F-35 vs J-20

The F-35 compared with other modern jets.
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wrightwing

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Unread post25 Mar 2017, 20:06

The materials used on the F-35 are effective against all radar frequencies, not just X band. Every frequency has greatly reduced (and tactically significant) detection/tracking ranges.
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Unread post25 Mar 2017, 22:24

inst wrote:@GarryA: I miscalculated the 8.6 turn rate, I had used 45 m/s^2 instead of 49 m/s^2, which ironically almost matches the difference between the 5G I used and the 4.6G that is the cited sustained turning rate for the F-35.

No ,it doesn't
4.6G is the threshold for A version but the demonstrated value is already 4.95G for F-35 240-3

inst wrote:On a more interesting note, let's talk radars again, check this out:

viewtopic.php?p=267142#p267142
Here, hornetfinn gives us scaling of APG-81 from 700 to 800 (my measurements suggest it's 750), and it follows the linear diameter rule. Converting it down to 0 dBsm, we get ~275 km detection on 17 kw with a 700 mm diameter.

It's hard to get wattage numbers for AEW&C, so let's look up the S-band AN/SPY-1 first. Ignoring the AN/SPY-1's different reception aperture, we get a detection range of roughly 1185 km vs 0 dBsm, since it has roughly 352 times the power output of the APG-81. Since it's S-band, we see reduced RCS to ~.01, or detection ranges of approximately 375 km vs a -20 dBsm target.

Here, I just found a document with claims of the APS-138's wattage. It's not fully credible, since it's the US DoD republishing a translated Chinese paper, but we'd assume the Chinese, operating AEW&C, would know the rough ballpark powers:

http://oai.dtic.mil/oai/oai?verb=getRec ... =ADA302748

The APS-138 is cited as having 1 MW peak power, with a 370 km detection range vs an A-6 Intruder. Now, assume the F-35's AESA is scaled from 17 kw to 1000 kw. We'd get roughly a 2.77 scale of detection range, ignoring the change in aperture size, so we'd go up to 760 km vs 0 dBsm or 428 km detection range vs -10 dBsm. But the APY-9 is a PESA radar (probably because phase modulators handle higher energies better), so some loss of performance must occur compared to an AESA implementation. At the same time, though, the increased aperture size must compensate to some extent.

1) You can't compare different radar like that (estimate range from peak power) because their duty cycle and beamwidth aren't the same, the cited figure isn't necessary for the same radar mode either (even for the same radar different mode can mean different beamwidth and also different PRF) .
2) You estimation calculation doesn't take into account loss ( reflection doesn't travel a direct path )
3) Those radar you taken as example working at massively different frequency. APS-138 at UHF , SPY-1 at S band , APG-81 at X band. Different frequency mean very different RCS and very different gain value even if radar aperture are of similar size.
4) You can't ignore something as important as aperture size.
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garrya

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Unread post25 Mar 2017, 22:57

inst wrote:if the former doesn't work
Check this out, it states (back in 2007) that the F-22's radar is expected to increase in range from over 100 mi to over 250 mi, on a 925mm radar. This puts Chinese radar claims into perspective; on a 1000mm radar you get a claimed range of 450 km, whereas the F-22 claims a range of more than 400 km

450 km detection range against target with RCS around 10 dBsm will be reduced down do around 44km against targets with RCS around -30 dBsm even without others background interference

inst wrote: If the technology wasn't mature then, it must have been mature for the APG-81, which was reported to have jammed the APG-77.

You don't need a more powerful radar/jammer to jam a certain radar. You only need to achieve a certain noise-signal ratio , which is actually quite easy for stealth fighter thanks to their low radar cross section
Image
Image
http://bit.ly/2nir279
inst wrote:
One other thing; if you're looking at PAC-3 and S-300s failing to track F-35, there's an extremely simple explanation for this. They're both X-band radars, not UHF-band radars.

an/mpq-53 is actually G/H band
US also purchased S-300P from Belarus in 1994 and S300V from Russia in the 90th anniversary
AFAIK ,original S-300P used 5N66 Clam shell and 30N6 FLAP LID radar which work at S band and I/J band respectively
S-300V used 9S15MV or 9S15MT BILL BOARD surveillance radar and 9S19 High Screen radar both are centimetric radar but not sure their exact frequency
Regardless, CNT RAM have very wide bandwidth
inst wrote:
Using the same figures, the J-20 should be able to detect the F-35 at about 25 km with radar, meaning it's still going to be an AEW&C + IR detection fight.

