J-20 5th Generation Fighter VII

Richard Santos said:

being able to count on not having to maneuver can be a great help to making the airframe aerodynamically efficient for going in a straight line.

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The compact nature of a fighter and the need to turn fast cut a bit of aerodynamic solutions. But it's not just about the engine. The j-20 got some aerodynamic tweaks during development with the slim back around the engine not seen in the first batch of prototypes.

taxiya said:

I think the "ABC" variant is ultimately designation from PLAF requirement/specification, not CAC's choice. PLAF put forward a list of requirement for an aircraft regardless what brand of component including engines, their bottom line is the performance spec. The outcome of that set of specs get a variant designation.

In this line of thinking, AL-31 and WS-10 powered J-20 would be the same variant IF both engines meet PLAF's requirement, while WS-15 powered would be a new variant as one of the major spec has changed (T/W). The merit of "ABC" is not based on how big the improvement is but rather what is the requirement PLAF put forward.

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Whether it is the PLAAF's decision or CAC's decision in terms of how fighters receive variant designations IMO is not that important.

What is important to us is how we in the past have received designations of new variants. J-10A, J-10B, J-10C, etc. J-11A, J-11B. JH-7, JH-7A. J-16, J-16D.

There is no clear and consistent trend between them that we can clearly point to as being "aha this XYZ cause" is the reason it has a different variant. Certainly there is no evidence to suggest that a mere engine change for engines in the same thrust category (Al-31 and WS-10) has merited a new variant in the past (J-11B and J-10C respectively as the most prominent examples).

However, the grapevine has also fed us information for which variants are which -- and IMO if the WS-10 equipped J-20 really was to be dubbed "J-20B" then I think we overwhelmingly would've had that information fed to us by now, considering when the first WS-10 equipped J-20 flew quite a few years ago now and how it has been in active production since 2019.


So IMO, no matter whether it is the PLAAF's decision or CAC's decision for how fighters receive their variant designations, at this stage I cannot come up with a reason for why the WS-10 equipped J-20 would be called J-20B. There is neither any sort of past precedent for it (in fact past precedent would suggest the WS-10 equipped J-20 should have the same variant as the Al-31 equipped J-20) -- nor is there any indications from the grapevine to suggest that is the case.

Bltizo said:

Whether it is the PLAAF's decision or CAC's decision in terms of how fighters receive variant designations IMO is not that important.

What is important to us is how we in the past have received designations of new variants. J-10A, J-10B, J-10C, etc. J-11A, J-11B. JH-7, JH-7A. J-16, J-16D.

There is no clear and consistent trend between them that we can clearly point to as being "aha this XYZ cause" is the reason it has a different variant. Certainly there is no evidence to suggest that a mere engine change for engines in the same thrust category (Al-31 and WS-10) has merited a new variant in the past (J-11B and J-10C respectively as the most prominent examples).

However, the grapevine has also fed us information for which variants are which -- and IMO if the WS-10 equipped J-20 really was to be dubbed "J-20B" then I think we overwhelmingly would've had that information fed to us by now, considering when the first WS-10 equipped J-20 flew quite a few years ago now and how it has been in active production since 2019.


So IMO, no matter whether it is the PLAAF's decision or CAC's decision for how fighters receive their variant designations, at this stage I cannot come up with a reason for why the WS-10 equipped J-20 would be called J-20B. There is neither any sort of past precedent for it (in fact past precedent would suggest the WS-10 equipped J-20 should have the same variant as the Al-31 equipped J-20) -- nor is there any indications from the grapevine to suggest that is the case.

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Don't know how easily ws-10 and al-31 can be swapped in the same plane ? Do we know if structural change are necessary or some adjustment in center of gravity ?

Atomicfrog said:

Don't know how easily ws-10 and al-31 can be swapped in the same plane ? Do we know if structural change are necessary or some adjustment in center of gravity ?

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If we had any indications that were the case, then it likely would have been conveyed to us by now that the WS-10 equipped J-20 variant would be called J-20B. Yet no such thing has happened.

And again, J-11B and J-10C underwent engine changes from Al-31 to WS-10 without a change in variant. I don't see why such a change in J-20 would demand it either.

Bltizo said:

If we had any indications that were the case, then it likely would have been conveyed to us by now that the WS-10 equipped J-20 variant would be called J-20B. Yet no such thing has happened.

And again, J-11B and J-10C underwent engine changes from Al-31 to WS-10 without a change in variant. I don't see why such a change in J-20 would demand it either.

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Do some j-11b got upgraded from al-31 to ws-10 ? or just they just put them on different planes/batch ... I would like to see a plane who got both engine in his lifetime. And for such comparable engine, i don't see the need either to change the name..

Atomicfrog said:

Do some j-11b got upgraded from al-31 to ws-10 ? or just they just put them on different planes/batch ... I would like to see a plane who got both engine in his lifetime. And for such comparable engine, i don't see the need either to change the name..

