Interesting detail ,fuel dump through the nozzles.

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Turning on AB fuel flow without ignition would be an effective fuel dump system. It would have to be done at low engine power to ensure it doesn’t auto light in the exhaust gas temperature. Activating the fan duct AB fuel flow only would reduce the chance of auto-ignition, but reduce the dump rate capability.

The real question is why you would want a fuel dump capability on a land based fighter. Landing on a very short runway is the only reason I can think of to avoid landing with a high fuel state.
 
Turning on AB fuel flow without ignition would be an effective fuel dump system. It would have to be done at low engine power to ensure it doesn’t auto light in the exhaust gas temperature. Activating the fan duct AB fuel flow only would reduce the chance of auto-ignition, but reduce the dump rate capability.

The real question is why you would want a fuel dump capability on a land based fighter. Landing on a very short runway is the only reason I can think of to avoid landing with a high fuel state.

Other reason for reducing the weight by dumping the fuel is when you don't want to enter a dog fight with suboptimal thrust to weight / lift to weight ratio.
 
Other reason for reducing the weight by dumping the fuel is when you don't want to enter a dog fight with suboptimal thrust to weight / lift to weight ratio.
The Su-27 thru -57 do carry a lot of fuel, and appear to be G-limited at at high fuel state, so maybe. However, you can dump fuel just as fast by engaging AB and entering the dogfight with higher energy. I guess dumping fuel would be similar to punching off full external fuel tanks, but it seems like there would be a very narrow set of situations where a pilot would sacrifice internal fuel.
 
The Su-27 thru -57 do carry a lot of fuel, and appear to be G-limited at at high fuel state, so maybe. However, you can dump fuel just as fast by engaging AB and entering the dogfight with higher energy. I guess dumping fuel would be similar to punching off full external fuel tanks, but it seems like there would be a very narrow set of situations where a pilot would sacrifice internal fuel.
Like that Chinese instructor said to pupil why he would engage in a dogfight and and correct answer was because you are stupid.

Its highly unlikely fighter jet would enter any kind of dogfight with G limiting fuel state.
 
Its highly unlikely fighter jet would enter any kind of dogfight with G limiting fuel state.

Its highly unlikely fighter jet would enter any kind of dog fight at all when we know that one fighter can be engaged from more than 200km away. :cool:

Something like this can be seen only during tests or exercises.
 

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Its highly unlikely fighter jet would enter any kind of dog fight at all when we know that one fighter can be engaged from more than 200km away. :cool:

Something like this can be seen only during tests or exercises.
I would say something like this is very likely to happen. The aircraft often has to go into visual range to warn a drone to back off before getting the go ahead to engage. These incidents are more likely to happen or at least precede actual peer to peer conflict
 
The Su-27 thru -57 do carry a lot of fuel, and appear to be G-limited at at high fuel state, so maybe. However, you can dump fuel just as fast by engaging AB and entering the dogfight with higher energy. I guess dumping fuel would be similar to punching off full external fuel tanks, but it seems like there would be a very narrow set of situations where a pilot would sacrifice internal fuel.

While I agree on the Su-27, I doubt that the Su-57 has the same set of limitations. As a matter of fact we know that the Su-57 has no G limitations even with some heavy air to ground payload so I doubt it will have them with full fuel load (Felon has different instability margin, different lift and load distribution in addition to much more smaller and more compact wing, much shorter "neck", additional airframe strengthening etc.).
But the huge amount of fuel will definitely have an impact on the wing loading and T/W ratio, and consequently on flight performance.

And it might not be tactically plausible to use the AB for the fuel dump because you would go supersonic very quickly, and that might not be useful for certain combat scenarios.

View: https://www.youtube.com/watch?v=QXbBihy61xw&t=48s


Here you can hear about practical implications of the fuel dumping.
 
But we haven't seen really high-G maneuvers on the Su-57; most airshows have been using prototypes, which at some point might have been g-limited and not using g-suits.
 
And it might not be tactically plausible to use the AB for the fuel dump because you would go supersonic very quickly, and that might not be useful for certain combat scenarios.

Some details from the Su-27SK F.M. Maybe something similar is recommended in the case of Su-57.

''В топливной системе предусмотрен аварийный слив топлива. Включение аварийного слива производится выключателем СЛИВ ТОПЛИВА. Аварийный слив топлива следует выполнять на оборотах двигателя n2 = 80-90 % на высотах менее 1100 м и скоростях 360-800 км/ч.''

