Su-57 Stealth Fighter: News #6

GarryB wrote:

But lmfs I think said something counts as supercruise only if its 1.8m+ like the F-22. Su-57 allegedly will only be able to achieve 1.6m with izd.30, and currently its below that.

That is called moving the goalposts...

Goalposts were moved several times in fact:

1. When the US conceived the F-22 and then they made a huge fuss about supercruising being a crucial characteristic of the 5G
2. When Europeans and essentially anyone producing aircraft with marginal supercruising capability started talking about them having that crucial capability too, distorting the meaning of the term.
3. When US created the F-35 which didn't have that capability despite its monster engine and then it was established as a common truth that supercruising is not relevant for 5G and networking capabilities are king.

Russians on the other hand always were true to the relationship 5G => Supercruising => VCE

Being able to cover more airspace than other aircraft without needing to use AB and greatly shorten your flight radius is a good thing.

Cd increases very strongly reaching speed of sound and then starts getting lower, but it does not start improving before 1.2-1.3 M (it actually depends of sweep angle), so if you don't go clearly beyond that speed you are just spending MUCH more fuel and in fact stressing the airframe for no significant increase in speed.

For a bomber it is amazing because the only aircraft that can catch you need to use AB which automatically halves their flight radius which means the gaps between airfields gets much bigger...

Bombers have huge amounts of fuel compared to their frontal cross section, plus in the case of Tu-22 and -160 variable sweep wings, that allows them to use AB in a completely different way compared to a tactical fighter, even the MiG-31 uses it very differently despite not being as big as the Tupolevs. Not saying that all those planes would not benefit from supercruising engines...

At high speed air intakes are closed and narrowed because the air coming in is supersonic and would choke a turbofan or turbojet engine... The only time it would need big wide open intakes is for takeoff for volume of air at low speeds... the intake suction relief doors on the Tu-22M3 and Tu-160 are for the same purpose... to increase airflow to the engines when the aircraft is not moving fast acting like a big air scoop.

What you refer is the deployment of the variable ramps to modify the position of the supersonic shocks necessary to slow down the airflow and improve the pressure recovery of the intake.

There are two competing effects influencing the airflow the engine receives in flight:
> Airspeed, the engine receives more air the faster it flies
> Altitude, as increasing altitude reduces extremely the air density.

Which effect is dominant depends on the design point of the engine / intake.

So back to the ramps you mention, they are not deployed to reduce the amount of air but to improve the intake performance. If the design point of the plane is placed at very high altitude and speed, you would need very big intakes due to the rarefied air and the fact that you are increasingly choking the intake's throat the faster you fly... interestingly this is the case of the Su-57, plus it includes variable design (supposedly impossible to combine with stealth requirements until the Russians did it) intended for operation at high Mach numbers. I think the design point of the Su-57 is significantly higher and faster than any other fighter with the exception of the MiG-31, if I have the time I will try to prove this. In fact I think this holds the key to know the performance of izd. 30 and the real concept of operation of the Su-57...

It gives your missiles more range, but you can't hide from anything... S-400s and S-500s will be looking for F-22s on top of the hill...

Yes, but it also allows you to detect those threats from far away and reduces substantially the engagement zone of their SAMs against you, as we discussed. If "SAMs" are someday placed in space it will work differently, but not yet  

Air dominance is not a game played by planes flying low & slow...

You mean they might have developed a hypersonic scramjet engine... man that would just blow the Russians away... I hope they can steal the technology and make something useful with it....  

I meant that the Russians could deploy a VCE, even if it is a two streams one, as a successor of the izd. 20, and not only close the gap to the F119, but actually leave it far behind in terms of performance and very specially SFC, I was not referring to the US leapfrogging the F119. In any case the adaptive engines are in a very advanced state of development in US and you can bet all your money they will invest all the resources needed and then some more to get them operational asap, that is the only thing that can save their asses after the terrible fighter force planing they have done in the last decades...

a completely different way compared to a tactical fighter, even the MiG-31 uses it very differently despite not being as big as the Tupolevs. Not saying that all those planes would not benefit from supercruising engines... wrote:

What is this different use of afterburners on bombers and MiG-31?

. I think the design point of the Su-57 is significantly higher and faster than any other fighter with the exception of the MiG-31, if I have the time I will try to prove this. In fact I think this holds the key to know the performance of izd. 30 and the real concept of operation of the Su-57... wrote:

The speed of the Mig-41 is expected to reach over 4M. It will be a revolution. The question is whether it will need completely new engines?

Arrow wrote:What is this different use of afterburners on bombers and MiG-31?

MiG uses AB quite normally to reach its characteristic high speed and altitude. Since it has a huge size and fuel fraction, plus its design is optimized for that flight regime, it can allow itself to do that. Most fighters can't.

The Tupolevs should have also significant time available on AB, due to their enormous range.

The speed of the Mig-41 is expected to reach over 4M. It will be a revolution. The question is whether it will need completely new engines?

