Striker or Interceptor? Assessing commentary on J-20's role

vesicles said:

What is with this fixation on the size of the J-20?? I thought many posters have presented convincing evidence that the J-20 is actually smaller than the Sukhoi family fighters (in satelite images where the J-20 sat side-by-side with other fighters including Sukhois), which have been thought to be some of the most agile fighters known to man. So size does not matter. And the current engine used by the J-20 is at least the same engine used by most of the Sukhoi fighters, again known to be very agile even with "less advanced engines". Some speculated that the J-20 might be using a highly modified version of the AL-31 engine. So let's drop the "size" / "engine" argument!


Let's also be clear that no one should be comparing the J-20 with either the F-22 or the T-50. There is simply no evidence whatsoever for anyone to compare. I don't think even the best experts in the world can do that comparison because no one in the world has the complete data on ALL 3 fighters. The only thing that most of the "non-anti-J-20" people are proposing is that there is no evidence to suggest the J-20 would be a dedicated striker/interceptor. That is all. The only thing that we can conclude from the available evidence is that the J-20 is a 5th gen stealth fighter. From what we know about how the PLA works, we can speculate with confidence that the J-20 should be a highly effective stealth fighter, based on how confident the PLA is about the J-20. We all know that the PLA is very careful/conservative about their weapons development. They will not let it roll out unless they are satisfied with their products. And we all know that they set a very bar for their new weapons because of their ambition and goals. And their past track record is consistent with this view. That is all we know.

With regard to whether different fighter lay-out could affect its stealth, I suggest that we give the Chinese fighter designers some benefit of the doubt. They should know better than most of us the armchair fighter designers. If they decided to stick with the current design after decades of research and development and billions of $$$ invested in the development, they should know what they are doing. At least they should have a better idea than most of us armchair fighter designers.

Click to expand...

Let me say first off that I agree with you on the size/powerplant statement, that's a dog that's been beat to death, so 1 big one in your favor, and you are among Sino Defense most honest and honorable posters, and I will fully support your statement.

On point 2 that none of us is capable of making "observations" relating the J-20 to T-50 or F-22??? whut are you talking about??? to say their is "no evidence whatsoever for anyone to compare" is in fact in-accurate. As a research scientist where would you be if you didn't in fact compare things that are not completely understood, develop a hypothesis, sell that to your funders, and then set out to either prove, or disprove your theory??

There are several of us who have more than enough data/experience to make very cogent/accurate statements about each of these fighters and how they stack up against one another, I stand by my "clinical observations", and if I am proven to have been in-accurate, I correct my hypothesis and offer an apology. I have a "body of work" here on the Sino Defense Forum, I have worked very diligently to make accurate cogent observations on military aircraft in particular, and I will continue to do so, even though some would prefer we only post pretty pictures, Sino Defense does require that each picture or post contain an observation or commentary?? yes?

As to your third point? let me respond that the J-20 is China's first endeavor at developing a large stealthy fighter, how well they have done, how well they do, remains to be seen, to assume its a success is asking a lot? Here in the US we have a long history of innovative successful aircraft design, has anyone assumed the F-35 is a success because of that very successful history??? NO, they haven't, and no one is going to assume the J-20 is a success until it is in full production and populating fighter squadrons.

So please don't take offense, and yes I get annoyed at all the "stupid or even dishonest" things that get said about aircraft, ours, yours, Russian, UK, and on down the line, we just have to note who is accurate and fair, and who are "goofballs"?? my final illustration is completely off topic, while at the same time puts these "preliminary" assessments in perspective.

I assume you have a wife, I have a lovely, beautiful wife! really, I married her because she is gorgeous, smart, naïve, innocent, sweet, and I nick-named her the Honey Badger. Now how much did I know about her when I asked her to marry me??? you see where I am going don't you, I know a lot more about her than I did, BUT, she is a WOMAN, and I still don't really know "jack" about women?? That's why ALL airplanes are FEMALE, love em, cuddle em, give everything you own to get the prettiest one you can, but don't ever assume you know all there is to know?? EVER, because when you do, they sense that, and they will show you just how naïve you really are? you may all show this to your wives, girlfriends??? at your discretion, but don't show it to the Honey Badger, she would "kill me"!