''The fuel system is equipped with an emergency fuel drain. The emergency fuel drain is activated using the FUEL DRAIN switch. The emergency fuel drain should be performed at engine speeds of n2 = 80-90%, at altitudes below 1,100 m and speeds of 360-800 km/h.''
 
I would say something like this is very likely to happen. The aircraft often has to go into visual range to warn a drone to back off before getting the go ahead to engage. These incidents are more likely to happen or at least precede actual peer to peer conflict

In the case of Su-57 and when UAV S-70 Hunter-B will be fully operational and completely usable, data linked with '57' via OSNOD and flying in stratosphere, S-70 armed with two Izd 180 or 810 e.g. will be ''outstretched arm'' of the '57'. OSNOD system and data link channels allows to be linked several hundreds of km away. If we add the potential AAM launch ranges ,that means Su-57 will be far away from any danger in the sky. Who knows, maybe they already test this or similar combat tactics.
 
Its highly unlikely fighter jet would enter any kind of dog fight at all when we know that one fighter can be engaged from more than 200km away. :cool:

Something like this can be seen only during tests or exercises.
In the era of stealth jets entering combat areas with switched off radar (because emission control) and basing their informational awareness on informations received trough data links from other aircrafts hundreds of km away the chances of surprise encounters may in fact increase. In bad weather conditions also the optronic systems can become ineffective for long ranges.
 
In the case of Su-57 and when UAV S-70 Hunter-B will be fully operational and completely usable, data linked with '57' via OSNOD and flying in stratosphere, S-70 armed with two Izd 180 or 810 e.g. will be ''outstretched arm'' of the '57'. OSNOD system and data link channels allows to be linked several hundreds of km away. If we add the potential AAM launch ranges ,that means Su-57 will be far away from any danger in the sky. Who knows, maybe they already test this or similar combat tactics.
You have to consider the diplomatic element of geopolitics. An unmanned platform doesn't have the same political weight as a manned platform. Shooting down an aircraft with a human pilot inside is a huge escalation, which means the manned platform is usually more effective to get the other aircraft to leave the airspace without escalation.
 
In the era of stealth jets entering combat areas with switched off radar (because emission control) and basing their informational awareness on informations received trough data links from other aircrafts hundreds of km away the chances of surprise encounters may in fact increase. In bad weather conditions also the optronic systems can become ineffective for long ranges.

There is no bad weather conditions in the stratosphere ( 15-20+km).

You have to consider the diplomatic element of geopolitics. An unmanned platform doesn't have the same political weight as a manned platform. Shooting down an aircraft with a human pilot inside is a huge escalation, which means the manned platform is usually more effective to get the other aircraft to leave the airspace without escalation.

As I wrote ,UCAV's will be in the first echelon hundreds of km away from manned platforms.Don't forget what did already happen to one UCAV S-70 on 5 Oct. 2024.
 
As I wrote ,UCAV's will be in the first echelon hundreds of km away from manned platforms.Don't forget what did already happen to one UCAV S-70 on 5 Oct. 2024.
I'm pretty sure I read what you wrote. It's just not relevant to what I said
 
I'm pretty sure I read what you wrote. It's just not relevant to what I said

Sorry but what kind of ''diplomatic element of geopolitics'' because ''An unmanned platform doesn't have the same political weight as a manned platform.'' ... have the known case when Su-35S fighter pilot Sergey Yermalov from 159GvIAP ( Bezovets air base) was shot down on 3 April 2022 in the vicinity of the city of Izyum ?

 
Sorry but what kind of ''diplomatic element of geopolitics'' because ''An unmanned platform doesn't have the same political weight as a manned platform.'' ... have the known case when Su-35S fighter pilot Sergey Yermalov from 159GvIAP ( Bezovets air base) was shot down on 3 April 2022 in the vicinity of the city of Izyum ?

You're talking about an active war. In case you had a hard time reading the first time, I quote here my previous statement in which you responded to without proper comprehending first:

"These incidents are more likely to happen or at least precede actual peer to peer conflict"

I think a better example for your argument would be when Turkey shot down a Russian manned fighter. However, this is still faulty logic. Having more political weight to deescalate doesn't mean an absolute solution that 10/10 times produce the desired descalation. You can always point to an exception to the rule/anecdotal incident it still simply does not invalidate my point. The fact remains that shooting down a patrolling/intercepting manned aircraft between nations not in active war is a much bigger escalation than a drone.
 
