GARGEAN

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the 101KS-O consists of two scanning arrays, which would not offer the same response time for MLD or all-aspect SA purposes compared to EODAS with six staring arrays. The former’s arrays are probably used to provide targeting information for the DIRCM system, which is likely to counter MANPADS. Proposed DIRCM systems against IR AAMs are considerably larger and more powerful than the KS-O and fitted on larger aircraft with more power generation.
First: KS-O targets are deliberately stated to be both SAMs and AAMs. Second: where from do you know its power levels? Wanna share? Third: why one would need DIRCM against MANPADs to be installed on a spine?..
 

icyplanetnhc (Steve)

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First: KS-O targets are deliberately stated to be both SAMs and AAMs. Second: where from do you know its power levels? Wanna share? Third: why one would need DIRCM against MANPADs to be installed on a spine?..

Contemporary DIRCMs of comparable size like Elbit’s MUSIC or Selex/Leonardo’s MIYSIS are mainly advertised against MANPADS and are mounted on quite large fixed-wing aircraft, and have power output of 1 kW or less. Perhaps KS-O is effective against AAMs, but the literature that I’ve read so far have indicated that DIRCMs aren’t specifically designed against a hardened FPA seekers in current AAMs. Future iterations may have enough power output to jam or spoof AAMs, but I haven’t seen reliable information that contemporary operational systems are capable of this.

A spine-mounted emitter can be useful in conditions where the aircraft is in a steep angle of bank.
 
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Trident

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RCS reduction is obviously useful thing, but all these numbers of -50...70dbsm reflecting very local minimums in aspects of angular minutes,

On a properly designed VLO airframe they are quite representative, actually. While the overall average RCS might be noticably larger than the quoted figures, it is of little practical relevance if the planform is carefully shaped to concentrate the vast majority of the reflected RF energy into a small number of very narrow spikes. Over large sectors, the RCS observable to an enemy radar will then be close to the low figure, with only fleeting (too fleeting to exploit for reliable tracking) "bright flashes" when the threat azimuth briefly encounters one of the spikes.

The former’s arrays are probably used to provide targeting information for the DIRCM system, which is likely to counter MANPADS. Proposed DIRCM systems against IR AAMs are considerably larger and more powerful than the KS-O and fitted on larger aircraft with more power generation.

I'd say that's too narrow a view, MANPADS are but a tiny fraction of the IR threat spectrum for a 5th generation fighter like the Su-57 (which will tend to operate even higher and faster still than legacy fighters already do). It can probably deal adequately with MANPADS, which to date rarely have imaging sensors, using just its kinematics in combination with conventional flares.

There is no reason to expect power to be short on an aircraft with 2x15-18tf engines either - given its vintage, is likely to sit further along the increasing trend line in electrical generating capacity (legacy -> F-22 -> F-35 ->... 6th generation with DEW) than most peers. I wouldn't be surprised if it had higher electrical power available onboard than much larger platforms up to an A400M in size! Also, being purpose-designed for a supersonic aircraft, the DIRCM will be designed with a low external profile for drag reasons - I don't think the size of the turret allows any conclusions about overall size and power to be drawn.

In my opinion there is every reason to believe this system to be designed to defeat modern IIR SRAAMs primarily.

The actual MLD system on the Su-57, the KS-U, consist of multiple staring UV arrays for all-aspect missile warning. Also don’t know what basis you have to say “way better optics”.

As you say, the situational awareness function is performed by 101KS-U, with 6 staring sensors for spherical coverage just like the F-35 and J-20, which kind of renders the earlier arguments (not yours) that it must be inferior moot. Beyond the observation that the basic system architecture is configured alike we have far too little information on the Russian system (and virtually zip all on its Chinese counterpart) to make any such judgement.

Not sure how TVC, at least as implemented on the F119 and Su-30/-35/-57 (2D vector only, although differential roll control can provide some yaw input on the Sukhois), allows the removal of the ventrals. At a minimum, you would require full 3D TVC for active yaw control.

While these Russian aircraft have nozzles which move about one axis only, that axis is canted so the system can provide yaw control. Think of it as the TVC equivalent to a v-tail. The Su-57 may very well rely on yaw TVC to get away with its dramatically reduced fin area.
 
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Trident

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Good point, for Checkmate specifically (with only one engine) you'd need a two-axis nozzle, but as you say this is something Russia has already demonstrated in the past.
 

