and thinner airfoil, which doesn’t require as much strengthening as the longer, ticker wings of the Su-27, but can store significant amount of fuel because of greater surface and better usage of internal space.
...
Overall body of the Su-57 is made out of different type of airfoils, which create huge amount of lift and in turn provide the possibility to install the wings with small relative thickness and sharp sweep angle (sharper than F-22 and much sharper than F-35) which in turn translates to excellent transonic and supersonic characteristics. The trapezoidal wing has a negative sweep of the trailing edge, which makes it possible to achieve high values of chord lengths in the root part, and to reduce the relative thickness of the wing in this zone at high values of the absolute thickness of the wing.
...
The consequence of the Su-57 flattened layout is a uniform distribution of the air load/pressure over the surface of the airframe and an increase in the load-bearing properties of the fuselage in terms of creating lift, which makes it possible to maintain the excellent aerodynamic characteristics of the aircraft as a whole with a smaller wing area and less airframe strengthening.

That's not correct, a thinner wing will need more strengthening because it has less area moment of inertia around the bending axis. A longer root chord is better structurally compared to Su-27, and also will help make the absolute thickness greater for the same t/c percentage but root chord of the Su-57 wing where they attach to the fuselage centroplane is not much different from the F-22 (a heavier aircraft than Su-27) mainly because of the centroplane's width. And while widening the fuselage to increase body lift helps reduce the load from the wings, the fuselage is a very low aspect ratio lifting surface, so it also has more induced drag while turning. So it's not always a benefit.

Structurally, the Su-57 fuselage design with the centroplane, while has good useful volume, is structurally risky because while the fuselage depth between the engines is greater than Su-27, a large amount of that depth is not structural because lot of volume is occupied by weapons bays which runs across the entire wing root chord where loads both bending and potentially torsion are the highest. And the weapon bays are structural "holes", not being closed structural loops and don't carry those loads. The only full depth bulkhead is the one pair between the weapons bays. Whereas the F-22's weapon bay volume is almost all in front of wing at the highest loads, so most of those bulkheads across wing root chord are full depth of fuselage which carries loads better.
Not to say that Su-57 can't be lighter, it's possible but that likely involves some tradeoffs in other areas. Nothing is "free" here, everything is part of a compromise in all aircraft designs.

The benefit to the Su-57 fuselage is that for a given fineness ratio, it has very large internal weapons bay capacity, something the Sukhoi patent specifically calls out and Strelets highlighted in interviews too. But the structural risk is undeniable, and you can see that part of the centroplane needing to be reinforced starting with T-50-4 with that visible patch of metal on the back compared to T-50-1 initial design. And T-50-1 and T-50-2 were reinforced too after suffering cracking from MAKS 2011. And this patch of reinforcement on back of centroplane carried over even to Stage 2 redesign and onto serial aircraft. Again Sukhoi's 85th anniversary book goes into the detail of the structural reinforcement needed because the initial T-50/Su-57 design couldn't perform necessary overload.

On the other hand, F-22 is using huge S shaped intakes that curve in horizontal and vertical plane occupying huge amount of space that could otherwise be used for more fuel and bigger/deeper weapons bay, and what is worse, they have placed the main weapons bay below the intakes, and fast weapons bay to the side of each intake.
That creates huge midsection (which is not so good for the best lift to drag ratio) that has “holes” above the holes, with the holes on the each side. So, we have huge surface of empty space that is far more demanding from strengthening point of view, when compared to the Su-57 layout.
F-22 bulkheads have to be much more ticker to be able to provide the most optimal performance.
...
On top of that Su-57 designers are claiming that the plane is lighter and faster than F-22, and there is absolutely no reason to doubt that.

No. The curve of the F-22 intake ducts do create the space for weapons bays. And while the weapons bays are structural "holes", most of it is in front of the wing. Which means that across most of the wing's chord, the structural bulkheads are full depth which carries structural loads better. While the Su-57 structural "holes" from the weapon bays run across the entire wing chord preventing full depth bulkheads at all except the one pair between the two main weapons bays, so the structural depth of the fuselage between the engines is otherwise quite thin. So it's the Su-57 layout that requires more strengthening. Again Sukhoi had to do an entire Stage 2 redesign of internal structure. And this is why some of the light weight numbers are implausible for the Su-57.
And from lift/drag perspective, take into account the overall volume. A wider, flatter fuselage on Su-57 is beneficial for max lift but also creates more surface area for parasitic drag. And while L/D ratio may be better, the reference area also bigger with a flatter wider fuselage, so for drag it can go either way depending on the flight condition. Especially since lift coefficient at level flight also reduces with increasing speed. Not saying either fuselage shape is better since there are tradeoffs but it's not just one being superior than the other as portrayed here.

When it comes to these weight and speed claims of Su-57 versus F-22, I've seen claims circling around media and by journalists but Sukhoi itself hasn't made any claims one way or the other.

Su-57 volume - 60.4 m3
Su-35S volume - 69.4 m3
F-22 volume - 65.3 m3
F-35A volume - 49.7 m3

Appears unlikely how can Su-57 managed more internal fuel volume, more internal weapons bay capacity, larger number of control surfaces, all while having less overall volume than the F-22? That does not seem plausible.

 

[paralay]

F-22
weapons bay volume 6.73 m3 (10%)
fuel system volume 14.01 m3 (21.5%)
airframe volume 65.3 m3

Su-57
weapons bay volume 6.5 m3 (11%)
fuel system volume 12 m3 (20%), fuel RT-1 0.775 kg/m3 or T-6 0.84 kg/m3
airframe volume 60.4 m3

 

[VTOLicious]

F-22
weapons bay volume 6.73 m3 (10%)
fuel system volume 14.01 m3 (21.5%)
airframe volume 65.3 m3

Su-57
weapons bay volume 6.5 m3 (11%)
fuel system volume 12 m3 (20%), fuel RT-1 0.775 kg/m3 or T-6 0.84 kg/m3
airframe volume 60.4 m3

Without a 3D model suitable for this purpose (solid body), it is difficult to determine the airframe volume precisely. If you have one, please share

 

[Squirrel]

This is a presentation powerpoint chart where the engine model graphics are all spaced evenly from each other in both horizontal and vertical axis, and no mention of whether its to scale or not. Doubtful this can be used to calculate thrust figures from.