I have SEVEN daughters, an EX Wife( the WARDEN), a lovely wife(Honey Badger), and I would hazard that our old sage BD would agree with me about women, no matter how much you know, or how much you think you can predict with accuracy their behavior, you don't know "jack", maybe that's what Vesicles was trying to say about the J-20???

Absolutely true about the women AFB. I would also say that if women have invented bombs, they would not actually kill anyone, but everyone in range would be left feeling bad and guilty for days afterwards.
Anyway end of silly off topic breakaway.

Air Force Brat said:

On point 2 that none of us is capable of making "observations" relating the J-20 to T-50 or F-22??? whut are you talking about??? to say their is "no evidence whatsoever for anyone to compare" is in fact in-accurate. As a research scientist where would you be if you didn't in fact compare things that are not completely understood, develop a hypothesis, sell that to your funders, and then set out to either prove, or disprove your theory??

Click to expand...

In my naive view, the design philosophy of the J-20 is so much different from of the F-22, visual comparison is almost impossible. We need actual data. then since the Chinese will not give their J-20 data to the Americans and the Americans will not give their F-22 data to the Chinese, no one will have the complete data for comparison. Also, we will need to perform testings on these two planes side-by-side in order to do proper comparison. My own experience dealing with comparisons is that, a lot of time, these comparison may not be as clear-cut as you would expect even when you compare two things that should be massively different... This is why I don't believe in comparisons of F-22 vs. J-20.

If I were to design a comparison between the F-22 and the J-20, I would use a single pilot, blindfold him and put him in a plane without telling him which plane he is flying (of course, I hope he would take off the blindfold when he does the flying). then he would make fly these planes using the same routine, on the same day, and at the same location. Those doing the data analysis should also be blinded and should not know which plane they analyze. Below would be my experimental design:
(1) test fly F-22;
(2) test fly J-20;
(3) test fly F-22 again;
(4) test fly F-4

My baseline would be: (1) and (3) should give me much better data than (4); (1) and (3) should give me identical data. With the baseline, I will be confident about (1) vs (2). If my baseline is all over the place, any difference between (1) and (2) would be meaningless.

And my experience would suggest that, a lot of times, the data will surprise you... IF someone has done some kind of comparison like listed above, I can almost guarantee you that the difference between (1) and (4) would not be as clear-cut as you would expect...

Air Force Brat said:

and good morning indeed, it is, and glad to hear from you, thanks for your many fine observations, I am thinking that you are likely correct that J-20 will not have OVT. Is that in fact an accurate assessment of your thoughts?? or do you think at some point they will in fact incorporate OVT???

Click to expand...

My belief have been, and still is, that the J-20 will not have thrust vectoring. To elaborate:

• Designing and building a F119-class engine is difficult enough as it is. Chinese engineers are not going to make life more difficult for themselves by incorporating thrust vectoring.
• The term "super manoeuvrability" is misleading, as it conjures up the thought that thrust vectoring could make the aircraft more manoeuvrable on top of being manoeuvrable. The correct term to use is actually "post-stall manoeuvrability". Here comes the problem: stall is a bad thing, and an aircraft in a stall can lose a lot of energy in very short time. It makes no sense to get into a stall, then having to use post-stall manoeuvrability, especially in a dog fight.
• Modern fighter aircraft can already turn at 9 G's. If you can make an aircraft turn at, let say, 13 G's, what then? Then you have a dead pilot. Ironically, adding more manoeuvrability is not desirable; but that isn't the purpose of thrust vectoring anyway.

b787 said:

I said my humble opinion but i can tell you that J-20 is large, and it is much larger than the F-22, i do not know if it is lighter, but larger it is, the F-22 has a small airframe, it looks big because its tail extends far aft the nozzles.

Western commentators said the J-20 looks an attack aircraft because its airframe and fuselage is larger than the F-22s.


Large aircraft like Su-27 can be modified into strike aircraft, J-20 surely can be used like a fighter, but it still lacks the stuff F-22 and T-50 have in terms of engine without their engines both aircraft are not that good, they fly on their engines.