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You're talking about an active war. In case you had a hard time reading the first time, I quote here my previous statement in which you responded to without proper comprehending first:

I know what you wrote ...

''The aircraft often has to go into visual range to warn a drone to back off before getting the go ahead to engage. These incidents are more likely to happen or at least precede actual peer to peer conflict.''

...and you already got the answer. To go to visually check the drone and to be exposed to enemy fire ,I don't think so ,especially in the case of very expensive 5th gen stealth fighters.
 
I know what you wrote ...

''The aircraft often has to go into visual range to warn a drone to back off before getting the go ahead to engage. These incidents are more likely to happen or at least precede actual peer to peer conflict.''

...and you already got the answer. To go to visually check the drone and to be exposed to enemy fire ,I don't think so ,especially in the case of very expensive 5th gen stealth fighters.
Again the threat is low to none among nations that are not in active conflict and against drones that have no chance of engaging back a 5th gen fighter. I can put them in colors for you if it help with the comprehension
 
But we haven't seen really high-G maneuvers on the Su-57; most airshows have been using prototypes, which at some point might have been g-limited and not using g-suits.

My claims were not based on the air show performance, they are based on the chief test pilot Sergey Bogdan claims.
Even without his testimony, we have seen Su-57 performing high G maneuvers with the second stage prototypes:

View: https://www.youtube.com/watch?v=je3ieoSb6AA


I haven't seen any modern fighter performing this kind of turn in the last 20 years.
 
My claims were not based on the air show performance, they are based on the chief test pilot Sergey Bogdan claims.
Even without his testimony, we have seen Su-57 performing high G maneuvers with the second stage prototypes:




I haven't seen any modern fighter performing this kind of turn in the last 20 years.

Back to June 1989 and Le Bourget/France .Famous Su-27 388 blue and its flight demonstration. From 2:25 full 9G- turn for only 13 sec .Of course unarmed and the question is what was the fuel volume before take off .

View: https://www.youtube.com/watch?v=c_lzjVkVm-U


 
Back to June 1989 and Le Bourget/France .Famous Su-27 388 blue and its flight demonstration. From 2:25 full 9G- turn for only 13 sec .Of course unarmed and the question is what was the fuel volume before take off .

View: https://www.youtube.com/watch?v=c_lzjVkVm-U


I'm well aware of that video, and that is the reason I have said "I haven't seen any modern fighter performing this kind of turn in the last 20 years". This was 37 years ago and almost all modern fighters have gained weight, and that demo was much shorter than the Su-57 demo which was about 9 minutes long and far more demanding, implying that the Felon was carrying more fuel.
 
How many gs do you need to pull to complete that turn in 15 seconds? I have yet to see a fighter turn faster than that flanker.
 
How many gs do you need to pull to complete that turn in 15 seconds? I have yet to see a fighter turn faster than that flanker.

It depends on the speed, lift and drag coefficient of the plane. Let's take the F-16 EM chart for example:

ghm.PNG

At just 22,000 lb, the F-16 can sustain 21.6 deg/s while pulling 9G at Mach 0.7.
The F-16 can also sustain 9G at Mach 0.8, but the turn rate will drop to below 19 deg/s.
It is clear that the ability to pull and sustain 9G at lower speeds will increase the turn rate and decrease the turn radius.

To finish a 360-degree turn in just 15 seconds, the Su-57 needs to sustain an average turn rate of 24 deg/s.
We can see that the F-16 can achieve 24 deg/s while pulling 9G at around Mach 0.61, but it can also achieve 24 deg/s while pulling 7G at around Mach 0.49.
In both cases, the F-16 can't sustain 24 deg/s and will start to lose energy very quickly. At Mach 0.49, it will lose energy faster than at Mach 0.61, but it will initially have a smaller turn radius.
So hypothetically, if the Su-57 could sustain 7G at Mach 0.49, it could finish a 360-degree turn in 15 seconds, but it could also do the same if it could sustain 9G at Mach 0.61.

I'm more inclined to believe that this was 8-9 G sustained turn for the 360 cricle.
 
My claims were not based on the air show performance, they are based on the chief test pilot Sergey Bogdan claims.

Now back to 2017 to see what he said about 9G and 10G maneuvers/turns. From his interview for the ''Popular Mechanics''.