And Sukhoi specifically said that their attempts at incorporating the 1461 Al-Li alloy did not work. It could not withstand impact riveting, and had unexpected failure mechanics with particular issue of plastic deformation, and Sukhoi also consider the test samples from VIAM to be cherry-picked. Sukhoi went into this in detail in their 85th anniversary book, and how after a dramatic failure with static testing of T-50-7 with the 1461 Al-Li alloy, Mikhail Strelets decided to abandon it and go back to alloys like B-95, with the conversion happening in phases so that it doesn’t disrupt production of prototypes, and by the time serial aircraft were made, the 1461 alloy is only in some non-load bearing parts. In fact this was reported by insiders back in 2016, and now Sukhoi’s own published account confirms it.

OK ,I know for this book ...'История взлета: ОКБ Сухого исполнилось 85 лет'

from: https://paralay.iboards.ru/viewtopic.php?p=732083#p732083

I've read it. Now in this page below it is written that by the beginning of 2011 during static /ground tests there was some problems with airframe strenght.First static tests began during 2009. Prototypes T-50-1 and T-50-2 were for the flying tests of the airframe's streghtiness. T-50-3 and T-50-4 were for the testing of the radar system N036 Byelka ( -3 with the main forward looking AESA and -4 with additional two AESA as SLAR). T-50-4 first got that big metallic skin section on the upper side of the centroplane,yes.

T-50-1/T-50-2 first fllights

Су-57 / Т-50 / И-21 / ПАК ФА | MilitaryRussia.Ru — отечественная военная техника (после 1945г.)

Сборник справочной информации по отечественным системам вооружений выпуска после 1945 г., форум

militaryrussia.ru

T-50-3 first flight

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www.1tv.ru

T-50-4 first flight

ПАК ФА Т-50-4 (фото)

4-й лётный экземпляр истребителя пятого поколения Т-50, первый полёт 12.12.2012+ 10 фото! (кликабельно)

sdelanounas.ru

Now some details about that '1461' .It was written that AL-Li Alloy 1461 was used only for some structural parts/ panels from prototype T-50-6 etc,so for the second stage prototypes with goal to reduce the weight by 100-120kg.This was done in accordance with construction documentation for the second stage prototypes.
After a while as we can read the problems went bigger and bigger and finally they decided to throw out that Alloy.Now I have some questions to ask. If '1461' was used from T-50-6 which Al-Alloy was used earlier ? We know for the problems with that big composite skin panel on the upper side of the centroplane which appeared earlier. Solution was found with that big cross Al Alloy section but which Alloy exactly? One more thing ,in the first part of the reportage 'From T-50 to Su-57' ,author Aleksey Egorov saw some details of the static strength testing of the T-50-7( sequences from 29th min ).Test was successful. It happened maybe during 2018 when reportage was made or even earlier.

View: https://www.youtube.com/watch?v=PUxPLJXFjHw

From T-50 to Su-57. The most modern and the most classified Russian 5th generation airplane. Part 1.​

View: https://www.youtube.com/watch?v=N4-RwreHRRg&t=1850s



About Al Alloys V95 and 1461 there is one pretty good comparative analyses ( from 2020) :

''Проведены усталостные испытания образцов, изготовленных из отформованных панелей сплавов В-1461 и В95, построены усталостные кривые. Фрактография поверхности усталостного излома показала наличие окислов у образцов сплава В-1461 в отличие от сплава В95. Обсуждаются результаты испытаний на усталость, показывающие, что характеристики технологического процесса формообразования и термообработки не ухудшают усталостные свойства исследованных сплавов. Сравнительные испытания показали, что сплав В-1461 имеет более высокие усталостные характеристики.''

Tranls :

''Fatigue tests were carried out on samples made from molded panels of Alloys V-1461 and V95 and fatigue curves were constructed.Fractography of the fatigue fracture surface showed the presence of oxides in samples of Alloy V-1461 in contrast to Alloy V95. The results of fatigue tests are discussed showing that the characteristics of the forming and heat treatment process do not degrade the fatigue properties of the Alloys studied.Comparative tests have shown that Alloy V-1461 has higher fatigue characteristics.''

Source: https://cyberleninka.ru/article/n/v...l-cu-li-zn-i-v95-al-zn-mg-cu-na-soprotivlenie

So it was 'fatigue issue' and VIAM/ Sukhoi knew that for sure.

More interesting data, first chief designer A.N.Davidenko once said that composites are used not only in the skin structure but also as structural material of inner parts and components. Let us see about :

''Композиционные материалы на основе алюминия

Замена сплава В95 при изготовлении лонжерона крыла самолета на титановый сплав с подкрепляющими элементами из сплава ВКА 1 увеличивает его жесткость на 45% и дает экономию в весе около 42%. К тому же дисперсионно упрочненные сплавы не имеют анизотропии свойств, как волокнистые композиционные материалы.''

Transl.

''Aluminum-based composite materials

Replacing the V95 Alloy in the manufacture of an aircraft wing spar with a Titanium Alloy with reinforcing elements from the VKA1 Alloy increases its rigidity by 45% and provides a weight saving of 42%. In addition ,dispersion-strengthened Alloys do not have anisotropy of properties like fiber composite materials.''

Sources :

Маркировка алюминия и алюминиевых сплавов используемых в авиации

Маркировка алюминия и алюминиевых сплавов используемых в авиации. Типы, характеристики и наименования.

clstunt.ru

Справочник по авиационным материалам и технологии их применения

СПРАВОЧНИК «АВИАЦИОННЫЕ МАТЕРИАЛЫ»

viam.ru

What if all of this marked with red lines is Ti Alloy/VKA1 Alloy ?