The F-22 and T-50 are good mostly because of their engine, they are aircraft highly compromised by stealth requirements.

I do not know how maneuverable J-20 is, i do not know that, but today with new advanced missiles you do not need to be so agile, Python 5 is a good example that is the philosophy behind the F-35.

However being a large aircraft it will be a good striker, perhaps it is also very maneuverable and quick, but most western commentators know the jet has its engines very likely behind the weapons bays and the intake ducts are not that big the J-20 i am sure it is thought and designed to carry some types of attack missiles.

Click to expand...

B787, have you actually read my paper?

I address all the points you make in it:
-J-20 is not that much bigger than F-22. Yes it has substantially more volume, and likely has a higher MTOW but in terms of dimensions it is actually not that much bigger. Its weapons bays arrangement also makes it a poor dedicated striker. HOWEVER no one is ruling out a strike role for it.
-J-20's maneuverability very much depends on its engines (and the thrust it has available), and the discussion around J-20's intended role should revolve around whether it is using Al-31 (interim engines) or WS-15 (intended engines)

-----

Also I'm not sure why you keep bringing up Su-27. No one is denying that J-20 is a large plane -- in the same way that F-22 and T-50 are also large planes. However to suggest that J-20 may be later converted into a more dedicated striker like Su-27 was converted to Su-34 is unfounded at present, mostly because for J-20 to be an effective striker it needs a much deeper weapons bay which will effectively change the entire structure of the plane itself -- in other words, why not just build a new dedicated striker instead?

Bltizo said:

B787, have you actually read my paper?

I address all the points you make in it:
-J-20 is not that much bigger than F-22. Yes it has substantially more volume, and likely has a higher MTOW but in terms of dimensions it is actually not that much bigger. Its weapons bays arrangement also makes it a poor dedicated striker. HOWEVER no one is ruling out a strike role for it.
-J-20's maneuverability very much depends on its engines (and the thrust it has available), and the discussion around J-20's intended role should revolve around whether it is using Al-31 (interim engines) or WS-15 (intended engines)

-----

Also I'm not sure why you keep bringing up Su-27. No one is denying that J-20 is a large plane -- in the same way that F-22 and T-50 are also large planes. However to suggest that J-20 may be later converted into a more dedicated striker like Su-27 was converted to Su-34 is unfounded at present, mostly because for J-20 to be an effective striker it needs a much deeper weapons bay which will effectively change the entire structure of the plane itself -- in other words, why not just build a new dedicated striker instead?

Click to expand...

I will tell you why you are using a very subjective position, first you have not official data, second you can not elaborate its future unless you have official plans and that is even not real, the future is only for prophets.


I do not know the length of J-20 so it is pointless say its its real size, i just can see, its nozzles go aft almost at the level of is tail booms, if you look at the nozzles they are not much far from the from the tip of the tail boom; however its intakes are quiet forward, it has a very long intake duct, so its fuselage is clearly longer than a F-22 not only proportionally but in size, even if it is 1 meter longer in length, the intake ducts and engines are longer.

its weight? well i can not elaborate and say it is lighter or heavier in empty weight, thus i can not elaborate.

maneuverability? i do not know, i have not the weight, neither the thrust it might get after 2018 so it is pointless to say it is as good as F-22 or in the class of F-35.
To say if will soldier as a dedicated air superiority, also is something i can not say, that is only answerable if i knew the future ( and here i am not prophet) so i just said if China does not have a third stealth aircraft, the J-20 will be the likely candidate to be used as an strike aircraft, by having a large fuselage it very likely with the right engine will have a long range in the strike mode, add refueling probe and the aircraft has the same possibilities the F-15E and Su-30 to become a long range strike fighter.

By 2025, the Russians alone will have S-500s, the S-400 and S-400 are marketed as able to down stealth aircraft and that includes F-22s and F-33s.

So conventional fighters like J-10 or JH-7s are not going to survive unless they attack in a second wave, then China will only have J-20 as a solution


If S-500 works well even the B-2 will be a target, the Americans might know something so they have decided to design a new generation bomber.

For China in order to power a large B-2 type aircraft, will require a large budget, experience (see the russians already have opted for a new Tu-160 variant the M variant) so it is unlikely China will have a PAKDA style aircraft soon.

