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



  • scale_2400.jpg
    2.4 MB · Views: 164
  • scale_22400.jpg
    2.1 MB · Views: 131
  • scale_24200.jpg
    2.6 MB · Views: 143
  • scale_223400.jpg
    770.3 KB · Views: 855
  • scale_242300.jpg
    1.4 MB · Views: 177
Visible changes on T-50M prototype:
- new sensor
- new 101KS-U sensor
- new helmet

Very good article, thanks for sharing. Just the helmet... It's not very clear from the photo if it's the good old Zosha or the new ZSh-10 with a HM display system.
In that article, among other things, there is an interesting note about the complexity of the structural solution of the fuselage with unprecedentedly large weapon bays with regard to overloading during demanding maneuvers, plus many other interesting things.

The Su-57 is sometimes the target of infantile criticism on discussion forums in the context of „generational pigeonholing“ (according to this logic, the F-35 would be generation 4.5 at most, as it lacks supermaneuverability and supercruise...).

In fact, the Su-57 is a respectable product of aviation development, and no aircraft in operational use will have comparable capability and flexibility at the end of this decade.

The Su-57, at that time already with the new Izdeiye 30 engines, will be a mature operational aircraft with universal hypersonic weapons such as the Lichinka-MD/Larva-MD, with a wide range of anti-surface weapons from the small-diameter Kh-MD modular missiles to the heavy Kh-69 ALCM, from Izd. 300M short-to-medium AA IIR missile to hypersonic ultra long-range anti-aircraft missile Izd. 810... - all this while being carried in INTERNAL weapon bays, i.e. while maintaining the excellent kinetic characteristics of the sophisticated design in the full range of the flight envelope and reduced detectability.

Not to mention the MUMT capability in connection with the miniature Molnya UAVs (also carried internally) or the huge S-70 Okhotnik.

Yes, it will be 20 years after the first flight of the prototype, after many difficulties, slowly starting mass production, but it will be. And although a number of very interesting new generation fighter aircraft programs are currently underway around the world, at that time the Su-57 will be a FULLY OPERATIONAL type with great modernization potential.

It is not a failed project. It's a success.
Visible changes on T-50M prototype:
- new sensor
- new 101KS-U sensor
- new helmet
Appears I was wrong in my initial observations regarding the new 101KS-U sensor, in terms of dimensions the bulge is still present as before. Not as slimmed down as I thought.

New generation technologies​

Highly intelligent, stealthy, supersonic - these are some of the main requirements for a fifth-generation fighter


When creating the Su-57 fighter, the Sukhoi Design Bureau developed dozens and hundreds of advanced solutions. The result is an aircraft that can adapt to the level of pilot training, has low visibility in the radio, infrared, optical and sound ranges, 70% of its surface area consists of composite materials, and the pilot's equipment anticipates and fends off overloads in advance. However, all these new technologies and solutions not only determined the appearance of the new machine, but also formed the criteria by which this or that device is now referred to as the fifth generation of military aircraft. They will become the basis for new developments.

Su-57 is traditionally called a new generation machine. But what should be considered the criteria by which this or that fighter could be attributed to the fourth, fifth or even sixth generation? “Of course, such a division into generations is rather arbitrary,” says Mikhail Strelets, Deputy General Designer of the UAC for Military Aviation, Director of the Sukhoi Design Bureau, Chief Designer of the Su-57. - Each country has its own criteria that determine the generation of military aircraft. But it is possible to single out general characteristics that would indicate that the aircraft belongs to one or another generation.”

If we talk about fifth-generation fighters, then their distinguishing features are the requirements for cruising supersonic flight. The second significant characteristic is the requirements for a lower level of radar, infrared, optical and sound visibility compared to previous generation aircraft. “Also, fifth-generation aircraft are subject to requirements related to the on-board equipment complex,” said Mikhail Strelets. “It is built on the principle of open architecture and allows you to implement the principle of modularity in the construction of avionics.” In addAttach filesition, new generation aircraft are also subject to increased requirements for automation and intelligent crew support. Multi-channel airborne sensors provide the pilot with spherical situational awareness. Consequently,
Everyone has their own characteristics


However, when creating a new aircraft, there were also specific requirements. “The first thing that distinguishes the Su-57 from all other representatives of the fifth generation aircraft family in the world is its versatility,” says Mikhail Strelets. “Our complex was required to solve both the air-to-air tasks inherent in an air superiority fighter and the air-to-surface strike capabilities characteristic of a fighter-bomber.”