We discussed a bit about it, I think it will use a new engine indeed, of the type ABVCE (After-Burning VCE). That is a variable bypass engine that works first as a turbofan, then as a turbojet and then as a ramjet, as the airspeed increases. The SR-71 already used a similar principle, but it was very complicated. Recently the YF120 has been developed in this direction and has potential for speeds similar to those claimed for the PAK-DP

LMFS wrote:

We discussed a bit about it, I think it will use a new engine indeed, of the type ABVCE (After-Burning VCE). That is a variable bypass engine that works first as a turbofan, then as a turbojet and then as a ramjet, as the airspeed increases. The SR-71 already used a similar principle, but it was very complicated. Recently the YF120 has been developed in this direction and has potential for speeds similar to those claimed for the PAK-DP

And does Izd 30 have the potential to power PAK-DP? It has a greater thrust than the D30-F6. Development of a completely new engine for PAK-DP will take them another 15 years, if not more. PAK DP will probably be a greater technological challenge than PAK FA. Sometimes it is mentioned that it will already be the 6th generation of the combat aircraft.

nded for operation at high Mach numbers. I think the design point of the Su-57 is significantly higher and faster than any other fighter with the exception of the MiG-31, if I have the time I will try to prove this. In fact I think this holds the key to know the performance of izd. 30 and the real concept of operation of the Su-57... wrote:

What maximum speed do you think the Su-57 can reach? The American new fighter is said to fly around 3.5M. So they already have a prototype. It is not known when PAK-DP will fly

magnumcromagnon wrote:Playing devils-advocate and say the YF120 is as capable as you say, they need to prove that they could have the same flight parameters with a useful weapons load. The SR-71 lacked a useful weapons payload (just sensors), which definitively made the MiG-25 the superior high-speed aircraft especially when you consider the MiG-25 was seriously mass produced while the SR-71 production number's were not even comparable. I mean a version of the MiG-25 without a useful weapons payload (Ye-266M) managed to nearly fly at 40km altitude with 1970's technology. FPI is working on a spin detonation ramjet (not to be confused with PDE) that detonates fuel as opposed to deflagrating like standard engines (significant fuel efficiency increase). That's my bet for PAK-DP.

First of all, maybe I should have used another wording, since the engine I referred is based on the YF120, its name is RTA-1. This was an experimental program, I don't know if they brought it into operation, if they followed further along this line of research with other concepts etc., I have not looked that much into it. So this is rather about theoretical capabilities of such kind of engine. It is too similar in its characteristics, and feasible based on a VCE as the ones Russia was designing already time ago (izd. 20 was the Russian cousin of the YF120), not to think that the propulsion part of the MiG-41 could be similar. Well, in fact the izd. 20 (AL-41F) was already in a similar size class as the D-30F6.

AFAIK, spin detonation is a form of PDE isn't it? I agree these engines are the future, but I would think they are still a bit further away... you need to have the engine, at least in terms of basic technology, before you design the plane, in this case it would not be the case from what I know. With a PDE the PAK-DP would not be limited to 4 M as was said, it could be highly hypersonic, based on the propulsion only.

Arrow wrote:And does Izd 30 have the potential to power PAK-DP? It has a greater thrust than the D30-F6. Development of a completely new engine for PAK-DP will take them another 15 years, if not more. PAK DP will probably be a greater technological challenge than PAK FA. Sometimes it is mentioned that it will already be the 6th generation of the combat aircraft.

D-30F6 is a much bigger engine than izd. 30 and is optimized for another flight regime. But the same as YF120 is used as the base for RTA-1 because of its VCE layout, the izd. 30 could be used as the base for a ABVCE powering the PAK-DP, at least that seems a very reasonable possibility to me. And it would not take another 15 years to develop, since the core and most of necessary technology would already be well tested in the PAK-FA program.

What maximum speed do you think the Su-57 can reach? The American new fighter is said to fly around 3.5M. So they already have a prototype. It is not known when PAK-DP will fly

My guess is ca. 2.5 M, but that is more my personal opinion than anything I can prove. Thrust, intake design and speed of similar planes would support it. But in my post I was referring the cruise speed and altitude of the plane, rather than the max speed. IMO it has the necessary elements to surpass the F-22 in that regard.

The new US fighter is a spaceship if one has to follow what is being written lately... I have seen enough yanki commercials before to lose sleep over their wild claims. So F-35 does not need supersonic flight but NGAD is faster than the SR-71, tailless and invisible right? Sure...

Russians on the other hand always were true to the relationship 5G => Supercruising => VCE

But then the US would fail them because they haven't made stealth the absolute tippy top priority that it is on US aircraft, which makes them so expensive and so hard to make well and of course so fussy when it comes to use to keep their stealth levels...

One idiot doesn't screw down a screw fully when replacing a panel and it sticks out half a mm and all that stealth work is ruined...

Cd increases very strongly reaching speed of sound and then starts getting lower, but it does not start improving before 1.2-1.3 M (it actually depends of sweep angle), so if you don't go clearly beyond that speed you are just spending MUCH more fuel and in fact stressing the airframe for no significant increase in speed.

No big deal... running the AB for 10 full minutes to cross the speed of sound and accelerate to a speed where dry power can maintain speed is nothing compared with having to run the AB for the rest of the flight to stay at supersonic speeds...

Linear acceleration through the speed of sound is not going to cause anywhere near the same stress and manouvering hard with a weapon and fuel load on.

Bombers have huge amounts of fuel compared to their frontal cross section, plus in the case of Tu-22 and -160 variable sweep wings, that allows them to use AB in a completely different way compared to a tactical fighter, even the MiG-31 uses it very differently despite not being as big as the Tupolevs. Not saying that all those planes would not benefit from supercruising engines...

They don't need it for what they do now... for the MiG-31 flying at mach 2.4 all the way to the target will get them there faster than being able to supercruise 3 times that distance maybe 5 times that amount of time, but fuel efficiency and range are not as important for the MiG as getting to a launch position and launching AAMs at the target... super cruise would not help most of the time because getting there faster is more useful than moving bigger distances.