This in my personal opinion will lead very likely to a multirole J-20, but well i am not prophet, so who knows

b787 said:

I will tell you why you are using a very subjective position, first you have not official data, second you can not elaborate its future unless you have official plans and that is even not real, the future is only for prophets.

Click to expand...

I've never claimed my position is unassailable, but I think I've clearly outlined the various premises for my position and the logical leaps between them.

I do not know the length of J-20 so it is pointless say its its real size, i just can see, its nozzles go aft almost at the level of is tail booms, if you look at the nozzles they are not much far from the from the tip of the tail boom; however its intakes are quiet forward, it has a very long intake duct, so its fuselage is clearly longer than a F-22 not only proportionally but in size, even if it is 1 meter longer in length, the intake ducts and engines are longer.

Click to expand...

We have enough evidence to make an estimate that J-20 is no more than 20.5m long, and likely a little shorter.

Its internal volume is no doubt larger than F-22s.

its weight? well i can not elaborate and say it is lighter or heavier in empty weight, thus i can not elaborate.

Click to expand...

Yes, estimates of its weight is even more difficult to make than length and volume.

maneuverability? i do not know, i have not the weight, neither the thrust it might get after 2018 so it is pointless to say it is as good as F-22 or in the class of F-35.
To say if will soldier as a dedicated air superiority, also is something i can not say, that is only answerable if i knew the future ( and here i am not prophet) so i just said if China does not have a third stealth aircraft, the J-20 will be the likely candidate to be used as an strike aircraft, by having a large fuselage it very likely with the right engine will have a long range in the strike mode, add refueling probe and the aircraft has the same possibilities the F-15E and Su-30 to become a long range strike fighter.

Click to expand...

We have enough information about WS-15 to make an estimated guess, and we have enough official sources to guess that it's almost definitely meant to be competitive in ACM.

By 2025, the Russians alone will have S-500s, the S-400 and S-400 are marketed as able to down stealth aircraft and that includes F-22s and F-33s.

So conventional fighters like J-10 or JH-7s are not going to survive unless they attack in a second wave, then China will only have J-20 as a solution

Click to expand...

Incorrect -- any offensive strike action does not need to only depend on strike aircraft. Cruise missiles, conventional ballistic missiles would all be part of any action.

J-20 will be part of that action, yes, and I've never denied that J-20 could be a useful striker, but it is almost certainly not a dedicated striker.

If S-500 works well even the B-2 will be a target, the Americans might know something so they have decided a new generation bomber.

For China in order to power a large B-2 type aircraft, will require a large budget, experience (see the russians already have opted for a new Tu-160 variant the M variant) so it is unlikely China will have a PAKDA style aircraft soon.

This in my personal opinion will lead very likely to a multirole J-20, but well i am not prophet, so who knows

Click to expand...

J-20 will be multirole without physical changes -- it can likely be able to launch PGMs from its internal weapons bay.

The issue I have with your position is that you believe it is easy for J-20 to be developed into an effective striker like Su-34 was from Su-27... when in reality J-20 is hindered by the fact that it is a stealth fighter and to be a more dedicated striker it will require larger weapon bays which will require substantial modification to the airframe if not a whole new airframe to begin with.

Again, this isn't to say J-20 can't be a viable striker with its current weapons bay configuration, but to think that they'll develop a "strike J-20" variant at this stage is very unlikely given the limitations of its weapons bay depth.
If they develop a "strike J-20" it will be forced to carry weapons outside its bays, meaning it will have to compromise its RF stealth.

Bltizo said:

We have enough evidence to make an estimate that J-20 is no more than 20.5m long, and likely a little shorter.

Its internal volume is no doubt larger than F-22s.




Yes, estimates of its weight is even more difficult to make than length and volume.



We have enough information about WS-15 to make an estimated guess, and we have enough official sources to guess that it's almost definitely meant to be competitive in ACM.




Incorrect -- any offensive strike action does not need to only depend on strike aircraft. Cruise missiles, conventional ballistic missiles would all be part of any action.