I will for a moment, ignore the fact that you think J-20 radar can have longer detection range than ground SAM radar. 25 km is much smaller than your original figure of over 75 km
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Unread post25 Mar 2017, 23:43

ricnunes wrote:
inst wrote:Considering the F-35 can pinpoint any radar with its ESM equipment and for example a Small Diameter Bomb (SDB) has a range above 110Km (and the F-35 can carry 8 of them internally) then there isn't much that such radars can do against the F-35 or at least they are very, very far from being a "magical solution against stealth".

Image

Image

Just for your info, that is where Pantsir-S1 is meant for: to protect bigger asset anti-air systems versus Tomahawk and SDB like systems.

(not to argue but simply as a system within system information part)
Last edited by botsing on 26 Mar 2017, 02:43, edited 1 time in total.
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Unread post26 Mar 2017, 01:39

@garry: It's 450km claimed vs 0 dBsm and 250 vs -10 dBsm. Going by claims about the F-35's radar, as well as claims about the F-22's radar, it's believable; the Chinese currently claim they're #2 after the US in radar technology, and given their military R&D spending, exhaustive espionage program (while the base design of the J-20 was probably the J-10, it's obvious that they made a lot of what they hacked out of Lockmart's subcontractors), as well as considerable consumer electronics industry, this claim is also plausible, although I suspect the Israelis might have something to say about that. Using hornetfinn's estimates about the APG-81, we'd extrapolate a Su-35-scaled F-35 radar with 0 dBsm detection at 500-562 km, so putting the Chinese knockoff at 80-90% is believable.

Against a -50 dBsm F-35, you'd get 25 km detection, which isn't that good, though.

===

About whether the J-20 can outrange ground radar, there's a rather simple explanation. For instance, we can look at the Smerch-A Pulse Doppler, which had a claimed range of 100 km against some sort of airborne target, but used a 400 kw peak power. The Zaslon PESA on the MiG-31, by comparison, had a claimed range of 200 km and a peak power of only around 10 kw. The point is that significant improvements in radar technology mean that new radar can outperform antiquated radar of much smaller size, and even with spans of only a decade, we see significant improvements in radar technology; for instance, APG-77 is claimed to have about 160 km worth of detection / tracking range, but APG-77v1 is supposed to have 400 km of detection range, a 1.5 fold improvement, simply using newer technology.

As to whether the J-20 can outrange, say, the SPY-6 radar systems on newer Arleigh Burkes, or upgraded PAC-3s (GaN radar is coming to PAC-3 this year), I'd say no; the aperture difference is simply too great. But whether it can outrange a more antiquated legacy system, I'd say yes simply because of how rapidly radar technology has improved.

====

About misusing the APS-138, I've just stated the comparison between the Zaslon and Smerch system, and you're correct. I've tried assiduously to dig out figures on AEW&C performance but I've been completely unable to find figures for modern AESA and PESA AEW&C, instead of obsolete systems like the EC-121, which uses 3 MW of peak power. Likewise, aperture matters, as does band. But I do think I've made my point in other ways; it is plausible that the reported 450 km vs 0 dBsm / 1 m^2 RCS is true, if you go by figures suggesting that comparable US airborne technology can achieve greater ranges. If I've misstated my figures, this is in response to newer information, such as the likely -50 dBsm on the F-35 and F-22.

====

@wrightwing:

The F-35 suffers from resonance effects at low-frequency, however, and for that matter, the JY-26 was reported to have detected F-22s flying in Korean exercises. Likewise, IIRC, RAM varies in type and works best against specific frequencies, covering all frequencies requires multiple layers, increasing operating costs and aircraft weight.

@ricnunes:

Increases in computing power promise to make UHF/VHF more viable as a tracking system, and likewise, any use of counter-stealth radar cannot be solitary, we aren't arming E-2D with AIM-120s, for instance. In the E-2D's case, what's more likely to happen is that once a target is detected, it datalinks the region information off to the F-35s, which can then use their EODAS to search the region for the target, then transfer tracking information off. Then the forward picketing F-35s will knock down the foe, while all the opponent sees is the AEW&C craft in the back. If we look at a Chinese clone of this tactic; they have a Divine Eagle high-altitude drone of appreciable size using bistatic radar, the J-20 has been demonstrated to have the apertures for EODAS, if not necessarily the software, and the J-20 is relatively stealthy. In either case, my guess is that UHF does not wholly defeat stealth, it only reduces detection degradation to roughly 40-60%.
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Unread post26 Mar 2017, 02:21

Inst, you're taking things too much as binary. "If J-20 can't maneuver..." No one is saying J-20 can't maneuver. I'm sure it can turn right if it wants to turn right.

