J-20 5th Gen Fighter Thread VI

[Inst]

On the meta-materials debate, the Chinese are indicating that they have used meta-material RAM on either the current J-20 or a future iteration. The West, in contrast, was first to meta-materials (British development), Lockheed Martin has its own meta-material research division, and there's been little noise about whether the F-35 uses metamaterial RAM, although descriptions of how the F-35 employs RAM suggests metamaterials (nano-composites with RAM baked into the composite structure).

It's reasonable to assume that the J-20 or a later version of the J-20 will use metamaterials. It's also reasonable to assume it's likely that the F-35 is using metamaterials.

The more important thing about the J-20 claims of using metamaterials is that the Chinese have published RCS reduction figures for their metamaterials, roughly putting it in a negative 20-30 dBsm RCS suppression. We have no equivalent numbers for potential Western metamaterials.

@Brumby :

If I recall, the traditional claim was that stealth was "shaping, shaping, shaping, and materials", i.e, implying that 75% of stealth effect was the result of shaping. But this quote came roughly from the Nineties and Noughts, when the best unclassified stealth RCS figure was around negative 20-30 dBsm. Hypothetically, say a material can provide an RCS reduction of negative 60 dBsm. This completely upturns the existing formula, i.e, RAM becomes highly dominant in the composition of stealth and you could theoretically make a MiG-21 extremely stealthy by slapping RAM onto it.

@siegecrossbow :

Which means we go back to the high-speed interceptor debate, no? This is obviously a highly emotional issue for Chinese posters here, but the J-20 design (long-coupled, large motors for elevators, intended to sport TVC) suggests it's more optimized for high-speed performance than low-speed performance. It's not necessarily to say that the J-20's low-speed maneuverability is "bad", but it emphasizes winning at high speeds (i.e, BVR missile launches at high Mach 1 or Mach 2-3 range) more than dogfights.

I still don't understand why posters here are addicted to the Soviet dogfight paradigm when, for instance, the MiGs in Vietnam took more casualties than the Americans did, and that modern WVR missiles of increasing capability are making short-range encounters suicidal.

 

[latenlazy]

@siegecrossbow :

Which means we go back to the high-speed interceptor debate, no? This is obviously a highly emotional issue for Chinese posters here, but the J-20 design (long-coupled, large motors for elevators, intended to sport TVC) suggests it's more optimized for high-speed performance than low-speed performance. It's not necessarily to say that the J-20's low-speed maneuverability is "bad", but it emphasizes winning at high speeds (i.e, BVR missile launches at high Mach 1 or Mach 2-3 range) more than dogfights.

I still don't understand why posters here are addicted to the Soviet dogfight paradigm when, for instance, the MiGs in Vietnam took more casualties than the Americans did, and that modern WVR missiles of increasing capability are making short-range encounters suicidal.

The F-15 could do Mach 2.5. Does that mean it was designed to be a high speed interceptor?

 

[Blitzo]

@siegecrossbow :

Which means we go back to the high-speed interceptor debate, no? This is obviously a highly emotional issue for Chinese posters here, but the J-20 design (long-coupled, large motors for elevators, intended to sport TVC) suggests it's more optimized for high-speed performance than low-speed performance. It's not necessarily to say that the J-20's low-speed maneuverability is "bad", but it emphasizes winning at high speeds (i.e, BVR missile launches at high Mach 1 or Mach 2-3 range) more than dogfights.

I still don't understand why posters here are addicted to the Soviet dogfight paradigm when, for instance, the MiGs in Vietnam took more casualties than the Americans did, and that modern WVR missiles of increasing capability are making short-range encounters suicidal.

Again, you are misrepresenting the argument.

The argument never suggested that the J-20 is meant to be a nimble low speed fighter designed explicitly to do close quarters dogfights.
The argument was to rebut the assertions in the early 2010s that J-20 was a dedicated high speed interceptor or a dedicated high speed striker, and instead its overall role is one of a general air superiority fighter.


Back in 2017 we had statements from J-20 pilots around the time of the PLA anniversary parade who made similar remarks about J-20's maneuverability, that in the subsonic regime it was "pretty good" but that in the supersonic regime it was "superb" -- which corresponded well with the profile of the aircraft as a general air superiority fighter.