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@Trident The claim of -50 dBsm comes from this study:

file.php


Obviously, the study ignores RAM, and average RCS is in the -10 to -30 range. The poo-poo-ing of minimal RCS claims vs a large number of emitters with differing azimuths and angles is still valid if an absolute minimal RCS is chosen, since minimal RCS is closer to a valley than a depression.
 

Avimimus

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the 101KS-O consists of two scanning arrays, which would not offer the same response time for MLD or all-aspect SA purposes compared to EODAS with six staring arrays. The former’s arrays are probably used to provide targeting information for the DIRCM system, which is likely to counter MANPADS. Proposed DIRCM systems against IR AAMs are considerably larger and more powerful than the KS-O and fitted on larger aircraft with more power generation.
First: KS-O targets are deliberately stated to be both SAMs and AAMs. Second: where from do you know its power levels? Wanna share? Third: why one would need DIRCM against MANPADs to be installed on a spine?..

Are you saying your doctrine isn't to immediately invert after releasing bombs in order for the pilot to be able to view the ground impacts better?
 

Avimimus

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I'd say that's too narrow a view, MANPADS are but a tiny fraction of the IR threat spectrum for a 5th generation fighter like the Su-57 (which will tend to operate even higher and faster still than legacy fighters already do). It can probably deal adequately with MANPADS, which to date rarely have imaging sensors, using just its kinematics in combination with conventional flares.

Unless two piece multicrew manpads become possible, or air-breathers without onboard guidance or something like that - there is no way they'd have the kinetic performance to actually catch a modern fighter - unless it is flying nape of the earth (which exposes your 5th generation jet to volume fire)...

The only situation where it could happen is if the attempt to suppress long range SAMs and fighters has failed miserable and the aircraft can't penetrate enemy airspace any other way - even then - maintaining high subsonic speed should defeat almost all manpads (even if one is on the deck).
 

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@LMFS, the 101KS-O consists of two scanning arrays, which would not offer the same response time for MLD or all-aspect SA purposes compared to EODAS with six staring arrays. The former’s arrays are probably used to provide targeting information for the DIRCM system, which is likely to counter MANPADS. Proposed DIRCM systems against IR AAMs are considerably larger and more powerful than the KS-O and fitted on larger aircraft with more power generation. The actual MLD system on the Su-57, the KS-U, consist of multiple staring UV arrays for all-aspect missile warning. Also don’t know what basis you have to say “way better optics”.
An IRST has typically a narrow field of view, mind you, much like a radar, and scans the airspace very much in the same way. Given it makes several revolutions per second as we have seen in some videos, what threat do you see appearing and hitting the plane in that time? Of course time multiplexing is not continuous, but for the targets under consideration that is not relevant in the detection phase, while sector tracking of an incoming missile is for sure one of the possible operational modes and actually the only one that makes sense for the use as DIRCM

Assuming such a complex system is installed in the upper and lower hemispheres of the Su-57 just against MANPADS and thinking the only capability in the detection field is guiding the laser seems an unreasonably low expectation to me, this is certainly no cheap CAS plane. We see the turret and mirrors, but we do not see the part of the system which is inside of the fuselage, so I don't know how you ascertain the power and capabilities available. The KS-U is a good resource against false positives caused by IR reflections against the surface of the earth in the KS-O, given the additional information in UV spectrum is a much more sure telling sign of a rocket's plume. Again, why did Sukhoi take the F-35 approach with the Su-35 and go "backwards" with the Su-57?

As to the "better optics", clearly the IRST has an exploring mechanism and high optical amplification, narrow field of view and therefore much more capability to detect a target at big distances than a big field of regard staring array. That is why IRST are done the way they are and why they detect targets further away than any other airborne EO device.

(I assume on SecretProjects the stealth vs reduced stealth conversation has been done to death).
You assume correctly. You can go to the thread of the Su-57 stealth to see us debunking all those tired talking points until we dropped dead
 

icyplanetnhc (Steve)

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If you think that two rapidly scanning IR arrays offer the same type of all-aspect SA and missile warning as six staring arrays, then I have a bridge to sell to you. Consider the FOV limitations combined with framerate to scan an entire hemisphere, and the image/video processing required, and that an IR array can’t range like a radar. From what you’re describing, why would the Su-57 even bother with the KS-N targeting pod then?

