F-35 vs J-20

The F-35 compared with other modern jets.
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gta4

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Unread post23 Mar 2017, 02:13

inst wrote:The pilot referring to 28 degree pedal turn isn't talking about a banking, sustained turn. A pedal turn is nose pointing-yaw rate at slow speeds.
The F-35 control laws limit roll and yaw to 25 degrees/second aproaching +/- g limits."


First, your link shows no proof that 25deg/sec is the upper limit.

Secondly, even though the 28deg/sec is not a conventional banked turn, when F-35 excecutes this turn, how could a fighter counter this maneuver if it is not capable of the "pedal turn"? The only way it could counter this maneuver is to perform a 28deg/sec sustained banked turn, which is not likely to happen.

So the question is, could J-20 perform pedal turn? Unlikely. The PLA fanbase would have boasted it if otherwise.
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eloise

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Unread post23 Mar 2017, 02:17

inst wrote:About combat ranges, the J-20 is reported to have 1500-2000 km internal fuel range. The F-35 is reported to have around 1250 km internal fuel range. That's a substantial range advantage.

F-35 in air to air configuration is credited to have 760 nm combat radius, which translate to at least 2815 km in range.
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garrya

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Unread post23 Mar 2017, 02:37

inst wrote:On the other hand, you ask me to specify radar aperture advantage. That's to say, since the J-20 is larger than the F-35, and you can measure it, it has a larger space for its radar antenna. From observations and measurements, the J-20 has a 1000 m^2 (same as Su-35) to 1100 m^2 radar aperture. Considering similar levels of radar stealth, as well as reported Chinese radar detection ranges vs 0 dBsm, the J-20 can radar-detect the F-35 between 42-75 km, allowing it to cue its EODAS.

I don't know where you get your figure but I am sure it is utter nonsense.
Current F-35 is even stealthier than F-22 and it is so stealthy that it actually caused trouble for Red/Green flag exercise since PAC-2/3 and S-300 radar ( yes US do own a S-300 battery, look it up ) can't even detect it
During a recent exercise at Mountain Home Air Force Base, Idaho, F-35 squadrons wanted to practice evading surface-to-air threats. There was just one problem: No one on the ground could track the plane.

“If they never saw us, they couldn’t target us,” said Lt. Col. George Watkins, the commander of the 34th Fighter Squadron at Hill Air Force Base, Utah.

The F-35s resorted to flipping on their transponders, used for FAA identification, so that simulated anti-air weapons could track the planes, Watkins said.

“We basically told them where we were at and said, ‘Hey, try to shoot at us,’ ” he said, adding that without the transponders on, “most likely we would not have suffered a single loss from any SAM threats while we were training at Mountain Home

https://www.airforcetimes.com/story/mil ... /87760454/

Even Eurofighter head of future requirement admitted that AWACs need to be stationed at specific direction to negate F-35 VLO advantage
According to Laurie Hilditch, Eurofighter's head of the future requirements capture, the F-35's frontal-aspect stealth can be defeated by stationing interceptors and AWACS at a 25º to 30º angle to the F-35's most likely approach path to a target.

https://www.flightglobal.com/news/artic ... 35-345265/

and you are telling me the tiny fighter radar (even Mig-31 radar is tiny in comparison to AWACS or S-300, PAC-2 radar) can somehow detect F-35 from 42-75 km ? Nope. Not gonna happen.
I also would like to see the " measurement" that you used to come to your conclusion
Last edited by garrya on 23 Mar 2017, 02:51, edited 1 time in total.
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gta4

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Unread post23 Mar 2017, 02:49

To inst:

You are using a speed-up version of the J-20 video. Check the original one:

https://www.youtube.com/watch?v=6bzCob_7oJw

Why are you cheating? You sped it up by almost 200%!
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gta4

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Unread post23 Mar 2017, 02:54

eloise wrote:
inst wrote:About combat ranges, the J-20 is reported to have 1500-2000 km internal fuel range. The F-35 is reported to have around 1250 km internal fuel range. That's a substantial range advantage.

F-35 in air to air configuration is credited to have 760 nm combat radius, which translate to at least 2815 km in range.
Image


Please note: range > radius*2 (not equal!) Normally, range is atleast 3 times as big as radius, because you need to remain on station and perform some maneuvers at A/B.

F-35 used to cover 1400km and consumed only 5000lbs of fuel.
https://www.aopa.org/news-and-media/all ... ight-stuff
Last edited by gta4 on 23 Mar 2017, 03:02, edited 1 time in total.
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eloise

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Unread post23 Mar 2017, 02:59

gta4 wrote:
Please note: range > radius*2 (not equal!)

I know, that why i used at least
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gta4

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Unread post23 Mar 2017, 03:01

eloise wrote:
gta4 wrote:
Please note: range > radius*2 (not equal!)

I know, that why i used at least


True, but I am sure someone as ignorant as inst will forget this detail :mrgreen:
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inst

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Unread post23 Mar 2017, 03:10

gta4 wrote:To inst:

You are using a speed-up version of the J-20 video. Check the original one:

https://www.youtube.com/watch?v=6bzCob_7oJw

Why are you cheating? You sped it up by almost 200%!



Your video is dated October 1st, my video is dated September 30th, and I'm not aware that the former video was sped up.

===

@garrya: Both PAC-3 and S-300 are on PESA. They're also ground-based radars, which seem to have an intrinsic disadvantage over air-based radars; see, for instance, the E-2D's PESA APY-9 can detect targets at over 550 km. PAC-3 is getting a GaN AESA upgrade this year, by the way.