For a bomber like the White Swan right now they fly 4 thousand kms to 1,000km short of the launch area and then accelerate to supersonic speed for that 1,000km... slow down and launch their missiles and then turn around and fly at mach 2 for 1,000km and then slow down for the 4K km trip back to base... with a refuelling hook up on the way.

Supercruise means they could cover that first and last 4,000km in half the time and their top speed might be mach 2.3.

For a theatre bomber like the Backfire it means it could only super cruise and be a much more difficult target for subsonic only interceptors to deal with while retaining a range of about 6,000km or so.

Yes, but it also allows you to detect those threats from far away and reduces substantially the engagement zone of their SAMs against you, as we discussed. If "SAMs" are someday placed in space it will work differently, but not yet

I would think if the plane is supercruising towards the SAMs it would increase the distance at which they were effective... a bit like the 140km range of AMRAAM against a closing target...

Air dominance is not a game played by planes flying low & slow...

S-300 and S-400 and S-500 and R-37M were designed to deal with Air dominance aircraft... JSTARS, AWACS, Stealth fighters, and Inflight refuelling tankers... three of which should be quite easy to find and take on, which renders all other fighters including stealth fighters in a much worse position... could even say on the defensive...

What is this different use of afterburners on bombers and MiG-31?

The MiG-31 generally uses its ABs all the time to reach their targets as early as possible and engage them as far away from their targets as possible in the hopes the B-52s and B-2s still have their bombs and missiles on board as one target.

The Bombers will use them for dashes near enemy airspace as they approach their launch areas... dash in... launch and then dash away... they are huge planes with lots of fuel and by the time they get to approach their launch positions they will be much lighter than when they took off and got refuelled in the air, but they will have lots of fuel for strategic missions to zip in and out and then cruise back to get a top up to land and rearm if possible... though unlikely.

What maximum speed do you think the Su-57 can reach?

To fly at mach 2.83 in a MiG-31 you have to wear an air conditioned space suit.... in case you have to eject at high altitude but also to protect you from the heat of the cockpit canopy which gets to over 70 degrees C at that flight speed

Su-57 should be able to fly about mach 2.4-2.6 at the very most.

The American new fighter is said to fly around 3.5M.

Their fighter or is it an interceptor. If it is a fighter then good... it will be very expensive...

GarryB wrote:But then the US would fail them because they haven't made stealth the absolute tippy top priority that it is on US aircraft, which makes them so expensive and so hard to make well and of course so fussy when it comes to use to keep their stealth levels...

It is one thing to fool someone with your sales pitch, it is another having to live yourself by it... that is the problem of the US MIC with stealth, after hyping it so much in order to get unlimited financing for its development and procurement, they have been trapped in strict VLO design... which is extremely unpractical on the one hand as you say and on the other is easily defeated by lower frequency radars. Big error IMO.

No big deal... running the AB for 10 full minutes to cross the speed of sound and accelerate to a speed where dry power can maintain speed is nothing compared with having to run the AB for the rest of the flight to stay at supersonic speeds...

How much time in AB do you think a plane has available at all? Those 10 minutes are a significant part of it, depending on the altitude it could be more than the whole fuel tank.

For instance, in uninstalled conditions, the 2 x RD33 engines of a MiG-29 in AB mode would use up the whole fuel tank of the plane in roughly 6 minutes...

They don't need it for what they do now... for the MiG-31 flying at mach 2.4 all the way to the target will get them there faster than being able to supercruise 3 times that distance maybe 5 times that amount of time, but fuel efficiency and range are not as important for the MiG as getting to a launch position and launching AAMs at the target... super cruise would not help most of the time because getting there faster is more useful than moving bigger distances.

It depends, it would allow them to cover more space.

Supercruise means they could cover that first and last 4,000km in half the time and their top speed might be mach 2.3.

Of course turnaround times and delivery effectiveness would improve, sure.

I would think if the plane is supercruising towards the SAMs it would increase the distance at which they were effective... a bit like the 140km range of AMRAAM against a closing target...

We already discussed that, the plane has manoeuvrability and that completely changes the calculation. It will transversally cross the SAM site at best, not approach it (unless it is performing a SEAD mission in which case it will try to launch while stand-off and egress asap), so the result of the supercruising is a reduced stay inside the SAM engagement zone and the substantial reduction of the missiles' no escape zone.

S-300 and S-400 and S-500 and R-37M were designed to deal with Air dominance aircraft... JSTARS, AWACS, Stealth fighters, and Inflight refuelling tankers... three of which should be quite easy to find and take on, which renders all other fighters including stealth fighters in a much worse position... could even say on the defensive...

Obviously I am talking about airborne assets not about SAM systems.

To fly at mach 2.83 in a MiG-31 you have to wear an air conditioned space suit.... in case you have to eject at high altitude but also to protect you from the heat of the cockpit canopy which gets to over 70 degrees C at that flight speed

Pressurised suits are needed to protect from ejections at high altitude (>20 km IIRC) due to the low ambient pressure.

EDIT: this limit altitude is called Armostrong limit and is normally at 18-19 km, interestingly this is the maximum altitude tactical fighters typically fly...

At such low pressure, water boils at human body's temperature... that is not good

Su-57 should be able to fly about mach 2.4-2.6 at the very most.

Makes sense, going much faster means substantial changes to the way fighters are designed in terms of dynamic pressures and fuselage temperatures.

It is one thing to fool someone with your sales pitch, it is another having to live yourself by it... that is the problem of the US MIC with stealth, after hyping it so much in order to get unlimited financing for its development and procurement, they have been trapped in strict VLO design... which is extremely unpractical on the one hand as you say and on the other is easily defeated by lower frequency radars. Big error IMO.