UV-based missile warning systems aren’t novel in the West, as the UV variants of the AAR-47 has seen widespread application, so why did the F-22 and F-35 use an IR system despite experience with UV systems? Frankly when a design choice from Sukhoi diverges from the approach in other 5th generation fighters, you seem to be treating Sukhoi’s decision as superior as a first principle; I don’t doubt the competence of Sukhoi, but I also don’t regard every decision it makes (any company, for that matter) as unassailable.
 

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@LMFS, the 101KS-O consists of two scanning arrays, which would not offer the same response time for MLD or all-aspect SA purposes compared to EODAS with six staring arrays. The former’s arrays are probably used to provide targeting information for the DIRCM system, which is likely to counter MANPADS. Proposed DIRCM systems against IR AAMs are considerably larger and more powerful than the KS-O and fitted on larger aircraft with more power generation. The actual MLD system on the Su-57, the KS-U, consist of multiple staring UV arrays for all-aspect missile warning. Also don’t know what basis you have to say “way better optics”.
An IRST has typically a narrow field of view, mind you, much like a radar, and scans the airspace very much in the same way. Given it makes several revolutions per second as we have seen in some videos, what threat do you see appearing and hitting the plane in that time? Of course time multiplexing is not continuous, but for the targets under consideration that is not relevant in the detection phase, while sector tracking of an incoming missile is for sure one of the possible operational modes and actually the only one that makes sense for the use as DIRCM

Assuming such a complex system is installed in the upper and lower hemispheres of the Su-57 just against MANPADS and thinking the only capability in the detection field is guiding the laser seems an unreasonably low expectation to me, this is certainly no cheap CAS plane. We see the turret and mirrors, but we do not see the part of the system which is inside of the fuselage, so I don't know how you ascertain the power and capabilities available. The KS-U is a good resource against false positives caused by IR reflections against the surface of the earth in the KS-O, given the additional information in UV spectrum is a much more sure telling sign of a rocket's plume. Again, why did Sukhoi take the F-35 approach with the Su-35 and go "backwards" with the Su-57?

As to the "better optics", clearly the IRST has an exploring mechanism and high optical amplification, narrow field of view and therefore much more capability to detect a target at big distances than a big field of regard staring array. That is why IRST are done the way they are and why they detect targets further away than any other airborne EO device.

(I assume on SecretProjects the stealth vs reduced stealth conversation has been done to death).
You assume correctly. You can go to the thread of the Su-57 stealth to see us debunking all those tired talking points until we dropped dead
Except with several revolutions per second, you now have issues with exposure time. The sensitivity of an EO sensor can be increased by increasing the exposure time. A long exposure has a better chance of picking up a minute IR signature at long distances, and if your IRST swivels multiple times per second, you're not going to get a long exposure because the camera keeps on moving. With a static sensor, in contrast, you can employ a long exposure, or, through data processing, bin together multiple images to statistically detect faint IR signatures.

Moreover, with a constantly rotating IR sensor, while you might have angle handled, what about azimuth? You're stuck with a 90 degree field of view if you want to fully map everything in the area without creating blind spots, which sort of cancels out advantages of a rotating IRST vs an EODAS, since you're forced to use wider angles (wider angles, lesser magnification / sensitivity).
 

Trident

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If you think that two rapidly scanning IR arrays offer the same type of all-aspect SA and missile warning as six staring arrays, then I have a bridge to sell to you.

Well, as you said yourself earlier, the Su-57 has an EODAS-like array of staring sensors for that job. So whether or not a pair of scanning sensors can provide the same capability is a moot point. Nonetheless, you can quite plausibly argue that they get close enough to render the difference largely irrelevant:


UV-based missile warning systems aren’t novel in the West, as the UV variants of the AAR-47 has seen widespread application, so why did the F-22 and F-35 use an IR system despite experience with UV systems? Frankly when a design choice from Sukhoi diverges from the approach in other 5th generation fighters, you seem to be treating Sukhoi’s decision as superior as a first principle; I don’t doubt the competence of Sukhoi, but I also don’t regard every decision it makes (any company, for that matter) as unassailable.