Let me repeat:

There's been no argument that J-20 is meant to excel at close quarters low speed dog fights.

The contention was to push back against the idea that J-20 was a dedicated high speed interceptor or dedicated high speed striker.

 

[Inst]

Again, you are misrepresenting the argument.

The argument never suggested that the J-20 is meant to be a nimble low speed fighter designed explicitly to do close quarters dogfights.
The argument was to rebut the assertions in the early 2010s that J-20 was a dedicated high speed interceptor or a dedicated high speed striker, and instead its overall role is one of a general air superiority fighter.


Back in 2017 we had statements from J-20 pilots around the time of the PLA anniversary parade who made similar remarks about J-20's maneuverability, that in the subsonic regime it was "pretty good" but that in the supersonic regime it was "superb" -- which corresponded well with the profile of the aircraft as a general air superiority fighter.



Let me repeat:

There's been no argument that J-20 is meant to excel at close quarters low speed dog fights.

The contention was to push back against the idea that J-20 was a dedicated high speed interceptor or dedicated high speed striker.

The thing is, the MiG-31 could do 5G sustained turn rates, although it couldn't do 9G instantaneous turn due to its airframe design.

In actuality, there were tactical situations where a MiG-31 could beat either a F-15 or an F-16; in the F-16's case, make sure the F-16 didn't have AEW&C support, detect the F-16 first (assuming the F-16 was using Pulse Doppler instead of more modern radar), track the F-16 first, and launch BVR missiles on it. Vs the F-15, the tactical situation described was for the MiG-31 to engage the F-15 (once again using obsolescent pulse doppler radar) at low speeds, then quickly turn away and scoot out of the F-15's engagement distance.

The problem is that you're thinking of a MiG-25 or F-4-type interceptor where the interceptor was garbage vs air superiority or multi-role aircraft. In actuality, by the time you get to the MiG-31, the MiG-31 is pretty specialized for a specific role, but it is also versatile enough to deal with air superiority and multi-role aircraft under the correct conditions.

The problem isn't the idea that the J-20 is a high-speed interceptor, although it would excel in that role, but the idea that a high-speed interceptor can't do squat against multi-role, strike fighters, and air superiority fighters. As I've said before here, the sole Iraqi air-to-air kill in Desert Storm was done by a MiG-25 which was less maneuverable than the MiG-31s the Russians are running now.

 

[Inst]

The F-15 could do Mach 2.5. Does that mean it was designed to be a high speed interceptor?

Thing is, the J-20's max speed is estimated at around Mach 2.5 using the J-15 and J-11 for comparison. If we assume that this is with a WS-10 or Al-31, with a WS-15 outputting 180 kN, the numbers spike to Mach 2.7 or Mach 2.8. Compare the MiG-31's sustained high-altitude speed of Mach 2.85, which is significantly higher than that of the F-15.

Another thing to point out is that the numbers strongly suggest that the J-20 is already capable of supercruise with the present engines. If you assume Mach 2.3 max speed, a drop to dry thrust would give it Mach 1.86 supercruise speed.

===

We'll just keep on going with the snark, ego, and so on. The fact of the matter is, the most successful anti-USAF strategy in the past few decades has been interceptor tactics, exploiting high speed to defeat slower USAF fighters before running away, not attempting to dogfight versus AIM-9X. Interception doesn't necessarily mean that anti-fighter capabilities at low speeds are fully compromised; the MiG-31 can reach 5Gs, and it would stand to reason that the J-20 can do 9Gs, perhaps needing the WS-15 to reach that level.

The high speed and high-speed maneuverability actually becomes a much more salient point vs the F-35. The F-35 may be highly stealthy, but the F-35 is slow and not designed for supercruise. If you can exploit high speed and high-speed maneuverability for hit and runs, using EODAS and AEW&C to engage the F-35 at long ranges, the F-35 can't run and it'll give the J-20 the kill ratios needed to remain competitive.

 

[Blitzo]

The thing is, the MiG-31 could do 5G sustained turn rates, although it couldn't do 9G instantaneous turn due to its airframe design.