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There would be a need for a change in designation, especially for quick identification of aircraft for logistic support and maintenance needs. Probably they will add another suffix to the original designation, just like adding a "G" to J11B.

Bltizo said:

@Deino,

Do you believe the WS-15 equipped j-20 should be called J-20C?

My issue with such a belief is that if it were the case then the WS-10 equipped J-20s would be dubbed J-20Bs by all of the Chinese PLA watchers but this isn't the case.


More importantly, I don't think we have any reason to expect a mere engine change in the same thrust category to lend itself to having a whole new variant name when there is little else different.
For example, the first batch of J-11B were powered by Al-31s while the rest were powered by WS-10s, but they are all still called J-11B.

Similarly, J-10Cs equipped with Al-31s and WS-10s will also both still be known as J-10C despite having different engines.

I would be surprised if that wasn't also the case for J-20, i.e. I think either the Al-31 and WS-10 equipped J-20s are called J-20 and J-20A respectively, or where both are just called J-20A.

But I cannot see any logical reason why the WS-10 powered aircraft would be J-20B.

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Actually I don't know. Given what we know it seems - in fact it is an accepted fact - that both the J-20 demonstrators, early and later prototypes as well as the first serial batches are called J-20 and now the WS-10 powered ones are J-20A, so that the WS-15 powered ones are most likely J-20B. For him at first the B was the supposed twin-seater and I explained that this one should be a J-20S or AS.

While Greg prepared his report, we were discussing several issues like the number of J-20s built, their production rate, units and so on including the designation issue and in one of the mails I told him that I don't like this as it seems to be since for me the changes from the demonstrators to the late prototypes (2016 & 2017) and LRIP birds are big enough to warrant a new designation. IMO the changes from J-10 to J-10A were even lesser apparent. In fact I still don't know why from Batch 04 the J-10 got the letter A?!!?

As such - and I noted this is my personnel opinion (and contrary to what seem to be) based on how it was for the J-10 - the demonstrators should be called J-20, the AL-31 powered prototypes and LRIP ones should be J-20A and those with WS-10C should be J-20B ... but again, it is not.

Why in the end he only took this IMO completely irrelevant part of the story and left out everything else, I don't know.

Hope this clears a bit of the confusion.

Deino said:

Actually I don't know. Given what we know it seems - in fact it is an accepted fact - that both the J-20 demonstrators, early and later prototypes as well as the first serial batches are called J-20 and now the WS-10 powered ones are J-20A, so that the WS-15 powered ones are most likely J-20B. For him at first the B was the supposed twin-seater and I explained that this one should be a J-20S or AS.

While Greg prepared his report, we were discussing several issues like the number of J-20s built, their production rate, units and so on including the designation issue and in one of the mails I told him that I don't like this as it seems to be since for me the changes from the demonstrators to the late prototypes (2016 & 2017) and LRIP birds are big enough to warrant a new designation. IMO the changes from J-10 to J-10A were even lesser apparent. In fact I still don't know why from Batch 04 the J-10 got the letter A?!!?

As such - and I noted this is my personnel opinion (and contrary to what seem to be) based on how it was for the J-10 - the demonstrators should be called J-20, the AL-31 powered prototypes and LRIP ones should be J-20A and those with WS-10C should be J-20B ... but again, it is not.

Why in the end he only took this IMO completely irrelevant part of the story and left out everything else, I don't know.

Hope this clears a bit of the confusion.

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Thanks.

So I'm a little confused by this (the underlined part) -- why do you think the demonstrators (200X) and prototypes (201X) are not both dubbed J-20? And why do you think the J-20s powered by Al-31 and WS-10 are not both also called J-20A?

I ask because between the J-20s powered by Al-31 and WS-10 it seems like the only difference is their powerplant, with no other notable differences to speak of.

For other fighter aircraft with similar changes -- i.e. J-11B and J-10C -- which have had powerplant changes from Al-31 to WS-10, without any other notable changes, they had retained their variant designations without becoming a whole new variant just based off the difference in powerplant alone.


I suppose what I'm saying is based on past practice, wouldn't it make more sense to believe that the change in powerplant from Al-31 to WS-10 mean we should expect the variant designation to stay the same, given there are no other changes between the J-20s powered by Al-31 vs the J-20s powered by WS-10?

Bltizo said:

Thanks.

So I'm a little confused by this (the underlined part) -- why do you think the demonstrators (200X) and prototypes (201X) are not both dubbed J-20? And why do you think the J-20s powered by Al-31 and WS-10 are not both also called J-20A?

I ask because between the J-20s powered by Al-31 and WS-10 it seems like the only difference is their powerplant, with no other notable differences to speak of.

For other fighter aircraft with similar changes -- i.e. J-11B and J-10C -- which have had powerplant changes from Al-31 to WS-10, without any other notable changes, they had retained their variant designations without becoming a whole new variant just based off the difference in powerplant alone.