It is worth pointing out here that it is purely conjecture that 101KS-U is UV-band - it's Butowski conjecture, which as conjecture goes is the best kind, but it's still conjecture, all the same. And there are certain clues that for once he got it wrong:

1) Butowski may have inferred it from its designation (i.e. U standing for UV), but other parts of the 101KS suite are named for their function, not their spectral coverage.
2) The previous generation Russian missile launch detector was an infrared-based (non-imaging) sensor named MAK-UL - so whatever the U stood for then may be the case again: https://ru.wikipedia.org/wiki/Мак_(теплопеленгатор)
3) As you say, infrared sensors (thanks to the ability to track missiles after motor burn-out and provide situational awareness imagery) are the gold standard. So there would have to be a very good reason for Sukhoi to use anything else, for example unavailability of such sensors. However, the company's own Su-35S is already fitted with an imaging infrared DAS (albeit from a different supplier) - so why not use that?
4) Directly from the horse's mouth, the manufacturer (helpfully including a somewhat obtuse translation) says the function of 101KS-U is to provide "the crew with the information on air and ground situation": http://bastion-karpenko.ru/VVT1/101KS_210324_02.jpg Sounds rather like a crude way of describing EODAS and is definitely at odds with UV band.
5) It is quite possible that BOTH options apply - i.e. 101KS-U is a dual-band UV/IR system. There are actually 3 lenses inside each aperture, one big (IIR?) and two small (UV? My own guess is LWR though): http://bastion-karpenko.ru/MAKS-2013/T-50_MAKS-2013_133.JPG

It seems to be one of those enduring misconceptions about the Su-57 (others of which have reared their heads here recently)
 
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icyplanetnhc (Steve)

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Well, as you said yourself earlier, the Su-57 has an EODAS-like array of staring sensors for that job. So whether or not a pair of scanning sensors can provide the same capability is a moot point. Nonetheless, you can quite plausibly argue that they get close enough to render the difference largely irrelevant:

https://www.mbda-systems.com/wp-content/uploads/2015/07/DDM-NG.pdf https://apps.dtic.mil/sti/pdfs/ADA427399.pdf

DDM-NG is still a staring array, albeit one with a rather massive FOV. For generating a high resolution track for cuing a DIRCM laser, I would imagine that the KS-O sensor would have a smaller FOV that can provide better angular resolution that can better cue countermeasures.

It is worth pointing out here that it is purely conjecture that 101KS-U is UV-band

As far as the band that the KS-U operates in, a case can be made for the system operating to operate outside the UV band, although to be frank the dual-band conjecture isn’t really convincing, as those two small apertures, if they really are lenses, would be too small for adequate light capture and image quality. Given that Butowski has provided the correct names for other components of the 101KS system that implies their function (KS-V, Vozdukh), I’m more inclined to trust his descriptions, though he certainly has made errors before (no one is immune from that). Furthermore, having a dedicated IR landing camera in the KS-P if the KS-V KS-U can already provides an IR image would be rather odd and wasteful.
 
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IIR correctly, from Paralay's forum thread on the Su-57, it was hypothesized with reliable info from zakupki.gov.ru and other manufacturer information found from the contract numbers that the sensors are wideband imaging in both SWIR and UV, and with the Su-35 having LWR, I find it probable that the two smaller lenses are for indeed for LWR.

As for the dedicated landing camera, for one, the KS-O system may not have the optimal minimum magnification capability to provide that widefield of view that is desired for a landing/low level flight camera, regardless of what band the KS-0 system images in.

Also, unlike the Su-35, the Su-57 doesn't have smaller IIR aperture next to it's main IRST station, so maybe KS-P also provides functionality for that as well, as obviously the IRST can provide far superior imagine, it is known that it is supposed to rotate around to present a RAM coated "face" to reduce RCS, so it would be rather uncomfortable to have such an expensive and complicated fighter vulnerable to a forward IIR AAM threat, so this KS-P seals the hole in the coverage.

In essence, you have all around SWIR/UV(in need of confirmation) staring sensors, along with the main IRST station likely in LWIR/MWIR and the dorsal and chin stations with probably MWIR for both general purpose thermal imaging and laser aiming. I honestly consider it to be more impressive than EODAS, especially since this is the first and only fighter(both fifth and fourth gen) that has DIIRCM. And I'm quite sure it's capable against more than just MANPADS lmao.
 