Now as we can see, there is no real info about Al Alloy that was used from the beginning ,from T-50-0/KPO then T-50-0KNS ,T-50-1/-2 etc. So both of us were right and were wrong. Maybe it is a V95 or maybe it is a 1441, or both of them ,we simply do not know. We now know that they tried to do some job with that Al Alloy 1164 but unsuccessfully.

In this material we can only see ''Al Alloys'' ( plural) but which exactly ,the rest is undefined.So there is more then one,like Ti Alloys,have found info that besides Alloy VT22, they also used VT23. For comp. USAF F-22A has 6 differ. Ti Alloys.




About empty weight of the Su-57,hm .This photo from 2010 is so interesting. Su-35UB and T-50-1. Su-35UB has empty weight close to 19 tons. T-50-1 is just like a baby besides him.

 

[paralay]

Without a 3D model suitable for this purpose (solid body), it is difficult to determine the airframe volume precisely. If you have one, please share

We compared your model with my calculations, the difference is insignificant.
Unfortunately, I can't get full-fledged models yet, but I can model weapons bay

 

[AGS-1787]

There is a satellite picture on Paralay’s site that has them parked near each other. The su-57 seems shorter. The su-57 looks way smaller sideways in comparison to the flanker, if sits lower to the ground and has smaller vertical tails. The frontal cross section seems bigger for the su-57. It’s really interesting how intentional these measurements and sizes look if you compare different aircrafts. For example if you compare a su-57 to an f-22 then it gets really interesting.

 

[Squirrel]

I can see bunch of models having poorly reproduced OMLs of prototypes. Regarding B-2 model tested 'ten years before IOC' - it is an utterly BS.

Thanks to T.B.Cavanagh ,Soviets knew for the B-2A from the beginning of 1980's.

Several details of the Su-57's wings we can see in this video.

View: https://www.youtube.com/watch?v=dim4MszL1WQ

 

[flateric]

Thanks to T.B.Cavanagh ,Soviets knew for the B-2A from the beginning of 1980's.

tell me more please what we did know from the beginning, please
you even don't know Cavanagh story per se

 

[VTOLicious]

We compared your model with my calculations, the difference is insignificant.

If you are talking about Gripen, the difference was significant! 24.2 m³ vs 33 m³

 

[paralay]

https://www.secretprojects.co.uk/threads/design-challenge-lightweight-multirole-fighter-lmf.38539/post-512729

Unfortunately, I deleted my other messages in protest, I probably need to repeat this again....

 

[Squirrel]

Cockpit of the Su-57E Bort number 057 blue as non-flyable technological demonstrator for the export version.It seems that Algeria is the first customer of the Su-57E.Arrangement of the HUD with small screen and one big panoramic screen was first shown to public on MAKS 2019 then inside the cockpit of Su-57E on MAKS 2021. It is produced by the company Elkus from St. Petersburg.

https://twitter.com/x/status/1175488542711193600

View: https://x.com/StefanKnippsch3/status/1175488542711193600

https://dzen.ru/a/YP_WMQFl71EwtuSM

This is not what cockpit of the serial/operational Su-57's looks like. This is what looks like cockpit of the serial Su-57.



Cockpit of the real serial Su-57 in KnAAZ ( from 2: 00 min)

View: https://www.youtube.com/watch?v=FtuN3E13AU8



Some nice walk-around pics of the Su-57E made at Kubinka AB , Army-2021 exhibition.

Su-57 (Interrupted) walkaround

Taken yesterday at Kubinka AFB, part of the Army-2021 exhibition. I was politely asked to stop taking pictures after few minutes.

www.arcforums.com

 

[Life of Tyo]

how about this Su-57 Simulator cockpit

 

[PeregrineFalcon]

Source? Because in the Su-27SK manual, 171,000 kg was specifically listed as "overload" (перегрузка) for conditions of under Mach 0.85, and even the formula was given. Of course the aircraft is capable of somewhat more but only as a safety margin, because all aircraft have some safety margin designed in.

Sorry for the late reply, I didn’t have the time for writing!

“перегрузка“ would be equivalent to the US “load factor - G”.
Under number 2. from your chart, it is stated that the maximal exploitation/operational load factor (G limit) is 8G under 21400 kg flight weight.
171000 kg of lift force corresponds to that weight and G load.
People should be careful with these data because as far as I know, that data is taken from the pilots handbook G limit for the Su-27, and there is different set of G limits for combat performance, from supplemental manual. From my understanding, Su-27 in peace time conditions is always limited to 8-8,5G’s.

Here is the chart for similar type of limitations for the F-15:



That only shows that your claim that Su-27 is somehow light because it can’t withstand G forces other fighters can under similar conditions is unfounded.
Here is the chart I was talking about:



It states, “перегрузка” - load factor for the sustained turns at the weight of 20000 kg (missiles included, 50% of fuel from the normal fuel load etc.)
The full lines represent the G load for the 8G limit, and intersected lines represent the G load when the exploitation 8G limit is exceeded/overridden.
If there was serious danger of destroying the airframe under 9G sustained turn at 20000 kg, there wouldn’t be such option on the EM chart, and the plane would be hard limited to 8G.

That's not correct, a thinner wing will need more strengthening because it has less area moment of inertia around the bending axis. A longer root chord is better structurally compared to Su-27, and also will help make the absolute thickness greater for the same t/c percentage but root chord of the Su-57 wing where they attach to the fuselage centroplane is not much different from the F-22 (a heavier aircraft than Su-27) mainly because of the centroplane's width. And while widening the fuselage to increase body lift helps reduce the load from the wings, the fuselage is a very low aspect ratio lifting surface, so it also has more induced drag while turning. So it's not always a benefit.

Su-57 is basically using cropped delta wing, and here are the basic structural benefits from using such wing:
“The long root chord of the delta wing and minimal area outboard make it structurally efficient. It can be built stronger, stiffer and at the same time lighter than a swept wing of equivalent aspect ratio and lifting capability.