А если говорить о физических кондициях пилотов — нужна ли для перехода на Т-50 дополнительная подготовка?


''Да, требования к физической подготовке для пилотов машин 5-го поколения выше. Дело в том, что самолеты 4-го поколения могли выходить на перегрузку 9 g, но этот пиковый режим длился не более 1−1,5 с. Дальше при такой перегрузке резко возрастало лобовое сопротивление, скорость самолета падала, а с ней и перегрузка. Однако истребители поколений 4++ и 5 имеют значительно более мощные двигатели, и, как следствие, могут выдерживать 9 g на протяжении гораздо большего времени — например, в течение одной или двух минут. И весь этот временной промежуток пилот должен находиться в тонусе и контролировать ситуацию. Тут к физической подготовке требуется, конечно, очень серьезное отношение.

Эксплуатация многофункциональных истребителей (МФИ) 5-го поколения ставит человека в условия запредельного уровня перегрузок — физических, психологических, информационных. Не зря говорят, что МФИ будет последним пилотируемым самолетом подобного класса. Далее последуют еще более крутые ЛА, находиться в которых человеку будет небезопасно, да и просто противопоказано.


МФИ 5-го поколения задуман и реализуется как «сетевой солдат» системы C4I (Computers, Command, Control, Communications, Intelligence). По существу, C4I — это глобальная система скоординированных групповых действий, но в ней, несмотря на интеллектуальные компьютерные технологии, главным решающим звеном остается человек: ему разбираться в ситуации, принимать решения и ему же самому их исполнять.


И это в условиях не только запредельных информационных, но и физических, и психологических нагрузок тоже. Перегрузка под 10 g становится обычным режимом маневрирования.''

Особенности воздействия на организм пилота МФИ 5-го поколения​

''Маневрирование с перегрузкой 10 g приводит к потере пространственной ориентации и возникновению зрительно-вестибулярных иллюзий при восприятии закабинного пространства: перегрузки нестандартно воздействуют на вестибулярный аппарат, а он в ответ формирует ощущения кажущейся вертикали. Врожденный механизм пространственной ориентации перестает работать.''


''And speaking of pilots' physical fitness, is additional training required to transition to the T-50?

Yes, the physical fitness requirements for 5th-generation aircraft pilots are higher. The fact is that 4th-generation aircraft could reach 9g, but this peak lasted no more than 1-1.5 seconds. At this point, drag increased sharply, the aircraft's speed dropped, and with it, the G-force.
However, generation 4++ and 5 fighters have significantly more powerful engines and, as a result, can withstand 9 g for much longer periods—for example, one or two minutes. And during this entire period, the pilot must remain alert and in control. This, of course, requires a very serious approach to physical fitness.


Operating fifth-generation multirole fighters (MRFs) exposes humans to extreme levels of stress—physical, psychological, and informational. It's no wonder they say the MRF will be the last manned aircraft of its class. Even more advanced aircraft will follow, which will be unsafe, if not simply contraindicated, for humans to fly.

The 5th-generation MFI is conceived and implemented as a "network soldier" for the C4I (Computers, Command, Control, Communications, Intelligence) system. Essentially, C4I is a global system of coordinated group actions, but despite intelligent computer technologies, humans remain the key decision-making element: they understand the situation, make decisions, and execute them.
And this is under conditions of not only extreme informational stress, but also physical and psychological stress. Overloads of 10 g become the norm for maneuvering.

Features of the impact of the 5th generation MFI on the pilot's body

Maneuvering with a 10-g force causes spatial disorientation and the development of visual-vestibular illusions when perceiving the space outside the cockpit: the g-forces exert an unusual effect on the vestibular system, which in response creates a sensation of apparent verticality. The innate mechanism of spatial orientation ceases to function.''


Source: https://vpk.name/news/197754_rossiiskii_istrebitel_5-go_pokoleniya_luchshii_v_mire.html
 
I was hoping to see better turn rates about of the su-57 that what it was demoed by the su-27. Might be able to go turn faster going by why he says.
 
and you already got the answer. To go to visually check the drone and to be exposed to enemy fire ,I don't think so ,especially in the case of very expensive 5th gen stealth fighters.
You don’t want to open that can of worms where interceptions becomes full blown BVR fighting instead of herding trespassers away. Strange mindset. Even the Soviets never became this irresponsibly violent.
 