In actuality, there were tactical situations where a MiG-31 could beat either a F-15 or an F-16; in the F-16's case, make sure the F-16 didn't have AEW&C support, detect the F-16 first (assuming the F-16 was using Pulse Doppler instead of more modern radar), track the F-16 first, and launch BVR missiles on it. Vs the F-15, the tactical situation described was for the MiG-31 to engage the F-15 (once again using obsolescent pulse doppler radar) at low speeds, then quickly turn away and scoot out of the F-15's engagement distance.

The problem is that you're thinking of a MiG-25 or F-4-type interceptor where the interceptor was garbage vs air superiority or multi-role aircraft. In actuality, by the time you get to the MiG-31, the MiG-31 is pretty specialized for a specific role, but it is also versatile enough to deal with air superiority and multi-role aircraft under the correct conditions.

The problem isn't the idea that the J-20 is a high-speed interceptor, although it would excel in that role, but the idea that a high-speed interceptor can't do squat against multi-role, strike fighters, and air superiority fighters. As I've said before here, the sole Iraqi air-to-air kill in Desert Storm was done by a MiG-25 which was less maneuverable than the MiG-31s the Russians are running now.

I have not argued that J-20 is meant to excel at or be dedicated to low speed dog fights as your previous post suggested.
I have never argued that high speed interceptors in general "can't do squat" against opposing fighter aircraft. High speed interceptors obviously can be effective in certain circumstances if their advantages can be leveraged.


My position has consistently been:
1: J-20 is not a dedicated high speed interceptor or a dedicated high speed striker, as it was suggested for the early years after it first emerged.
2: J-20's role is best conceived as a general air superiority fighter as its primary role.

 

[Air Force Brat]

siegecrossbow said "domestically produced fighter". J-11A is a licensed build fighter where the kits are imported from Russia. That's why I excluded it. If we include the J-11A, then the Mach 2.35 is the best value since that value applies to the Su-27SK as well. Wiki entry for the J-15 can be disregarded. According

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the J-15 is powered by the WS-10, which we know is not the case.

J-8II is probably the fastest locally produced fighter. The max speed of Mach 2.2 seems to be consistent across multiple sites. One issue though is, whether the original J-8 was faster than the modern J-8II. Original J-8 with the nose intake would have been lighter than the J-8II. So the Mach 2.4 value may apply to the J-8.

Headed to Oshkosk wisconsin to see the F-22 fly today, F-35 to fly in Milwaukkee tommorow,. J-20 near peers.

 

[Inst]

I have not argued that J-20 is meant to excel at or be dedicated to low speed dog fights as your previous post suggested.
I have never argued that high speed interceptors in general "can't do squat" against opposing fighter aircraft. High speed interceptors obviously can be effective in certain circumstances if their advantages can be leveraged.


My position has consistently been:
1: J-20 is not a dedicated high speed interceptor or a dedicated high speed striker, as it was suggested for the early years after it first emerged.
2: J-20's role is best conceived as a general air superiority fighter as its primary role.

For 1., the issue is whether you see those claims as a compliment or an insult. The much of the ethnic Chinese PLAAF watching community has been treating it is as an insult, as if to say that the Chinese can't compete with the F-22 and F-35. But it can also be seen as a compliment.

The biggest problem with the J-20 is the relative numbers deployed. It is being deployed later than the F-22, which is around 100-150 active airframes, and information does not yet exist to say with certainty that the J-20 has introduced more than 100 units into production. Likewise, the F-35, despite its teething problems, has already exceeded a number built of 400.

Strategically, the Chinese need to crank out the J-20s like hotcakes to match force on force, which is what you're implying with 2. However, Western observers have noted the weaknesses of the USAF, its dependency on support aircraft (AEW&C, tankers), as well as its naval defenses. A stealth aircraft that is advanced enough not to be intercepted on its attack run can wipe out these support assets, and hopefully return to base without being shot down. That is a smart and adroit policy they are assigning to the J-20, and tactically and strategically speaking, it is the best employment of an aircraft that is expensive and limited in numbers.

For 2, as I've mentioned prior, the assumption is that the J-20 is going to behave force-on-force against what's going to be 1200 F-35s deployed against it, when the J-20 is not believed to have a stealth advantage vs the F-35. Heavyweight air-superiority fighters have traditionally defeated lightweight and mediumweight air defense / strike fighters in BVR, closing to WVR should they fail to finish off the enemy.