Its long root chord also allows a deeper structure for a given airfoil section. This both enhances its weight-saving characteristic and provides greater internal volume for fuel and other items, without a significant increase in drag. However, on supersonic designs the opportunity is often taken to use a thinner aerofoil instead, in order to actually reduce drag.”



Su-57 has significantly shorter wings, and when pressure is applied, much longer and narrower wings of the Su-27 suffer from much greater moment arm/leverage from the force acting upon it, so they need more strengthening for the same load.

And when we talk about lift to drag ratio, I have almost no doubt that Su-57 is superior in this regard. F-22 according to measurements has worse L/D ratio than Su-27 (11,6 vs 10,1 if I remember correctly).
Taking into account the amount of fuel F-22 can carry, it has very poor range (not so efficient engines and not so stellar lift to drag ratio will do that).
Su-57 is highly unstable plane (both in pitch and lateral direction) which provides excellent L/D ratio in subsonic/supersonic area, and that was possible to do with the use of LEVCON’s which can actively control the center of lift.
There was a study where they were comparing standard model with fixed LERX, and the one that had movable frontal part (LEVCON).
For example, the data for the 25 deg. AoA, shows that the model without LEVCON deflection has Cl - 0,726 and Cd - 0,329.
For the same AoA, model with LEVCON deflection has Cl - 0,835 and Cd - 0,364.
We can see significant increase in Cl and just a slight increase in Cd which leads to better lift to drag ratio.
But in practical terms, LEVCON deflection also decreases drag for the similar lift that is generated.
In other words, model with the LEVCON deflection can generate Cl - 0,742 at 20 deg. AoA, which is even greater than what the model without LEVCON deflection can generate at 25 AoA, but at the same time model with LEVCON deflection will have Cd - 0,241, which is significantly lower than the Cd for the model with fixed LEVCON.
That means the plane with LEVCON deflection will have significantly better lift to drag ratio and SEP (specific excess power).
In practical terms you can generate the same or higher amount of lift at lower AoA, but at the expense of less drag which leaves you with power reserve (you need less power to fight lesser amount of drag), and that translates into better sustained turn rates, or you can use more available lift for better instantaneous turn rates.
And that is just one aspect of many advantages LEVCON’s provide.

Here is how that looks in practical terms:

View: https://youtu.be/je3ieoSb6AA?si=09iduyZAhiWHpHXW


Years back Su-57 demonstrated minimum radius turn in just 15 seconds at an air show, so the plane obviously doesn’t have any issues with increased drag in a turn, even if it uses AL-41F-1 engines.

Structurally, the Su-57 fuselage design with the centroplane, while has good useful volume, is structurally risky because while the fuselage depth between the engines is greater than Su-27, a large amount of that depth is not structural because lot of volume is occupied by weapons bays which runs across the entire wing root chord where loads both bending and potentially torsion are the highest. And the weapon bays are structural "holes", not being closed structural loops and don't carry those loads. The only full depth bulkhead is the one pair between the weapons bays. Whereas the F-22's weapon bay volume is almost all in front of wing at the highest loads, so most of those bulkheads across wing root chord are full depth of fuselage which carries loads better.
Not to say that Su-57 can't be lighter, it's possible but that likely involves some tradeoffs in other areas. Nothing is "free" here, everything is part of a compromise in all aircraft designs.

The benefit to the Su-57 fuselage is that for a given fineness ratio, it has very large internal weapons bay capacity, something the Sukhoi patent specifically calls out and Strelets highlighted in interviews too. But the structural risk is undeniable, and you can see that part of the centroplane needing to be reinforced starting with T-50-4 with that visible patch of metal on the back compared to T-50-1 initial design. And T-50-1 and T-50-2 were reinforced too after suffering cracking from MAKS 2011. And this patch of reinforcement on back of centroplane carried over even to Stage 2 redesign and onto serial aircraft. Again Sukhoi's 85th anniversary book goes into the detail of the structural reinforcement needed because the initial T-50/Su-57 design couldn't perform necessary overload.


No. The curve of the F-22 intake ducts do create the space for weapons bays. And while the weapons bays are structural "holes", most of it is in front of the wing. Which means that across most of the wing's chord, the structural bulkheads are full depth which carries structural loads better. While the Su-57 structural "holes" from the weapon bays run across the entire wing chord preventing full depth bulkheads at all except the one pair between the two main weapons bays, so the structural depth of the fuselage between the engines is otherwise quite thin. So it's the Su-57 layout that requires more strengthening. Again Sukhoi had to do an entire Stage 2 redesign of internal structure. And this is why some of the light weight numbers are implausible for the Su-57.
And from lift/drag perspective, take into account the overall volume. A wider, flatter fuselage on Su-57 is beneficial for max lift but also creates more surface area for parasitic drag. And while L/D ratio may be better, the reference area also bigger with a flatter wider fuselage, so for drag it can go either way depending on the flight condition. Especially since lift coefficient at level flight also reduces with increasing speed. Not saying either fuselage shape is better since there are tradeoffs but it's not just one being superior than the other as portrayed here.

When it comes to these weight and speed claims of Su-57 versus F-22, I've seen claims circling around media and by journalists but Sukhoi itself hasn't made any claims one way or the other.


Appears unlikely how can Su-57 managed more internal fuel volume, more internal weapons bay capacity, larger number of control surfaces, all while having less overall volume than the F-22? That does not seem plausible.

While the Su-57 weapons bays are not “structural”, they don’t have to be because the solution Russian designers applied is very smart and practical.



We can see that the Su-35S can hold 4 missiles in the tunnel between air intakes and engines. If you just close that tunnel with doors you are not going to compromise the structural integrity of the plane.
In a sense, that is exactly what the Russians did with the Su-57.
They have applied proven solutions with blended wing-body layout, and they have calculated the optimal structural depth for the fuselage between the engines/intakes for structural rigidity, and they have added weapons bay doors at the point where they find it the most optimal for the weapons needed to be carried inside, while also taking aerodynamic properties into consideration.
Weapons bay doors are also stressed during high G maneuvering, so additional strengthening of the side walls (where they are attached) is needed.
We can see that on the drawing from the T-50 patent:



For that reason Su-57 doesn’t need the full depth bulkheads in that region, and the bulkhead between the weapons bays is simply additional strengthening measure.

