F-35 vs J-20

The F-35 compared with other modern jets.
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inst

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Unread post22 Mar 2017, 10:44

Oh hey, since the F-22 vs J-20 thread is locked, I'm interested in seeing whether or not this would have better luck, since it's more a more realistic contest. The Chinese, according to this article (http://www.ainonline.com/aviation-news/ ... production ), are planning to put up 500-700 J-20s. Compared to a US deployment of about 2450 F-35s, it's a reasonable counter; the US splits its air fleet among several regions, and the J-20s are intended as an air superiority fighter (large canards, large wing area resulting in roughly 380 kg/m^2 wing loading), instead of a multi-role strike fighter. If the aircraft performs remotely close to as promised, it could counter US F-35 deployments in the Asia-Pacific region.

As an airframe, the J-20 has certain advantages; it is built for very long ranges, it has a larger radar aperture, and it is probably more maneuverable in sustained turns. On the other hand, the F-35 has different advantages; its stealth is likely more comprehensive, lacking the 0-degree zone of death on the J-20, its radar and EODAS are liekly more advanced, and it has superior WVR missiles; the latest PL-10 / PL-ASR is rated at about 22 km of range, whereas AIm-9X Block II has around 50 km of range.

Here's some interesting facts you might be interested in. The J-20 is capable of at least 50 degree AOA, due to the PLA requirements. Normally, a canard-delta layout should create more limited max AOA, but the complex lerx-canard-lerx lifting body delta set-up apparently bypasses that. A lot of this might also be accountable to simply the LERX; the Eurofighter team, for instance, found that by adding LERX to their airframe, they were able to increase max AOA by at least 10 degrees. The F-35, on the other hand, has achieved 110 degrees of AOA in testing, but its official max AOA is 50 degrees.

Of course, this entire thing could be moot. IIRC, someone from Lockmart mentioned a while back that "let the missiles do the turning"; i.e, WVR HOBS missiles are getting so good, any WVR engagements would essentially come down to the quality of the missiles or alternately turn into an attritional battle. The decisive factor in any real engagement might not even be combat training, but the software integration of system of systems. The Chinese have the large Divine Eagle anti-stealth drone, but the US has the E-2D Hawkeye, with detection ranges of over 250 km vs LO targets.
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popcorn

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Unread post22 Mar 2017, 11:54

"When a fifth-generation fighter meets a fourth-generation fighter—the [latter] dies,”
CSAF Gen. Mark Welsh
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wrightwing

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Unread post22 Mar 2017, 13:36

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....
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Unread post22 Mar 2017, 14:38

Whatever it has going on the J-20 has what amounts to a bad heart. Engines are really the critical piece for 5th generation aircraft. You need very high thrust and efficiency to overcome the other challenges that going all internal for gas and weapons can present. Talking about the rest of it prior to getting the engines right is doing it backwards.
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Unread post22 Mar 2017, 15:45

viewtopic.php?f=55&t=52510&start=75

All critics from pilots focus on F-35's transonic performance (sustained G, acceleration), but so far no complain is about F-35's subsonic performance. However, F-35's subsonic performance are widely praised (constant turn rate, acceleration, roll rate, nose-pointing rate, controllability...). I don't see any adversary could get a favorable exchange ratio against a F-35 WVR

All major aversaries are underperformed in certain aspects:

Su-27/30 (non-TVC version): does not have the subsobnic energy recovery like F-35 (20%+ gap); does not have any approach to counter F-35's pedal turn (28deg/sec sustained); does not have the high roll rate like F-35 (exceeding 300deg/sec).

Su-30 (with TVC): does not have the subsobnic energy recovery like F-35 (20%+ gap); may have approaches to counter F-35's pedal turn when TVC is engaged, but still could not acheive the nose-pointing rate in a controlled spin (F-35 could acheive 90+deg/sec in a controlled spin); does not have the high roll rate like F-35 (exceeding 300deg/sec).

Su-35 (with TVC): similar to the previous case, except that subsonic acceleration is closer to F-35.

T-50: similar to the Su-35 case, and bear in mind that T-50 is a prototype with insufficient avionics and structure strengh. T-50 may subject to weight increase and maneuverability reduction when in mass production.

J-31: the worst performer, needless to say.

J-20: similar to the Su-27/30 (non-TVC version) case.
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Unread post22 Mar 2017, 16:04

inst wrote:...and the J-20s are intended as an air superiority fighter (large canards, large wing area resulting in roughly 380 kg/m^2 wing loading), instead of a multi-role strike fighter. If the aircraft performs remotely close to as promised, it could counter US F-35 deployments in the Asia-Pacific region.