Only if they have children that serve in the Air Force....

How much time in AB do you think a plane has available at all? Those 10 minutes are a significant part of it, depending on the altitude it could be more than the whole fuel tank.

For instance, in uninstalled conditions, the 2 x RD33 engines of a MiG-29 in AB mode would use up the whole fuel tank of the plane in roughly 6 minutes...

But an Su-27 could fly all week in AB...

Fuel burn rate is easy to calculate, but most engine specs include most efficient fuel burn rate.

Fortunately the D-30F6 in the MiG-31 is intended to be operated in full AB for its entire flight, so efficient and full power fuel burn rates are listed and would probably reflect normal AB fuel burns for other similar turbofans...

The Max AB fuel burn rate for the D-30F6 is 1.9 kg/kgf per hour, while its fuel efficient rating is 0.72 kg/kgf per hour. Full power is 15.5 tons of thrust but we don't know what fuel efficient thrust settings are.

At full AB the fuel burn would be 29.4 tons of fuel, but at Mach 2.83 that would equate to a flight range of about 3,200km... we know it has a flight radius of about 720km, so flying at about 3,200km/h flying 720km would mean full AB for about 26 minutes... about 13 minutes going out and 13 minutes coming back...

The full AB range of the Backfire is about 2,000km radius at mach 2 or so. That means at about 2,300km/h it can therefore fly at full AB for approximately two hours.

A supercruising aircraft will be moving at roughly twice as fast as the same plane operating at subsonic speed, but it will be burning fuel faster than if it was efficiently cruising at a subsonic speed of perhaps 700-800km/h, so if its flight range at subsonic is say 3,000km which would take about 4.2 hours, when it supercruises at say mach 1.5 to mach 1.6 then its flight range might be 2,800km but it will take 2.1 hours to fly that far.

It is not more fuel efficient, but it is faster and is certainly more fuel efficient than flying in Full AB because you also get there faster but your fuel range would be 500-600km at the very most. (most planes are not as efficient in full AB like the MiG-31 and MiG-25 are).

It depends, it would allow them to cover more space.

It would but its missiles are even faster so flying to 700km at mach 2.83 and launching four mach 6+ missiles gets the missiles to a 900km range target faster than flying 800km at mach 1.6 taking more than 13 minutes to get there... you can see how getting to the launch position in 13 and a half minutes is a good thing even though you are burning through fuel so rapidly. The key is time not range or fuel...

Of course turnaround times and delivery effectiveness would improve, sure.

The main feature is that flight times will be dramatically shorter and the ability for subsonic interceptors to catch you are greatly diminished... so if only supersonic interceptors are a problem then the flight range of most interceptors is dramatically reduced... even more so for most western aircraft that use external fuel tanks to boost their range because that will reduce their speed potential too.

We already discussed that, the plane has manoeuvrability and that completely changes the calculation.

In the case of a MiG-31 there is the manouver issue but a big bomber will be limited to 2 maybe 3 g at the very most so flying at mach 2 that is not manouvering... that would be terribly minor course corrections that likely would not effect interception calculations at all.

It will transversally cross the SAM site at best, not approach it (unless it is performing a SEAD mission in which case it will try to launch while stand-off and egress asap), so the result of the supercruising is a reduced stay inside the SAM engagement zone and the substantial reduction of the missiles' no escape zone.

Very long range missile systems rarely are used as barrier defence, and would most often be located near a target... so coming over the pole a B-52 would avoid ports and populated areas with its flight path, but S-400 is mobile and they could easily have looked at maps of their own territory and guessed which paths they would take... knowing their likely targets and the range of their weapons so therefore also their likely launch positions... when long range radar detects them approaching it would be fairly straight forward to then time launching your weapons without using your search radar and relying on target data from other platforms and sources so the missiles might be coming up from directly below them or slightly ahead of them... no manouver could get them to safety... it would be down to electronics...

Obviously I am talking about airborne assets not about SAM systems.

They will all be tied in to the same IADS including long range ground based radars too...

Pressurised suits are needed to protect from ejections at high altitude (>20 km IIRC) due to the low ambient pressure.

EDIT: this limit altitude is called Armostrong limit and is normally at 18-19 km, interestingly this is the maximum altitude tactical fighters typically fly...

At such low pressure, water boils at human body's temperature... that is not good

I know, but most of the time they don't fly that high but flying at mach 2.6+ will result in an unbearably hot cockpit canopy, which requires protective gear to operate under.

Makes sense, going much faster means substantial changes to the way fighters are designed in terms of dynamic pressures and fuselage temperatures.

For most aircraft flying at top speed in full AB just wastes fuel most of the time... it takes a while to accelerate to top speed and once you are going that fast you do cover a lot of ground but you wont have any freedom of manouver... you will mostly be going straight...

?
1. pilot needs 0.25 bar of oxigen.
2. if the external pressure less than 0.25, and the pilot lung has 0.25 bar then the pressure difference makes it impossible to breath in good case, in bad case it explode the lung.

At top speed the MiG-31s cockpit is heated to 70 degrees C, so an entire protective suit is required. AFAIK the cockpit is pressurised, so as long as you don't need to leave the aircraft breathing shouldn't be the biggest problem...

GarryB wrote:Only if they have children that serve in the Air Force....

They have, they will be the next crop of generals waiting at the revolving door haha

Fuel burn rate is easy to calculate, but most engine specs include most efficient fuel burn rate.

