Sukhoi Su-57 flight testing and development

icyplanetnhc (Steve) said:
The izdeliye 30 (AL-51F-1) was designed to be a drop-in replacement for the AL-41F-1 (izdeliye 117), and production Su-57s (the so-called second stage T-50 design with the reworked internal structure) were to be able to accommodate it. Note that the "second stage" T-50 is separate from the "Su-57M" project (Megalopolis) which would incorporate improved mission systems as well. "Second stage" needs clarification when discussing the Su-57 because depending on the context, it can refer to the airframe, or the engine, or an overall PAK FA modernization program.

More recently though, the izdeliye 177 has been pitched for re-engine of the domestic Su-57 as well, not just the export variant.
https://rostec.ru/media/news/energiya-poleta-80-let-okb-imeni-lyulki/

It's possible that this is viewed as more practical and economical than the izdeliye 30, especially given that the progress on this program has not exactly been quick or smooth. Even back in 2019-2020, Piotr Butowski in his book discussed the "Udlinitel" as a fallback in case the izdeliye 30 runs into problems. The 177 appears to incorporate an izdeliye 30-derived fan with the hot section ("gas generator") derived from the 117, and also likely a drop-in replacement. The rectangular nozzle appears to be engine-agnostic.
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Despite the marketing campaign, there are more questions than answers surrounding the 177/177S.

Butowski had previously spoken about the engine as a backup solution in case of delays with the 30 engine within the PAK FA program, but then somehow a narrative emerged and gained traction claiming that the 177/177S is purely an export product.

E. Marchukov himself speaks about the significant modernization potential of the 177/177S and about tests already conducted involving the addition of a third air stream.
See the video from the Dubai Airshow 2025, time 32:39:
View: https://youtu.be/CvJz7lK0niI?is=hFtficdbZFNcqr7O
 
EmoBirb said:
> alleged hit on an airfield

> "Shot down"

> No footage

> "GLORY TO UKRAINE

One doesn't have to be German to be mildly amused by this...attitude.
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Probably an imperfect translation.

That Russia have had multiple hits to their "stealth" fighters on airfields is pretty funny though.
 
Wouldn't a backup be developed concurrently with the hoped for engine? Timing is odd, everything about it is odd. If izd177 was chosen wouldn't it be in a more rapid state of development? Does anyone have a clue on the prospects of izd30?
 
EmoBirb said:
Or more, and that's far more likely, pure copium.

What is rather funny is that they managed to hit one of the prototypes sitting in the open rather early in the war (what was it, 2023?) and since then nothing came of it since. Unless the Satellite imagery that shows nothing happened is now meant to imply that something has in fact happened.

The funniest thing is though that there's nothing to show with all these Ukrainian "strikes", meanwhile a country like Iran was able to release infrared footage when they hit that "stealth" F-35 (and pumped the Pilot with a bit of shrapnel in the process).

Truly funny, isn't it? It tickles my German humor.
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Good point (from my own experience I know that there are two types of German humor - different not in content, but in form. The Ossi one is always more emotional, the Wessi one closer to the dry English one. I enjoy both).
 
177 and 177S aren't purely export products. They are result of "common engine" program to upgrade Flanker series. That's why they have 905mm inlet diameter - so they can be installed even in original Su-27 w/o changes to an airframe, as 905 mm is standard inlet diameter of AL-31F.
 
Can anyone post a relevant screenshot please? I cannot open the Video!
 
What are we looking at? That doesn’t look like a two seater… ok I see that it is an unrelated post
 
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Deino said:
Can anyone post a relevant screenshot please? I cannot open the Video!
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Sorry ,I tried last night so many times to post both videos & comments but I was unable to do that .Don't now why. In fact two comments are :

For the first video :

'' Russian stealth in the north of the Motherland. The 5th generation fighter Su-57 was spotted in the sky over Karelia.''

For the second video:

''Another video from our subscriber with the Su-57.
In this case, the 5th generation fighter was hunting for Ukrainian drones in one of the central regions of Russia.''


Video posted by 'flateric' is the second video ,not the first one.
 
OK ,this is the first video:

''Русский стелс на севере Отечества.

Истребитель 5-го поколения Су-57 был замечен в небе над Карелией.''

https://t.me/warhistoryalconafter/270228


From the second video ...

JetBrain said:
It seems the SU-57 carried something under the wing.
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Hm, it looks something like 101KS-N under the wing ?
 
Isn't the two seat configuration that they chose going to hamper the aircrafts RCS ? Seems like the J-20 layout is a bit stealthier.
 
alberchico said:
Isn't the two seat configuration that they chose going to hamper the aircrafts RCS ? Seems like the J-20 layout is a bit stealthier.
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Indeed. Beyond that though it is absolutely stunning!
 
alberchico said:
Isn't the two seat configuration that they chose going to hamper the aircrafts RCS ? Seems like the J-20 layout is a bit stealthier.
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J-20 has almost no seat stagger , pure WSO second station like many twin seat jets these days , Sukhoi for some reason continues to have considerable cockpit stagger like for twin controls trainer with rear seat actually having forward visibility. But that is likely customers requirement more than Sukhois decision.

*Picture on the runway looks like some AI or photoshop at work so would not trust the proportions one bit at this stage.

Patent drawing has much less cockpit stagger
MyCollages-5-4.jpg
 
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Not much really changed from orginal su57 canopy. Outside bracing at an unfavorable angle. Only times two now.

J20s design is somewhat better but that also applies to single seater. Actually, S variant possibly affected A rcs more than su57 twin seater affected single seater rcs, relatively speaking. Because su57s solution was bad to begin with.
 
EmoBirb said:
Or more, and that's far more likely, pure copium.
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There is certainly plenty of that in this thread...