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Just one last question. How do the Russians evaluate the RCS of the F-35? Do they view it as stealthier or less stealthy than the F-22? The Checkmate would make a lot of sense if they viewed the F-35 as a 0.2 or 0.1 m^2 RCS fighter; then the math on detection range suggests that the Checkmate, given the claimed 0.2 m^2 average RCS as well as the substantially larger radar, would get a radar detection advantage vs the F-35 on average. Of course, in practice, the availability, presence, and survivability of a counterstealth radar is still extremely crucial, since counterstealth radars can cue EO / IRST systems. And when we consider the combination of counterstealth for detection and EO / IRST for tracking, IR stealth becomes highly crucial. What known IR-signature suppression features are extant on the Checkmate?
According to Russian experts, the RCS of the fifth-generation fighter can not be lower than 0.3 m2. F-22 rating - 0.35 m2, F-35 - 0.4 m2 (with short - range missiles under the wing - 2.4 m2) The engine of the izd. 30 has a reduced IR signature. In the future, it will be equipped with a flat nozzle with even better data. This is officially stated. As far as I understand, the Russian doctrine provides for reducing visibility only in narrow sectors. The maximum coverage with radio-absorbing materials in the front and the minimum from other angles. This allows you to dramatically reduce the cost of maintaining the readiness of the fighter. For the LTS $ 5,000 is claimed for an hour of flight, which is seven times less than that of the F-35
 

Trident

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As far as the band that the KS-U operates in, a case can be made for the system operating to operate outside the UV band, although to be frank the dual-band conjecture isn’t really convincing, as those two small apertures, if they really are lenses, would be too small for adequate light capture and image quality.

Yeah, as pointed out I'm more inclined to think the small lenses are laser warning sensors myself. I was offering it as a possible explanation of how everybody came to think 101KS-U worked in UV (a dual-band system would, just not exclusively).

Furthermore, having a dedicated IR landing camera in the KS-P when the KS-V can already provides an IR image would be rather odd and wasteful.

Depends on how high Sukhoi set the bar for landing camera image quality and missile tracking performance, these requirements might be difficult to reconcile in the same sensor. For example, LWIR should offer good detection of coasting missiles at range, but is generally not preferred for FLIR use. The PIRATE IRST on Typhoon has a dedicated MWIR channel for imaging/ID and many F-14s fitted with the LWIR AAS-42 retained TCS for the same purpose, even though the IRST had an imaging capability. In the latest business jets, the EVS actually comprises up to 6 sensors in different bands just for the landing camera function alone!

I think the very fact that we're having this discussion about what band the system operates in just goes to show how futile it is to take it for granted that the F-35 and J-20 are superior in this regard. If we can't even establish such a fundamental characteristic for certain, how are we to draw any useful conclusions at all (especially with respect to the J-20, where we know even less)?
 
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Jackonicko

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If you come up with the tail wing as your only justification for "purer stealth" or whatever that means, I should first ask you about what an "impure stealth" would be and also gotta tell you that its not that simple to say that the Checkmate has better low observability characteristics just because it has less tailwing because on the flipside it has the nose mounted (non-stealth) IRST that non of the American and Chinese counterparts you've mentioned have.
Let's be objective here. OLS on Su-57 and Checkmate (specially when not in use) does have RCS treatment. There are some RCS penalties but they're nowhere near as big as some people are trying to portray.

As for what gives you a bigger RCS penalty, OLS or moving tails on F-35? IMHO tails bring a bigger penalty.

Rivets like ship-builders' bolts and ill-fitting panels, would, I suggest, be a bit of a clue that this is not in the same class as the F-22 and F-35.
 

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Just one last question. How do the Russians evaluate the RCS of the F-35? Do they view it as stealthier or less stealthy than the F-22? The Checkmate would make a lot of sense if they viewed the F-35 as a 0.2 or 0.1 m^2 RCS fighter; then the math on detection range suggests that the Checkmate, given the claimed 0.2 m^2 average RCS as well as the substantially larger radar, would get a radar detection advantage vs the F-35 on average. Of course, in practice, the availability, presence, and survivability of a counterstealth radar is still extremely crucial, since counterstealth radars can cue EO / IRST systems. And when we consider the combination of counterstealth for detection and EO / IRST for tracking, IR stealth becomes highly crucial. What known IR-signature suppression features are extant on the Checkmate?
According to Russian experts, the RCS of the fifth-generation fighter can not be lower than 0.3 m2. F-22 rating - 0.35 m2, F-35 - 0.4 m2 (with short - range missiles under the wing - 2.4 m2) The engine of the izd. 30 has a reduced IR signature. In the future, it will be equipped with a flat nozzle with even better data. This is officially stated. As far as I understand, the Russian doctrine provides for reducing visibility only in narrow sectors. The maximum coverage with radio-absorbing materials in the front and the minimum from other angles. This allows you to dramatically reduce the cost of maintaining the readiness of the fighter. For the LTS $ 5,000 is claimed for an hour of flight, which is seven times less than that of the F-35
Iirc, the old Chinese / Russian RCS measurement of the F-22 was 0.1 m^2, was it not? I know at least the Chinese had a "representative" RCS measurement of the F-22 at 0.1 m^2, so maybe I'm conflating Russian measurements and Chinese measurements.

