Sukhoi Su-57 / T-50 / PAK FA - flight testing and development Part II [2012-current]


I love it! Where's this weird (and weirdly numerous) crowd now who liked to claim so adamantly that Sukhoi went with the configuration we know as the Su-57 today not on merit but because they were variously unwilling to or downright incapable of departing from the legacy Flanker template?! Everything from canard-deltas with tip fins (ok, known for a few months already) to a freaking FSW got considered before arriving there - but sure, it's nothing more than a Silent Flanker...
 
Looks like the aircraft is primarily made from aluminum with titanium primary load bearing/load path bulkheads/structure.

I don't see anything in this CFRP surface & metal bulkhead/spar construction which makes the Su-57 fundamentally different in structural composition to the F-22, F-35 or Eurocanards. Except maybe the preference for honeycomb sandwich instead of solid panels in large parts of the upper fuselage, I don't think any of the Western jets do that to anything like the same extent.
 
I love it! Where's this weird (and weirdly numerous) crowd now who liked to claim so adamantly that Sukhoi went with the configuration we know as the Su-57 today not on merit but because they were variously unwilling to or downright incapable of departing from the legacy Flanker template?!
Why bother?
People claiming that literally sign they don't understand what a plane is, on the most fundamental level.
May as well skip directly.
 
Exactly the same story happened with the MiG-29M thirty years ago, no conclusions were drawn
IMO if BOTH MiG and Sukhoi have called out VIAM for issues with Al-Li alloy on both MiG-29M and Su-57, then I think the problem might really be with VIAM.

You can say that MiG and Sukhoi didn’t adjust properly for the unique properties of Al-Li like suitability for impact riveting and different failure characteristics, but things like cherry-picking test samples is absolutely an issue with VIAM.
 
I find it confusing as I have seen the specifications of some other Russian aircraft which use large quantities of Al-Li alloys. For example the yak-130 intentionally went away from composites and instead predominantly used aluminum magnesium and aluminum lithium alloys.

I also found it interesting the failure modes described that alloy. I got the impression that the alloy exacerbated the usual work hardening and malleability issues inherent to aluminum.
 
This reminds me of the long queue when we all wanted to take a look inside the Tu-144LL at MAKS 1999 ;) .
 
Su-57 serial No.21 Published 29.11.2024
View attachment 750234
First hi to everyone here.

Sorry Life of Tyo but I must correct you. It is not serial but so called Bort ( Aircraft/tactical) number. If I rememeber well,last known/visible Bort number was 11 red ( pic from Sept 2023). All other Bort numbers were censored when we talk about fighters that were delivered from Dec 2022 and during 2023/24. In the meantime ,first operational unit got all 24 serial/operational Su-57's . It is famous 23rd Guards Fighter Aviation Regiment called Tallinnsky based in Dzyomgi air base near the KnAAZ factory.
 
First hi to everyone here.

Sorry Life of Tyo but I must correct you. It is not serial but so called Bort ( Aircraft/tactical) number. If I rememeber well,last known/visible Bort number was 11 red ( pic from Sept 2023). All other Bort numbers were censored when we talk about fighters that were delivered from Dec 2022 and during 2023/24. In the meantime ,first operational unit got all 24 serial/operational Su-57's . It is famous 23rd Guards Fighter Aviation Regiment called Tallinnsky based in Dzyomgi air base near the KnAAZ factory.
thank you for correction, btw here I am sharing photos of Su-57 production (serial) so that maybe friends can KNOW if the Su-57 is still produced for VKS,And some rare photos of a prototype Su-57 ( PAK FA)
 
That is what you call a good start on a board... amazing, thanks

I would only point out that, in order to be carried in the weapon bays, the Product 810 should be 4.2 m long at most
Hi !

Thank you and thank you for corrections. I've found this info :

''The Su-57 has the largest internal bays of any 5th generation fighter two tandem main internal weapon bays each approximately 4.4 m (14.4 ft) long and 0.9 m (3.0 ft) wide.''

Some Russian sources give info that fuselage weapon compartments are almost 5m long and the space between engine nacelles is 1.2-1.4 m wide. I think this is from paralay?


