F-35 vs J-20

The F-35 compared with other modern jets.
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wrightwing

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Unread post23 Mar 2017, 01:01

inst wrote:
wrightwing wrote:The requirements could be as high as 500-700, though I'd be surprised if they end up with more than 200. As for superior turning capabilities, sustained/instantaneous, that hasn't been demonstrated, nor has 50 deg AoA, supercruise, distribute aperture systems, etc....


The Chinese want a large quantity because the J-20 is their first shot at having peer capabilities to the US in their region. If the J-20 performs as advertised (doubtful at the present rate, and mainly due to subsystems, such as engine, radar, eodas, maturity), it'd outclass the F-35 similarly to how a Flanker can outclass a late-model F-16 (different weight classes). Then if you have 700 J-20s vs 1400 F-35s in the region, you're at strategic parity. Likewise, facing the F-22, there's only 186 or so F-22s, minus training and parts models, so the J-20 has a significant numerical advantage.

As to turning capabilities, we've seen videos of the J-20 with 20 deg / sustained turn rate, which puts it higher than the F-35, which has around 10-15 degree STR.


Again, you're confusing "want to acquire" with "will acquire." Secondly, the F-35 doesn't have a STR of 10-15 deg/sec, nor is it inferior to the J-20 in turn performance.
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gta4

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Unread post23 Mar 2017, 01:03

inst wrote:About the J-20's high AOA, that was rumored on different websites, after going over the aerodynamic plans for the J-20, as well as reports of the J-20's rival...

...if you trust the Chinese to have gotten empty weight down to 17500 kg...

We should remind Mr. inst a few things:

First, PLA never made any "advertisements" about the performance of J-20. What you said "advertised performance" are purely web rumors which indicated the hope of Chinese military fanbase. The "17500 kg" empty weight is from Chinese web encyclopedia which could be edited by anyone. Web encyclopedia always has wrong data, such as the empty weight of F-16C block 30 (which should be 8100kg instead of 8500kg. It confuses block 30 with block 40), and it even marks the rate of climb of F-16 to be only 254m/s (which should be superior than 300m/s).

Secondly, If you have any video showing J-20 has 20deg/sec sustained turn rate, please post the link. Remember F-35 could uses some unconventional turing technique to sustain 28deg/sec, which is never shown by J-20.

Last, no proof shows J-20 has EODAS. It has a diamond pod at the chin of its fuselage, but nothing could prove what's inside. Worse still, there is no clue that J-20's potential EODAS could cover its rear hemishpere. That is a decisive disadvantage once it gets into a merge with a F-35.
Last edited by gta4 on 23 Mar 2017, 01:12, edited 3 times in total.
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wrightwing

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Unread post23 Mar 2017, 01:06

inst wrote:About the J-20's high AOA, that was rumored on different websites, after going over the aerodynamic plans for the J-20, as well as reports of the J-20's rival, what was essentially a stealth Su-30 that was unfortunately unstable in the 50-60 AOA regime. As to the J-20's stealth and stealth performance, Kopp simulations show that the J-20 is capable of -30 to -40 dBsm depending on angle, although it also has frontal angles where it drops to -10 or -5 dBsm. The main game for J-20 vs F-35 is going to turn into a fight between the respective EODAS systems, and the F-35 likely has more mature coatings, while being smaller as well.

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.

Likewise, the networking advantage of the F-35 is overstated, considering the Chicoms managed to get their hands on the F-35's subsystems data, and have a notable IT industry themselves, see Huawei / Baidu / DJI. There's nothing stopping the Chinese from replicating the F-35's networking advantages into the J-20.