If we compare the Su-57, for example, with the F-22 Raptor, then the "American" was originally created only as a fighter to gain air superiority. Destroyer missions dominate him, occupying about 90% of the total scope of application options. Another American aircraft of the fifth generation F-35 Lightning II , on the contrary, was created as a fighter-bomber with an emphasis on strike missions. Of course, each of them has some degree of versatility. But compared to the Su-57, this multifunctionality is distributed, so to speak, less evenly between different types of tasks. The Su-57 fighter is capable of solving fighter and strike missions in approximately equal proportions.

The second difference lies in the fact that the main stake in the use of the F-22 aircraft in the field of fighter missions is placed on long-range air combat. Therefore, the requirements for low visibility and the possibility of using intra-fuselage compartments to accommodate aircraft weapons became priority. For the Su-57, both are important. “We tried to find a compromise between all these requirements: to ensure a low level of aircraft visibility to gain advantages in long-range air combat, but at the same time to implement the principle of high maneuverability for close air combat,” says Mikhail Strelets. “The result is a fighter that is as nimble as the best fourth-generation aircraft.”

Model with cutouts


The very appearance of the Su-57 radically distinguishes the aircraft from the representatives of the fourth generation. After all, the new fighter was developed taking into account the requirements of low visibility. The project implements the so-called stealth technologies. “Unlike previous aircraft, the Su-57 airframe was originally designed to meet these requirements,” Mikhail Strelets explained. “Therefore, it has a characteristic shape with sloping sides, parallel edges, and the like.”

In addition, to ensure low visibility on the Su-57, aviation weapons are placed in the internal compartments of the aircraft. This also required a special approach to the design of the fighter. “One of the critical technologies that had to be implemented was the creation of the fuselage itself,” recalls the director of the Sukhoi Design Bureau. - It has cutouts for very large cargo compartments to accommodate aircraft weapons. It was necessary to solve the problem of strength when the fighter reached maximum overloads. This is quite a unique thing. Neither on domestic nor on foreign aircraft, such a task has never been solved before.

The aerodynamic design of the Su-57 is also unique. It contains controls that have not previously been used on any of the aircraft. For example, the deflected front part of the influx. “It provides a stable and controlled flight of the aircraft at high angles of attack,” explained Mikhail Strelets. “At the same time, it is included in the overall control system, allowing for maneuvering to improve the aerodynamic quality of the aircraft.”



Special mention should be made of the materials used in the design of the Su-57. It also uses traditional metal alloys, but there were some innovations here too. For example, in the airframe of the Su-57 there are four times fewer parts than in the Su-27. This was achieved, first of all, due to the capabilities of high-performance machining tools, as well as due to electronic prototyping in the development of the aircraft. As a result, there was a qualitative transition to large milled parts, the number of fasteners and small parts was reduced. “This made it possible to significantly simplify the design,” says Andrey Filatov, head of the research department (R&D) of materials and technologies at the Sukhoi Design Bureau. – According to production specialists, it has become much easier to assemble the aircraft, because large parts come to the assembly.

If we talk about the outer surfaces of the Su-57, then about 70% of their area is made up of parts made of composite materials. It was composites that made it possible to make larger skin elements, while simultaneously reducing the number of fasteners and the number of conventional parts. There were new technological methods, methods of work that required additional equipment.

Close ties between the Sukhoi Design Bureau and composite manufacturers, developed in previous projects, contributed to the widespread introduction of composite materials. “For example, we used to work well with NPP Technologiya in Obninsk,” Andrey Filatov recalls. “For the Su-57, they had to master the production of many new specific parts, use new materials.” On the other hand, according to Andrei Anatolyevich, when using composite materials, the designers of the Design Bureau got the opportunity to control the properties of parts by changing the options for laying the filler. “After all, you can put all the material in one direction, you can put part of it perpendicularly, you can put it at 45 degrees. Combinations of these stackings determine the final properties of the part,” Andrey Filatov explained. - So far, composite materials have only one significant drawback: they are more expensive than metal ones.