J-20 will be part of that action, yes, and I've never denied that J-20 could be a useful striker, but it is almost certainly not a dedicated striker.




J-20 will be multirole without physical changes -- it can likely be able to launch PGMs from its internal weapons bay.

The issue I have with your position is that you believe it is easy for J-20 to be developed into an effective striker like Su-34 was from Su-27... when in reality J-20 is hindered by the fact that it is a stealth fighter and to be a more dedicated striker it will require larger weapon bays which will require substantial modification to the airframe if not a whole new airframe to begin with.

Again, this isn't to say J-20 can't be a viable striker with its current weapons bay configuration,.

Click to expand...

Sorry is no point to argue, most of what you say is your opinion, you are talking as if you know the size of the weapons bay, and actually measured and not only that you went and measured PAKFA`s weapons bays, come on, you also talk as if you actually know the real size, you use a conjecture from a picture as factual data, further more, you talk as if you saw or know when the WS-15 will appear.

I do not base my opinion upon things like that, so as i said from the beginning it is my personal opinion, if you want to believe it is as big as a F-22 (or just slightly bigger), lighter, more maneuverable, already powered by WS-15, that is fine with me, i do not know the real data, but i think these types of deductions are not going to be known unless the J-20 goes to war or it is tested by the Russians or Americans if ever happens to be captured.

wait a few years more perhaps official data appears soon and in few years we might know how does the program evolve.

In my opinion it is multi role and the western commentators said it is a ideal candidate for a long range interdictor due to the state of the Chinese order of battle and its proportions

b787, this is turning into a senseless arguement.

Bltizo has written a good article about the aircraft. Better than most.

The fact is, we have ample photos of the J-20 next to vehicles and other aircraft that we know the exactly dimensions of.

Based on that...while we may not be able to get an exact measurement...we can certainly get measurements easily to within a half a meter and less.

Once we know the overall length and width to that degree...it is relatively easy to come up with dimensions for the weapons bay to the same degree. We have pictures of the open wepaons bay, and can use proportional methods to come up with those dimensions. This is all very straight forward.

Not an exact measure it is true...but well within reason.

There is simply no need to argue against that. Bltizo has not said he has an exact measurement. But his figures are going to be very close and certainly good enough for the basis of the discussion and the things he is projecting based on them.

b787 said:

Sorry is no point to argue, most of what you say is your opinion, you are talking as if you know the size of the weapons bay, and actually measured and not only that you went and measured PAKFA`s weapons bays, come on, you also talk as if you actually know the real size, you use a conjecture from a picture as factual data, further more, you talk as if you saw or know when the WS-15 will appear.

Click to expand...

I think it is very likely that J-20's weapon bay is poorly suited for carrying strike weapons, and I think PAK FA's weapon bay may be more suited for carrying strike weapons yes, based on their respective depth, position and geometry. I never said I knew what their actual dimensions, only their depth relative to each other.

And yes, based on rumours and collective consensus I do believe WS-15 exists and is intended for J-20 as its primary powerplant.
I never claimed a date for when WS-15 will appear.

I do not base my opinion upon things like that, so as i said from the beginning it is my personal opinion, if you want to believe it is as big as a F-22 (or just slightly bigger), lighter, more maneuverable, already powered by WS-15, that is fine with me, i do not know the real data, but i think these types of deductions are not going to be known unless the J-20 goes to war or it is tested by the Russians or Americans if ever happens to be captured.

wait a few years more perhaps official data appears soon and in few years we might know how does the program evolve.

In my opinion it is multi role and the western commentators said it is a ideal candidate for a long range interdictor due to the state of the Chinese order of battle and its proportions

Click to expand...

You've made a whole heap of assumptions as well, about J-20's role in the chinese air force based on the viability of other projects, assumptions about their supporting force multipliers, the way they may want to conduct strike, and the capability of the adversary.

No one is claiming to know the actual specifications of the aircraft, but based on what little reliable information we do have, we can infer a reasonable conclusion which is what I think I have done. I'm not claiming this conclusion is final or not subject to change, but at present with the information we have I think my position is well supported.

And just for the record I believe J-20 is multirole as well, in the same way that F-22 is multirole and other modern fighter aircraft are also multirole.