. images (1).jpg

Also we can see that Izdeliye 180 is much longer then Izdeliye 170-1 / 171-1 ( 3.7m lenght) and that AAM thanks to foldable stabilisers can be carried inside of fuselage weapon bays.

Su-57 sa 10 Izd 180.jpeg
 
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oh yeah I remembered something, 10 years ago in 2014 the T-50-5 prototype caught fire after landing after engine failure

View: https://youtu.be/Nwfq-BmRKJM?si=kmZxMLibarXFOpOX

Yes, I know for that,Bort number 055 blue called the 'Great white shark' by some people. What is unknown for the public even today ,Indian military delegation from IAF was there and unfortunately happened that. After that event ,IAF reconsidered about FGFA project .They already invested about 200 mil $ in that joint Russo-Indian project for two-seat version of PAK-FA / T-50.

''Damaged by fire of the right engine in 10th June 2014 in Zhukovsky when landing, pilot Kondratyev left airplane after landing, but plane was damaged beyond repair. Was ressurected using airframe of T-50-6 and fire survived pieces (rudders, fins), renamed to T-50-5R (sufix R means ремонтный = repaired), first flight after repairs on 16th October 2015. Damaged fuselage of T-50-5 remains in Zhukovsky, wings were reused for static tests.'' Source: http://su57.mariwoj.pl/su57-index.html
T-50-5 June 2014.jpg
 
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thank you for correction, btw here I am sharing photos of Su-57 production (serial) so that maybe friends can KNOW if the Su-57 is still produced for VKS,And some rare photos of a prototype Su-57 ( PAK FA)
Forgot to answer .You are welcome of course. Thank you for the new photo of the serial/operational Su-57 ,Bort number 21 red. I have some info that almost 30 serial Su-57's are produced so far.
 
I highly doubt this as that would mean it cannot be carried internally by Su-57. Weight can be heavier (e.g use of denser more metal rich propellant)



Well that thing is supposedly Izd-180

Max carrying weight for the UVKU-50U as universal internal catapult launcher is 750-800kgs so that R-97 can be for sure carried
inside fuselage weapon bays when we talk about weight. Now about lenght,if fuselage weapon bays are really almost 5m long then there is chance to accomodate Izd 810 ? About body diameter as far as I know,tactical cruise missile Kh-69 has body diameter of 420mm. Anyway ,Izd 810 has much bigger body diameter in comparison with Izd 610M ,am I right?

This is something interesting when we talk about either Izdeliye 180 or 810. We can see that there is Izdeliye 180 but also Izdeliye 180PD( PD meaning of course Pryamotochny Dvigatel or ram-jet engine). Both of them are classified as light weight load and Izdeliye 810 as heavy weight load. So maybe the AAM that was presented besides Su-75 was Izd 180 and those two carried in flight by one prototype were Izd 180 PD ?


Izd 810 na UVKU-50U.jpg UVKU-50L.jpg UVKU-50L 1.jpg UVKU-50U.jpg
 
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2x Kh-69 is almost an exact mold of the internal space at the bays, minus clearances, so I doubt that the weapons for internal carriage can be longer than 4,2 m and 40 cm in diameter... but I am open to learn more for sure, if there is more to it than that
 
2x Kh-69 is almost an exact mold of the internal space at the bays, minus clearances, so I doubt that the weapons for internal carriage can be longer than 4,2 m and 40 cm in diameter... but I am open to learn more for sure, if there is more to it than that

If these doors are 0.5 m wide then I must agree that limit for the body diameter of AAM/ASM is 0.4m. About 'FWC' doors length ,if they are really 5m long then 4.2 m limit is questionable,if .


Su-57 FWC doors.jpg
 
The I-810 is clearly designed for internal carriage... what other Russian designs exist which could carry an air-to-air missile internally? Unless the PAK-DP is much further along than anyone imagines - I think it is pretty inevitable that these missiles have to fit the Su-57... so the bays are longer or the missiles are shorter.

The interesting questions relate to the reports of carrying eight internal missiles (six in the main bays)... this raises questions as to the type and arrangement - but the idea of carrying four I-810 in the main bays is something I always thought could be assumed.
 