Actually fuel burn in real conditions is work for an aerospace engineer. There are all kinds of calculations and adjustments to be done due to airspeed, altitude, intake performance, weight and different forms of drag of the plane etc... and worst of all actual fuel burn has so little to do with spec values than guessing based on them is not very useful.

Fortunately the D-30F6 in the MiG-31 is intended to be operated in full AB for its entire flight, so efficient and full power fuel burn rates are listed and would probably reflect normal AB fuel burns for other similar turbofans...

SFC data for engines normally is in uninstalled conditions at sea level for max (full AB) and mil settings. I have seen some data for Russian engines giving the optimal SFC in dry settings too.

I doubt the D-30F6 can be operated in full AB all the time, that would take it beyond the 2.83 M limit. Fuel would be spent also very fast at that pace. SFCs for relatively modern turbofans are not extremely different from each other actually, from 0.6 to 0.8 kg/kgf.h in mil settings and ca 1.9-2 kg/kgf.h in AB. But as said, that doesn't mean anything when trying to calculate actual fuel burn rates since calculating the thrust at a given flight condition is quite tricky.

The Max AB fuel burn rate for the D-30F6 is 1.9 kg/kgf per hour, while its fuel efficient rating is 0.72 kg/kgf per hour. Full power is 15.5 tons of thrust but we don't know what fuel efficient thrust settings are.

Mil settings

At full AB the fuel burn would be 29.4 tons of fuel, but at Mach 2.83 that would equate to a flight range of about 3,200km... we know it has a flight radius of about 720km, so flying at about 3,200km/h flying 720km would mean full AB for about 26 minutes... about 13 minutes going out and 13 minutes coming back...

30 t of fuel per hour per hour PER ENGINE... the plane carries 16 t of fuel so it would be enough for barely 15 minutes of full AB at full uninstalled thrust.

Clearly the plane does not cruise (2.35 M) at full AB and even if it did, full AB thrust at 20 km altitude and at that speed is a far cry from thrust at sea level and therefore fuel burn is also way slower. Some numbers:

1440 km at 2.35 M is roughly 35 minutes flight time. If we assume there is a reserve fuel of 20%, that would leave 12904 kg to be used in those 35 minutes (fuel rate would change with time but this is a rough number) or 22,121 kg/h, that is three times less than fuel rate at full AB, sea level. It needs to be considered that both TSFC and thrust have strong dependencies with altitude and airspeed though...

The full AB range of the Backfire is about 2,000km radius at mach 2 or so. That means at about 2,300km/h it can therefore fly at full AB for approximately two hours.

Bigger planes have proportionally much more range, that is why I said they could use AB differently to tactical fighters.

A supercruising aircraft will be moving at roughly twice as fast as the same plane operating at subsonic speed, but it will be burning fuel faster than if it was efficiently cruising at a subsonic speed of perhaps 700-800km/h, so if its flight range at subsonic is say 3,000km which would take about 4.2 hours, when it supercruises at say mach 1.5 to mach 1.6 then its flight range might be 2,800km but it will take 2.1 hours to fly that far.

Drag increases with square of airspeed so it is much worse than that in terms of range, but still supercruising allows to cover more space and brings important kinematic advantages despite that. It is clear than to use it big tanks and economic engines are needed, constant AB is not an option for conventional tactical fighters.

It is not more fuel efficient, but it is faster and is certainly more fuel efficient than flying in Full AB because you also get there faster but your fuel range would be 500-600km at the very most. (most planes are not as efficient in full AB like the MiG-31 and MiG-25 are).

I don't know if they are very efficient, in any case they fly very high and have low drag. The main difference is that the MiG-31 has very big fuel tanks, > 50% bigger than a Flanker...

It would but its missiles are even faster so flying to 700km at mach 2.83 and launching four mach 6+ missiles gets the missiles to a 900km range target faster than flying 800km at mach 1.6 taking more than 13 minutes to get there... you can see how getting to the launch position in 13 and a half minutes is a good thing even though you are burning through fuel so rapidly.  The key is time not range or fuel...

I see it a bit more complex. They have Konteyner so they will see (they have said as much recently re. the latest B-52 simulated attacks) the planes at max range. So maybe it would be better to cruise at 2.35 M with AB off (a much lower speed would make no sense for a MiG-35), because they can still reach the stipulated launching point in time, and still have the fuel to go for another target. As said, it depends on the concrete situation, but a plane that can fly longer has more military value because it allows to cover more airspace, this is clear.

In the case of a MiG-31 there is the manouver issue but a big bomber will be limited to 2 maybe 3 g at the very most so flying at mach 2 that is not manouvering... that would be terribly minor course corrections that likely would not effect interception calculations at all.

To sustain 2g at high speed and altitude is already not that bad, actually does not manage to do that... In any case, agility matters, both in subsonic and supersonic flight. That is probably why the Su-57 has such huge lifting surface, even when it increases friction drag. That is a characteristics fighters need to have, but interceptors like MiG-31 can sacrifice quite a bit more.

Very long range missile systems rarely are used as barrier defence, and would most often be located near a target...

Mainly I think they would not be used against a fighter type of target, because they give it too much time to react.

I know, but most of the time they don't fly that high but flying at mach 2.6+ will result in an unbearably hot cockpit canopy, which requires protective gear to operate under.

I dont think so, why would that be needed? You say 70ºC cockpit glazing can be reached, but that is no big issue. The pilot is not touching it and there is air conditioning available.

