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

I agree that the military and love beautiful pictures, but the choice of the F-22 was justified, it really is better


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There was some post about a new nozzle in Paralay forum, it would be cool if the updated design uses that nozzle. It would also be interesting to find out how sukhoi will do the deflections for it.
I noticed the additional fins below the H-stab.
Which is optional according to description of patent:

[...]В качестве дополнительного средства повышения устойчивости на хвостовых балках фюзеляжа могут быть установлены неподвижные под фюзеляжные гребни 11, плоскость хорд которых формирует угол с вертикальной плоскостью самолета.[...]
Still hard to understand why do they need a double seater.
From this patent:

[...]Возможность использования двухместного многофункционального самолета в качестве воздушного пункта управления, с возможностью обеспечения взаимодействия между авиационными и войсковыми формированиями при решении боевых задач, проведения анализа информации, поступающей от собственных систем и внешних источников информации с последующей выдачей рекомендаций экипажу и команд самолетам группы, а также в качестве пункта управления беспилотными летательными аппаратами, достигается за счет широкой номенклатуры средств связи, включающей в себя спутниковую связь, оборудование для групповой передачи информации, оборудование для передачи информации на большие удаления и высокоскоростного канала связи для получения и передачи аудио, фото, видео, текстовой, голосовой и телекодовой информации и специализированного командно-информационного поля задней кабины экипажа, (который, по сравнению с передней кабиной имеет следующие отличия: расширенный панорамный авиационный индикатор и дополнительный индикатор для увеличения рабочего поля оператора, устанавливается органы управления для передачи приоритета управления из одной кабины в другую, а также исключаются органы правления, не требующие управления вторым членом экипажа), что позволяет в оперативном режиме получать информацию из различных внешних источников (как авиационных, так и сухопутных и морских), проводить ее анализ на борту самолета и выдавать рекомендации или команду на выполнение боевой задачи самолетам группы с учетом их запаса топлива и боевого оснащения.[...]
I'm curious if there is any studies or papers from Russia on utilization of Radar absorbers, be it RAM paint or RAS (Radar Absorber Structure). Knowing that Su-57 skin is like 20% composite by weight yet about 70% by surface area makes me think that, the composite skin could host some RCS reduction means.

I have been fixated on absorber paint for a while, which kinda forgetting the Radar Absorber Structure and the composite skin is also a RAS (previously i thought it's something like Bulkhead etc) But anyway. been trying to figure some scheme on possible layout of Su-57 coating, the wide area application of the composite kinda make me think something like this.


So basically the Absorber paint would be on top of primer. The composite panel which is of honeycomb type will have some treatment in its core to provide it with absorbing ability. The face would be dielectric and matched to the primer and the RAM paint so that EM wave that managed to pass through the RAM would seamlessly enter the composite panel. The wave got absorbed then reflected by the composite's back panel which should be conductive otherwise the wave will just penetrate inside the aircraft.

The problems then would be the thickness and the electrical properties of the material. Simulating materials in software e.g Ansys or other EM solver of your choice NEEDS material's electrical properties namely :

1. Relative Permittivity (Dielectric Constant)
2. Permeability
3. At least Impedance or Resistance in case you are using POFACETS.
4. Dielectric and Magnetic tangential loss.

Commonly available research papers often specify 1 and 2 in complex notation ( x-jx) as these materials have Imaginary and Real properties (the "j" notation). They need to be solved first to get the value of Relative Permittivity and Permeability. Not all papers however specify them but instead showing Reflection loss instead which totally useless for modeling purpose.

Back to Su-57 Skin. For the purpose of modeling i selected Barium Hexaferrite playing the role as "Iron ball paint" while for the composite i choose one from a Korean research paper on RAS on honeycomb material. The model itself are as usual my old Su-57 model, it's now have more extensive RAM coverage.

Most of the body are treated except some parts, but otherwise it's almost fully covered inlet features radar blocker and wall treatment with same material. The parts that are radomes like leading edge and nose are left as PEC (Perfect Electric Conductor) as it's kinda close to FSS/bandpass radome, canopy is also left as PEC for same reason except instead of FSS it has gold or conductive coating.

The absorber specification as follows :

Barium Hexaferrite paint : 1 mm thickness.
Composite panel : 6 mm thickness.

The thickness for the paint are trial and error as too thick and the reflectivity grows or too think and it not work well with the composite. while the composite thickness are selected based on some guesstimates on Su-57 at assembly line. not really exact but possible given the apparent thickness in the available photo.

