PLA AEW&C, SIGINT, EW and MPA thread

[by78]

Looks a little too assymetrical to be an AEWC radome.

Not necessarily... Here is a asymmetrically shaped airborne AESA under development in China. In fact, there is a good chance the array being transported is this one.

 

[Skywatcher]

Not necessarily... Here is a asymmetrically shaped airborne AESA under development in China. In fact, there is a good chance the array being transported is this one.

Interesting. That makes sense if you want to have a more powerful array at one point of view.

 

[Solaris]

Interesting. That makes sense if you want to have a more powerful array at one point of view.

With those kinds of angles I wonder if the flank-facing arrays could scan directly to the rear of the aircraft.

 

[no_name]

Radome for KJ-200

 

[volleyballer]

Radome for KJ-200

You mean KJ-500 right? The 200 has a beam radar I thought ..

 

[Blitzo]

Interesting. That makes sense if you want to have a more powerful array at one point of view.

I suspect the arrays are all the same size and power. It is only the radome design which differs due to aerodynamic reasons.

 

[Solaris]

I suspect the arrays are all the same size and power. It is only the radome design which differs due to aerodynamic reasons.

The flank arrays look noticeably longer. I suspect this was not so much an aerodynamic consideration as a compromise between a "balance beam" type of AESA with superior sideways-looking arrays but non-existent forward/rear coverage, and an equilateral 360 degree radome with more moderate capabilities all-around. This is one of several airborne AESA designs that compromise one thing for another. Another example would be the rotating back-to-back arrays that are also larger than the equilateral fixed arrays but introduce a potential SPOF (single-point-of-failure), namely the rotating mechanism.

 

[Blitzo]

The flank arrays look noticeably longer. I suspect this was not so much an aerodynamic consideration as a compromise between a "balance beam" type of AESA with superior sideways-looking arrays but non-existent forward/rear coverage, and an equilateral 360 degree radome with more moderate capabilities all-around. This is one of several airborne AESA designs that compromise one thing for another. Another example would be the rotating back-to-back arrays that are also larger than the equilateral fixed arrays but introduce a potential SPOF (single-point-of-failure), namely the rotating mechanism.

Well, this array is fixed/three sided, just like KJ-2000. So I don't see how it is a compromise, unless you are suggesting the side/rear arrays of KJ-500 are somehow less powerful than its forward array or something. And on that note, I think the side/rear arrays are wider but shorter than the forward array, and the forward array is in turn taller but narrower than the side/rear arrays. That is to say, I have a suspicion each array may be of equal total area (which should also thus correspond to TR count and thus power)

I think the key point is that they didn't have to go out of their way to develop such a unique radome. They could have simply used the same radome geometry as KJ-2000 but sized down.

 

[Solaris]

Well, this array is fixed/three sided, just like KJ-2000. So I don't see how it is a compromise, unless you are suggesting the side/rear arrays of KJ-500 are somehow less powerful than its forward array or something.

For an AESA, the number of T/R modules determines the potential maximum signal that can be generated from that array toward a single target as well as determining the versatility of the array, i.e. how many modules can be tasked to how many different tasks at a given time from the same array. Therefore, since the flank arrays in the teardrop-shaped radome are larger than they would be in a perfectly circular radome, they offer more power and versatility than those arrays, at a potential loss of rearward coverage, as they would have to be able to scan in a greater than 120 degree arc to directly face the rear. If they cannot, then this may possibly be offset to some degree by embedding the T/R modules in the flank arrays at an angle so that they are already somewhat facing the rear to begin with.

We are talking probably about the difference of only a few dozen T/R modules here, but clearly designers feel this makes a big difference given all the different designs and their various strengths/weaknesses. For example, why have a dual, back-to-back pair of rotating arrays when you can just have a triangular, fixed radome? Simple, dividing a radome in half instead of thirds gives you a greater length and therefore greater cross-sectional surface area to install T/R modules in. The tradeoff is that this rotating mechanism could fail on you. And have you ever seen a rotating radome with 3 equilateral arrays? Of course not.

Taking this idea to the extreme gets you the balance beam array. You can make this array really long if you want, and with it you will get superior sideways looking performance, but you are completely blind in the front and rear unless you install chin and tail radars, which some AEWC aircraft do. And now try imagining a balance beam array installed inside a rotating radome that can enclose it. I'm imagining that such a flying mushroom won't actually be able to fly.

That is why I say that a teardrop-shaped radome is a design that is in between the balance beam and the equilateral fixed radome. You get better sideways coverage but also good forward coverage and some rear coverage, and all this without having to install a potential SPOF with a rotating mechanism.

And on that note, I think the side/rear arrays are wider but shorter than the forward array, and the forward array is in turn taller but narrower than the side/rear arrays. That is to say, I have a suspicion each array may be of equal total area (which should also thus correspond to TR count and thus power)

I don't know how you got all of that from the CG or the photos. Speaking strictly about the CG, which is more clear than the photos, the flank arrays are definitely longer, but to my eyes betray no evidence of being thicker or thinner than the frontal array.

 

[nemo]

I think the key point is that they didn't have to go out of their way to develop such a unique radome. They could have simply used the same radome geometry as KJ-2000 but sized down.

Actually, I am surprised they didn't do it earlier for KJ-2000. Since these radars don't need to spin, there is no reason that the radome has to be round. A more aerodynamic shape will decrease drag and improve flight performance.