If you're right with what you say that "J-20s are intended as an air superiority fighter" than this only proves one thing, that the J-20 is even more limited (even in the air-to-air arena) compared to the F-35.
Nowadays all and every new fighter aircraft are designed as multi-role. Again if you're correct the J-20 would be an exception and that exception is more likely due to technological limitations rather than a "design option/optimization".
Even the Brits are changing their Eurofighter Typhoons role - an aircraft also designed as an air superiority fighter - to a multi-role fighter like for example the Typhoon FGR4 variant.

Moreover I still don't get why people trend to think that Canards are some sort of a "magical aeronautical solution" that makes fighter aircraft turn like hovering helicopters?? And speaking of Canards from what I've read, Canards seem to increase the aircraft's RCS which means that in terms of RCS the J-20 is even more at a disadvantage compared to the F-35.
Even without Canards I doubt that the J-20 RCS would be better or much better than the Russian T-50 RCS which by itself is far from being "stellar" (around 0.5 square meters according to the Russians themselves).


inst wrote:As an airframe, the J-20 has certain advantages; it is built for very long ranges,


So is the F-35 with it's long range on internal fuel only (and very large internal fuel tanks/capacity).


inst wrote:it has a larger radar aperture,


What do you mean with "larger radar aperture"? :?


inst wrote:and it is probably more maneuverable in sustained turns.
....
The J-20 is capable of at least 50 degree AOA, due to the PLA requirements.


Where did you get that?



inst wrote:Of course, this entire thing could be moot. IIRC, someone from Lockmart mentioned a while back that "let the missiles do the turning"; i.e, WVR HOBS missiles are getting so good, any WVR engagements would essentially come down to the quality of the missiles or alternately turn into an attritional battle. The decisive factor in any real engagement might not even be combat training, but the software integration of system of systems. The Chinese have the large Divine Eagle anti-stealth drone, but the US has the E-2D Hawkeye, with detection ranges of over 250 km vs LO targets.


Trying to reply to the thread's title-question "F-35 vs J-20", it would be something like this:
1- F-35 detects and "locks" the J-20 much sooner and at much longer ranges than vice-versa.
2- The J-20 still doesn't have a clue that it was detected and "locked" by the F-35.
3- F-35 shoots an AMRAAM (pick your variant)
4- The J-20 still doesn't have a clue that it was detected and "locked" much less that it was shot at by the F-35.
5- Booommm, the J-20 explodes, crashes and burns

This is not to say that the J-20 doesn't have its own merits. For example a force equipped with 4th and 4.5th generation fighter aircraft like the Super Hornet, Rafale, Typhoon, Gripen, etc... which would have to face the J-20s could be at serious disadvantage (this is for you CANADA!) so in these cases similar steps as the above 1- to -5 steps could be repeated but this time in the J-20's favour!
I guess that in my opinion a more "interesting thread" would be something like: "Super Hornet vs J-20"
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 post22 Mar 2017, 20:14

I would suggest the j-20 is more likely to have an interceptor role, more like the mig-31, rather than an air superiority fighter. With primary targets like aew or tanker aircraft as key targets, it will still have to cross the f-series fighters defending such aircraft.

imho, the weakest link for the f-35 (and f-22) in the a2a role is probably the amraam missile. With pakistan getting the c5 variant, it can be presumed that the missile characteristics are fully studied by the plaaf, notwithstanding the improvements of the d variant. The second the missile is launched, the j-20 probably knows its targeted. The usaf needs a new aam.
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Unread post22 Mar 2017, 20:44

weasel1962 wrote:I would suggest the j-20 is more likely to have an interceptor role, more like the mig-31, rather than an air superiority fighter. With primary targets like aew or tanker aircraft as key targets, it will still have to cross the f-series fighters defending such aircraft.


Yes, when I first saw the J-20 I though the same thing and I still do.
The J-20 certainly looks (to me) to be more like a "stealthy" Mig-31 with probably some air-to-ground capabilities to conduct deep strikes.


weasel1962 wrote:imho, the weakest link for the f-35 (and f-22) in the a2a role is probably the amraam missile. With pakistan getting the c5 variant, it can be presumed that the missile characteristics are fully studied by the plaaf, notwithstanding the improvements of the d variant. The second the missile is launched, the j-20 probably knows its targeted. The usaf needs a new aam.


