055 DDG Large Destroyer Thread

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Blitzo

Lieutenant General
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This is not correct. The GT25000 is the designation of the Ukrainian GT that the PLAN indigenized into the QC280, and subsequently further developed into the R0110 heavy GT.

That was the understanding in the past, until this came along.

After that, the current body of knowledge is:
UGT25000 is the Ukrainian gas turbine.
GT25000 is the indigenous UGT25000 built by 703 institute of CSIC, and is the gas turbines used widely by PLAN ships
QC280 was the failed attempt by 430 factory of AVIC to manufacture UGT25000
 

by78

General
Update from Feb. 21st, courtesy of ZY3-02 imaging satellite.

49579843621_295c59179b_k.jpg
 

Iron Man

Major
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Except that if the signal has to be traveling further, even a communication signal has to be beam formed to achieve the range. And when you use a phase array for that, if the beam is steered off center it loses gain, and won't have the gain as if the target is on center. You don't seem to understand that both the transmit and receive gain of an antenna depends greatly on the direction it is facing, and that is true even with mechanical antennas. That is why IFF arrays even with mechanical arrays also and always face and are fixed with the direction of the antenna.

This does not look like a small IFF array on the bottom. Even with communication, bigger arrays have better receive gain because a larger area catches more of the radio signals.

So even if I were to use a smaller IFF array, It would still rather go on top of the main radar array rather than an offset position, just like on the 052D. There is nothing stopping for the ship designers from doing so.

And lol, why do even you think the bar is one entire single array by itself, with mostly horizontal resolution and don't give a shite about elevation? What if I tell you the "bar" is a series of independent transponders. Its not a "single" array, but a number of square arrays, each with its own transponder.

IFF with a set of four transponders.

And each square you see is a transponder by itself.

If each transponder happens to be a mini phase array by ttself, it would be equal square with the equal ability to beam form for both the azimuth and the elevation. Each transponder would have its own beam form from one another.

I have already shown to you the larger bar arrays is clearly segmented.

Each segment is an transponder all by itself, and if there is a beam steering antenna in front of the transponder, it would be a square one that can scan both the horizontal and the vertical. Those are pretty large transponders.

I cannot see close enough if the smaller quarter of arrays are also segmented on the back. Two things are possible. First is that if they are radar, they are LPI AESA X-band surface scanning and navigation array that is used by the ship as it goes around. They would be in the right position for it. Second, if they are IFF, they would be the IFF for the X-band arrays on the integrated mast as they are in the proper quadrant for them, and in the right position for it. IFF are either above or below the main radar they serve for.
You keep harping on the off-axis steering as if that actually means anything in this conversation. The main radar array does NOT have to either transmit the interrogation signal NOR listen for the target's IFF transponder ping, so whether or not it is aligned with the IFF array is totally irrelevant. In addition, if this was as big a problem as you claim it is, then all IFF arrays would be circular in shape because even if the bar array was aligned with the main radar array and the main radar array was sending the interrogation signal, it would still occasionally have to send beams off the main axis, sometimes even way off the main axis, which means at the 90 degree corners of the radar/IFF arrays there would be a significant problem with identifying friend vs enemy. Since the PLAN seems to have absolutely no problem with using bar arrays for its IFF system, I can only conclude that your concern is not even remotely shared by the PLAN.

As for your quip about each segment being its own transponder, if your reasoning here is to be at all reasonable, then the ship would really only need a single transponder facing each quadrant, maybe two for redundancy, not the 6 or 7 per quadrant that we actually see. In actuality, each IFF bar array is an AESA or PESA, which means each segment is really functioning more or less like a SPY-6 RMA, all linked together for more transmission power and more resolution, which means with a horizontal arrangement the azimuth resolution is high while the elevation resolution is low. The fact that it is an IFF array doesn't change the fact that it is an AESA/PESA that provides more sensitivity with more modules per face.

As for the other bar array being an IFF, you can't have your cake and eat it too. You made a gargantuan effort to try and distinguish the two types of arrays by shape and attached structures but are now trying to claim they are both IFF arrays! I don't think so. More likely one of the arrays is an IFF array and the other may possibly be a navigation radar, blended into the structure and kept from rotating to reduce RCS.
 

Tam

Brigadier
Registered Member
You keep harping on the off-axis steering as if that actually means anything in this conversation. The main radar array does NOT have to either transmit the interrogation signal NOR listen for the target's IFF transponder ping, so whether or not it is aligned with the IFF array is totally irrelevant. In addition, if this was as big a problem as you claim it is, then all IFF arrays would be circular in shape because even if the bar array was aligned with the main radar array and the main radar array was sending the interrogation signal, it would still occasionally have to send beams off the main axis, sometimes even way off the main axis, which means at the 90 degree corners of the radar/IFF arrays there would be a significant problem with identifying friend vs enemy. Since the PLAN seems to have absolutely no problem with using bar arrays for its IFF system, I can only conclude that your concern is not even remotely shared by the PLAN.