Still, if what you are saying is correct, with a claim of 0.2 m^2 vs 0.35 and 0.4, the claim is being made that the Checkmate, in Russian eyes, is stealthier than the F-22 and F-35, no?

===

For other readers, please remember that the RCS of an aircraft cannot be represented by a single number, but instead by massively complex graphs that vary depending on combinations of angle, azimuth, and frequency. The assumption being made is that the Americans prefer listing minimal RCS figures that represent the lowest RCS of an aircraft, while the Russians prefer listing average or usable RCS figures that represent a wider range of angles and azimuths.
 
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torginus

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In the future, it will be equipped with a flat nozzle with even better data. This is officially stated.
?..
You mean further refined using the data from in-flight testing?
Further development of the engine ed.30 will be with a flat nozzle. At least for the LTS, it is possible for the Su-57 and the PAK DP
What are the advantages of flat nozzles? Are they worth it?
I read an article on the F-22 where they said the flat nozzle was great for radar and IR signature reduction.
On the flip side, it's heavy, produces has less thrust than a circular one, and probably less efficient at some exhaust velocities due to the lack of adjustable diameter.
I'm not convinced that it's appropriate for a modern fighter, unless you are going for absolute, all-aspect stealth, which is not the Russian way as I understand.
Are there some other advantages to it?
 

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For other readers, please remember that the RCS of an aircraft cannot be represented by a single number, but instead by massively complex graphs that vary depending on combinations of angle, azimuth, and frequency. The assumption being made is that the Americans prefer listing minimal RCS figures that represent the lowest RCS of an aircraft, while the Russians prefer listing average or usable RCS figures that represent a wider range of angles and azimuths.
In the characteristics of Russian radars, this is one digit - the average value with which the SAM works
 

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riggerrob

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1. This will reduce the radar visibility to the desired value of 0.2 m2 from other angles
2. It will reduce the infrared signature
3. This will allow to close the nozzle for option a short take-off and vertical landing
2D nozzles are also relatively easy to install thrust reversers for STOL (see SAAB Viggen). 2D nozzles have far fewer moving parts than 3D nozzles (round).
Just look at 2D engine inlets ... they are common and pretty much standard on planes that fly Mach 2 or faster.
 

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Are thrust reversers justified on modern planes though? Aren't the flaps+ all moving tails provide enough braking force?
And with regards to STOVL, are there rumors on the grapevine that something is in the works?
Personally I'm not seeing the appeal of STOVL compared to STOL, and canards or movable root extensions allow for planes with pretty good STOL performance.
 

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Our article on the Sukhoi T.75 Checkmate is now up on the FaceBook Aerospace Analysis & insight (A2&i) page.

https://lnkd.in/ecffX8Nf

Please do check out our 'prototype' YouTube video.

https://lnkd.in/eKDWPg-3

And finally, please subscribe to our YouTube channel!
With all due respect, that video is a bit late hyping that this plane is just an airshow stunt, once Borisov, Strelets and Manturov have put previous negative Western speculation to rest with their explanations of the last weeks.

It is designed, it is funded, and it is clearly expected that VKS will buy it, as explained before in this thread, what you see is nothing but the typical MO of the Russian MIC before a new proposed weapon has been fully developed, tested and debugged. You are much safer in your analysis taking that as a basis than speculating with Sukhoi's ineptitude.

Let me add something: the West getting Russia wrong systematically just shows flawed understanding and/or ideological bias, when not a political agenda. It cannot be sustained as worthy analysis any more, in the face of non-stop failures to predict outcomes in the real world.