Before launching parts made of composite materials into mass production, a large number of their full-scale samples were tested. At the enterprises-suppliers of products, they achieved full reproduction of the specified indicators due to the regulation of the production process, strict adherence to technology and strict control.

Inconspicuousness is welcome


In the manufacture of the Su-57 skin panels, it was very important to meet the highest requirements for accuracy and for one more reason. “The quality of the surface seriously affects the visibility characteristics,” Mikhail Strelets explained.
In addition, other special events were implemented. These, according to the director of the Sukhoi Design Bureau, included, for example, the use of special radio-absorbing and radio-reflecting materials. Shielding materials were also used, in particular on the antenna compartments. “All onboard equipment, for example, facing the leading edges, was designed to meet the requirements for low radar visibility,” Mikhail Strelets specified. - To reduce infrared visibility, certain measures were also implemented. For example, shielding of engine emissions is provided by blowing through the heat exchangers of on-board equipment.”

There were also requirements for reducing optical visibility. They were realized, among other things, thanks to the special coloring of the airframe. “There were also requirements to reduce acoustic characteristics,” explained the head of the Sukhoi Design Bureau. “If we compare the flights, for example, of the Su-30SM, Su-35 and Su-57, then the latter flies much quieter.”

One for three


Su-57 is a multifunctional machine. An increase in the number of tasks should have led to an increase in the load on the pilot. At the very beginning of work on the project, the Sukhoi Design Bureau somehow jokingly calculated that at least three people should be on board a fifth-generation single-seat fighter: one should be a pilot, the second should be an equipment operator, and the third should be a flight engineer. But that did not happen. “To complete the main task, it was necessary to unload the pilot from secondary functions,” says Alexander Kornev, chief designer of supercomputer technologies at the Sukhoi Design Bureau. – The combination of all mathematical models allowed us to build a digital system in such a way as to minimize the load on a person. But the decision, of course, remains with the pilot.

Digital systems have appeared on domestic aircraft for a long time. They stood in different subsystems of the onboard complex. But the degree and depth of the tasks they solved each time, with each generation, increased and became more complicated. “And when we were instructed to create a single-seat multifunctional aircraft, this task came to the fore,” says Vladimir Beketov, chief designer for the intended use of the Sukhoi Design Bureau. – We tested some of these solutions on Su-30MKI and Su-35 aircraft. But the Su-57 has become the pinnacle that we have been able to achieve in recent years. On this plane, the entire board is digital. Although our sensors are analog, their signals are also converted into digital. And all the processing is done digitally.”

Since the Su-57 is a multifunctional aircraft, it is equipped with a huge number of systems and subsystems operating in different frequency ranges. The developers had a big task of managing this entire complex. “It was immediately obvious that one person could not cope with such rich equipment, with such a rich complex,” recalls Vladimir Beketov. - On the one hand, we had multitasking, on the other, multi-mode and multi-system. We immediately decided that a person on the Su-57 should be not so much a pilot, and not so much an operator, as a fighter. He must work at the level of making extraordinary decisions.”

Of course, the designers could automate any stage of the Su-57 flight, the solution of any of its tasks. But these would all be deterministic solutions. An intelligent adversary would quickly recognize such solutions and find countermeasures. Therefore, in any intellectual system that was included in the Su-57 project, there was always an unformalizable human factor that can make extraordinary, unexpected decisions that ultimately lead to victory.

Highly intelligent board


Sometimes you can hear the opinion that the Su-57 uses artificial intelligence technology. Vladimir Beketov, chief designer for the intended use of the Sukhoi Design Bureau, does not agree with this. “Artificial intelligence in the classical sense is a system that has the ability to self-learn,” he explains. – But no regulatory framework of the air force provides for the development of self-learning systems. In all manuals for testing aviation equipment, it is strictly prescribed: there must be something, check how it is done. And how the system will learn itself is impossible to predict. The second difficulty is replication. We will train one system, it will be able to do something. But how to put it into mass production? Therefore, we are not saying that the Su-57 has artificial intelligence, but we are talking about the high intellectualization of the board.”

