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    Chengdu J-20 Stealth Fighter

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    miketheterrible

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    Re: Chengdu J-20 Stealth Fighter

    Post  miketheterrible on Sat Sep 30, 2017 10:17 pm

    Let me remind some members here, this isn't the first time that it was claimed that J-20 has been entered service.
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    KiloGolf

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    Re: Chengdu J-20 Stealth Fighter

    Post  KiloGolf on Sat Sep 30, 2017 10:31 pm

    miketheterrible wrote:We know for a fact China faces critical issues building jet engines.  Who knows about the rest?

    The MiG-15 had essentially a British engine. The Brits in the 40s (much like Russians in the 90s) gave away their tech. Sold it off cause they were broke.

    That very plane, using a British engine (few exported under licence, the rest were reverse engineered and modified) kicked major arse in the Korean war. The same war the Australians deployed... Meteors (RAF had nothing better operational, Hunter came online 1954).

    And it didn't stop the Soviets from progressing through the 50s till now.
    China is where USSR was in the 50s in terms of learning curve. They can build the planes and (for now) they used foreign engine designs. In a decade from now they will be far ahead with their own engines (as the USSR was in the 60s vs. Britain).
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    OminousSpudd

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    Re: Chengdu J-20 Stealth Fighter

    Post  OminousSpudd on Sun Oct 01, 2017 12:45 am

    KiloGolf wrote:
    This is what being surpassed looks like (watching you Russia/UAC).
    Sure. That's why they're buying Russian Su-35s, as well as anything else they can get their hands on.
    When China acquires a fully functioning IADS comparable to Russia in quality and quantity, then we can talk about "surpassing". Not to mention the fact we know nothing about the J-20, and what its capabilities actually are, whereas with the Su-57 we have a general idea of its level of sophistication, which is nothing short of outstanding.
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    Vladimir79

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    Re: Chengdu J-20 Stealth Fighter

    Post  Vladimir79 on Sun Oct 01, 2017 3:17 pm

    Hannibal Barca wrote:What Chinese did is staggering. They developed a 5th gen plane in 5 years.

    What exactly did they develop?  The engines are Russian and not even latest ones at that.  The airframe isn't LO except from the front,



    The radars are still PESA...



    The maneuverability is poor making it best suited as a strike aircraft that better hope it doesn't get shot down when it reveals its massive RCS from its ass.


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    miketheterrible

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    Re: Chengdu J-20 Stealth Fighter

    Post  miketheterrible on Sun Oct 01, 2017 4:02 pm

    I'm going to have to defend the J-20 on some accounts though. Just because it is PESA, doesn't make it not advanced. PESA radar is rather easier to provide massive power output compared to AESA giving PESA the chance to be able to have scan/tracking ranges greater than most AESA. Add to that, AESA has a rather poor performance at max output and in terms of its operational function. What I mean is that it has a failure rate of about 10% or greater when in use, and they normally operate at only 5W on normal per module. Get them to run at full 10 - 15W, they may have higher failure rate.

    I know Russians are working around the clock to make their aesa modules more efficient and less heat output, but even then who knows success.
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    kvs

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    Re: Chengdu J-20 Stealth Fighter

    Post  kvs on Sun Oct 01, 2017 5:20 pm

    miketheterrible wrote:I'm going to have to defend the J-20 on some accounts though. Just because it is PESA, doesn't make it not advanced. PESA radar is rather easier to provide massive power output compared to AESA giving PESA the chance to be able to have scan/tracking ranges greater than most AESA. Add to that, AESA has a rather poor performance at max output and in terms of its operational function. What I mean is that it has a failure rate of about 10% or greater when in use, and they normally operate at only 5W on normal per module. Get them to run at full 10 - 15W, they may have higher failure rate.

    I know Russians are working around the clock to make their aesa modules more efficient and less heat output, but even then who knows success.