Now, look at the structural depth of the fuselage of the Su-35S:


It is also “thin”, but no one is complaining, Su-35S is a monster of a plane!
As a matter of fact, to me Su-57 looks more robust in that area even taking the weapons bay into consideration:



Now, in my opinion the main reason for structural cracks during testing faze is predominantly tied to the materials used (that are not used in Su-35S construction).
Russians wanted to make the Su-57 as light as possible, and the new materials used were simply not adequate. Using different materials, that have somewhat higher specific weight has solved the problem.
The “Sukhoi book” states that the rejected alloy saved 100-120 kg, which is not that significant on the grand scale, and we can’t make educated guess how heavier Su-57 became, but most of the time almost every plane is getting heavier going from the prototype to operational stage.

But all available data suggests that the Su-57 is lighter than F-22, while being bigger plane dimensionally.

Here is the size comparison between F-22 and F-15:



Aside from the bigger wing surface, F-22 is about the same as F-15 dimensions vise, but when we compare cross sections of both planes, difference is huge!





F-22 has huge midsection because it needs to store extremely long and curved air ducts, weapons bays, and considerable amount of fuel inside airframe that has similar layout as the F-15 with closely coupled engines.



Basically the whole area behind the cockpit is essentially empty space that is susceptible to bending under high load, and that needs strengthening. Flat belly of the F-22, while not generating lift in the way body of the Su-57 does, is generating lift, and weapons bay doors, and air ducts are also stressed.

This is the bulkhead of the F-22 in the region in front of the engines where weapons bay ends:


It is massive, and since the F-35 basically has the same airframe layout as F-22 (just with one engine), here is the bulkhead of the F-35 from the similar region:



It is huge!

F-35 is even heavier than the much bigger, two engined, heavy fighter like F-15!



Now, when we compare the midsection of the Su-57 and Su-35S, there is absolutely no radical difference between the two (as is the case with the F-22 and F-15):



In essence Su-57 retains all the advantages of the Flanker layout (highly maneuverable, huge range, big weapons capacity etc.) with not so much downside effects.

F-22 layout with close coupled engines and huge curved air intakes is the main limiting factor for the better exploitation of the internal space, and overall performance.



So much thinner, but so much better usage of the space. Su-57 is a true air superiority/multirole fighter, and when talking about speed, there is a reason Su-57 is having complex variable air intakes:

https://patentimages.storage.googleapis.com/63/d6/81/d9a5d5024c9e9c/US20140182697A1.pdf

While the air intakes are Mach 3 capable, canopy, composites, and RAM will not allow for that speed (2600 km/h is the usual cited top speed), but my guess is that the Russians are aiming at Mach 2 supercruise with AL-51F-1 engines, where this type of intake will come handy.

 

[Squirrel]

how about this Su-57 Simulator cockpit
View attachment 751705

Nice, is it real simulator and is it in Sukhoi or in 929GLITc in Akhtubinsk AB ? Screen under the HUD is obviously bigger then previous.

 

[Life of Tyo]

4 Su-57 on assembly from "Крылья Родины" №5-6 за 2024 год BORN ON THE AMUR (to the 90th anniversary of the Branch of PJSC UAC - KnAAZ named after Y.A. Gagarin)

 

[Squirrel]

About mentioned Al Alloys 1441 and 1461 ....

Very interesting material of comparative analysis made by NASA and VIAM ,topic is Al Alloys 1441 vs 1163 :

Al-Li Alloy 1441 for Fuselage Applications

''A cooperative investigation was conducted to evaluate Al-Cu-Mg-Li alloy 1441 for longservice life fuselage applications. Alloy 1441 is currently being used for fuselage applications onthe Russian Be-103 amphibious aircraft, and is expected to be used for fuselage skin on a newTupolev business class aircraft. Alloy 1441 is cold-rollable and has several attributes that make itattractive for fuselage skin applications. These attributes include lower density and higher specificmodulus with similar strength as compared to conventional Al-Cu-Mg alloys.Cold-rolled 1441 Al-Li sheet specimens were tested at NASA Langley Research Center(LaRC) and at the All-Russia Institute of Aviation Materials (VIAM) in Russia to evaluate tensileproperties, fracture toughness, impact resistance, fatigue life and fatigue crack growth rate.The All-Russia Institute ofAviation Materials (VIAM) has developed a new Al-Li alloy series with attractive characteristics.

Fuselage Panel Pressurization Fatigue Tests

Nine longitudinal blade stiffeners fabricated from V95pchT2 Al (analog to 7475 Al) alloy were rivetedto each panel. In addition, three ring frames fabricated from 1441 Al-Li alloy were riveted to thepanel circumference. Ina ll cases, however, the panels with 1441 Al-Li skin had a longer pressurization fatigue life thandid panels with conventional 1163 Al alloy skin.

Conclusions

The results of this study have shown that Russian 1441 Al-Li alloy mechanical propertiesare better than or similar to those for a conventional aluminum fuselage skin alloy. 1441 Al-Lisheet specimens exhibited strength, toughness, and tensile fatigue life similar to that for 1163 Al(2524 Al) sheet. In addition, the 1441 Al-Li had greater fatigue crack growth resistance than did 1163 Al. On a structural level, Tu-204 fuselage panels fabricated by Tupolev Design Bureauusing 1441 Al-Li skin and ring frames and V95pchT2 Al (7475 Al) stiffeners had longerpressurization fatigue lives than did panels constructed from conventional aluminum alloys. The measured structural properties combined with the lower density of 1441 Al-Li indicate the potential to increase life of fuselage structure and decrease structural weight.''