Each pilot has his own Su-57


On the one hand, the fifth generation fighter is a rather complicated machine. But on the other hand, a medium-trained pilot should be able to fly on it. Therefore, several levels of automation have been implemented on the Su-57. For the least trained pilots, the aircraft can solve all the problems itself, but with an average quality. For a more trained level of pilots, it is possible to vary the systems with which this or that task is solved. Quite the same luminaries can delve into the level of control of the modes of systems. Thus, even an average pilot can operate this aircraft with a sufficient degree of efficiency. Over time, he will be able to increase his level and begin to use all the capabilities of the Su-57 in all situations.
This approach is very important for those pilots who have previously flown other aircraft. “Today, our flight crew training system is focused on solving some specific tasks: fighter, strike, interception,” explains Vladimir Beketov. - For pilots trained according to such a system, the solution of specific tasks is already in the spinal cord. But on the Su-57, one person must solve all the variety of such tasks. Therefore, we decided to raise a person above the level of these tasks. The pilot should be a fighter who determines what to do in a given situation, based on the clues that the board forms for him. On the Su-57, the pilot sees the whole situation, and the board gives him deterministic clues. As a result of this, the person either agrees with the prompts or introduces corrections, and then the board solves these problems automatically, but on other branches.

Comfort and safety

The Su-57 is distinguished by its high maneuverability and high cruising speed. But these characteristics also bring with them problems for the pilot: he has to endure large overloads. To facilitate the work of the pilot, special measures had to be taken. For example, the seat in the cockpit of the Su-57 is set at an angle of 22 degrees. This also helps to more easily endure existing overloads.

In addition, the pilot's equipment, developed at the Zvezda enterprise named after V.I. G. I. Severina. In particular, the logic of the high-altitude compensating suit, which performs anti-G functions, has changed. Such a suit, under the action of overloads, compresses certain parts of the body, preventing blood from flowing in or out. The suit of the previous generation began to react at the moment when an overload appeared. “The new suit is ahead of the curve,” says Stanislav Rubanov, formerly the chief designer for the complex emergency escape system at the Sukhoi Design Bureau. “When the pilot is just starting the action, giving a command to the aircraft’s control organs, the high-altitude compensation suit immediately begins to act proactively.”

The aircraft ejection seat was also modified. It provides rescue in all modes: from parking on the ground, to supersonic cruising, as well as in any permissible maneuvers. Before ejection, the seat forms a special position for the pilot, which is necessary to protect him from oncoming flows and to safely leave the aircraft.

The complete picture at every point

Digitalization in the program of the fifth generation fighter manifested itself in another direction. The creation of the Su-57 significantly accelerated the development of digital models. “Since the start of the project, most of the work has been covered by mathematical modeling,” says Alexander Kornev, chief designer of supercomputer technologies at the Sukhoi Design Bureau. “Initially, we used this approach to reduce the number of possible design errors, and then we already used it in the testing process.”

Digital models have been used to solve many design problems. For example, due to the requirement of multifunctionality for the Su-57, it was necessary to create an original airframe shape. “Mathematical models made it possible to test a whole series of different variants of the aircraft shape,” recalls Alexander Kornev. “Moreover, if blowing in wind tunnels would take 1-2 years, then on a supercomputer we calculated such a model from a week to a month.” In addition, the mathematical model provided another important advantage: a complete picture was shown at each point of the space or surface under study. This data proved to be fertile material for engineers to make decisions.

Thanks to advances in the field of mathematical modeling, it has become possible to model all systems of an aircraft. Thus, it became possible to apply the concept of digital twins for the Su-57 - to create an integrated digital model of the entire aircraft. “Such a concept makes it possible, for example, to predict how an aircraft will behave in different situations,” Alexander Kornev explains. - Or find the causes of failures, study their process, predict the consequences. These are quite complex mathematical models. And we are in the process of creating them. This helps a lot to understand the processes both in regular situations and in critical ones.