This is officially stated
Where, if I may ask? I have seen the nozzles you showed in the Zvezda documentary about the Su-57, but I have not seen any confirmation about that design being the future. If made rotating, it would allow to realize a true 3D nozzle with the basic layout and advantages of a 2D, which is indeed interesting.
 

icyplanetnhc (Steve)

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IIR correctly, from Paralay's forum thread on the Su-57, it was hypothesized with reliable info from zakupki.gov.ru and other manufacturer information found from the contract numbers that the sensors are wideband imaging in both SWIR and UV, and with the Su-35 having LWR, I find it probable that the two smaller lenses are for indeed for LWR.

The massive disparity in aperture size frankly makes a dual UV/SWIR band KS-U unlikely. I’m inclined to agree with @Trident that those two smaller apertures are instead LWR. Given that UOMZ is supplying the entire 101KS EO system, a SWIR array may be used by another component, such as the KS-O. I made a typo earlier; if the KS-U has an IIR function, then the KS-P landing camera would be unnecessary.

@Trident, the PIRATE is a dual band MWIR/LWIR system for IRST/FLIR function, although I’m not sure if it’s a primary or secondary source stating this. A similar arrangement was planned for the F-22’s AIRST before it got cut, although there’s still an empty bay under the nose reserved for that. As a side note, I believe the Lockheed Martin’s IRST21 has AAS-42 lineage, being also a LWIR system.
 

Evgeniy

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Rivets like ship-builders' bolts and ill-fitting panels, would, I suggest, be a bit of a clue that this is not in the same class as the F-22 and F-35.

The evolution of the surface of the Su-57 is quite noticeable. Nothing prevents it from continuing and spreading to the entire plane.
The same goes for "75".
 

Trident

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I made a typo earlier; if the KS-U has an IIR function, then the KS-P landing camera would be unnecessary.

@Trident, the PIRATE is a dual band MWIR/LWIR system for IRST/FLIR function, although I’m not sure if it’s a primary or secondary source stating this. A similar arrangement was planned for the F-22’s AIRST before it got cut, although there’s still an empty bay under the nose reserved for that. As a side note, I believe the Lockheed Martin’s IRST21 has AAS-42 lineage, being also a LWIR system.

Yes, I understood what you meant. I brought up these Western IRSTs merely to illustrate the point that there could be a conflict between the requirements of a landing camera and MAWS/DAS going on. If only Sukhoi set the performance bar for each function high enough there might not be a way to provide adequate landing camera image quality in a sensor which meets the missile tracking requirement and vice versa.

Perhaps because the only way to do the latter would be for 101KS-U to use LWIR (for all the same reasons why IRSTs generally do) which would then give too poor a scenery rendition to be an acceptable landing camera, thus necessitating the separate 101KS-P. AAS-42 could provide imagery output, yet was generally supplemented with TCS (or a separate FLIR in the F-15K/SG/SA/QA) for that purpose as the LWIR image was not much good.
 

icyplanetnhc (Steve)

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To date, IIR missile warning systems have been in the MWIR band, which should provide adequate resolution and contrast at ambient temperatures for FLIR purposes while still maintaining good detection capabilities. A dedicated IRST may use the LWIR band.

That said, this discussion is veering off topic.
 
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Kurfust

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IIR correctly, from Paralay's forum thread on the Su-57, it was hypothesized with reliable info from zakupki.gov.ru and other manufacturer information found from the contract numbers that the sensors are wideband imaging in both SWIR and UV, and with the Su-35 having LWR, I find it probable that the two smaller lenses are for indeed for LWR.

The massive disparity in aperture size frankly makes a dual UV/SWIR band KS-U unlikely. I’m inclined to agree with @Trident that those two smaller apertures are instead LWR. Given that UOMZ is supplying the entire 101KS EO system, a SWIR array may be used by another component, such as the KS-O. I made a typo earlier; if the KS-U has an IIR function, then the KS-P landing camera would be unnecessary.

@Trident, the PIRATE is a dual band MWIR/LWIR system for IRST/FLIR function, although I’m not sure if it’s a primary or secondary source stating this. A similar arrangement was planned for the F-22’s AIRST before it got cut, although there’s still an empty bay under the nose reserved for that. As a side note, I believe the Lockheed Martin’s IRST21 has AAS-42 lineage, being also a LWIR system.

IRST/FLIR from Pirate works in LWR band. I dont know if Pirate get some update, but on beggining only worked on LWR band.