The I-810 is clearly designed for internal carriage... what other Russian designs exist which could carry an air-to-air missile internally? Unless the PAK-DP is much further along than anyone imagines - I think it is pretty inevitable that these missiles have to fit the Su-57... so the bays are longer or the missiles are shorter.

The interesting questions relate to the reports of carrying eight internal missiles (six in the main bays)... this raises questions as to the type and arrangement - but the idea of carrying four I-810 in the main bays is something I always thought could be assumed.

Next AAM's can be carried inside of the FWC-fuselage weapon compartments : Izd.180 ( PD) and of course Izd 810 but max 4 pcs. Izd 171-1 and Izd 270 can not be carried beacuse those lattice stabilisers are not foldable.
Inside two UWC-underwing weapon compartments can be carried Izd. 300M and Izd. 760.
 
I noticed that there was story about construction materials.If I may, will give some info. This topic will be something like ''metal/alloys vs composites'' .As we know the main construction material of the Su-57 is а special alloy Aluminum-Lithium 1441. I must say/write that this Alloy is the pride of the mentioned VIAM. By the way, Al-Li alloy was first used 40 years ago on the MiG-29M/K ( Izd 9.15 and 9.31) and Yak-141. It was alloy Al-Li 1420.

Citation: ''A cooperative investigation was conducted to evaluate Al-Cu-Mg-Li alloy 1441 for longservice life fuselage applications.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 did1163 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. Themeasured structural properties combined with the lower density of 1441 Al-Li indicate thepotential to increase life of fuselage structure and decrease structural weight.''

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

Percentage of this alloy in the empty weight of the serial/operational Su-57 is almost 50%. It is a bit higher then in some prototypes,why ?Answer will come soon in textual and pictorial shape. Flying prototypes /so called first test stage / number 51/051,52/052 and 054 blue were used for the real flying/dynamic tests of the structure, structural strenghtiness.
Immediately after several test flights with Sukhoi chief test pilot Sergey Bogdan they noticed that something is going on with that big composite skin panel on the upper side of the fuselage.Every time when Sergey made 90° roll and went to sustain turn with 10G overload,minor cracks and depressions would appear. They first used special so called 'hermetic glues' which we could see on some aerodynamic control surfaces ( wings,vertical and horizontal stabilisers).

After a while,T-50-1 got completely new very big transversal skin section made of that Al-Li 1441. After that ,Sergey Bogdan told one very important detail that he repeated in one interview: Перегрузка под 10 g становится обычным режимом маневрирования.Transl :'' An overload of 10 g becomes the normal maneuvering mode.''
Source: https://www.techinsider.ru/weapon/392902-rossiyskiy-istrebitel-5-go-pokoleniya-luchshiy-v-mire/

After that they tested some new solutions such as the composite skin of the vertical stabilizers.Prototype T-50-8 got composite skin on the vertical stabilizers but very soon they noticed that this was not good solution.Vertical stabilizers as most sensitive aerodynamic control surface had some issues ,the same as that big composite skin panel on the upper side of the fuselage. After several test flights they decided to turn back Al-Li 1441 skin for the vertical stabilizers. Same happened with the horizontal stabilizers too.As Englishmen use to say ''all news'' ( nothing new) ,Americans had the same problems during F-22 static/dynamic tests .They also discovered that metals/metallic alloys are simply stronger then composites and thus have more endurance/strenghtiness ,especially in the aerodynamic pressure domain. Aerodynamic pressure is the ratio of the given weight and G-load during given phase of the flight.
Alloy Al-Li 1441 has less specific weight then most of Al alloys. It is important to know because as I can read many sources mention that empty weight of the Su-57 is 18-19 tons ??? Hm, how can it be when Su-57 has 25% less construction details then Su-27 which by the way has empty weight of 16.5 tons. OK ,wing area of the Su-57 is 30% bigger ( 82m2 vs 62m2) but we must keep on mind that Al-Li 1441 is lighter then Dural and its skin is mostly made from composites. Maybe I am wrong and certainly want to read other comments,opinions and conclusions,tnx.