Magnetic and dielectric part are derived from papers, for example this is for the Hexaferrite paint :

Excerpt depicting the properties for the honeycomb composite absorber :


Notice the complex number notation for the permittivity.

As for comparison, the model will be compared with the Su-57 model that only use paint (3 mm for skin and 5 mm for inlet) and a clean F-16.

The result are as follows :


As can be noticed, the one with composite skin and RAM paint have lesser RCS compared to one that relies only to paint. Both aircraft however are, at least when compared to conventional, have relatively much lower RCS. The model with only paint have about 0.5 sqm in X-band while the one with both RAM paint and RAS composite absorber are 0.2-0.3 sqm.

I also would like to introduce a "new standard" that i use to present my RCS data namely "Equivalent Spherical RCS" Which a simplified representation of aircraft RCS which obtained by doubling the Median of the RCS data. I adopted this from book ""Principles of Air Defense and Air Vehicle Penetration" - Frank Heilenday (ADA375233)".

On the subject of new standard which includes some comparisons i made :


This modeling attempt however are still speculative in nature, especially on the RAM and RAS composition and their electrical specifications. It could perhaps be possible to have some large values of both permittivity and permeability within the composite which could be retained for considerable amount of bandwidth. But at least it can be shown the benefit and the amount of reduction of RCS resulted from the attempt.

as a closing remarks.. Enjoy some 3D graphics of interaction between the model and the Radiowave.

Su-57 ANimations.gif
A one of a new batch showed up in Novosibirsk:

(-37C outside)

Official press-release soon(?)
well, according to rumors(?), 8 airframes in two batches were delivered in 2023 as of yet.
True, but 18 planes in total might be enough that a small operational squadron always keeps a pair available for a daily combat mission.
True, but 18 planes in total might be enough that a small operational squadron always keeps a pair available for a daily combat mission.
Squadron is 12, so most probably 23th IAP either already has one, or will have in the immediate future.

But su-57 production goes on top of now rather substantial su-35 fleet, which is also too new&capable to be discounted.

In the global context, while Felon production isn't especially large (nor it will be), it now gives a notable 'addition' to the J-20 one.


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Awesome. Cannot wait for the izd30 and new nozzles as well as the other sensor updates.

Edit: look closely at that dark square on it's back. If you zoom in you can see the unique sawtoothing they use on the grating seen on other parts of the su-57 like behind the cannon. I do not remember seeing this particular grate before...
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Source: serial Su-57s transferred to the VKS in 2024 will receive engines of the second stage
As the agency's interlocutor noted, in 2023, more than 10 Su-57s with first-stage engines have already been transferred to the Aerospace Forces
MOSCOW, December 28th. /tass/.
All serial Su-57 fighters transferred to the Russian Aerospace Forces (VKS) in 2024 will receive second-stage engines. This was reported to TASS by two high-ranking sources close to the Russian Aerospace Forces."The engine of the second stage has been tested and is ready for operation," said one of the agency's interlocutors. A second source confirmed this information and added that "all production aircraft of the fifth generation Su-57, transferred to the VKS in 2024, will receive a fifth-generation engine."TASS has no official confirmation of this information.According to the agency interlocutor, in 2023, more than 10 Su-57s with engines of the first stage have already been transferred to the VKS. They successfully solve tasks in the zone of a special military operation.

According to the plan, 12 Su-57s should be transferred in 2024
This guy claims they are already using AL-51F engines allegedly based on the TASS report, but I cannot find the original file stating they can maybe be re-engined at a later stage: Can anyone find the mentioned text or correct me?

The TASS article is clear: until now, all production aircraft have AL-41F1 engines installed, and from the new year all will have AL-51F1. Dot.
If the source was right, we will see in the next few months.
I wonder if the new engines will necessitate changing the intakes and/or the airframe. With the J-20, it definitely seemed to be the case.

On an unrelated note - does anyone know if the Su-57 uses hydraulic actuators or does it have electric/electrohydraulic ones?
350bar/5000psi centralized hydraulic system (think B-2 or Rafale), AFAIK. There is a development roadmap to an EHA architecture though, so the second stage airframe might get that.
Open question to the gentlemen here: does this announcement of deliveries with the second stage engines already in 2024 indicates that the rest of the improvements slated for the M version are going into the series too?
So Is the new engine true 3d TVC, or uses the canted 2D design? I remember the Mig-29OVT had it and it was pretty neat.
The Controlled Thrust Vector (УВТ) and the Deflected Thrust Vector (ОВТ) are two different systems from two different companies


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