    They already have the gallium nitride components. It is not hypothetical, it is real. GaN parts can sustain extreme power loads and by extension
    offer unprecedented sensitivity levels to AESA systems of a given size. There was extensive discussion of Russian GaN parts on the Key Publishing
    forum. Russian companies are even advertising GaN parts. Of course, the full specs of latest gen Russian AESA are not going to be spread
    around for obvious reasons.
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    miketheterrible

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    Re: Chengdu J-20 Stealth Fighter

    Post  miketheterrible on Sun Oct 01, 2017 6:21 pm

    Im aware they are looking at GaN but it was mentioned Russia lacks production of needed material to produce GaN modules. I know Mikran and istok are working towards GaN but seems right now they are focusing in greatly reducing size and heat build up of GaAS while increasing output. In doing so, they could find alternatives. I have no idea of course where they are at in GaN development. No one is.
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    GarryB

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    Re: Chengdu J-20 Stealth Fighter

    Post  GarryB on Mon Oct 02, 2017 4:47 am

    The MiG-15 had essentially a British engine. The Brits in the 40s (much like Russians in the 90s) gave away their tech. Sold it off cause they were broke.

    The British and the Germans also gave their jet engine tech to the Americans too... At least the Soviets paid the British for their Jet engine tech.

    That very plane, using a British engine (few exported under licence, the rest were reverse engineered and modified) kicked major arse in the Korean war. The same war the Australians deployed... Meteors (RAF had nothing better operational, Hunter came online 1954).

    The Soviets had their own expertise in jet engines.... the knowledge gained from the British Derwent and Nene engines was used to further improve both types.

    The Russian engines sold to China were copied and not improved. New engines are still sold to China because they still can't make engines better so it is hardly the same thing as you are trying to imply.

    China is where USSR was in the 50s in terms of learning curve.

    Not really. The Soviets had plenty of knowledge regarding metalurgy and engines... access to British designs of radial and axial flow engines is what was needed for them to move ahead in a significant way.

    This is what being surpassed looks like (watching you Russia/UAC).

    Hahahahaha... to be honest... it looks to me to be more of a SAAB Draken with canards.

    It is no fighter with that sort of control surface layout I would expect its manouver capability to be pretty ordinary without TVC engines.

    This looks like a strike bomber type rather than a 5th gen fighter.

    If anything it is probably an interceptor or strike aircraft.


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    Vladimir79

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    Re: Chengdu J-20 Stealth Fighter

    Post  Vladimir79 on Mon Oct 02, 2017 2:16 pm

    miketheterrible wrote:I'm going to have to defend the J-20 on some accounts though. Just because it is PESA, doesn't make it not advanced. PESA radar is rather easier to provide massive power output compared to AESA giving PESA the chance to be able to have scan/tracking ranges greater than most AESA. Add to that, AESA has a rather poor performance at max output and in terms of its operational function. What I mean is that it has a failure rate of about 10% or greater when in use, and they normally operate at only 5W on normal per module. Get them to run at full 10 - 15W, they may have higher failure rate.

    The reason AESA is better for LO aircraft is its ability to avoid detection even at max output. A PESA is like a huge flashlight advertising to everyone where you are.


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    medo

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    Re: Chengdu J-20 Stealth Fighter

    Post  medo on Mon Oct 02, 2017 11:31 pm

    Vladimir79 wrote:
    miketheterrible wrote:I'm going to have to defend the J-20 on some accounts though. Just because it is PESA, doesn't make it not advanced. PESA radar is rather easier to provide massive power output compared to AESA giving PESA the chance to be able to have scan/tracking ranges greater than most AESA. Add to that, AESA has a rather poor performance at max output and in terms of its operational function. What I mean is that it has a failure rate of about 10% or greater when in use, and they normally operate at only 5W on normal per module. Get them to run at full 10 - 15W, they may have higher failure rate.

    The reason AESA is better for LO aircraft is its ability to avoid detection even at max output.  A PESA is like a huge flashlight advertising to everyone where you are.

