F-35 vs J-20

The F-35 compared with other modern jets.
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inst

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Unread post23 Mar 2017, 06:22

Your diagram works great for model airplanes at short-distances, but if the aircraft is over 1-2 km off engines are sufficient. Mendacious as always.
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Unread post23 Mar 2017, 06:46

inst wrote:Your diagram works great for model airplanes at short-distances, but if the aircraft is over 1-2 km off engines are sufficient. Mendacious as always.

Think before you type next time.
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inst

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Unread post23 Mar 2017, 07:43

It's easy to win an argument if you misinterpret a point. You arranged your image horizontally, instead of vertically. If you had the aircraft at C, it would actually be facing down, because the belly was shown at C.

In either case, my point IS invalid, simply because reviewing the video, it takes place at relatively close distances to the viewer. Doing a 1km-based calc would give you 70 degrees based off a 300 m/s airspeed,
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ricnunes

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Unread post23 Mar 2017, 13:47

@inst,

The "misconceptions" here are all on your part!

Anyway, that's look at your "misconceptions":

- First and like citanon said, the Canards serve primarily the purpose to help to improve takeoff or resuming taking off on shorter runways - Something important for an Interceptor by the way. Or are you going to say that the Saab Viggen (one of the first fighter aircraft that I remember that uses Canards) is more agile than the F-16 because it uses canards?? :roll:
Also about canards, the use of them on aircraft like the Rafale or Typhoon or even the J-20 is there for a reason:
Canards also serve to overcome the limitations of Delta Wing design in terms of agility/maneuverability (they bleed energy fast and thus looses lift fast during tight maneuvers).
So and since the Canards objective is also to reduce the Delta Wing's limitations is also the reason why you basically only see them on Delta Winged aircraft like the Viggen, Gripen, Rafale, Typhoon and your "beloved" J-20!
Then you claim that Canards won't or wouldn't affect RCS or "stealth aircraft" much because there are "concepts" of proposed 6th gen fighter aircraft that have Canards.
Let me tell you "a secret": There were also some the concepts for some programs that originated on the JSF program (you know the program that originated the F-35) which "used Canards", so do does this means that the final aircraft of those programs in this case the F-35 also uses Canards?? Or course not!
Besides there's no Stealth aircraft in service (or entered on service in the past) - F-117, B-2, F-22 and F-35 that uses Canards and that's for a reason! Heck even "your" Chinese "Stealth" J-31 also in development doesn't use Canards as well as the Russian T-50.

- Secondly, you say "the J-20 is said to...", "the J-20 is reported to..." but where are your sources?? A speeded up Youtube video?? :roll:
At the same time you ignore every source that have been kindly provided to you!

-Third, you said that the F-35 range is 1250 km internal fuel range. But first that value is wrong! The F-35A combat radius in an air-to-air configuration is 760 nautical miles (nm) which is more than 1407km and again this range is combat radius or taking of from an airbase, reaching a point and returning to the same airbase of origin. You can check an actual diagram of the F-35's 760nm combat radius here:
viewtopic.php?f=22&t=49956
Next you say that the J-20 has 1500-2000 km with internal fuel range and again where and what are your sources??
And what range is that?? Combat Radius?? Ferry Range?? These details makes all the difference or else you're just comparing apples with oranges!

- Fourth, then you ramble about T/W ratio when it is well known that the Chinese industry lags behind in terms of effective performing engines and continue your ramble about the J-20 using 3D titanium and yet you ignore that the F-35 is made with extensive use of advanced composite materials which are even more lightweight than titanium! Resuming you came up with magical values with absolutely NO valid source and compare them to well known and official data/values from the F-35! Nice way to make comparisons :roll:

- Fifth and in line with fourth, perhaps the most comical of your "J-20 magical values" is RCS. You say that the J-20 RCS is -30 to -40 dBsm on some angles (You're really trying to convince us that the J-20's RCS is similar to the F-35?? Really?? :roll: ) and then you proceed to say that in FRONTAL ANGLES the J-20 RCS is -10 or -5 dBsm, really???
Let me tell you "another secret": Aircraft have LOWER RCS in their FRONTAL ANGLES. What does this mean?? It means that in all and every other angle the RCS is HIGHER (compared to the frontal angle). So there's a snowball chance in hell for the J-20 to have an RCS as low as -30 to -40 dBsm in any possible angle!!
With luck you may be right with your J-20 -10 or -5 dBsm (around 0.3 or 0.1 square meters) values for its frontal angle which would be the lowest RCS value possible for the J-20 which is still very, very far from the lower than 0.001 square meter RCS value of the F-35 which is an average angle RCS which means that the frontal angle of the F-35 is quite lower than 0.001 square meter.
So please do us all a favour: Spare us from lies and/or propaganda!

- Sixth, your radar aperture explanation (that the bigger the nose, bigger the radar aperture) is as in line with the J-20 RCS, simply hilarious!
So in your opinion the Mig-25 and/or the Mig-31 are the fighter aircraft with the biggest radar aperture?? Right... :roll:
Besides it's also hilarious that you say that the J-20 radar will be able to detect a F-35 at 75km when nobody knows for sure that will be the J-20 radar's performance which according to some experts it will be a radar called KLJ-5.
Also curious is that last year the Chinese unveiled an AESA radar, called the KLJ-7A which has a reported detection range of 170Km for a 5 square meter RCS target. Using an RCS for the F-35 of 0.001 square meters (and the real F-35 RCS is reportedly lower than this) means that the Chinese AESA KLJ-7A radar can at best detect a F-35 at a maximum range of 22Km (only Twenty Two Kilometers - this is almost nothing nowadays). OH, and let's not forget that detecting is one thing but TRACKING is another different thing! What does this mean? It means that the tracking range for that AESA KLJ-7A radar against a F-35 is quite lower than 22Km - And basically you can only shoot what you can TRACK!
And you're saying that the KLJ-5 will be able to detect the F-35 more than three (3) times further (than the KLJ-7A)?? LOL, keep dreaming :doh:
Source on the AESA KLJ-7A radar - it's in French but the paragraph "A noter que le chiffre de 170 kilomètres en portée de KLJ-7A devrait être obtenu en mode Air-Air, sur une cible standard d’une SER de 5 m²." should be clear:
http://www.eastpendulum.com/airshow-chi ... esa-klj-7a

- Seventh, the following comment from you:
the main problem with the J-20 is that its capabilities are seen as static

It's really funny because I have the idea that it's you that thinks that the F-35 capabilities are static when even it's software was designed as an Open Architecture in mind which grants it upgrade/improvement capabilities never seen in any other fighter aircraft. So, let me ask you one thing? Is the J-20 software designed to have an Open Architecture in mind?? And please don't reply me with:
"It's is reported that the J-20 <insert your wildest dreams here>"

- Finally regarding to J-20 vs F-35 agility and TWR. You only came up with nothing but your "wildest dreams" and speculations without ever posting sources - For example I did post an account from a Norwegian pilot (which flew both F-16 and F-35) and clearly states that the F-35 is superior in terms of agility. Yet, your "wildest dreams" seem to contradict this real pilot.
So if you can post speculations so can I and as such I will post now what I believe is my only speculation of this long post:
- The J-20 won't even beat a F-16 in terms of agility/maneuverability and TWR and much less it will ever beat a F-35 (namely the -A variant)!
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, 14:02

inst wrote:
In either case, my point IS invalid, simply because reviewing the video, it takes place at relatively close distances to the viewer. Doing a 1km-based calc would give you 70 degrees based off a 300 m/s airspeed,


To inst:

I have to inform you that, changing 70 deg heading does not mean turning 70 deg. It could be only 40 deg if you turn at 30 deg AOA.