Captura-de-pantalla-2021-09-22-162654.jpg
 

LMFS

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The evolution of the surface of the Su-57 is quite noticeable. Nothing prevents it from continuing and spreading to the entire plane.
The same goes for "75".
People get annoyed when airshow F-22s are accused of having poor maintenance of the coatings, but they don't seem to be able to tell the difference between a rough prototype where RCS does not matter at all either and a serial unit...
 

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Where, if I may ask? I have seen the nozzles you showed in the Zvezda documentary about the Su-57, but I have not seen any confirmation about that design being the future. If made rotating, it would allow to realize a true 3D nozzle with the basic layout and advantages of a 2D, which is indeed interesting.
During the presentation, the General Director of the UAC, Yu. B. Slyusar, said:
- this nozzle (engine izd.30) is of a transitional nature

Since all types of axisymmetric nozzles were created by the Russian industry and tested in practice, I assume that we are talking about a rectangular nozzle
 

F119Doctor

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Where, if I may ask? I have seen the nozzles you showed in the Zvezda documentary about the Su-57, but I have not seen any confirmation about that design being the future. If made rotating, it would allow to realize a true 3D nozzle with the basic layout and advantages of a 2D, which is indeed interesting.
During the presentation, the General Director of the UAC, Yu. B. Slyusar, said:
- this nozzle (engine izd.30) is of a transitional nature

Since all types of axisymmetric nozzles were created by the Russian industry and tested in practice, I assume that we are talking about a rectangular nozzle
To increase the specific thrust as is claimed for the izd.30, the nozzle pressure ratio has to go up. Since the nozzle is structurally a pressure vessel with moving parts, design surprises can happen even with a previously proven design
 

F119Doctor

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In the future, it will be equipped with a flat nozzle with even better data. This is officially stated.
?..
You mean further refined using the data from in-flight testing?
Further development of the engine ed.30 will be with a flat nozzle. At least for the LTS, it is possible for the Su-57 and the PAK DP
What are the advantages of flat nozzles? Are they worth it?
I read an article on the F-22 where they said the flat nozzle was great for radar and IR signature reduction.
On the flip side, it's heavy, produces has less thrust than a circular one, and probably less efficient at some exhaust velocities due to the lack of adjustable diameter.
I'm not convinced that it's appropriate for a modern fighter, unless you are going for absolute, all-aspect stealth, which is not the Russian way as I understand.
Are there some other advantages to it?
Structurally a rectangular nozzle is not as efficient as a round nozzle, since all of the flat surfaces try to bend in the middle under the air pressure loads.

There are challenges in keeping a high coefficient of discharge with a rectangular nozzle, careful design is necessary to keep air leakage under control and to provide sufficient cooling for AB operation. See structure challenges.

However, in addition to the signature benefits, a vectoring rectangular nozzle has full control of both the convergent throat and the divergent flaps, providing both thrust vectoring and optimal divergent expansion area for maximum thrust throughout the flight envelope, better that most round nozzles.
 
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Avimimus

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Our article on the Sukhoi T.75 Checkmate is now up on the FaceBook Aerospace Analysis & insight (A2&i) page.

https://lnkd.in/ecffX8Nf

Please do check out our 'prototype' YouTube video.

https://lnkd.in/eKDWPg-3

And finally, please subscribe to our YouTube channel!

Thoughts:
- The development of a single engined Mig-21 replacement started in the early 1980s...
- This may well be the result of the LMFS program...
- The appearance of a new airframe without warning used to be quite common (i.e. the old Ramenskoye codes were a thing)... and certainly secrecy about systems has increased massively in the past five years.
- It isn't unheard of to cobble together funding from various government departments and countries (e.g. it has even been debated whether Canada intended to buy the JSF when we first joined the program, or if it was primarily done to open the way for Canadian subcontractors to participate).

As for re-using the airframe components... without a CFD analysis or structural analysis to show that the losses are high from using these components I'm withholding judgment.
 

LMFS

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During the presentation, the General Director of the UAC, Yu. B. Slyusar, said:
- this nozzle (engine izd.30) is of a transitional nature

Since all types of axisymmetric nozzles were created by the Russian industry and tested in practice, I assume that we are talking about a rectangular nozzle
If I remember well, he said that in the context of being questioned about the engine that LTS would employ, he referred to the engine not being izd 30 but the nozzle being already transitional. At least that is the way I understood that, using the translator I admit I can be dead wrong.... but it made sense to me.
 
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