If we look at a Chinese clone of this tactic; they have a Divine Eagle high-altitude drone of appreciable size using bistatic radar


Where are you getting all this stuff from? Pop-science articles and youtube videos? Bistatic radar? That's not a bistatic radar, if carrying a radar is its intended purpose. And a prototype of "something" is now "the Chinese have it". Have what? Perhaps it is intended for ground surveillance with a SAR radar like Global Hawk.

A LOT of made-up info on the internet, and often poorly made up.

Try taking the BS you read on Wikipedia with a mine-full of salt.
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Unread post26 Mar 2017, 02:43

inst wrote:@garry: It's 450km claimed vs 0 dBsm and 250 vs -10 dBsm. Going by claims about the F-35's radar, as well as claims about the F-22's radar

I never heard such official claim about F-22 and F-35 radar.
As far as i know 450 km is against target with RCS around 10 m2
inst wrote:About whether the J-20 can outrange ground radar, there's a rather simple explanation. For instance, we can look at the Smerch-A Pulse Doppler, which had a claimed range of 100 km against some sort of airborne target, but used a 400 kw peak power. The Zaslon PESA on the MiG-31, by comparison, had a claimed range of 200 km and a peak power of only around 10 kw.

AFAIK, Peak power of Smerch-a RP-25 is 600 watt , not kw
Image
https://books.google.co.uk/books?id=BNl ... &q&f=false
Anyway, citing peak power without knowing duty cycle is very misleading. 2 radar, one with peak power of 10 kW and 1 % duty cycle the other with peak power of 1 kW and 10% duty cycle will have similar detection range ( assuming range ambiguity isn't an issue)

inst wrote:for instance, APG-77 is claimed to have about 160 km worth of detection / tracking range, but APG-77v1 is supposed to have 400 km of detection range, a 1.5 fold improvement, simply using newer technology.

Can you tell me where you get that information from?

inst wrote:The F-35 suffers from resonance effects at low-frequency

The smooth curve on F-35 actually reduce surface scattering significantly compared to full facet design such as one of F-117 ( i gave links in previous post already )
inst wrote:the JY-26 was reported to have detected F-22s flying in Korean exercises.

The question is at what aspect ? and did F-22 carry Lundberg lens? such as those in photo below
F-22:
Image
F-35 :
Image

inst wrote:Likewise, IIRC, RAM varies in type and works best against specific frequencies, covering all frequencies requires multiple layers, increasing operating costs and aircraft weight

It depend on the kind of RAM and LM patent suggest that their RAM has very wide bandwidth between 0.1 Mhz up to 60 Ghz while still thin and light enough to be put on fighter aircraft
https://www.scribd.com/document/3420932 ... l-material

P/s: bravo for remain calm, that a good trail
Last edited by garrya on 26 Mar 2017, 02:48, edited 1 time in total.
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Unread post26 Mar 2017, 02:47

botsing wrote:Just for your info, that is where Pantsir-S1 is meant for: to protect bigger asset anti-air systems versus Tomahawk and SDB systems.


Yes and no. Systems like Pantsir and Tor and Tunguska etc were designed for a 1980s-1990s war to protect high value targets against things like cruise missiles and LGBs. A time when such attacks would have been carried out by a limited number of munitions because it was not possible to have massed simultaneous attacks. And being less numerous, the number of high-value targets needing protection was also limited.

Ie in a world like Desert Storm where 10-20% of the minitions would be guided weapons. Not for a world where 90-100% of munitions would be so, and where a single plane can launch a dozen or more SDBs against a target. In such a world, the defender would need masses of Pantsirs to defend a single target, because the systems are limited both in sector coverage and the number of simultaneously engaged targets, which means individual units can be easily overwhelmed. But then it becomes cost prohibitive to have so many defensive systems defending high-value targets, when the other side can produce tens of thousands of JDAMs per year as if they were potatoes.

So in a sense SDBs, and other systems which rely on stealth rather than numbers, were the response to defensive systems like Pantsir or Tor, rather than the other way around. To defend against SDBs etc., one would need 360 deg coverage with fire and forget missiles, and dozens if not hundreds of them ready to fire.

