J-20 5th Gen Fighter Thread VI

[Totoro]

J-16 doesn't seem to have any side arrays visible though. So if indeed the radar can look sideways then it's either a mechanically steered phased array or a more protruding, in regards to the length of the radome, array complex. So the side looking arrays are also covered by the radome. That would also mean the main array may be moved so much forward that it's overal area is slightly smaller than what it could have been if there was no such protrusion.

 

[Hyperwarp]

J-16 and the J-20 most likely have provisions for side arrays, but that doesn't mean they currently have them installed. If there were side arrays then you should clear see it on unpainted planes right out of the factory. Where is the dielectric material? You see it on the radome and other sensors (

Please, Log in or Register to view URLs content!

,

Please, Log in or Register to view URLs content!

)

 

[Blitzo]

That was my point. Everybody is guessing.

Lol what I meant by that, is there are guesses and then there are "guesses". They are not equivalent.

Some are educated guesses made with a sound and logical basis sourced from people and communities with a good track record, whereas other guesses are from people or groups with no demonstrable credibility and no logical basis for being able to make the scale or the precision of the claims that they try to make.

Some guesses are much better than others, while some guesses are much less credible. That is what I was getting at.

 

[Blitzo]

I just have to say I find this sudden question about J-20s radar a little strange. The original claims of the aircraft having an AESA was from back when it was still known as J-XX.

Now in 2019 considering the kinds of radars -- even not including other fighter AESAs like on J-16, 10C -- that the Chinese industry is producing, the idea that J-20 may not be using an AESA is hard to entertain.

That said I can appreciate the desire for wanting a couple of sources to make reference to for academic reasons, but practically speaking the usage should be very limited given the scope and timeline of claims like this.

 

[Brumby]

So, if we are to aggregate all the indications so far, we have these:

1. Interview with a 14th institute spokesperson at Zhuhai 2018 saying "J-20 and J-16 use some kind of a phased array radar"
2. Interview with director of 14th institute saying "our airborne radar is completely comparable to the F-35's APG-81 radar and the F-22's APG-77 radar" though he doesn't go into details, whether he's talking about radars on actual PLAAF planes or whether he's talking about 14th institute's radars in some stage of development. Also, "completely comparable" is a rather vague statement, but it does give credence he's talking about active phased array.
3. Export geared model of AESA radar is marketed for JF17 at Zhuhai 2018.
4. Two different phased array designs seen on J10B and J10C, via imagery. While the first one does resemble what Russians tried with their PESA technology, the latter one looks different, and is somewhat closer looking to the US AESA radars. Though of course, superficial visual similarities don't have to be conclusive.
5. I also remember there were some research papers on use of AESA radars for J10 radar, though I don't remember the details nor can I find those papers.
6. Myriad of larger AESA radars in use on other platforms for some years now might also be somewhat indicative of the fighter based AESA radar presence in J-20 and J-16.

I will use your summary as a framework to address the pertinent issues regarding the AESA radar discussion. First off, there are AESA radars and then there are AESA radars. In other words, all AESA radars are different due to manufacturing design and the intended applications which they in turn affect significantly the complexities of the product and how quickly one can get to a stable design that meet performance criteria. I will therefore address each of the above points in turn.

1. I am not disputing whether J-20 or J-16 use phased arrays. The starting point is that they do.
2. What is being said by the 14th institute that what is being built is comparable to APG-81 and APG-77 is highly misleading and disingenuous. In terms of analogy it is like saying the Nissan Skyline is comparable to a Porsche. Other than the fact that both have four wheels and that they can get from point A to point B very quickly - it is very misleading in terms of product comparison. Even though we have limited information on both APG-81 and APG-77 we would never say that they are comparable. For example, we don't know their respective TR average power, we don't know whether they are using the same TR design, we don't know their respective signal processors, we don't know their respective radar mode algo, we don't know their respective gains, we don't know their respective frequencies settings, et al. All these are key drivers to their respective performance metrics and applications. We can do a reasonable guesstimate that the packaging technology used in the APG-81 is denser than the one in APG-77 by approximately 16 % (from memory).
3.AESA development is all software driven and depending on performance criteria it can be basic or complex. We know block 3 has been repeatedly delayed and that could be due to the radar not being ready for prime time. One can declare victory for a simpler design but that does not mean the one for the J-20 or J-16 would have a similar pathway. For example, the APG-79 for years had design stability issues even though it came after APG-63(V)2 and APG-77 in terms of timeline.
4. The complexities of an AESA radar cannot be judged based on visual imagery. The complexities are specs dependent. For example, T/R module count is affected by packaging technology. The more aggressive the target, the more problems you have to solve with thermal management and grating issues. Generally the size of TR modules must be small enough that they can be packed to about half wavelength apart in the highest operating frequency. This would give widest field of view (distance of lower than 0.5 equals +-90 degree FOV, 0.536 the wavelength equals to +- 60 degree FOV and 0.586 equals +-45 degree FOV). One way to widen FOV is to use a mechanical gimbal. If the intend is to integrate the radar to the EW system than it will give rise to another layer of complexity with signal interference issues I believe this was the problem with the APG-79.
5. and 6. Basically to sum up, I believe Butowski's statement that there is "no production series" is meant to be intentional to project a view that the radar development has not reached a stage where it can go into series production. Essentially there is a long pathway in product testing and there may be some installed for further operational evaluation but not necessarily ready for prime time. .