    Not really. PESA have one transmitter, but it doesn't sent full signal outside itself like in old mechanical radars. Signal went through many T/R modules, which send this signal out in many low power signals in different locations covering large space at the same time similarly as AESA. To detect target at max range both PESA ans AESA have to concentrate max power output in one spot that te returning signal will be strong enough to be tedected.
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    miketheterrible

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    Re: Chengdu J-20 Stealth Fighter

    Post  miketheterrible on Tue Oct 03, 2017 4:52 am

    Vladimir79 wrote:
    miketheterrible wrote:I'm going to have to defend the J-20 on some accounts though. Just because it is PESA, doesn't make it not advanced. PESA radar is rather easier to provide massive power output compared to AESA giving PESA the chance to be able to have scan/tracking ranges greater than most AESA. Add to that, AESA has a rather poor performance at max output and in terms of its operational function. What I mean is that it has a failure rate of about 10% or greater when in use, and they normally operate at only 5W on normal per module. Get them to run at full 10 - 15W, they may have higher failure rate.

    The reason AESA is better for LO aircraft is its ability to avoid detection even at max output.  A PESA is like a huge flashlight advertising to everyone where you are.

    AESA, like everything else in the radar category lets off radiation.  Even simple radiation detectors would be able to pick up the AESA elements no less than that of PESA.  At max output it lights up like a christmas tree too.  Especially when you have all those individual modules lighting up.

    Modern sensors from a jet like Su-35 or F-35 will pick up PESA or AESA radiation at massive ranges.  Probably sooner than the radar would pick up the jet.

    When we replaced our radar up north with AESA rather than PESA, you still couldn't stand in front of it, it would kill you. The radar was still pumping the same amount of wattage as the PESA. Different was, the resolution was greater than that of PESA so we had a clearer image. Even then, we found greater faults with the AESA elements was they didn't all work as intended and had to be constantly replaced, compared to the PESA. On top of that, they couldn't work at maximum use continuously compared to the PESA so even though it was rated in the high MW, it wouldn't operate at its intended use. So there were general complaints. When the AESA worked, it worked well. But the F-16's that flew were able to pick up the radiation no problem on both.
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    Vladimir79

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    Re: Chengdu J-20 Stealth Fighter

    Post  Vladimir79 on Tue Oct 03, 2017 2:30 pm

    medo wrote:

    Not really. PESA have one transmitter, but it doesn't sent full signal outside itself like in old mechanical radars. Signal went through many T/R modules, which send this signal out in many low power signals in different locations covering large space at the same time similarly as AESA. To detect target at max range both PESA ans AESA have to concentrate max power output in one spot that te returning signal will be strong enough to be tedected.

    Like you said, PESA only has one transmitter so it doesn't have many T/R modules. The T stands for transmit and it only has one transmitter. The only thing that can be changed is the oscillation and power of the frequency. It can be hard to jam using frequency hopping but it is still easy to detect where it is coming from. As we well know AESA has a thousand+ beams scanning the sky at much lower power outputs per transmit module, virtually undetectable at range.


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    Vladimir79

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    Re: Chengdu J-20 Stealth Fighter

    Post  Vladimir79 on Tue Oct 03, 2017 2:36 pm

    miketheterrible wrote:

    AESA, like everything else in the radar category lets off radiation.  Even simple radiation detectors would be able to pick up the AESA elements no less than that of PESA.  At max output it lights up like a christmas tree too.  Especially when you have all those individual modules lighting up.

    Modern sensors from a jet like Su-35 or F-35 will pick up PESA or AESA radiation at massive ranges.  Probably sooner than the radar would pick up the jet.

    When we replaced our radar up north with AESA rather than PESA, you still couldn't stand in front of it, it would kill you.  The radar was still pumping the same amount of wattage as the PESA.  Different was, the resolution was greater than that of PESA so we had a clearer image.  Even then, we found greater faults with the AESA elements was they didn't all work as intended and had to be constantly replaced, compared to the PESA.  On top of that, they couldn't work at maximum use continuously compared to the PESA so even though it was rated in the high MW, it wouldn't operate at its intended use.  So there were general complaints.  When the AESA worked, it worked well.  But the F-16's that flew were able to pick up the radiation no problem on both.