Source: https://ntrs.nasa.gov/api/citations/20040086797/downloads/20040086797.pdf

Hm, it is obvious that Sukhoi designers tried to lower the empty weight by 100-120kg of the Su-57 with that new Al-Li Alloy 1461 but failed to do that and we know now that 1461 had some fatigue issues in fact.It seems that Al Alloys 1441 and V95 have best overall characteristics when we look all of analyses.
As time passes, we realize that the Sukhoi designers tried to reduce the weight of the Su-57 as much as possible.Only one more important detail should be added to this, at the same time they worked on a new, much more powerful engine. With that, everything has been said when we talk about the potential energetic /kinetic capabilities of this fighter.

 

[Sundog]

Sorry for the late reply, I didn’t have the time for writing!

“перегрузка“ would be equivalent to the US “load factor - G”.
Under number 2. from your chart, it is stated that the maximal exploitation/operational load factor (G limit) is 8G under 21400 kg flight weight.
171000 kg of lift force corresponds to that weight and G load.
People should be careful with these data because as far as I know, that data is taken from the pilots handbook G limit for the Su-27, and there is different set of G limits for combat performance, from supplemental manual. From my understanding, Su-27 in peace time conditions is always limited to 8-8,5G’s.

Here is the chart for similar type of limitations for the F-15:

View attachment 751667

That only shows that your claim that Su-27 is somehow light because it can’t withstand G forces other fighters can under similar conditions is unfounded.
Here is the chart I was talking about:

View attachment 751447

It states, “перегрузка” - load factor for the sustained turns at the weight of 20000 kg (missiles included, 50% of fuel from the normal fuel load etc.)
The full lines represent the G load for the 8G limit, and intersected lines represent the G load when the exploitation 8G limit is exceeded/overridden.
If there was serious danger of destroying the airframe under 9G sustained turn at 20000 kg, there wouldn’t be such option on the EM chart, and the plane would be hard limited to 8G.



Su-57 is basically using cropped delta wing, and here are the basic structural benefits from using such wing:
“The long root chord of the delta wing and minimal area outboard make it structurally efficient. It can be built stronger, stiffer and at the same time lighter than a swept wing of equivalent aspect ratio and lifting capability.

Its long root chord also allows a deeper structure for a given airfoil section. This both enhances its weight-saving characteristic and provides greater internal volume for fuel and other items, without a significant increase in drag. However, on supersonic designs the opportunity is often taken to use a thinner aerofoil instead, in order to actually reduce drag.”

View attachment 751448

Su-57 has significantly shorter wings, and when pressure is applied, much longer and narrower wings of the Su-27 suffer from much greater moment arm/leverage from the force acting upon it, so they need more strengthening for the same load.

And when we talk about lift to drag ratio, I have almost no doubt that Su-57 is superior in this regard. F-22 according to measurements has worse L/D ratio than Su-27 (11,6 vs 10,1 if I remember correctly).
Taking into account the amount of fuel F-22 can carry, it has very poor range (not so efficient engines and not so stellar lift to drag ratio will do that).
Su-57 is highly unstable plane (both in pitch and lateral direction) which provides excellent L/D ratio in subsonic/supersonic area, and that was possible to do with the use of LEVCON’s which can actively control the center of lift.
There was a study where they were comparing standard model with fixed LERX, and the one that had movable frontal part (LEVCON).
For example, the data for the 25 deg. AoA, shows that the model without LEVCON deflection has Cl - 0,726 and Cd - 0,329.
For the same AoA, model with LEVCON deflection has Cl - 0,835 and Cd - 0,364.
We can see significant increase in Cl and just a slight increase in Cd which leads to better lift to drag ratio.
But in practical terms, LEVCON deflection also decreases drag for the similar lift that is generated.
In other words, model with the LEVCON deflection can generate Cl - 0,742 at 20 deg. AoA, which is even greater than what the model without LEVCON deflection can generate at 25 AoA, but at the same time model with LEVCON deflection will have Cd - 0,241, which is significantly lower than the Cd for the model with fixed LEVCON.
That means the plane with LEVCON deflection will have significantly better lift to drag ratio and SEP (specific excess power).
In practical terms you can generate the same or higher amount of lift at lower AoA, but at the expense of less drag which leaves you with power reserve (you need less power to fight lesser amount of drag), and that translates into better sustained turn rates, or you can use more available lift for better instantaneous turn rates.
And that is just one aspect of many advantages LEVCON’s provide.

Here is how that looks in practical terms:

View: https://youtu.be/je3ieoSb6AA?si=09iduyZAhiWHpHXW


Years back Su-57 demonstrated minimum radius turn in just 15 seconds at an air show, so the plane obviously doesn’t have any issues with increased drag in a turn, even if it uses AL-41F-1 engines.



While the Su-57 weapons bays are not “structural”, they don’t have to be because the solution Russian designers applied is very smart and practical.

View attachment 751669

We can see that the Su-35S can hold 4 missiles in the tunnel between air intakes and engines. If you just close that tunnel with doors you are not going to compromise the structural integrity of the plane.
In a sense, that is exactly what the Russians did with the Su-57.
They have applied proven solutions with blended wing-body layout, and they have calculated the optimal structural depth for the fuselage between the engines/intakes for structural rigidity, and they have added weapons bay doors at the point where they find it the most optimal for the weapons needed to be carried inside, while also taking aerodynamic properties into consideration.
Weapons bay doors are also stressed during high G maneuvering, so additional strengthening of the side walls (where they are attached) is needed.
We can see that on the drawing from the T-50 patent:

View attachment 751672

For that reason Su-57 doesn’t need the full depth bulkheads in that region, and the bulkhead between the weapons bays is simply additional strengthening measure.

Now, look at the structural depth of the fuselage of the Su-35S:

View attachment 751674
It is also “thin”, but no one is complaining, Su-35S is a monster of a plane!
As a matter of fact, to me Su-57 looks more robust in that area even taking the weapons bay into consideration:

View attachment 751675

Now, in my opinion the main reason for structural cracks during testing faze is predominantly tied to the materials used (that are not used in Su-35S construction).
Russians wanted to make the Su-57 as light as possible, and the new materials used were simply not adequate. Using different materials, that have somewhat higher specific weight has solved the problem.
The “Sukhoi book” states that the rejected alloy saved 100-120 kg, which is not that significant on the grand scale, and we can’t make educated guess how heavier Su-57 became, but most of the time almost every plane is getting heavier going from the prototype to operational stage.