 

[latenlazy]

I will use your summary as a framework to address the pertinent issues regarding the AESA radar discussion. First off, there are AESA radars and then there are AESA radars. In other words, all AESA radars are different due to manufacturing design and the intended applications which they in turn affect significantly the complexities of the product and how quickly one can get to a stable design that meet performance criteria. I will therefore address each of the above points in turn.

1. I am not disputing whether J-20 or J-16 use phased arrays. The starting point is that they do.
2. What is being said by the 14th institute that what is being built is comparable to APG-81 and APG-77 is highly misleading and disingenuous. In terms of analogy it is like saying the Nissan Skyline is comparable to a Porsche. Other than the fact that both have four wheels and that they can get from point A to point B very quickly - it is very misleading in terms of product comparison. Even though we have limited information on both APG-81 and APG-77 we would never say that they are comparable. For example, we don't know their respective TR average power, we don't know whether they are using the same TR design, we don't know their respective signal processors, we don't know their respective radar mode algo, we don't know their respective gains, we don't know their respective frequencies settings, et al. All these are key drivers to their respective performance metrics and applications. We can do a reasonable guesstimate that the packaging technology used in the APG-81 is denser than the one in APG-77 by approximately 16 % (from memory).
3.AESA development is all software driven and depending on performance criteria it can be basic or complex. We know block 3 has been repeatedly delayed and that could be due to the radar not being ready for prime time. One can declare victory for a simpler design but that does not mean the one for the J-20 or J-16 would have a similar pathway. For example, the APG-79 for years had design stability issues even though it came after APG-63(V)2 and APG-77 in terms of timeline.
4. The complexities of an AESA radar cannot be judged based on visual imagery. The complexities are specs dependent. For example, T/R module count is affected by packaging technology. The more aggressive the target, the more problems you have to solve with thermal management and grating issues. Generally the size of TR modules must be small enough that they can be packed to about half wavelength apart in the highest operating frequency. This would give widest field of view (distance of lower than 0.5 equals +-90 degree FOV, 0.536 the wavelength equals to +- 60 degree FOV and 0.586 equals +-45 degree FOV). One way to widen FOV is to use a mechanical gimbal. If the intend is to integrate the radar to the EW system than it will give rise to another layer of complexity with signal interference issues I believe this was the problem with the APG-79.
5. and 6. Basically to sum up, I believe Butowski's statement that there is "no production series" is meant to be intentional to project a view that the radar development has not reached a stage where it can go into series production. Essentially there is a long pathway in product testing and there may be some installed for further operational evaluation but not necessarily ready for prime time. .

So...basically you’re filling gaps in information with your own select choice of speculations? Granted the technical complexities of AESAs that you mentioned are real, but why is the default assumption that they’re struggling with those technical challenges when they’ve been fielding AESAs in other forms for well past a decade now, and have been fielding production AESAs in two other fighters for the last 3-5 years? Sure, the technology can always be iterated on, but you don’t put out 200+ J-10C and J-16 combined in production if their radars aren’t also in serial production.

...wrt to what the director of the 14th institute might know about the APG-81 and APG-77, you do know what all that espionage on US miltech companies is for right? If they’ve taken so much data on the F-35 and F-22 and don’t have a rough idea of how their systems perform then either Chinese cyberespionage really isn’t that big a deal or they really have no clue what they’re doing. Neither seem to be particularly sensible assumptions. It’s not hard imagining the the APG-77 and APG-81 being roughly comparable. Packing on the APG-81 is probably more efficient, but it’s also using a smaller array than the APG-77. As you say, SW is a critical part of performance for AESAs. A lot of the improvements of the APG-81 from APG-77 that’s software related is also probably backwards compatible.

 

[ougoah]

We should give this philosophical debate a miss. Seriously everyone is beginning to talk from totally different points. You're all right in your own ways but the conversation has long ago become disconnected. It's now in the hear my voice for I am right territory. Enough talk about what is truth what is reliable information, radars and weight? Bottom line is nobody really knows. We can all choose to believe whatever we want whether it is j-20 doesn't have an aesa or j-20 is some engineering miracle and has weight advantage on its equivalent in USAF but still able to carry more etc. All groundless speculation. Believe what you want, reality moves on. In a forum filled with entertaining discussion and speculation, this is some of the worst examples of pointlessness.

 

[siegecrossbow]

Just like to send out a friendly reminder that no matter our differences in opinion, we should be able to discuss civilly, without resorting to borderline personal/national attacks. Thanks.

 

[Hyperwarp]

I'd expect something like this in the future. This should apply to the J-16 as well,

 

[Totoro]

the idea that J-20 may not be using an AESA is hard to entertain.

I personally fully expect J-20 to be using AESA. My writings on sources in this thread have little to do with my personal assessments of the situation.

That said I can appreciate the desire for wanting a couple of sources to make reference to for academic reasons

And that's precisely why I am looking for sources. If one's writing a book, a paper or even a wiki article, having a source still often beats conjecture and guesstimates, however good they may be.