That's how we get Syria where even though the Syrians now have modern AD systems like Buk and Pantrsir protecting high value targets around Damascus, the Israelis can attack with impunity.
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Unread post26 Mar 2017, 02:52

Totally agree arian, I just wanted to point out that layer of defense and where it was meant for.
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Unread post26 Mar 2017, 03:05

arian wrote:Inst, you're taking things too much as binary. "If J-20 can't maneuver..." No one is saying J-20 can't maneuver. I'm sure it can turn right if it wants to turn right.

If we look at a Chinese clone of this tactic; they have a Divine Eagle high-altitude drone of appreciable size using bistatic radar


Where are you getting all this stuff from? Pop-science articles and youtube videos? Bistatic radar? That's not a bistatic radar, if carrying a radar is its intended purpose. And a prototype of "something" is now "the Chinese have it". Have what? Perhaps it is intended for ground surveillance with a SAR radar like Global Hawk.

A LOT of made-up info on the internet, and often poorly made up.

Try taking the BS you read on Wikipedia with a mine-full of salt.


arian: There's also the KJ-2000, KJ-500, and KJ-3000. The KJ-2000 and KJ-500 are L-band, while the band of the KJ-3000 is unknown. There was a recent export of ZDK-03 AEW&C to Pakistan, although I'm doubtful of its capability.

You are also right that I'm mischaracterizing the argument as one of the J-20's maneuverability, when it's actually about whether the F-35 is more maneuverable than the J-20. On this subject, the evidence we've been shown suggests that the J-20 has demonstrated ITR of at least 22.5 degrees, and that the F-35 has ITR of at least 30 degrees under certain regimes and that the F-35 has STR of roughly 10.8 degrees at 15,000 feet and at Mach 0.8 with 60% fuel loading.
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Unread post26 Mar 2017, 03:35

inst, do not try to confuse indicated air speed with true air speed. If you cannot out-smart us, do not try to fool us:
viewtopic.php?f=55&t=52918&start=15
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Unread post26 Mar 2017, 05:17

inst wrote:arian: There's also the KJ-2000, KJ-500, and KJ-3000. The KJ-2000 and KJ-500 are L-band, while the band of the KJ-3000 is unknown. There was a recent export of ZDK-03 AEW&C to Pakistan, although I'm doubtful of its capability.


Yes China is developing AWACS planes. No surprise there. And it doesn't mean anything inherently about "anti-stealth" capabilities or much at all in fact. The US and its allies in Asia also have about 130 AWACS planes combined in operation.

China still faces about a 10:1 numerical inferiority towards its adversaries in Asia, whether it be in terms of aircraft, or ships or other assets. And enemies which currently have a large technological and capability gap with China.

But lets not get carried away with imaginary "bystatic radar UAVs" that don't actually exist, or other such internet rumors.
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Unread post26 Mar 2017, 15:26

Anyway, J-20 has no DAS that covers the rear hemisphere. That is a decisive disanvantage
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Unread post26 Mar 2017, 15:45

inst wrote:@garry: It's 450km claimed vs 0 dBsm and 250 vs -10 dBsm. Going by claims about the F-35's radar, as well as claims about the F-22's radar, it's believable; the Chinese currently claim they're #2 after the US in radar technology,


I could also claim that I'm Santa Claus or Donald Duck or even Donald Trump :roll:
That's does mean this is true. Actually such claim would only mean that I'm a liar!

China still lags behind in terms of avionics and engines (two of the most important components for fighter aircraft) not only to the USA but also it lags behind Western Europe countries (such as UK and France) and it even lags behind Russia and then there's also Israel. So no, China is not #2 and it's not even #3 or #4. Perhaps a #5 and this if we consider "Western Europe" as a whole.

And just because China build the vast majority of the world's electronics doesn't mean that they can assembly these components and make systems like we have in the F-35.
First, many of those electronics "blueprints" come from western countries and/or western companies. They are mainly built in China because of one sole reason: They are cheaper to manufacture in China, period!
Secondly it order to build effective and integrated systems like you have in the F-35 you need to develop an effective but overly complex SOFTWARE. Speaking of which of many world renown software do we have which is developed in China??
You simply can't ignore software - For example it's the software which allows F-35's DAS to be used in several and simultaneous different tasks such as Pilot's 360º vision, Missile Warning System, IRST, etc...
And if you think that developing Software is "easier" than Hardware than you don't have a clue!
And the reason for this is that in order to develop a combo of advanced Software coupled with advanced hardware you need a vast "KNOW HOW" which is still lacking in China. Countries like China which trends to supress "free thinking" tends to lack in terms of "Know how".
Note that I'm not saying that there isn't any "Know how" in China, of course there is. However the "Know how" to create completely new stuff in China is at best "limited".
And just because you can build some parts of the F-35 (due to espionage or any other means) doesn't mean you can build the other parts "missing" and much less how to "glue them" together as an single effective system.