Watch the video below: F-16 and F-18 are turning at 60-80deg/sec by your standard:

http://v.youku.com/v_show/id_XMzAyMjE0MjY0.html

http://www.bilibili.com/video/av3518523/

Do you think J-20 is outclassed by 4th gen?
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Unread post23 Mar 2017, 17:20

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, 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.


And yet Patriot was recently able to shoot down a tiny toy drone with a miniscule RCS.
"There I was. . ."
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Unread post23 Mar 2017, 20:54

inst wrote:@garrya: Alternately, you could claim the second video was slowed down. In either case, I'm pointing you to a CNN source with the aircraft doing 30deg/sec turns both to the 90 degree and 180 degree point. The CNN source does show that the video was taken by CCTV, but CCTV is less likely to speed up the video compared to hobbyists taking videos with DSLR.

Others have addressed this point so it is unnecessary for me to comment more

inst wrote:About F-35's turn rate, we have Mach 0.8 = 1160*.8 km/h at 15000 ft. Convert to m/s, and we get 2320/9 m/s

Using standard acceleration formula, with 5g inputted, we get r * 49 m/s^2 = (2320/9)^2, giving us a turn radius of 1356.1098.

The circle's circumference is ~8520 m, the airspeed in a sustained turn is 2320/9 m/s, meaning that the F-35 travels about 3% of the total circle per second. Multiplied by 360, we get about 11 deg / second, when the F-16, by comparison, is doing 14 deg / second in this regime.

I haven't double check your calculations yet, but
a) the speed for F-35 KPP is Mach 0.8, speed in gta4 chart is Mach 0.9, from the manual page i posted there more than 1 G different between 2 speed.

b) F-16 configuration in the chart is 50% fuel and 2 wing tip AAM. F-35 in similar configuration can fly almost twice as long because it carry significantly more fuel

c) Your own calculations doesn't support your claims. You said earlier that F-35 can only sustain 7.5 degrees/second at 15000 feet, Mach 0.8. Your calculation shows that it can sustain 11 degrees/second. That is around 46% bigger than in your previous claim
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Unread post24 Mar 2017, 04:57

garrya wrote:
b) F-16 configuration in the chart is 50% fuel and 2 wing tip AAM. F-35 in similar configuration can fly almost twice as long because it carry significantly more fuel

c) Your own calculations doesn't support your claims. You said earlier that F-35 can only sustain 7.5 degrees/second at 15000 feet, Mach 0.8. Your calculation shows that it can sustain 11 degrees/second. That is around 46% bigger than in your previous claim


Under the "same A/B duration" condition, F-35 out-turns Su-27 in a sustained turn fight
viewtopic.php?f=55&t=52918
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Unread post25 Mar 2017, 01:08

This thread is going places, drawing conclusions on an obviously and poorly done fake video, and an endless discussion about things that no one knows anything about based purely on internet rumors and make-belief.

As for the F-35 vs. J-20, or any other aircraft, the real issues that matter aren't turn rate and speed and physical characteristics of the plane etc. If maneuverability is what you're pinning you hopes in in 2017, you're going to die a fiery death just like every MiG-29 has met a fiery death anytime it has come up against woefully inadequate fighters in terms of maneuverability. Meaning, it doesn't matter all that much.

What matters is how these planes fit into the overall system of each country. They face a different set of circumstances than we face, and hence they will design and optimize on something different than we will. This set of circumstances is a lot wider than simply the opposing side's main fighter.
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Unread post25 Mar 2017, 10:02

About the canards, note that the Viggen's canards are non-moving, but with tail-flaps. For the J-20, similar lift advantages could have been obtained through the Viggen's configuration, improving RCS at the same time, since the moving surface is now on the rear. There's also the issue of the ventral strakes on the J-20, commonly used to improve high AOA performance; previously, I had thought that the J-20 had an easy transition to a X-36 layout, like Boeing's proposed F-X fighter (which uses canards, but has no rudders: the point is that the absence of rudders cancels out the presence of canards), but I've been watching videos arguing that with TVC, the J-20's aerodynamic layout provides for superior high alpha control (see US RCPowers playing with RC models).