You're not a serious person.
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gta4

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Unread post23 Mar 2017, 01:07

We should definitely remind Mr. inst about the turning capability of F-35 which helps it to dominate a neutral turning fight:

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Last edited by gta4 on 23 Mar 2017, 01:24, edited 1 time in total.
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wrightwing

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Unread post23 Mar 2017, 01:10

The J-20 will NEVER have a lower RCS than either the F-22 or F-35. It will NEVER have superior avionics, sensor fusion, networking. It will NEVER enjoy T/W advantages. Stop posting youtube and APA nonsense.
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citanon

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Unread post23 Mar 2017, 01:12

inst wrote:@citanon: first, long time no see! Second, the main problem with the J-20 is that its capabilities are seen as static, when, like the F-35 and Su-27, it has high development potential. Second-generation datalinks and avionics on the J-20 can end up being replaced by more modern types during its lifetime, and if we estimate the J-20's combat weight at 31000-32000 kg, it gets a .9-1.1 TWR at different fuel weights, which is comparable to that of the F-35, which we don't call an interceptor. More importantly, with later engine upgrades, it can begin to sport F-22-like 1.1 to 1.4 TWRs, and if TVC is added to later airframes, the tailfins and strakes could be potentially ditched, creating an aircraft that is stealthier than the F-35 at the least, and potentially stealthier than the F-22.


I think at this point in the version 1.0 the J20 still looks like a learning as you go platform, which dictates small production numbers, which in turn dictates the most efficient strategies for leveraging its available capabilities, which in turn influences the requirements, etc. It's a big feedback cycle that drives the development in a certain direction.

The Chinese may choose to make iterative changes, but they may also decide to do a clean sheet design once component capabilities are mature. They do have a lot of money and are starting from zero for the 5th gen. At this point I don't think they've committed either way.
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inst

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Unread post23 Mar 2017, 01:36

Depends on how you define turn performance. The F-35 is extremely strong in ITR; this was a design choice, since ITR lets you scoot out of the way of missiles near the end of NEZ. STR, on the other hand, is not emphasized, because when you're fighting HOBS maneuverability is obsolete, as Lockmart stated.

4.2G Sustained Turn, likewise, is not a good sustained turn capability; compared to Eurofighters, F-22, and the Su-35, it's outclassed. The F-35 is supposed to more more agile than a loaded F-16, and I definitely see that to be the case, but the F-35

For maneuverability videos, here's roughly 180 degrees in 5-6 seconds, or 30-36 degree ITR.

https://www.youtube.com/watch?v=3kKFEraGVzI

There's another video where the J-20 does a long turn of about 270 degrees in about 14 seconds, but I can't find that.

Here's this video, check the footage leading to 3:08, https://www.youtube.com/watch?v=ZLLg77TK3pE&t=151s

About 270 degrees in 12 seconds, implying 22.5 degree / sec.
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inst

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Unread post23 Mar 2017, 01:47

wrightwing wrote:The J-20 will NEVER have a lower RCS than either the F-22 or F-35. It will NEVER have superior avionics, sensor fusion, networking. It will NEVER enjoy T/W advantages. Stop posting youtube and APA nonsense.


The modernized Type-59s are probably better than the M60s, if there are still any left in service. It has nothing to do with whether China has better R&D and design capability than the US, but rather that the M60 is obsolete as is the Type-59, but the Type-59 is still being developed. Likewise, the J-10C is superior to the F-16, not because the Chinese are better than the Americans, but because the J-10C is still being developed, while the F-16 got APG-80 is EOL, and for that matter, the J-10C is a 1990s design while the F-16 is a 1970s design.

The question is essentially research tempo; will the Chinese be able to get WS-15 into service, as well as TVC-ed J-20s into service, before the F-35 and F-22 are replaced by the F-X and F-XX? Before, we could be reasonably confident that they would not, but with the ramping up of Chinese R&D rate this is now an open question.

As to EODAS, check this out: https://tiananmenstremendousachievement ... s-nose.jpg We don't know if the J-20 has 360 degree EODAS coverage, but it looks as though it'll have at least 270 degree EODAS coverage.
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Unread post23 Mar 2017, 01:49

inst wrote:4.2G Sustained Turn, likewise, is not a good sustained turn capability;


Your figure is terribly wrong.