T-50-8 with composite skin on its vert. stabilizers.
T-50-8 Bort broj 058.jpg



Serial Su-57 with big Al-Li 1441 skin cross panel on the upper side of the fuselage.As we can see ,alloy Al-Li 1441 has yellow color that comes from the galvanization process. Note: it is very interesting to see that skin of the horizontal stabilizers is made half from Al-Li 1441 and half from the composites.

Su-57 Serial, Al-Li 1441 skin.jpg

T-50-4 as we know had first test flight on Dec. 12 2012 and we can see that big cross Al-Li 1441 skin section.

T-50-4 mod.jpg

Т-50-0 ,KPO with two small Al-Li 1441 panels and with big cross Al-Li 1441 skin panel.

T-50-0 i T-50-7 static tests.jpg

Т-50-0 ,KPO with that new big cross Al-Li 1441 skin section.

T-50KPO new Al-Li 1441 skin panel.jpg

Т-50-0 ( KPO) with two small Al-Li 1441 skin panels on the upper side of the fuselage.

T-50KPO.jpg

Т-50-1 during its first test flight.Red arrows show us two very small Al-Li 1441 skin panels.

T-50-1 Al-Li skin panels mod.jpg

In this video from the manufacturer KnAAZ we can see all of this details.

View: https://www.youtube.com/watch?v=R0ykwDn9Tcs


About this ''issue''.

View: https://www.youtube.com/watch?v=zjJL5wWNQtE


What can I write... Rivets,screws,bolts,clecos...that is something inevitable in the aircraft industry.Of course in the video was fourth flying prototype T-50-4 ,not serial/operational one.But there will always be people who will find something to criticize even though there is no basis for it. By the way , that prototype T-50-4 achieved some records 10 years ago. First was initial rate of climb at 1000m of 382m/sec ( with 50% of fuel on tarmac before take off). Fouth flying prototype also climbed to 24400m and continue to fly straight.

Next time will be topic about composites or 'polymer composit material' ( in Russian). To be continued....
 

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I noticed that there was story about construction materials.If I may, will give some info. This topic will be something like ''metal/alloys vs composites'' .As we know the main construction material of the Su-57 is а special alloy Aluminum-Lithium 1441. I must say/write that this Alloy is the pride of the mentioned VIAM. By the way, Al-Li alloy was first used 40 years ago on the MiG-29M/K ( Izd 9.15 and 9.31) and Yak-141. It was alloy Al-Li 1420.
This seems to run directly against what the Sukhoi book is telling us as well as various Sukhoi presentations over the years. IIRC, most of the T-50/Su-57 structure is aluminum alloy B-95, attempts to substitute it with 1461 Al-Li alloy didn’t work out. Again, in 2018 an OKB Sukhoi presentation on T-50 materials is as follows:
file.php


By the way , that prototype T-50-4 achieved some records 10 years ago. First was initial rate of climb at 1000m of 382m/sec ( with 50% of fuel on tarmac before take off). Fouth flying prototype also climbed to 24400m and continue to fly straight.
Again this doesn’t seem plausible because by the time PI-1 (Предварительные испытания 1) concluded in 2014, the envelope expansion is as follows:

145290551985608682.jpg

Altitude: 14,000 meters
Mach number: 1.7
Indicated airspeed: 1,000 km/h
Max g: +6.5

In 2013, there was a purported “radioscanners” post claiming the extreme altitude and airspeeds you mentioned but those turned out to be fake.
 
Not "fake", but not confirmed by anyone ;)

"... So during tests this spring (2013), with a full load of fuel and mass-dimensional models of weapons, the 4th board (054) took off from 310 meters, reached a cruising speed of 2135 km / h and a maximum speed of 2610 km/ h (M = 2.46), at the same time, there was still a potential for acceleration, and I also climbed 24,300 meters - they didn't let me go any further"
 
Yes, this was posted back in 2013 and on the old Key Publishing forums by either @flanker (aka berkut on Key Pubs) or @flateric, but even then it was treated with a lot of salt and skepticism because of the questionable source, and OKB Sukhoi’s own presentation in 2014 on envelope expansion from ПИ-1 debunked that.