However, with the F-35 having a stealth advantage (Chinese models without RAM imply that the F-35 can reach -50 dBsm in some sectors), the J-20 is forced to rely on its radar.to compensate. But what we know is that the F-35 is 700mm radar aperture, while the J-20 is 900-1000mm radar aperture, which is not enough to beat a 10-20 dBsm advantage on the F-35. Even then, the effects of stealth and jamming mean that radar detection becomes less preferred versus IR detection (the EOTS and EODAS on both the J-20 and F-35), and the J-20, as a heavier fighter with greater thrust, will have more disadvantages there.

And even in a best-case scenario under this structure, the J-20 is still in trouble even if it achieves a 1.5:1 kill ratio, because the F-35s are just so numerous due to their smaller size and mass production.

What are the J-20's advantages then, and how can it beat the F-35 sufficiently?

Well, the J-20 is more maneuverable than the F-35. But the F-35 is going to have SACM, and at the engagement ranges created by stealth the J-20 is not going to reduce NEZ / effective range with TVC.

On the other hand, the J-20 is going to be significantly faster than the F-35. That's an exploitable advantage in that the J-20 can launch missiles with better kinematics, then run away, hopefully getting out of the SACM's NEZ / effective range before the latter impacts. That is a way to get above 2:1 kill ratios or even get to 1:0 kill ratios.

 

[Inst]

I can also put this another way.

The MiG-31 is an interceptor, but its airframe can sustain 5G and has shown around 15-18 deg/sec turn rates. It is an interceptor, but it has reasonable basic maneuverability to provide it with versatility and robustness should it be caught WVR.

The YF-22 was selected over the YF-23, despite the latter having better speed, sustained turn rates, payloads, and stealth. Why? Because the YF-22 was more agile than the YF-23; i.e, while its stealth gave it a decisive advantage over 4th generation aircraft, the agility meant that if the YF-22 somehow lost its stealth advantage, it could still dogfight its way out of an engagement.

The J-20 is what Tyler Rogoway of The Drive calls a "fighter-interceptor". It's shown decent, at least at the level of 4th generation, maneuverability subsonically. But the point is, this is not what the J-20 is going to rely on. It's not a Su-57 which is designed to be stealthy enough to get into the merge, then win with exceptional maneuverability (realistic scenario: 1:1 K/D vs lightweights, but then again, the Su-57 is advertised as super cheap). The maneuverability is a "failsafe" should the J-20 be caught WVR, as with both the MiG-31 and F-22. What the J-20 wants to do is to exploit its speed and exploit its radar to kill what it wants to kill, then get the hell out.

 

[Blitzo]

For 1., the issue is whether you see those claims as a compliment or an insult. The much of the ethnic Chinese PLAAF watching community has been treating it is as an insult, as if to say that the Chinese can't compete with the F-22 and F-35. But it can also be seen as a compliment.

The biggest problem with the J-20 is the relative numbers deployed. It is being deployed later than the F-22, which is around 100-150 active airframes, and information does not yet exist to say with certainty that the J-20 has introduced more than 100 units into production. Likewise, the F-35, despite its teething problems, has already exceeded a number built of 400.

Strategically, the Chinese need to crank out the J-20s like hotcakes to match force on force, which is what you're implying with 2. However, Western observers have noted the weaknesses of the USAF, its dependency on support aircraft (AEW&C, tankers), as well as its naval defenses. A stealth aircraft that is advanced enough not to be intercepted on its attack run can wipe out these support assets, and hopefully return to base without being shot down. That is a smart and adroit policy they are assigning to the J-20, and tactically and strategically speaking, it is the best employment of an aircraft that is expensive and limited in numbers.

For 2, as I've mentioned prior, the assumption is that the J-20 is going to behave force-on-force against what's going to be 1200 F-35s deployed against it, when the J-20 is not believed to have a stealth advantage vs the F-35. Heavyweight air-superiority fighters have traditionally defeated lightweight and mediumweight air defense / strike fighters in BVR, closing to WVR should they fail to finish off the enemy.

However, with the F-35 having a stealth advantage (Chinese models without RAM imply that the F-35 can reach -50 dBsm in some sectors), the J-20 is forced to rely on its radar.to compensate. But what we know is that the F-35 is 700mm radar aperture, while the J-20 is 900-1000mm radar aperture, which is not enough to beat a 10-20 dBsm advantage on the F-35. Even then, the effects of stealth and jamming mean that radar detection becomes less preferred versus IR detection (the EOTS and EODAS on both the J-20 and F-35), and the J-20, as a heavier fighter with greater thrust, will have more disadvantages there.