At top speed the MiG-31s cockpit is heated to 70 degrees C, so an entire protective suit is required. AFAIK the cockpit is pressurised, so as long as you don't need to leave the aircraft breathing shouldn't be the biggest problem...

The pilot needs to escape the plane immediately in case anything goes wrong, so it needs to be carrying the suit he may need for that under any flight circumstances...

I doubt the D-30F6 can be operated in full AB all the time, that would take it beyond the 2.83 M limit.

True, but not quite full AB during the 13.5 minute flight out to the launch position... we know from the speed records the aircraft has unloaded that it gets to altitude very fast and once at altitude it can accelerate quite quickly because of the thinner air at altitude... the figures I have seen state the MiG-31 from the 1980s and 1990s could fly at mach 2.83 for five minutes, at mach 2.6 for 20 minutes and mach 2.4 as long and as often as it likes, and this was due to heating of the airframe/canopy etc etc.

When carrying R-60 AAMs the limits are much stricter, because unlike the R-33 and R-37 and the R-40 families of missiles they were not designed for continuous high speed flight.

Ironically the bomber model with 6 x 1,500kg bombs it could fly at max speed because they were designed especially for that job and had special heat resistant fuses... they were just FAB-1500s and were not guided... they were the precursor to the Gefest & T targeting system intended for area targets and using very big bombs to compensate for accuracy not being the best. 9 tons is better than the Su-24 could manage...

Fuel would be spent also very fast at that pace. SFCs for relatively modern turbofans are not extremely different from each other actually, from 0.6 to 0.8 kg/kgf.h in mil settings and ca 1.9-2 kg/kgf.h in AB.

Some Turbofans with more bypass air can often have even higher fuel burn rates because there is more cold oxygen rich air going through the system, but I would agree with those figures. There are also some engines that really dump fuel rapidly for emergency rating thrust levels like the engine in the MiG-21 with 9 tons emergency thrust options...

But as said, that doesn't mean anything when trying to calculate actual fuel burn rates since calculating the thrust at a given flight condition is quite tricky.

The numbers I have given seem consistent...

Bigger planes have proportionally much more range, that is why I said they could use AB differently to tactical fighters.

For any aircraft you can trade speed for range, and vice versa...

Drag increases with square of airspeed so it is much worse than that in terms of range,

True, but an aircraft like the MiG-31 can benefit from an altitude of 20km, while bombers are normally limited to 10-12km altitude...

constant AB is not an option for conventional tactical fighters.

The MiG-31 is an interceptor it uses AB from take off to just before landing. Not necessarily full AB all the way, but AB all the way.

I don't know if they are very efficient, in any case they fly very high and have low drag.

They have no competition.

I see it a bit more complex. They have Konteyner so they will see (they have said as much recently re. the latest B-52 simulated attacks) the planes at max range. So maybe it would be better to cruise at 2.35 M with AB off (a much lower speed would make no sense for a MiG-35), because they can still reach the stipulated launching point in time, and still have the fuel to go for another target. As said, it depends on the concrete situation, but a plane that can fly longer has more military value because it allows to cover more airspace, this is clear.

The locations of the air bases are known as are the performance characteristics of the interceptors... they are not blundering blindly... they will choose their penetration points carefully and the launch locations specifically too to minimise the chance of an easy interception...

In any case, agility matters, both in subsonic and supersonic flight.

Bullshit. The gun on the MiG-31 is for chasing down and shooting subsonic cruise missiles... for which it does not need to be manouverable at all.

I believe when the EU consortium that designed the Typhoon realised that its manouver performance was less than both the Flanker and the Rafale they emphasised that climb rate and top speed are important for missile energy...

That is probably why the Su-57 has such huge lifting surface, even when it increases friction drag.

The Su-57 is a fighter, not an interceptor, but most of the time altitude and speed for missile launches will be the most important thing...

Mainly I think they would not be used against a fighter type of target, because they give it too much time to react.

Do they? How many fighter radars look up that high for such small targets?

Most fighter aircraft have self defence suites that have angles of about 60 degrees... about 30 up and 30 down...

I dont think so, why would that be needed? You say 70ºC cockpit glazing can be reached, but that is no big issue. The pilot is not touching it and there is air conditioning available.

It is why they wear them. They fly fast more often than they fly very high...

The pilot needs to escape the plane immediately in case anything goes wrong, so it needs to be carrying the suit he may need for that under any flight circumstances...

He flys fast more often than he ejects...

GarryB wrote:The numbers I have given seem consistent...

We already knew the speed and range so we already had a max value for the fuel rate... but if you didn't have the range, to calculate the burn rate based on the plane's airframe and propulsion would be far from trivial...

Bullshit. The gun on the MiG-31 is for chasing down and shooting subsonic cruise missiles... for which it does not need to be manouverable at all.

Even being a super-specialist in high and fast flight, it will also need to egress after having launched its missiles, it will need to react to missiles launched at it... MiG placed LERX on the -31 as a way to improve its turning capabilities vs. the -25, which was very limited in that regard. For the Su-57 supersonic manoeuvrability is one of the key design requirements from the onset, because he is intended to fly in that regime most of the time while in combat.

I believe when the EU consortium that designed the Typhoon realised that its manouver performance was less than both the Flanker and the Rafale they emphasised that climb rate and top speed are important for missile energy...

The Typhoon was designed as an air superiority fighter focused in BVR combat with high & fast flight very much as F-22. They didn't even placed close coupled canards on it as the Rafale has.

The Su-57 is a fighter, not an interceptor, but most of the time altitude and speed for missile launches will be the most important thing...