Of course, digital twins are needed, first of all, to make it easier for engineers to understand complex processes. But there are other applications for them, for example, personnel training. After all, a digital twin is able to show what the sequence of actions should be in various situations.

At the heart of the present and future is the backlog

The story about new technologies and solutions used in the fifth generation fighter program can be continued indefinitely. All of them did not arise from scratch, but based on the experience, previous developments of both the lead developer - Sukhoi Design Bureau, and all of its contractors. And all these technologies and developments will also form the basis of future projects. “Any, even a revolutionary aviation complex is being created, of course, on the basis of a scientific and technical reserve,” Mikhail Strelets, head of the Sukhov Design Bureau, is sure. - It is impossible to make a leap without having developments in technologies that would allow us to implement the requirements in a new quality. All new qualities are based on technical solutions, which are based on scientific and technical groundwork.”
Last edited:
Visible changes on T-50M prototype:
- new sensor
- new 101KS-U sensor
- new helmet
Appears I was wrong in my initial observations regarding the new 101KS-U sensor, in terms of dimensions the bulge is still present as before. Not as slimmed down as I thought.

That picture shows T-50-11 before the modification. That "new sensor" Quadro spots, has been there from the very beginning of the second stage (T-50-6-2 onward, in fact the hole for it was seen in the second static model already).

This is the picture Quadro made that cut from:

That is T-50-11 as it was seen at MAKS 2021, before the upgrade.

Here are some pictures of it after the modification:



And here it is a few weeks after the revelation in November, the apparently new 101KS-U sensor having been removed:
Paralay what do you know of izd 30? I haven't heard anything for a few months and the project has been particularly guarded so its hard to find new info. Most sites I've researched have just repetitious info already heard before.
Nothing new. Planned to start installing these engines from the middle of the first ordered batch of Su-57 (76 pieces). I suspect that they postponed

It will be interesting to know what the actual afterburning thrust of serial Izd.
30 will be. The published figures ("18 t" or "176 kN") so far were based only on an estimated percentage increase compared to the existing engines.
As far as I remember, twenty years ago it was stated that the maximum afterburner thrust for the upgraded AL-31F is + 40%. 12500 kgf * 0.4 + 12500 kgf = 17500 kgf
Izd. 30 is upgraded AL-31F? Despite Marchukov's claims? Or what's the point?
Nothing new. Planned to start installing these engines from the middle of the first ordered batch of Su-57 (76 pieces). I suspect that they postponed
The photo shows the nozzle divergent / external flaps with chevron trailing edges, but every thing else is straight edges both internal and external. Looks like LO considerations are mostly cosmetic.
The inside of the f-35 nozzle Look very similar to me. The only thing I don’t see is serrated edges on the engine covers and a better seal between the el tailerons and fuselage. Who knows if they are planning on adding them later. Maybe they don’t want to waste time and money doing it yet. 1D5E2720-A642-45C4-9DB9-FE4A616EB50A.jpeg
The inside of the f-35 nozzle Look very similar to me. The only thing I don’t see is serrated edges on the engine covers and a better seal between the el tailerons and fuselage. Who knows if they are planning on adding them later. Maybe they don’t want to waste time and money doing it yet.View attachment 690836
The internal liner to Convergent flaps and trailing edges of the convergent flaps can be relatively hidden with the nozzle closed. It will be interesting to see if they come up with anything at the front of the augmentor to hide turbine blades and eliminate the highly reflective flame holder and sprayrings /spraybars.
Static discharge wicks, most likely.

Regarding the Izd. 30 nozzle, consider that none of the installations seen to date (prototype #052 flying test bed, #057 mock-up, LTS mock-up) is necessarily representative. Also, it's a TVC nozzle that actuates in up-and-away flight, unlike the F135 TBSN that requires doors on the bottom to open for movement. That might require some compromises on sealing solutions round the outside flange.
It's being used to fire missiles from inside Russian territory. So same thing all the other aircraft and bombers have been doing. Interestingly that base is even closer than Engels though.
if it's used to launch missiles from inside russia then why even bother using a stealthy platform? its role is to test its sensor suites maybe?
Because it is a brand new aircraft with secret technologies. Because they barely have a few of them.

Similar threads

Top Bottom