And even in a best-case scenario under this structure, the J-20 is still in trouble even if it achieves a 1.5:1 kill ratio, because the F-35s are just so numerous due to their smaller size and mass production.

What are the J-20's advantages then, and how can it beat the F-35 sufficiently?

Well, the J-20 is more maneuverable than the F-35. But the F-35 is going to have SACM, and at the engagement ranges created by stealth the J-20 is not going to reduce NEZ / effective range with TVC.

On the other hand, the J-20 is going to be significantly faster than the F-35. That's an exploitable advantage in that the J-20 can launch missiles with better kinematics, then run away, hopefully getting out of the SACM's NEZ / effective range before the latter impacts. That is a way to get above 2:1 kill ratios or even get to 1:0 kill ratios.

The relative lateness of J-20 being deployed and/or the numbers of aircraft being deployed at any one time does not effect the range of roles that the aircraft is designed to be capable of conducting.

Obviously the way that an aircraft may be deployed in a conflict will differ depending on how many of the aircraft exists -- having 40 J-20s or having 400 J-20s will obviously effect the conservativeness vs boldness that the PLA will be willing to use them in during a conflict.
E.g.: when a smaller number of J-20s are in service, during a high intensity conflict it would make sense to use them in a more conservative manner to seek and make them conduct missions that will bring the greatest effects while exposing them to the lowest risk (such as seeking to target support assets, force multipliers etc, and avoiding combat against opposing fighters directly). However, in a conflict when more J-20s exist, it would make sense to use deploy them in missions that are (relatively speaking) higher risk (i.e.: including missions that may lead to direct combat against opposing fighters), in addition to the aforementioned lower risk/high effect missions.

This is no different to how the PLA had only a small number of Su-27s in the mid/late 1990s and the way in which they would have been employed then during a conflict would be different to how the PLA's much larger 4th/4+ gen fleet would be employed today.



The range of roles that an aircraft is capable of is dictated by its design.
The role in which an aircraft specifically plays during a specific conflict will depend on a myriad of factors including the nature of the conflict, and the number of aircraft of that type which are in service during the conflict... among other factors.


In relation to J-20, none of the above invalidate my points 1 and 2, and if anything they dovetail with my aforementioned points.

I can also put this another way.

The MiG-31 is an interceptor, but its airframe can sustain 5G and has shown around 15-18 deg/sec turn rates. It is an interceptor, but it has reasonable basic maneuverability to provide it with versatility and robustness should it be caught WVR.

The YF-22 was selected over the YF-23, despite the latter having better speed, sustained turn rates, payloads, and stealth. Why? Because the YF-22 was more agile than the YF-23; i.e, while its stealth gave it a decisive advantage over 4th generation aircraft, the agility meant that if the YF-22 somehow lost its stealth advantage, it could still dogfight its way out of an engagement.

The J-20 is what Tyler Rogoway of The Drive calls a "fighter-interceptor". It's shown decent, at least at the level of 4th generation, maneuverability subsonically. But the point is, this is not what the J-20 is going to rely on. It's not a Su-57 which is designed to be stealthy enough to get into the merge, then win with exceptional maneuverability (realistic scenario: 1:1 K/D vs lightweights, but then again, the Su-57 is advertised as super cheap). The maneuverability is a "failsafe" should the J-20 be caught WVR, as with both the MiG-31 and F-22. What the J-20 wants to do is to exploit its speed and exploit its radar to kill what it wants to kill, then get the hell out.

I.e.: what you've described fulfills the description of a "general air superiority fighter," and also corresponds to my points 1 and 2.



Every half year or so you recreate this conversation, and every time I think you don't understand why this "controversy" exists.

No one is suggesting that J-20 is intended to be a dedicated close in low speed dogfighter.

However, what has been repeatedly stated over the years in "mainstream defense media" is that it is either a dedicated high speed interceptor or a dedicated high speed striker.

The push back has been against that narrative -- however you seem to interpret that pushback to suggest that people believe J-20 is meant to be a dedicated low speed dogfighter or something.