I was hoping to see better turn rates about of the su-57 that what it was demoed by the su-27. Might be able to go turn faster going by why he says.

With more fuel and AAM's inside of the fuselage ,Su-57 will certainly be faster than old Su-27.Keep in mind ,during demonstrations there is no fuel in the wings,during real air combat is different situation.

You don’t want to open that can of worms where interceptions becomes full blown BVR fighting instead of herding trespassers away. Strange mindset. Even the Soviets never became this irresponsibly violent.

BVR fighting during real combat yes ,herding trespassers away during peacetime.
 
As far as I understood it the AL-51 will be introduced with the Su-57M and the Su-57S won't be retrofitted with the new engine
I have heard from Engineers that it will be plug and play. So its designed with a modular architecture to house the AL-51F-1/Izdeliya 30 engine as soon as it is available, with the Al-41F-1 acting as a place holder till than, this is so that production and industry can mature around the available platform and hence the project isn't tied to engines which can be complex and tedious to develop and are usually subject to delays.
 
BVR fighting during real combat yes ,herding trespassers away during peacetime.
Scenario: currently at peace, some intruder wanders into your airspace. So you send expensive Su-57 to go herd it away. Surprise, it's a drone and it lit you up with a quartet of heat-seeking HalfRAAMs for the start of an offensive. (Or F-22/F-47 shoots at you from full stealth)
 
Scenario: currently at peace, some intruder wanders into your airspace. So you send expensive Su-57 to go herd it away. Surprise, it's a drone and it lit you up with a quartet of heat-seeking HalfRAAMs for the start of an offensive. (Or F-22/F-47 shoots at you from full stealth)
Doubtful this is a plausible scenario because it would ("the start of an offensive") result in a strategic exchange. And at that point, it's way beyond the discussion of jets and drones.
 
I have heard from Engineers that it will be plug and play. So its designed with a modular architecture to house the AL-51F-1/Izdeliya 30 engine as soon as it is available, with the Al-41F-1 acting as a place holder till than, this is so that production and industry can mature around the available platform and hence the project isn't tied to engines which can be complex and tedious to develop and are usually subject to delays.
I heard so too, but also that existing aircraft won't receive the new engines.
 
All this talk about the politcal weight of interceptions, manned and unmanned and how advanced aircraft are allegedly too valuable to conduct such menial tasks is slowly straying off topic.
 
Scenario: currently at peace, some intruder wanders into your airspace. So you send expensive Su-57 to go herd it away. Surprise, it's a drone and it lit you up with a quartet of heat-seeking HalfRAAMs for the start of an offensive. (Or F-22/F-47 shoots at you from full stealth)

Why Su-57 when there are Su-30SM/SM2, Su-35S and of course main 'patroling player' MiG-31BM.
 
Scenario: currently at peace, some intruder wanders into your airspace. So you send expensive Su-57 to go herd it away. Surprise, it's a drone and it lit you up with a quartet of heat-seeking HalfRAAMs for the start of an offensive. (Or F-22/F-47 shoots at you from full stealth)
Well, technically any civilian airliner can be a Q-ship.
But you need authority, unmanned interceptors (aka missiles) have rather bad story of working with civilian aircraft. It's constabulary function, and as such you need authority on spot. This authority ideally shouldn't be helpess.

Su-57, Hornet, Eurofighter, whatever.

Ultimately, if a major nation begins armed attack at you from this action - they've wasted the element of surprise for one aircraft.
 
Why Su-57 when there are Su-30SM/SM2, Su-35S and of course main 'patroling player' MiG-31BM.
Because Su-57 replaced Su-30 and Su-35. And may replace MiG-31.



Ultimately, if a major nation begins armed attack at you from this action - they've wasted the element of surprise for one aircraft.
And what if this happens to be ~1-5min before the rest of their world starts exploding?
 
And what if this happens to be ~1-5min before the rest of their world starts exploding?
World may explode in different ways and to different degree. Nuclear warfare is warfare, and minutes can be world of difference in this field.

In more normal situations, however, no one shoots at fighters, so constabulary action is just normal. And yes, i am against shooting unresponding civilian airliners on sight :)
 
^

Full video for those who are interested in.


PS

''Sukhoi is probably employing a new kind of composite material on the front section of the Su-57's fuselage, based on the cream-colored panels you can spot in that video going around the web. But who knows for sure!"

View: https://x.com/WDequid/status/2028968642625351947/photo/1
 
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