I suppose what I'm saying is based on past practice, wouldn't it make more sense to believe that the change in powerplant from Al-31 to WS-10 mean we should expect the variant designation to stay the same, given there are no other changes between the J-20s powered by Al-31 vs the J-20s powered by WS-10?

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I hope I did not add additional confusion by not being clear enough ... as such give me another try.

Given on what we know (or at least what I rate the commonly accepted "that's the way it is" opinion) it looks like:

- demonstrators & prototypes and first batch of AL-31 powered ones are all J-20 (without an additional letter)
- WS-10C powered ones are called J-20A

Or do you think all serial J-20s are already J-20A?

This is most of all based on quite a long discussion I had with Henri K and several Chinese guys at another forum and again IMO not logical, since the differences between the demonstrators (I would call them J-20) and the later true prototypes (I would therefore call them all J-20A) are bigger than between AL-31 and WS-10C powered production aircraft.

In fact I agree with you given the J-11B batch 01 story it makes no sense, while on the other side - and maybe typically for CAC - I still don't understand why the Batch 04 J-10s with even lesser changes are called J-10A, while at the same time the difference between J-10B and C is also not very straightforward?!! In fact the changes from B to C are at least externally less obvious than between the AL-31FN and WS-10 powered later batches. But as it seems, the new AESA might be reason enough and similar the less obvious J-10A might also have internal changes. ... but why then putting all J-10B/Cs together in one continuing batch system with Batch 01 = J-10B and from Batch 02 on J-10C?

In fact I don't know for sure.

Deino said:

I hope I did not add additional confusion by not being clear enough ... as such give me another try.

Given on what we know (or at least what I rate the commonly accepted "that's the way it is" opinion) it looks like:

- demonstrators & prototypes and first batch of AL-31 powered ones are all J-20 (without an additional letter)
- WS-10C powered ones are called J-20A

Or do you think all serial J-20s are already J-20A?

This is most of all based on quite a long discussion I had with Henri K and several Chinese guys at another forum and again IMO not logical, since the differences between the demonstrators (I would call them J-20) and the later true prototypes (I would therefore call them all J-20A) are bigger than between AL-31 and WS-10C powered production aircraft.

In fact I agree with you given the J-11B batch 01 story it makes no sense, while on the other side - and maybe typically for CAC - I still don't understand why the Batch 04 J-10s with even lesser changes are called J-10A, while at the same time the difference between J-10B and C is also not very straightforward?!! In fact the changes from B to C are at least externally less obvious than between the AL-31FN and WS-10 powered later batches. But as it seems, the new AESA might be reason enough and similar the less obvious J-10A might also have internal changes. ... but why then putting all J-10B/Cs together in one continuing batch system with Batch 01 = J-10B and from Batch 02 on J-10C?

In fact I don't know for sure.

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Well, my idea is that:
Tech demo J-20s (200X) and prototype J-20s (201X) = J-20
Al-31 equipped production J-20s = J-20 OR J-20A
WS-10 equipped production J-20s = J-20A

I'm not sure whether the Al-31 equipped production J-20s should better be considered as J-20 or J-20A --- however I definitely think the WS-10 equipped J-20s should be called J-20A and not J-20B.


As far as batches and variants are concerned -- I think it might be easier just to ignore that entirely, and to look at the differences that led to different variants -- as well as changes which did not lead to different variants.

For J-10A to J-10B, the differences are the structural changes (DSI, nose), radar, cockpit, various other avionics etc.
For J-10B to J-10C, the differences are largely avionics from the radar, to additional antennae and MAWS placement and likely additional datalink and other internal avionics differences.
For J-10C, there are Al-31 powered aircraft succeeded by WS-10 powered aircraft -- but the variant remains the same, despite the change in powerplant.

For J-11B, initially the aircraft produced was powered by Al-31, while successive aircraft were powered by WS-10 -- but the variant remains the same, despite the change in powerplant.


So what this means for J-20, imo is that the difference between J-20s powered by Al-31 and J-20s powered by WS-10 -- if the differences alone are only the powerplant, then there should be no difference in variant between the two.

If however there are other differences (none of which that we've seen tbh), then perhaps a change in variant could be justifiable.

BUT, the fact that no one is calling the J-20s powered by WS-10 as "J-20B" and instead it's being called "J-20A" --- imo means there are only two possibilities:
1. Production J-20s powered by Al-31s are called J-20A, and production J-20s powered by WS-10s are called J-20A as well (only change being powerplant, therefore no change in variant -- per the J-11B and J-10C examples).
2. Production J-20s powered by Al-31s are called J-20, and production J-20s powered by WS-10s are called J-20A (change being powerplant and some sort of other possible internal changes in the aircraft that we are unable to externally identify).


However, I see no permutation of possibilities based on past patterns and based on what we know of J-20, for us to believe the idea that the J-20s powered by WS-10s are called "J-20B".