Получены следующие характеристики: скорость -1000 км/ч (с открытыми отсеками вооружения - 800 км/ч); число М полёта -1,7; высота полёта -14 км пере грузка дозвуковая - +6,5; -2; сверхзвуковая-4.

The following characteristics were obtained: speed -1000 km/h (with open weapons bays - 800 km/h); flight Mach number -1.7; flight altitude -14 km; subsonic overload - +6.5; -2; supersonic -4.
 
That’s very implausible. Even a lightweight, totally clean F-16C Block 50 at 22,000lbs (so T/W ratio of 1.34 which puts even F-22 to shame) has Ps=1,200 ft/s at sea level which means maximum rate of climb of 72,000ft/s or 364m/s, so a Su-57 with about 18,500kg empty weight and 5,000kg of fuel would have T/W ratio of 1.23, since these are definitely only with izd.117 engines.

No offense but it feels like some here are getting really carried away by speculation, at times even contradicting published information from Sukhoi itself.
 
That’s very implausible. Even a lightweight, totally clean F-16C Block 50 at 22,000lbs (so T/W ratio of 1.34 which puts even F-22 to shame) has Ps=1,200 ft/s at sea level which means maximum rate of climb of 72,000ft/s or 364m/s, so a Su-57 with about 18,500kg empty weight and 5,000kg of fuel would have T/W ratio of 1.23, since these are definitely only with izd.117 engines.

No offense but it feels like some here are getting really carried away by speculation, at times even contradicting published information from Sukhoi itself.

I 'm pretty sure it is Al-Li 1441 but I will check it ( V-95 is another Al alloy, yes ). Question is,why they changed those two small composite skin panels with one very big cross mettalic /alloy in a very short period of time. Mentioned before that empty weight of 18-19 tons is very questionable. Do you think that Sukhoi represented all possible achieved results? Why did they use in so many cases that 'hermetic glues' on the skin of some aerodynamic control surfaces during first years of flight testing?
 
I 'm pretty sure it is Al-Li 1441 but I will check it ( V-95 is another Al alloy, yes ). Question is,why they changed those two small composite skin panels with one very big cross mettalic /alloy in a very short period of time. Mentioned before that empty weight of 18-19 tons is very questionable. Do you think that Sukhoi represented all possible achieved results? Why did they use in so many cases that 'hermetic glues' on the skin of some aerodynamic control surfaces during first years of flight testing?
It’s widely known and reported that the initial T-50 design did not have enough structural strength or fatigue life. In fact, after MAKS 2011, both T-50-1 and T-50-2 were grounded for about a year to reinforce their structure because of cracks from their demo flights even though it was at 5g. The large patch of metal on the back of the centroplane first appeared on T-50-4 and was retrofitted on -1 and -2 and all subsequent test and production aircraft.

It was the structural issues, along with other issues including fuel tank feeding, that resulted in a complete structural redesign, and all of the prior airframes up to T-50-6-1 were called 1st Stage while everything from T-50-6-2 after are called 2nd Stage, the structural difference, and the troubles with the VIAM 1461 Al-Li alloy being highlighted in both insider reports in 2016 and the recently published Sukhoi 85th anniversary book that corroborates it. The larger patch of metal on the back of centroplane that first appeared on T-50-4 also carried over to 2nd Stage and production aircraft.

As far as Su-57 empty weight, it’s more than the Su-27 simply because it needs more volume for internal weapons bays, more avionics, and also a bit higher fuel capacity. Put it another way, how can the Su-57 weigh less than 16.4 metric tons empty (the empty weight of the Su-27) like you imply, when it has more internal fuel capacity, larger internal weapons bay capacity, is longer and wider than the F-22 which weighs 19.7 metric tons empty? Even if you think Sukhoi doesn’t publish everything, there’s no confirmation for all this other stuff, and especially when some of it contradicts Sukhoi’s information.
 