But all available data suggests that the Su-57 is lighter than F-22, while being bigger plane dimensionally.

Here is the size comparison between F-22 and F-15:

View attachment 751676

Aside from the bigger wing surface, F-22 is about the same as F-15 dimensions vise, but when we compare cross sections of both planes, difference is huge!

View attachment 751677

View attachment 751678

F-22 has huge midsection because it needs to store extremely long and curved air ducts, weapons bays, and considerable amount of fuel inside airframe that has similar layout as the F-15 with closely coupled engines.

View attachment 751679

Basically the whole area behind the cockpit is essentially empty space that is susceptible to bending under high load, and that needs strengthening. Flat belly of the F-22, while not generating lift in the way body of the Su-57 does, is generating lift, and weapons bay doors, and air ducts are also stressed.

This is the bulkhead of the F-22 in the region in front of the engines where weapons bay ends:

View attachment 751680
It is massive, and since the F-35 basically has the same airframe layout as F-22 (just with one engine), here is the bulkhead of the F-35 from the similar region:

View attachment 751681

It is huge!

F-35 is even heavier than the much bigger, two engined, heavy fighter like F-15!

View attachment 751682

Now, when we compare the midsection of the Su-57 and Su-35S, there is absolutely no radical difference between the two (as is the case with the F-22 and F-15):

View attachment 751684View attachment 751685

In essence Su-57 retains all the advantages of the Flanker layout (highly maneuverable, huge range, big weapons capacity etc.) with not so much downside effects.

F-22 layout with close coupled engines and huge curved air intakes is the main limiting factor for the better exploitation of the internal space, and overall performance.

View attachment 751706

So much thinner, but so much better usage of the space. Su-57 is a true air superiority/multirole fighter, and when talking about speed, there is a reason Su-57 is having complex variable air intakes:

https://patentimages.storage.googleapis.com/63/d6/81/d9a5d5024c9e9c/US20140182697A1.pdf

While the air intakes are Mach 3 capable, canopy, composites, and RAM will not allow for that speed (2600 km/h is the usual cited top speed), but my guess is that the Russians are aiming at Mach 2 supercruise with AL-51F-1 engines, where this type of intake will come handy.

Actually, Volumetrically, the Su-57 makes much less efficient use of space. If you want to look at that compare the amount of surface area, which translates into drag, into how much volume there is. Also, there's the issue of moments of inertia. The F-22 layout allows for less control power for the same amount of control input due tot the tighter grouping of the mass. Also, the deeper fuselage of the F-22 should make it lighter to be able with withstand the amount of being under load, as section depth is everything.

 

[Anduriel]

Su-35S, being a redesigned Su-27 airframe with modern materials, lighter engines and lighter avionics became heavier than Su-27.

 

[Squirrel]

Su-35S, being a redesigned Su-27 airframe with modern materials, lighter engines and lighter avionics became heavier than Su-27.

Now we must check that. OK, Su-35S has the same dimensions as older Su-27S but it is constructed with new very light and strong materials. E.g. new Al( Al-Li) Alloys are lighter then Dural and V95 applied in Su-27S.Also new Ti Alloys like VT-22/-23 are also lighter. I will check this again and again but it seems that new Al-Li Alloys get that yellow color during galvanization process as mentioned before.As we can see all new Russian fighters are 'yellow aircraft' in their production lines ,from MiG-29M/M2 ,MiG-35S/UB,Su-30SM/SM2,Su-34/M,Su-35S and of course Su-57, even Yak-130. Was this the case with old Al-Li Alloy 1420 during 1980's ,applied on MiG-29M and Yak-141 ,really don't know right now. About engine AL-41F1S that is wider than old AL-31F ,it has wider core of the engine ,turbine =932mm vs 905 mm and like many sources tell us, it is a little bit heavier but not much (~1600kg vs 1530 kg).On the other side ,mentioned that before,thanks to the new lighter structural materials ,AL-41F1 for Su-57 is 150 kg lighter than old AL-31F.

Then we have much lighter digital FBW with all components then old analogue FBW in Su-27S, there is fiber optic wiring and many other lighter digital systems and subsystems in comparison with heavier analogue in Su-27S. Of course lighter fuel system with about 2 tons more internal fuel,so there is more empty space.Possible lighter hydraulic system also etc. Radar N035 Irbis is lighter than giant N001 Myech with all possible components.So how can Su-35S be heavier then Su-27S because I don't see any detail,parameter that can tell us vice versa. Maybe ,maybe they used more structural components and parts,e.g in the wings,centroplane etc but I doubt it .As we know e.g. Su-57 has 25% less details then Su-27S.

The same story goes with Su-57. If we look that pic with giant Su-35UB and T-50-1 and even if we put 1 ton of equipment inside it ,it will be lighter than that giant by several tons.From the Sukhoi book we can clearly understand now that their designers wanted lightened fighters with very powerfull engines.

 

[Squirrel]

@Sundog

F-22A's test pilot known as 'JB ' once said this :

''As to limitations, the F-22 airframe is rated between +9G to -3G. Although 9G “is not fun and hurts,” anywhere below around 10,000 feet the F-22 can, fatigue-wise, maintain 9G until it runs out of gas. The Raptor is not limited by angle of attack, however, and JB recalls seeing the F-22 happily fly at an angle of attack of 110 degrees. There is also a temperature-limiting region within the flight envelope — at the speeds and altitudes the Raptor works, the surface temperature of the jet can reach 467 degrees Fahrenheit, sufficient to cook a pizza.''

F-22 Test Pilot Details The Raptor’s Incredible Speed

A chief test pilot on both the F-117 and the F-22, James “JB” Brown III, provides a fascinating inside look at these remarkable stealth jets.

www.twz.com

On the other side,Sukhoi chief test pilot Sergey Bogdan told once that 10G maneuvers will be normal maneuvering mode and that 9G load can lasts up to 2 mins.