Agree, that is the starting point of the engagement and the Su will try to have the upper hand already then. The only realistic way of getting lopsided exchange ratios is to be in conditions to attack while the enemy is not.

Do they?  How many fighter radars look up that high for such small targets?

Normally fighters are not alone. The launch of a SAM like the 40 or 48N6 is not a very "stealthy" event.

It is why they wear them. They fly fast more often than they fly very high...

Do you have any source? I have seen MiG pilots wearing normal suits more than once...

He flys fast more often than he ejects...

By that logic you can spare the ejection seat too

Even being a super-specialist in high and fast flight, it will also need to egress after having launched its missiles, it will need to react to missiles launched at it... MiG placed LERX on the -31 as a way to improve its turning capabilities vs. the -25, which was very limited in that regard

Neither the MiG-25 nor MiG-31 can do more than 5g manouvers, and the LERX on the 31 are nothing to do with manouver performance, and everything to do with the shift in cg as it accelerates to max speeds. It is more about trim balancing the aircraft...

And dodging missiles?

What missiles?

The MiG-31 are intended to be intercepting B-52s and B-2s... the only missiles involved will be cruise missiles

For the Su-57 supersonic manoeuvrability is one of the key design requirements from the onset, because he is intended to fly in that regime most of the time while in combat.

I agree, because one of the aircraft it would be tasked with fighting is a supercruising F-22.

Normally fighters are not alone. The launch of a SAM like the 40 or 48N6 is not a very "stealthy" event.

It will likely be going on all the time, but if they do notice it happening 300km away I would be impressed, and considering those missiles launched have a range of 400km then those missiles could be headed to intercept a target anywhere within a circle 800km across.

Do you have any source? I have seen MiG pilots wearing normal suits more than once...

I can't say I have ever seen a MiG-31 pilot in anything but a space suit or an immersion suit which performs a similar function...

GarryB wrote:Neither the MiG-25 nor MiG-31 can do more than 5g manouvers, and the LERX on the 31 are nothing to do with manouver performance, and everything to do with the shift in cg as it accelerates to max speeds. It is more about trim balancing the aircraft...

It may serve both ways. The MiG-31 has better turning / bigger CL than the -25.

And dodging missiles?

Not dodging but staying out of their reach. It is not a very stealthy plane and attacking any ISR aircraft or bombing raid it will necessarily face fighter escorts and BVR shots from max range.

It will likely be going on all the time, but if they do notice it happening 300km away I would be impressed, and considering those missiles launched have a range of 400km then those missiles could be headed to intercept a target anywhere within a circle 800km across.

Not considering that SAM batteries do have radars and may switch them on, the launch of a big missile has a huge IR footprint, plus other airborne radars in theater are easily going to see it from 500 km away, more as the missile climbs. That is some reaction time (ca. 4 minutes), even if your missile flies very fast.

I can't say I have ever seen a MiG-31 pilot in anything but a space suit or an immersion suit which performs a similar function...

https://www.youtube.com/watch?v=JyeeFdgJlkg

Isos wrote:Not realistic.

Awacs will be kept away from S-400 and will never go above front line... Their radar detection ranges are not great at all. Some 300 km against a 4th gen fighter so against a missile of 30cm diametre it will be 50 or so km.

Against an su-57 it should be around 150-200km so with a r-77M it will be able to sneak in and shoot it down. No need for r-37M.

Tracking a mach 5 missile is also unlikely by an airborne radar. In front of those S400 you will have a buk battery and 3 or 4 pantsir protecting the S-400. So the plane being attacked by s-400 will go down and change course and probably fall in range of anther AD system.

The real advantage of S400 is that its radars can spot and give away position of enemy fighters at great distance and coordinate smaller systems to destroy them which waiting in ambushes. That's why they need to buy thousands of shorads and cover all the area with them. S400 will oblige enemy fighter to fly low and then even a zsu-23-4 will be very good at shooting them down.

Where are you taking all those conclusions from?

> AWACS have a radar horizon of >500 km. That is more than S-400 range so they have an observation line to see them and still be safe from their missiles.
> I am talking about airborne radars, that does not necessarily mean AWACS
> How is detection range of an AWACS vs a S-400 missile 50 km? And how do you know the different ISR means don't detect the emissions of the radars, the lock on the target, or the different data links being used during the engagement? How do you know no space based asset is going to detect the flare, or any other IR/EO detector present in the battlefield?
> Where do you get the AWACS detection range vs. the Su-57?
> How is it that no airborne radar can track a 5 M missile?

It may serve both ways. The MiG-31 has better turning / bigger CL than the -25.

Neither are considered dogfighters.

Not dodging but staying out of their reach. It is not a very stealthy plane and attacking any ISR aircraft or bombing raid it will necessarily face fighter escorts and BVR shots from max range.

For which high g turns are less important than high speed escape after all the missiles have been launched.

Not considering that SAM batteries do have radars and may switch them on, the launch of a big missile has a huge IR footprint,

In a 400km radius on a battlefield there will likely be hundreds or thousands of radars operating, and tens of thousands of missiles being launched... why would a fighter notice one in particular?

plus other airborne radars in theater are easily going to see it from 500 km away, more as the missile climbs. That is some reaction time (ca. 4 minutes), even if your missile flies very fast.

Reaction time to do what? Most long range S-400 SAMs probably fly above 30km altitude on their way to the target so what exactly could any fighter do as they blow past on their way to your AWACS platform first I would suspect...

Once that has exploded you are probably going to be next but who scans upwards for incoming threats?