It’s widely known and reported that the initial T-50 design did not have enough structural strength or fatigue life. In fact, after MAKS 2011, both T-50-1 and T-50-2 were grounded for about a year to reinforce their structure because of cracks from their demo flights even though it was at 5g. The large patch of metal on the back of the centroplane first appeared on T-50-4 and was retrofitted on -1 and -2 and all subsequent test and production aircraft.

It was the structural issues, along with other issues including fuel tank feeding, that resulted in a complete structural redesign, and all of the prior airframes up to T-50-6-1 were called 1st Stage while everything from T-50-6-2 after are called 2nd Stage, the structural difference, and the troubles with the VIAM 1461 Al-Li alloy being highlighted in both insider reports in 2016 and the recently published Sukhoi 85th anniversary book that corroborates it. The larger patch of metal on the back of centroplane that first appeared on T-50-4 also carried over to 2nd Stage and production aircraft.

As far as Su-57 empty weight, it’s more than the Su-27 simply because it needs more volume for internal weapons bays, more avionics, and also a bit higher fuel capacity. Put it another way, how can the Su-57 weigh less than 16.4 metric tons empty (the empty weight of the Su-27) like you imply, when it has more internal fuel capacity, larger internal weapons bay capacity, is longer and wider than the F-22 which weighs 19.7 metric tons empty? Even if you think Sukhoi doesn’t publish everything, there’s no confirmation for all this other stuff, and especially when some of it contradicts Sukhoi’s information.

5G ? Hm, that is highly unlikely.We must first count on the static ground tests of the T-50-0/KPO which was used for the static strength tests during 2009. I have pic of the T-50-1 with that big Alloy cross section on the upper side of the centroplane from 2011 but must find it. As soon as I do it, I will post it here.

About empty weight of the Su-57 as mentioned before, we must count on that it has 25% less construction details and parts then Su-27 ,has very light composite skin besides 'whatever Al-Li Alloy' that is for sure lighter then Al-Alloy used in the costruction of the old Su-27. About empty weight of the F-22A , I am even today suspicious that empty weight is almost 20 tons. Hm, how can it be with fighter which is constructed from six Ti-Alloys ( about 40% of the empty weight) and light composites ( about 25% ). For comparison, MiG-25 has the same empty weight of about 20 tons and 80% of all structural materials is in fact Steel/Steel Alloy.

Archive is like a gold mine. This is one article from 1995. Citation :

''THE US AIR FORCE and Lockheed Martin/Boeing have agreed to allow the F-22's empty weight to increase by 610kg, or 3%, to avoid pushing costs up. The growth comprises a 385kg weight-budget increase and a further 225kg allowance for uncertainty.

The F-22's projected empty weight has increased from 13,980kg at the preliminary design-review in 1992 to 14,365kg at the critical design-review, completed in February. Programme officials are confident that the additional 225kg allowance will not be needed.''


Now may I ask how empty weight of the serial/operational F-22A was increased from about 14.5 tons to about 19.5 tons? It is 'increased' by 5 tons.How it was possible?

About that Al-Alloy V95 ,one Indian document ,citation:

''Replacement and Reinduction of High Strength Aluminium Alloy B95High strength Al-Cu-Mg-Zn alloy, grade B95 is usedfor fabrication of many important load-bearing components in the airframe Russian combat-1 of mid 60’s aircraft. Cold rolled sheet, extruded bar and hot forging arethe basic raw materials for this grade. It is found that inRussian combat-2 (late 70’s aircraft) and Russian combat3 (early 80’s aircraft), the alloy grade B95 is partiallyreplaced by B93. However, in the subsequent aircraft,Russian combat-4 (mid 90’s aircraft) and Russian combat5 (early 2000’s aircraft), this alloy B93 once again isreplaced by B95 and B95PCh grades.''

Source: file:///C:/Users/Windows%207/Downloads/2005+May+Vol+57.+2-62-68.pdf

About Sukhoi or UAC presentation materials ,I can only write one thing. I believe more in what Sukhoi test pilots said and mentioned in so many interviews. Especially 'stories' from Sergey Bogdan, then Andrey Shendrick,Sergey Chernyshev,Rafael Suleymanov and others.

P.S.