Unless the J-20 carries an advanced Missile Warning System the only way for a J-20 RWR to detect an incoming AMRAAM is when the AMRAAM is already on the last stages (12Km or so) of the missile's flight profile, or resuming when the missile is already close to the targeted J-20 aircraft when the AMRAAM's turns its radar ON thus giving the J-20 little time to react.

So yes you're right that the J-20 will or could likely be able to detect an incoming AMRAAM but when it does it will probably be too late for the J-20.

Which prompts me the following question: Will future variants of the AMRAAM or even current ones be able to turn on the radar when closer to the targeted aircraft (for example 5 km away alternatively to 12km away) thru for example a pilot selectable option?
Last edited by ricnunes on 23 Mar 2017, 11:14, edited 1 time in total.
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 post23 Mar 2017, 00:10

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.
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Unread post23 Mar 2017, 00:33

Here's a few misconceptions; first, the J-20 is not intended as an interceptor, although it might be interceptor-like, especially with the hobbled early engines. If it were an interceptor, why would it add canards, which increase drag and RCS, two factors contrary to what an interceptor wants? Second, canards, while not necessarily the be-all-end-all of maneuverability, see the XB-70 Valkyrie, when properly applied and implemented, can increase the maneuverability of aircraft to near-OVT levels, such as with the Eurofighter and Rafale. Nor is it unviable for 5th gens, the Northrop NATF proposal had canards, the KF-X had canards, and the proposed Boeing 6th gen F-XX is a finless-canard fighter. Third, the J-20 is not sensor dead; it has a visible EOTS and is reported to have an EODAS. It will likely track AMRAAM from medium ranges.

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. And about the engine figure; if you trust the Chinese to have gotten empty weight down to 17500 kg through extensive use of 3D titanium, then factor in 12500 kg of fuel and 1000 kg of weapons, you'd get about 31000 kg. Fully loaded, with 142 kn engines, you'd get .93 T/W, which is still better than the full F-35, with 1.14 T/W at 60% fuel, compared to the F-35A's 1.04 T/W at 60% and .87 T/W fully tanked.
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Unread post23 Mar 2017, 00:36

I think the other posters are right about the J20 being an interceptor.

In fact I would say it's a node of the Chinese as/ad network. It's designed to complicate the combat picture for an atracker by disappearing into airspace using its long range, then threatening adversary tanker, early warning, and naval assets both with risk of direct attack and by collecting Intel.

The adversary force will have to commit large amounts of air assets to find or defend against attack, slowing down offensive air operations.

The numbers of J20 will probably be fairly small because this is a first gen aircraft that China will not want to over invest in and because of the aforementioned operations concept which emphasizes leveraging of a relatively small number of platforms to tie up a large enemy force.

Because of this, and the state of Chinese engine development, I doubt the J20's aerodynamic performance will be fantastic. More important to the Chinese is sensor fusion and network integration, just like the F35.
Last edited by citanon on 23 Mar 2017, 00:43, edited 2 times in total.
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Unread post23 Mar 2017, 00:42

inst wrote:Here's a few misconceptions; first, the J-20 is not intended as an interceptor, although it might be interceptor-like, especially with the hobbled early engines. If it were an interceptor, why would it add canards, which increase drag and RCS, two factors contrary to what an interceptor wants? Second, canards, while not necessarily the be-all-end-all of maneuverability, see the XB-70 Valkyrie, when properly applied and implemented, can increase the maneuverability of aircraft to near-OVT levels, such as with the Eurofighter and Rafale. Nor is it unviable for 5th gens, the Northrop NATF proposal had canards, the KF-X had canards, and the proposed Boeing 6th gen F-XX is a finless-canard fighter. Third, the J-20 is not sensor dead; it has a visible EOTS and is reported to have an EODAS. It will likely track AMRAAM from medium ranges.

.


The canards are to help with takeoff and landing on improvised landing strips once the air bases are taken out. It helps make up for lack of good engines.
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Unread post23 Mar 2017, 00:42

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.
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Unread post23 Mar 2017, 00:50

Kopp's anything on stealth is ignorant trash and should be disregarded completely. We have zero real info on their relative lo performance.

The AoA is just fanboy fanfiction and also give no real information.

The size of the apertures are only one of several equally important factors determining performance.

I do agree that Chinese electronic and networking capabilities are quite advanced, but they lack experience. This will be a learning generation for them.
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Unread post23 Mar 2017, 00:56

@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.
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