    It does let off radiation, but it is divided by a thousand times as the modules don't beam at the same point, they are "actively scanning." At range this is unlikely to be detect and impossible to pin-point. This is why it is the perfect radar for LO aircraft that don't want to be detected. For aircraft with large RCS, PESA makes more sense as it is cheaper and more reliable.


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    medo

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    Re: Chengdu J-20 Stealth Fighter

    Post  medo on Tue Oct 03, 2017 11:38 pm

    Vladimir79 wrote:
    medo wrote:

    Not really. PESA have one transmitter, but it doesn't sent full signal outside itself like in old mechanical radars. Signal went through many T/R modules, which send this signal out in many low power signals in different locations covering large space at the same time similarly as AESA. To detect target at max range both PESA ans AESA have to concentrate max power output in one spot that te returning signal will be strong enough to be tedected.

    Like you said, PESA only has one transmitter so it doesn't have many T/R modules.  The T stands for transmit and it only has one transmitter.  The only thing that can be changed is the oscillation and power of the frequency.  It can be hard to jam using frequency hopping but it is still easy to detect where it is coming from.  As we well know AESA has a thousand+ beams scanning the sky at much lower power outputs per transmit module, virtually undetectable at range.  

    True, PESA have only one or in Irbis radar two transmitters, but modules in PESA are not just receivers, although they are not real transmitters as well. Point is, that in PESA radar output signal doesn't go dirrectly from transmitter in the space, like with mechanical radars, but through modules, which than send thousand+ lower power beams in the scanning space. This is why PESA radar could scan with fixed antenna in sector +/- 70° in azimut at the same time and in different modes, the same as AESA, while mechanical radar have to move antenna as transmitter send only one beam and could work in one mode at one moment. This is also the reason, why PESA radar doesn't have side lobes as mechanical radars have. This is why older RWRs could not detect PESA radar.

    But for all radars is true, that output signal have to be strong enough, to travel to target and than travel back and be still strong enough, that receiver detect it. This mean the signal, which come to target is the same strong from PESA or AESA radar, because returning signal have to be the same strong, that receivers in PESA or AESA radar could detect it. There is no difference in detecting PESA or AESA radar.
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    Vladimir79

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    Re: Chengdu J-20 Stealth Fighter

    Post  Vladimir79 on Wed Oct 04, 2017 12:16 am

    medo wrote:

    True, PESA have only one or in Irbis radar two transmitters, but modules in PESA are not just receivers, although they are not real transmitters as well. Point is, that in PESA radar output signal doesn't go dirrectly from transmitter in the space, like with mechanical radars, but through modules, which than send thousand+ lower power beams in the scanning space. This is why PESA radar could scan with fixed antenna in sector +/- 70° in azimut at the same time  and in different modes, the same as AESA, while mechanical radar have to move antenna as transmitter send only one beam and could work in one mode at one moment. This is also the reason, why PESA radar doesn't have side lobes as mechanical radars have. This is why older RWRs could not detect PESA radar.

    But for all radars is true, that output signal have to be strong enough, to travel to target and than travel back and be still strong enough, that receiver detect it. This mean the signal, which come to target is the same strong from PESA or AESA radar, because returning signal have to be the same strong, that receivers in PESA or AESA radar could detect it. There is no difference in detecting PESA or AESA radar.

    True, there is no difference in detecting with PESA or AESA radar. Everything behind the transmitter is roughly the same. The difference is in the way it transmits. PESA does not have 1000+ transmit modules with phase shifters, if it did, it would be an AESA. It only had one, now two phase elements. Old RWRs could not detect newer PESAs because they did not have digital mapping for frequency hopping. Side lobes have to do with how much interference the transmitting radar will receive, not what the target it is scanning can detect. Mechanically steering an array increases its azimuth and the same holds true no matter what the type. The downside is you have moving parts which can fail, increased weight for the mechanism and you need longer nose cones to give it space to rotate.


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    miketheterrible

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    Re: Chengdu J-20 Stealth Fighter

    Post  miketheterrible on Wed Oct 04, 2017 1:04 am

    Do you guys have more details of the said radar for J-20? Name of it, power usage, etc?

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