EmoBirb said:
What is rather funny is that they managed to hit one of the prototypes sitting in the open rather early in the war (what was it, 2023?) and since then nothing came of it since. Unless the Satellite imagery that shows nothing happened is now meant to imply that something has in fact happened.
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I'm not really sure what exactly you're trying to imply here.
Are you expecting Russia to officially acknowledge the Su57 hits?
Or Ukraine to somehow release more evidence from the strike?
You keep saying that the satellite imagery shows nothing. Do you have any idea:
a) How little damage is required to put a fighter jet out of action?
b) How little you can assess the extent of damage from satellite photography?

EmoBirb said:
The funniest thing is though that there's nothing to show with all these Ukrainian "strikes", meanwhile a country like Iran was able to release infrared footage when they hit that "stealth" F-35 (and pumped the Pilot with a bit of shrapnel in the process).
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There is a big difference between using something like a SAM system to hit a jet flying directly over your airspace, which you can see directly, versus striking something 1,700km away behind enemy lines with drones.
The one-way attack drones used for these deep-strikes are autonomous. You don't control them remotely with a video feed sent back to you like the short-range FPV drones we commonly see killing Russian troops/vehicles. It would be far too easy for them to be jammed if they used something like Starlink to control drones over long distances, and it would give Russia plenty of warning.

Interesting for you to be questioning the stealth capability of the F-35 in the Su-57 thread of all places though. VLO doesn't mean invisible/invincible. One non-fatal hit out of thousands of sorties isn't exactly terrible odds, especially when you take into account how gung ho the Americans can be.
You're right that the pilot was injured by shrapnel, although they went on to land the plane safely at an airbase.

EmoBirb said:
Truly funny, isn't it? It tickles my German humor.
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What tickles me is when someone is so eager to keep reminding everyone of their nationality...
 
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Aviationist article points out patents emphasizing C2, and the new tail logo suggestive of M/UMT.

Russian aviation has famously involved a low level of pilot autonomy and a high emphasis on ground control. Could it be that they're essentially trying to address concerns about communication jamming--not by training their pilots to a higher level of autonomy, but by moving the commander into the air?

In which case, if this is meant as a commander/drone-controller plane, the higher RCS (already not the Su-57s strong point) may not be a concern because it's supposed to remain behind a line of other aircraft/drones. Although if that's their theory of operation, I feel like it begs the question of why use a Su-57 as the base, rather than just upgrade the avionics on an existing two-seater, but I guess that some RCS reduction is better than no RCS reduction?
 
The bracing is not much more of a concern than it is on the F-35, if it's covered by the coated canopy like on the American jet or has RAM applied like on the Su-57, the concept is similar. In that case structural needs were a priority.

That aside, I'm curious where the notion comes from, that two seat aircraft are somewhat inherently hindered with regards to low observability?
 
Ainen said:
https://t.me/bomber_fighter/25281
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Very interesting logo on the vertical stabilizer. Su-57D as a command centre for the S-70 'Hunter-B' ,FFF( Flanker Family Fighters) and some other air assets ?

@JetBrain​


Not only under the wing but also under the left air intake. It can be well seen on your and the ComradeVortex 's photo.
 
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EmoBirb said:
That aside, I'm curious where the notion comes from, that two seat aircraft are somewhat inherently hindered with regards to low observability?
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For most aircraft, the two-seater version is larger than the single-seater.
 
From the front, a raised rear seat places more cockpit/canopy in direct line of sight, while a low rear position is essentially mostly hidden behind the front canopy/cockpit. The cockpit can be one of the harder parts of an aircraft to reduce RCS for.

From the side, its more side area.
 
overscan (PaulMM) said:
From the front, a raised rear seat places more cockpit/canopy in direct line of sight, while a low rear position is essentially mostly hidden behind the front canopy/cockpit. The cockpit can be one of the harder parts of an aircraft to reduce RCS for.
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Does that mean one HUD/Pilot combination behind the coated canopy is significantly more reflective than one and a half one staggered above, covered by the same canopy? The B-21 opted to reduce window area as much as possible, which makes sense for a large strategic bomber that seeks to minimize it's signature to the fullest extent. But fighter jets, with their large canopies are in that sense compromised from the start, one just has to look at the huge bubble canopy of the F-22 for example. Then we also have the J-36, most likely a generational leap, where you have two forward facing cockpits for two people with a fairly large canopy area.

Point being, while there are differences to single seat aircraft, these differences are ultimately rather trivial. Especially compared to the impact on aerodynamics.
 
In fact any change to the OML of a stealth aircraft requires careful handling to avoid spoiling stealth properties. Su-57 has some stealth shaping and a lot of puzzling stuff to screw that up, so changing the canopy shape is probably no big deal in the scheme of things.
 
overscan (PaulMM) said:
In fact any change to the OML of a stealth aircraft requires careful handling to avoid spoiling stealth properties. Su-57 has some stealth shaping and a lot of puzzling stuff to screw that up, so changing the canopy shape is probably no big deal in the scheme of things.
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My 2 cents is that stealth aircraft are quite sensitive to changes to shaping in the horizontal plane, but not so much when it comes to the vertical, as all radar energy hitting the top surfaces is going to do so at a very shallow grazing angle and deflect off into the sky.
And after all, all stealthy aircraft tend to retain the aerodynamic curves of wings and other lifting surfaces.
 
The "unknown munition" reminds me a bit of the smaller ALBMs other countries deploy and in general of ALBMs like the Kinzhal. Perhaps an ALBM for the internal bays on the Su-57? That would be quite the payload and the large bays of the Su-57 could allow to tandem carry two sizeable ALBMs, while other stealth fighters are more limited in that regard.

Alternatively - a new AAM following up on the R-77M which aims to reduce drag further.
 
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