''An overload of 10 g becomes the normal maneuvering mode.''

https://www.techinsider.ru/weapon/392902-rossiyskiy-istrebitel-5-go-pokoleniya-luchshiy-v-mire/

Of course ,pilot was always be and will be limitation factor here.

 

[aim9xray]

anywhere below around 10,000 feet the F-22 can, fatigue-wise, maintain 9G until it runs out of gas.

Umm. Not exactly. What the pilot meant to say was "anywhere below around 10,000 feet the F-22 can, overstress-wise, maintain 9G until it runs out of gas".

That is to say, the aircraft will not incur overstress damage in the band between -3 to +9G. (Damage to include permanent deformation of structures from spars and frames down to brackets, latches and racks, i.e. a "bent airplane".) The aircraft will incur cumulative (lifetime) fatigue damage, scored as FLE (Fatigue Life Expended) outside of the deadband of -1 to +2G (or thereabouts).

This is critically important in the life management of aircraft over the long term (30+ years).

 

[QuadroFX]

 

[stealthflanker]

I'm curious if Sukhoi finally solved the loss of thrust issue from changing nozzle geometry

 

[Ainen]

I'm curious if Sukhoi finally solved the loss of thrust issue from changing nozzle geometry

Well, it's al-51f.
They solved it the American way, by adding more of it. Now can spend some.

 

[Squirrel]

Well, it's al-51f.
They solved it the American way, by adding more of it. Now can spend some.

AL-51F ? Is it maybe a prototype of 6th gen engine ? They started flight/dynamics tests on T-50-2LL prototype after static/ground tests phase with which engine then,AL-51F-1 with that flat nozzle or with completely new 6th gen three-stream adaptive-cycle engine? We must keep on mind that Su-57M with two flying prototypes so far , number 058 and 511 blue from the Project 'Megapolis' has many technical inovations. Inovations to become 5+/6 gen fighter.

Плюс контур, плюс поколение​

Параллельно с разработкой двигателя второго этапа для Су-57 конструкторы уже создают и научно-технический задел для двигателей шестого поколения.

Transl :

Plus stream , plus generation

In parallel with the development of the second stage engine for the Su-57, designers are already creating the scientific and technical basis for the sixth generation engines.


Source: https://nplus1.ru/material/2019/03/06/engines






As we know on June 2023 on Samara's University ,general menager of OKB after the name of A.M. Lyulka Evgeniy Marchukov said that they already tested on testbed this ceramic flat nozzle with some other parts and components of the 6th gen engine ( ceramic chamber and some other ceramic and metallic parts ).He mentioned that third air stream and details about it.He even said that they planned to take that flat nozzle into the air during 2023.So this presentation was year and half ago.All details from 1:48:48 ...From 1:52:18 ( we can see engine with green color on the blured screen) he told some interesting details about three-stream engine with adaptive cycle that is on static tests as he said( stendovaya ispitaniya) and the result was that this engine has 5% less fuel consumption on cruise mode and that he expects even 10% during real flight conditions on cruise mode.Three stream engine with adaptive cycle is for sure 6 h gen engine.

Source: https://m.vk.com/video-69812_456239...AA2FLmk1eIdpW1XwCQ_aem_NzgFcd1ST_dpEtnMNGA4Eg

P.S. Very interesting detail from that conference by ODC. If this is right,we can see ilustation with AL-41F-1 and AL-51F-1 as the same engines,engine with new flatt nozzle is completely different.Coincidence or not ?

1000021637

Изображение 1000021637 расположенное в Radikal.HOST (Радикал.ру)

radikal.host

 

[QuadroFX]

Some gifs and screencaps. More footage will be this Sunday.
Thanks to Georgiy Novoselov.

 

[Ainen]

Gotta say, it looks almost marvel

 

[sanjeev.k]

I am not so sure if this is going to installed as part of the stage 2 upgrade program - because if you ** really** want to take advantage of flat nozzles, one would have to redesign the entire rear engine nacelle shape as well (make it trapezoidal rather than circular). The Su-57 does have a weakness in rear side aspect RCS (because I think the circular nacelles meet the fuselage and wing surface at right angles). There are no 'blending Nurb patches' either at the transition boundary between the circular nacelles and the wing/lower fuselage surface.
Such redesign would be costly and also time consuming.

Its more probable (like squirrel says) that this is proving as a test-bed for installing flat nozzles on their sixth gen. If u look at the placeholder images of the Russian sixth gen posted by flateric, the engine nacelles do not seem to be circular. I guess that's the most realistic 'speculation' at this time about the russian sixth gen. Any other attribute of the sixth gen (like those klingon bird of prey downturned wingtips) is just pure speculation at this point in time.

 

[QuadroFX]

Its more probable (like squirrel says) that this is proving as a test-bed for installing flat nozzles on their sixth gen.

It's been discussed before: the Air Force wants flat nozzles on the Su-57. Period.

 

[sanjeev.k]

It's been discussed before: the Air Force wants flat nozzles on the Su-57. Period.

So, if that's the case,what was the whole point of spending $$$$ developing LOAN nozzles on Izd-30?
I thought the whole point of LOAN was to get maximum IR signature reduction without incurring the cost and complexities associated with the flat nozzle. Thats the reason why F-35 opted for LOAN.

 

[AGS-1787]

So by putting the nozzles canted they retain the z axis maneuverability. Looks funky and cool

 

[QuadroFX]

I think it is a prototype of 6th gen engine

It is a prototype of flat nozzle for Su-57. Stop dreaming.

 

[Squirrel]

It is prototype of flat nozzle for Su-57. Stop dreaming.

Sorry but flat nozzle for Su-57 ??? May I ask for which engine as it is logical ? AL-51F which has nozzle with serated petals or for completely new one that is in fact 6 gen engine like many Russian sources wrote about .

Russian source: https://www.ixbt.com/news/2023/07/0...7-s-novym-dvigatelem-shestogo-pokolenija.html

 

[baschil]

The flame holder in not annular looks different.