inst wrote:@ricnunes:

Increases in computing power promise to make UHF/VHF more viable as a tracking system, and likewise, any use of counter-stealth radar cannot be solitary, we aren't arming E-2D with AIM-120s, for instance. In the E-2D's case, what's more likely to happen is that once a target is detected, it datalinks the region information off to the F-35s, which can then use their EODAS to search the region for the target, then transfer tracking information off. Then the forward picketing F-35s will knock down the foe, while all the opponent sees is the AEW&C craft in the back. If we look at a Chinese clone of this tactic; they have a Divine Eagle high-altitude drone of appreciable size using bistatic radar, the J-20 has been demonstrated to have the apertures for EODAS, if not necessarily the software, and the J-20 is relatively stealthy. In either case, my guess is that UHF does not wholly defeat stealth, it only reduces detection degradation to roughly 40-60%.


The world's most advanced "Increases in computing power promise to make UHF/VHF more viable as a tracking system" culminated in the Nebo-M AESA VHF system which as you can see from my last post it's far from being an effective counter-F-35 system. Note again, that this is an AESA (VHF) radar and it's likely the best we have around the world in terms of ground based detection against the F-35.
Moreover, for you as well as for many other "F-35 critics" which I've been having discussion with over the web it seems that radar (and other) technologies which promise to be good "anti-Stealth" measures will evolve (to the point of rendering stealth "useless") but at the same time people like yourself trend to think that for some odd reason that "Stealth technology" will stay "static" forever and thus that it won't ever evolve/improve.

Besides you can only reach to a certain point with UHF/VHF radar or with any other radar technology - Remember that you cannot break the "laws of physics"!

I also find somehow amusing your following comment:
" any use of counter-stealth radar cannot be solitary"

Guess what?? Neither is the use of the F-35 (or any other Western Stealth combat aircraft)!
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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Unread post26 Mar 2017, 15:53

arian wrote:
botsing wrote:Just for your info, that is where Pantsir-S1 is meant for: to protect bigger asset anti-air systems versus Tomahawk and SDB systems.


Yes and no. Systems like Pantsir and Tor and Tunguska etc were designed for a 1980s-1990s war to protect high value targets against things like cruise missiles and LGBs. A time when such attacks would have been carried out by a limited number of munitions because it was not possible to have massed simultaneous attacks. And being less numerous, the number of high-value targets needing protection was also limited.

Ie in a world like Desert Storm where 10-20% of the minitions would be guided weapons. Not for a world where 90-100% of munitions would be so, and where a single plane can launch a dozen or more SDBs against a target. In such a world, the defender would need masses of Pantsirs to defend a single target, because the systems are limited both in sector coverage and the number of simultaneously engaged targets, which means individual units can be easily overwhelmed. But then it becomes cost prohibitive to have so many defensive systems defending high-value targets, when the other side can produce tens of thousands of JDAMs per year as if they were potatoes.

So in a sense SDBs, and other systems which rely on stealth rather than numbers, were the response to defensive systems like Pantsir or Tor, rather than the other way around. To defend against SDBs etc., one would need 360 deg coverage with fire and forget missiles, and dozens if not hundreds of them ready to fire.

That's how we get Syria where even though the Syrians now have modern AD systems like Buk and Pantrsir protecting high value targets around Damascus, the Israelis can attack with impunity.


Exactly Arian!

Actually with my example I took into consideration that the SDB is actually a stealth bomb which makes it much, much harder to be intercepted any Air Defence Systems such as the mentioned Pantsir or Tor.

Moreover, remember that each F-35 (namely the F-35A and F-35C) can carry eight (8) of them internally so you would not only have the stealth advantage but with this same weapon (SDB) you have the numbers - Even if systems like the Pantsir or Tor protecting a target like the Nebo-M could effectively intercept a SDB (which I have my doubts due to the SDB's Stealth) you could "saturate" the target with lots of SDBs.
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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