That is an immersion suit... the valves on the arms are for improved buoyancy. Used when operating over water... It would inflate in the water to improve floatation and also insulation from the cold water...

> AWACS have a radar horizon of >500 km. That is more than S-400 range so they have an observation line to see them and still be safe from their missiles.

Their range against missile sized targets is not greater than 500km, plus the S-400 does not need to turn on its radar to engage AWACS platforms... an emitting AWACS plane of what ever type will reveal its location to all and passively directed missiles can be launched in its direction without any warnings at all.

> How is detection range of an AWACS vs a S-400 missile 50 km? And how do you know the different ISR means don't detect the emissions of the radars, the lock on the target, or the different data links being used during the engagement?

In a war against Russia there will be dozens of SAMS engaging of various different range performances with all sorts of signals... but when the target is emitting enormous amounts of radar energy a lock is not required... especially for ARH missiles.

How do you know no space based asset is going to detect the flare, or any other IR/EO detector present in the battlefield?

There are going to be hundreds of IR flares... from ballistic and cruise missiles to SAMs...

> How is it that no airborne radar can track a 5 M missile?

Even if it could... what could it do about it?

Maximum G turning is not exceptional due to the thin wing profile but its own sustained one beneficiate nevertheless from LERX and is more than up to the need i.e. being able to launch missiles and turning around fast before than the enemy escort/CAP fighters would close up and fire their own missiles.

It is optimised for high speed high altitude interception... it will not be dogfighting with anything called a fighter lower and slower...

The LERX are not big and don't turn it into an Su-27...

GarryB wrote:For which high g turns are less important than high speed escape after all the missiles have been launched.

See the table above, nobody is going to make high g turns at high altitude, the air is too thin for that. Lift is the critical parameter for sustained turn and LERX are lift augmentation devices.

In a 400km radius on a battlefield there will likely be hundreds or thousands of radars operating, and tens of thousands of missiles being launched... why would a fighter notice one in particular?

That is currently the focus even for tactical fighters, to be turned into ISR assets themselves with very sophisticated sensors and automated threat classification / data sharing provisions. I guess there is nice incentive for an attacking force to detect a possibly concealed S-400 battery, even more when they start launching interceptors...

Reaction time to do what?  Most long range S-400 SAMs probably fly above 30km altitude on their way to the target so what exactly could any fighter do as they blow past on their way to your AWACS platform first I would suspect...

The AWACS is quite likely not going to put itself in range of the S-400, that is, they will not go beyond the point that is considered safe / has been already cleared by the SEAD teams, or so it should be. Therefore the first planes to be in risk are attack planes and their escorts, not AWACS. In the case of a fast plane attacked by a SAM at maximum range, four minutes are more than enough to turn around and defeat the missile.

That is an immersion suit... the valves on the arms are for improved buoyancy. Used when operating over water... It would inflate in the water to improve floatation and also insulation from the cold water...

OK, makes sense since this is a MiG stationed in Kamchatka. The face mask is the normal one isn't it?

Isos wrote:At 500km it won't see anything smaller than a civilian aircraft.

Source?

Radar horizon works in both ways. If s-400 can't see the awacs then the awaxs can't see him too.

Sure, but at 500 km the S-400 cannot hit the AWACS.

Awacs have radar similar to ground search L band radars. Their only advantage is that they are not affected by ground and have no radar horizon.

Well of course they have a radar horizon, only it is much further away.

In use awacs have ranges of around 300-400km against 4th generation jets. With its shapes su57 bounces away a part of the energy and its coating absorbs also a part, less effective than against X band radar but still somehow effective. So I assume they have a 200km range against it.

Between this guess of yours and Russian officials' statements that "no AWACS can detect it" I guess we have quite a window of uncertainty...

S-400 missiles have a tiny diameter and won't be detected at 500km. They may be lucky if they deect it at 50km. Those radar are not meant to compute a target flying at mach 5. It's not magical, if it wasn't designed to do it don't expect it do it. Even detecting such target may not be possible.

All I am asking is a source to back those claims.

Other fighter based radars are far less effective and their search field of view is much smaller.

What is the detection range of a APG-83 or 77 vs a S-400 missile then? Such missile directly after launch is a huge vertical metal cylinder with corner reflectors attached to it and several sqm RCS, it will probably be seen from hundreds of km away. The simply huge IR flare of the boost stage is likely to be visible from hundreds of km away, too.

S-400 are not egyptian sa-6. They are not SARH missiles but Track via missile. Not an expert about it but the tracking can happen only at the last moment and uses the missile's radar with processing made buy the ground radar and the missile cruise unoticed with no signal until that mement. An awaxs to be effective needs to operate at 10km altitude. And we are not taking into account r37M.

I am aware they would not activate the active radar seeker until the last moments, that does not mean a 7.5x0.5 m missile, almost 2000 kg flying 7 M is a stealthy target or can be launched without nobody noticing.

Russia uses an IADS. Elint plateform will detect mai ly emmissions in L and S bands from radars far away. S-400 engaging radars will work for few second to allow a hit. They won't know where they are.

That is the way they would like to use them, sure, but the battery also has search radars themselves, probably they think they may need them. Remember the original claim and origin of this discussion is that long range missiles are not very effective against fighter type targets and I would add, they serve the purpose of keeping AWACS/ISR and similarly high valued, slow flying assets as far as possible from your airspace.

A nabo U can detect your awacs from 400km on your left but a s-400 may be 50km away from you and destroys you with you RWR noticing it only 10 seconds before impact.

In which case you would use a 9M96 missile and not a 40N6, as I keep saying.