You are still not explaining why you want the IFF arrays to be arranged that they are transmitting and receiving the weakest while beamforming towards targets where the main radar array is at its strongest. This means the IFF cannot match the range of the radar where it is at its strongest --- main lobe directly perpendicular to the array face --- because the lobe from the IFF array is angled and offset from its main direction.

Receive and transmission gain are directly affected with the direction of the antenna. You want to spin that?

As for your quip about each segment being its own transponder, if your reasoning here is to be at all reasonable, then the ship would really only need a single transponder facing each quadrant, maybe two for redundancy, not the 6 or 7 per quadrant that we actually see.

How many targets can a single transponder talk to? How many targets do you intend your transponders intend to talk to? If your radar is capable of tracking an X number of targets, your IFF needs to interrogate as many of them simultaneously.

As for the other bar array being an IFF, you can't have your cake and eat it too. You made a gargantuan effort to try and distinguish the two types of arrays by shape and attached structures but are now trying to claim they are both IFF arrays! I don't think so. More likely one of the arrays is an IFF array and the other may possibly be a navigation radar, blended into the structure and kept from rotating to reduce RCS.

The need is real since targets that are being tracked at the quadrants of the X-band would need IFF interrogation, and this would be an issue if the IFF on top of the S-band are interrogating targets being tracked by the S-band.
 

Iron Man

Major
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You are still not explaining why you want the IFF arrays to be arranged that they are transmitting and receiving the weakest while beamforming towards targets where the main radar array is at its strongest. This means the IFF cannot match the range of the radar where it is at its strongest --- main lobe directly perpendicular to the array face --- because the lobe from the IFF array is angled and offset from its main direction.

Receive and transmission gain are directly affected with the direction of the antenna. You want to spin that?
Unlike some I have no need to spin anything. Again, you fail to understand that the main radar array need have absolutely nothing to do with the IFF 'transaction' at any step, thus no need to be aligned with the IFF array. The IFF array itself can interrogate a target and simultaneously listen for the encoded reply, or lack thereof. In addition, at a perpendicular 90 degree angle WRT the main radar array or even close to it, you could actually have 2 IFF bar arrays that can be used to interrogate a target.

How many targets can a single transponder talk to? How many targets do you intend your transponders intend to talk to? If your radar is capable of tracking an X number of targets, your IFF needs to interrogate as many of them simultaneously.
Apparently this isn't an issue, since IFF transponders like the rotating ones on the 052C are small and puny compared to the larger IFF arrays on the 052D, 055, 016 and 017.

The need is real since targets that are being tracked at the quadrants of the X-band would need IFF interrogation, and this would be an issue if the IFF on top of the S-band are interrogating targets being tracked by the S-band.
The need isn't real because you claim it is so. If they are both IFF arrays why are they so different in both size and shape? As you yourself pointed out the smaller bar array has a middle structure in the back that is not present in the larger bar array.
 

Tam

Brigadier
Registered Member
Unlike some I have no need to spin anything. Again, you fail to understand that the main radar array need have absolutely nothing to do with the IFF 'transaction' at any step, thus no need to be aligned with the IFF array. The IFF array itself can interrogate a target and simultaneously listen for the encoded reply, or lack thereof. In addition, at a perpendicular 90 degree angle WRT the main radar array or even close to it, you could actually have 2 IFF bar arrays that can be used to interrogate a target.

What you don't seem to get is that the main radar array selects the target to be interrogated, so yes, it has an important part in the process at the start. While the target is still being interrogated --- it may not respond at once --- it will still be tracked by the main radar. The main radar has to tell the IFF array here it is and this is where you send the signal to. If the target has not responded at all, the main radar remains tracking the target, continue to try to interrogate the target, and until it responds or not, should it not, time to use ATR or some other forms of non cooperative target recognition and may prioritize it as a threat.

Apparently this isn't an issue, since IFF transponders like the rotating ones on the 052C are small and puny compared to the larger IFF arrays on the 052D, 055, 016 and 017.

What rotating IFF transponders on the 052C?

The need isn't real because you claim it is so. If they are both IFF arrays why are they so different in both size and shape? As you yourself pointed out the smaller bar array has a middle structure in the back that is not present in the larger bar array.

What makes you ever ever think that for an entire service branch you can only have one IFF model.

And of course I'm still think that its also an X-band naval navigation radar, and being straight in front of the ship works for that. Its the other one of my considerations.
 
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antiterror13

Brigadier
That was the understanding in the past, until this came along.

After that, the current body of knowledge is:
UGT25000 is the Ukrainian gas turbine.
GT25000 is the indigenous UGT25000 built by 703 institute of CSIC, and is the gas turbines used widely by PLAN ships
QC280 was the failed attempt by 430 factory of AVIC to manufacture UGT25000

I am confused ... QC280 is widely used by PLAN 052D and 055 and possibly aircraft carrier as well
 
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