Another factor is scaling; it takes about a 4x increase in radar power to create a 2x increase in range. AESA has less of a scaling issue compared to PESA; AESA increases in both transmit power and receive power with size.
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gta4

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Unread post23 Mar 2017, 03:11

inst wrote:@gta4: check out 0:09 on that video, then, it's roughly 90 degrees in 3 seconds.


since your video is sped up, all your claims about the turn rate of J-20 backfired.

In the non-sped up video, the J-20 spent 7 sec to turn a little more than 90 deg.
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inst

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Unread post23 Mar 2017, 03:15

gta4 wrote:
eloise wrote:
gta4 wrote:
Please note: range > radius*2 (not equal!)

I know, that why i used at least


True, but I am sure someone as ignorant as inst will forget this detail :mrgreen:


Actually, the figure I gave you was combat radius, not range. I guess the overall impression you're giving me is not that the F-35 is qualitatively superior (even though it's stealthy, has good avionics, and good subsystems), but that the F-35 community is somewhat insecure; the F-35 project has gotten a terrible rap in the media, and from objective results it's one of those Churchill things; you know, "The Americans always make the right choice, but not before exhausting all other alternatives". The F-22 community, on the other hand, was more given to take this in stride, given its comprehensive superiority in everything but IR sensors. Anyways, I'm out for tonight.
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gta4

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Unread post23 Mar 2017, 03:26

Another reason why we need to double check the source before citing it:

inst claims that F-35's yaw rate is limited to 25deg/sec, but in fact it is way beyoud 90deg/sec and it is still under control:

https://www.youtube.com/watch?v=5hERYdmjZWA
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garrya

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Unread post23 Mar 2017, 03:27

inst wrote:@garrya: Both PAC-3 and S-300 are on PESA. They're also ground-based radars, which seem to have an intrinsic disadvantage over air-based radars; see

The only different between ground radar and airborne radar is radar horrizon, which is irrelevance here since F-35 didn't use nap of the earth tactic. Other than that they have the same limitation. Even though ground radar in question are PESA , their aperture and transmitting power is so big that they can easily get bigger detection range than fighter radar.

inst wrote:for instance, the E-2D's PESA APY-9 can detect targets at over 550 km

What is the RCS of target though?
inst wrote:Another factor is scaling; it takes about a 4x increase in radar power to create a 2x increase in range.

No, with others factors remain the same, to get 2 times the range, you need at minimum 16 times transmitting power ( not take into account loss )
Image

inst wrote:AESA has less of a scaling issue compared to PESA; AESA increases in both transmit power and receive power with size.

No, AESA radars often have better range than PESA radars because on an AESA design, the low noise amplifier is put near the receiver , before the lossy components, thus AESA radar can achieve better signal to noise ratio compared to PESA
Image

P/s: please read more about basics of radar before you writing those claims, it is rather laughable
https://basicsaboutaerodynamicsandavion ... ermeasure/
https://basicsaboutaerodynamicsandavion ... s-part-ii/
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inst

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Unread post23 Mar 2017, 03:33

gta4 wrote:
inst wrote:@gta4: check out 0:09 on that video, then, it's roughly 90 degrees in 3 seconds.


since your video is sped up, all your claims about the turn rate of J-20 backfired.

In the non-sped up video, the J-20 spent 7 sec to turn a little more than 90 deg.


Actually, the first video cut together two videos.

Likewise, even the F-22 can turn 90 degrees in 7 seconds, absence of evidence is not evidence of absence.

For more objective sourcing, i.e, no one's sped it up or slowed it down, check out the Zhuhai video:

http://www.cnn.com/2016/10/31/asia/chin ... show-j-20/

Roughly 4 seconds to do 90 degrees, 6-8 seconds to do 180 degrees.

But it's all up to you.

Also, 5 G at Mach 0.9 for the F-35 is roughly a 11 deg/sec turn rate. If you extrapolate to Mach .7, you get 14deg/sec, which is not good either. Check out the F-16A chart for comparison, the F-16C/D is 18 deg/sec peak turn rate, while the Eurocanards are around 22 deg-sec STR.
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garrya

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Unread post23 Mar 2017, 03:39

inst wrote:
Also, 5 G at Mach 0.9 for the F-35 is roughly a 11 deg/sec turn rate. If you extrapolate to Mach .7, you get 14deg/sec, which is not good either. Check out the F-16A chart for comparison, the F-16C/D is 18 deg/sec peak turn rate, while the Eurocanards are around 22 deg-sec STR.

Inst, the value for F-35 is at 15000 feet, not at sea level.The different due to altitude is massive.
For example:
Image
For sea level performer look at this

Between 2:44-2:52 ( or 8 seconds ) , f-35 finished a 180 degrees turn, that equal to average turn rate of 22.5 degrees/second
Last edited by garrya on 23 Mar 2017, 03:53, edited 1 time in total.
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gta4

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Unread post23 Mar 2017, 03:45

inst wrote:
gta4 wrote:
inst wrote:@gta4: check out 0:09 on that video, then, it's roughly 90 degrees in 3 seconds.


Also, 5 G at Mach 0.9 for the F-35 is roughly a 11 deg/sec turn rate. If you extrapolate to Mach .7, you get 14deg/sec, which is not good either. Check out the F-16A chart for comparison, the F-16C/D is 18 deg/sec peak turn rate, while the Eurocanards are around 22 deg-sec STR.


You are terriblly wrong
14deg/sec is extremely high at 15000ft.
Sustained G and T to W.jpg

YOU ARE COMPARING TURN RATE AT 15000 FT to THAT AT SEA LEVEL AGAIN, POOR PETHETIC CHEATER!

Thank you for proving my opinion :mrgreen:
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