About Alloy V-1461 ( real designation) , you were right,congrats. Source and page 201 :


One citation,source and transl. :

''РЗ: Что представляют собой алюминий-литиевые сплавы третьего поколения?

За последние годы наши ученые разработали современные высокопрочные и высокоресурсные алюминий-литиевые сплавы третьего поколения: В-1461, В-1469, В-1480 и В-1481, которые по своим характеристикам превосходят зарубежные аналоги и являются альтернативой основным конструкционным алюминиевым сплавам 1163 и В95, широко применяемым в отечественном авиастроении.''


''What are the third generation aluminum-lithium alloys?

In recent years, our scientists have developed modern high-strength and high-resource third-generation aluminum-lithium alloys: V-1461, V-1469, V-1480 and V-1481,which in their characteristics are superior to foreign analogues and are an alternative to the main structural aluminum alloys 1163 and V95, widely used in the domestic aircraft industry.''
 
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That’s very implausible. Even a lightweight, totally clean F-16C Block 50 at 22,000lbs (so T/W ratio of 1.34 which puts even F-22 to shame) has Ps=1,200 ft/s at sea level which means maximum rate of climb of 72,000ft/s or 364m/s, so a Su-57 with about 18,500kg empty weight and 5,000kg of fuel would have T/W ratio of 1.23, since these are definitely only with izd.117 engines.

No offense but it feels like some here are getting really carried away by speculation, at times even contradicting published information from Sukhoi itself.
Hi, new guy here

I have few remarks regarding your comment.
F-16C Block 50 at 22000 lbs is flying with around 32% of internal fuel.
If we assume that the Su-57 empty weight is 18,5 tones (the worst case scenario because it could weigh less), and if we assume that AL-41F-1 are producing 15 tones of thrust (there are different reports going from 15 to16 tones), and if we assume that the plane is flying with 32% of fuel like the F-16C Block 50, we get T/W ratio of 1,38:1, which is higher than F-16C Block 50.

If we want to be more objective, we will use fuel fraction into consideration.
Since the Su-57 has superior fuel fraction, it would need less fuel (percentage wise) to be able to match the F-16C range on 32% of fuel.
If we assume Su-57 is carrying 20% of fuel we get around 1,46:1 T/W ratio which is significantly superior to F-16C Block 50!

We can also make a speculative guess and assume that the Su-57 is 18 tones empty, and that the AL-41F-1 is producing 15,5 tones of thrust. With 20% of fuel on board we get T/W ratio of 1,55:1 which is brutal!
No matter how you turn it around, Su-57 will always have superior T/W ratio compared to the F-16C Block 50 if they are fueled for the same mission.

Now, we are talking about static T/W ratio here, but without knowing dynamic thrust numbers, we can’t have absolutely clear picture, but there is good reason to believe that the Su-57 has excellent climb rate because what was demonstrated so far at an air shows was simply brutal!

View: https://youtu.be/hXY233uuS9M?si=I7AzJkYBahZbWlwJ


I have never seen any other fighter climbing under similar conditions like the Su-57, and I’m assuming that the plane is not flying with minimal amount of fuel on board, since there were some reports that the plane is flying a demo with considerable amount of fuel.
According to the Sergey Bogdan, he was flying the Su-35S demo at an Paris air show at 25 tones takeoff weight, and taking into account that both planes have shown similar performance, my guess is that the Su-57 is doing its demo at similar takeoff weight, but that is only speculation on my behalf.

In any case, it seems that even in early 2013 they have achieved some serious progress, producing better results than expected, according to one of the top Su-57 program leaders, Mikhail Strelets:


If I get more time, I will give my take on the empty weight of the Felon?!
 
The F-22's projected empty weight has increased from 13,980kg at the preliminary design-review in 1992 to 14,365kg at the critical design-review, completed in February. Programme officials are confident that the additional 225kg allowance will not be needed.''

Just FYI, the empty weight stated here represents the weight that the F-22 airframe contractor is responsible, so it does not contain government-furnished equipment (GFE), such as the gun and most notably the F119 engines which weighs approximately 5,000 lbs (2,270 kg) apiece. The operating empty weight of the F-22 has always been understood to be in the 40,000 lb class.
 

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