First, It is >4.6g instead of 4.2g. Secondly, it is a threashold value instead of the true value (the former is always inferior than the latter). The most important thing is that, it is at 5000 kg fuel, 15000 ft (instead of at sea level)!

If you need the same A/B duration, a Su-27 must carry 6200kg fuel, resulting in even worth sustained G than F-35 at the same hight.

Anyway, since you are either blind or ignorant, it would be normal if you refuse to post any reliable rebuttal
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gta4

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Unread post23 Mar 2017, 01:53

inst wrote:For maneuverability videos, here's roughly 180 degrees in 5-6 seconds, or 30-36 degree ITR.

https://www.youtube.com/watch?v=3kKFEraGVzI



Sorry to slam your face one more time:

https://www.youtube.com/watch?v=RfQZs5ERqP4

check 00:39. J-20 is significantly outcalssed by a fighter-bomber
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inst

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Unread post23 Mar 2017, 01:56

gta4 wrote:We should definitely remind Mr. inst about the turning capability of F-35 which helps it to dominate a neutral turning fight:

Image

Image



Via Key Aviation:

"While the pilots have made it clear that the F-35 is very capable and has impressive performance. Hyperbole isn't needed. 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."

http://forum.keypublishing.com/showthre ... sion-(2016)-take-III/page145
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inst

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Unread post23 Mar 2017, 02:05

Actually, since we've all gotten emotional, it's probably wise not to play.

About the F-18: I see a 90 degree turn in 3 seconds, a nice 30 degree ITR for a fighter noted for its ITR.

@ Citanon: We can probably compromise here; if you go with the more Russian designation versions and see different versions of the J-20 as fundamentally different aircraft, not unlike how later versions of the F-16 are more equipped for strike / BVR, increasing weight without wing area, resulting in higher wing loading.

From this angle, though, if you assume Chinese sources are talking about J-20 developments, instead of simply the LRIP J-20, we're looking at something around 100 or so initial J-20A variants with the current 142kn engines, then future developments will fill out the 500-700 number.
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gta4

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Unread post23 Mar 2017, 02:06

inst wrote:For maneuverability videos, here's roughly 180 degrees in 5-6 seconds, or 30-36 degree ITR.

https://www.youtube.com/watch?v=3kKFEraGVzI



Sorry man, according to this video, J-20 turned only 90 degrees instead of 180 degrees. The camera is also rotating which caused some illusion:
roof edge.jpg
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eloise

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Unread post23 Mar 2017, 02:08

inst wrote:

As to turning capabilities, we've seen videos of the J-20 with 20 deg / sustained turn rate, which puts it higher than the F-35, which has around 10-15 degree STR
4.2G Sustained Turn, likewise, is not a good sustained turn capability; compared to Eurofighters, F-22, and the Su-35, it's outclassed. The F-35 is supposed to more more agile than a loaded F-16, and I definitely see that to be the case, but the F-35

Firstly, you are mistaken between sustained G value in 15k feet, Mach 0.8 condition with maximum sustained G values. As you go higher, air density is lower so sustained G capability reduced. So your comparison is horrible. It is like saying top speed of car 1 is 50 km/h on flooded road while top speed of car 2 is 100 km/h on dry road so car 2 is faster than car 1


Secondly, the threshold of sustained G value for F-35 at 15K feet, Mach 0.8 is 4.6G for F-35A and 5G for F-35C not 4.2G. The demonstrated sustained G at that condition is 4.95G for F-35A 240-1 configuration
Last edited by eloise on 23 Mar 2017, 02:21, edited 2 times in total.
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inst

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Unread post23 Mar 2017, 02:09

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

In either case, let me leave on something we can all agree on. Raytheon's MSDM and SACM systems are radical gamechangers, and relatively mature; if the J-20 is intended as an interceptor, it will be extremely difficult for it to successfully intercept once Raytheon's systems come online due to their ability to intercept enemy missiles.
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