@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.

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.
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Unread post25 Mar 2017, 10:22

@arian: I'm having fun here. This is the first time I've heard of pedal turns, and while I'd insist it's just an instantaneous turn, even possibly just a yawing action, it's interesting to note this about the capabilities of the F-35. Also, please note that I've talked repeatedly about the uselessness of maneuverability in dogfighting against HOBS missiles. But maneuverability still matters as a show of intent; I would actually have seen the YF-23 as superior to the F-22, since the YF-23 is better suited to attack roles and would have better BVR capabilities (larger radar, better stealth, better supersonic kinematics), but the F-22 had TVC and the YF-23 didn't. If the J-20 can't maneuver, it's unsuited for non-interception missions (but we've seen it maneuver to 20 deg/sec at least instantaneously, when the MiG-31 is known to have an instantaneous turn rate of 2.16 degrees at speed).

As to what makes sense for the Chinese, the thing is, the J-20 is actually going to end up facing the F-35 very soon. The Chinese are violating what we consider Japanese airspace, and the JASDF is regularly dispatching aircraft to escort them out. In fact, recently a J-11 and F-15J got into a pseudo-dogfight; the reason you don't hear about it is because the F-15J ended up shooting flares and leaving (this is not dissimilar to the Hellenic Air Force and the Turkish Air Force doing weaponless dogfights on their border). In the next few years, we may end up hearing of F-35s barking out the GPS coordinates of intruding J-20s and vice versa (although you'd contest that the J-20 would be able to IR-detect the F-35).

In fact, if we're talking about the needs of the Chinese, this is one of the reasons they rushed the aircraft into service; the F-35 was entering service soon, and the Chinese had no stealth fighters to contest it. They'd be at a strong disadvantage with their "bullying" actions if they didn't have aircraft capable of contesting incoming F-35s; the J-11s are kinematically equal or superior to older F-15Js. That's to say, if you're considering what role the Chinese need the J-20 to fulfil, they need it to counter the F-35.

Against the United States, they're at least 10 years away from military parity just in their own region; the PLAAF is advancing relatively quickly in capabilities, but stuff like the DF-21D and DF-26 get countered almost as soon as they come up, Raytheon's SM-6 system seems relatively capable of stopping everything but a multi-thousand missile barrage, while the E-2D is effective anti-stealth counter to the J-20. But against the JASDF, until recently they had a numerical superiority and material parity; the Japanese have roughly 300 4th generation aircraft, often including antiquated versions of the F-15, while the Chinese have roughly 400 fourth generation Flankers and Flanker-derivatives, and then 250+ J-10s.
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Unread post25 Mar 2017, 11:48

Also, @GarryA: Two other things about radar ranges:

http://webcitation.org/6Qpsm5PUo?url=ht ... 010807.pdf

http://69.73.131.148/6Qpsm5PUo?url=http ... 010807.pdf
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. 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.

=====

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. Using a base 300 km range, (if we assume it's against 0 dBsm), tracking ranges drop to 30 km with -40 dBsm, and with other information on stealth technology on this website, it suffices to guess that the F-35 and F-22 could be -50 dBsm craft, using -25 dBsm shaping and -25 dBsm RAM. That drops their detection ranges down to 17 km. 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.
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Unread post25 Mar 2017, 12:19

I'm procrastinating on other things, but here's a source that states that the obsolete Lockheed E-121 had a radar with 450 km range and 3 MW peak power output. It's crazy.

http://www.dean-boys.com/ec-121.htm
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Unread post25 Mar 2017, 16:12

inst wrote:I'm procrastinating on other things, but here's a source that states that the obsolete Lockheed E-121 had a radar with 450 km range and 3 MW peak power output. It's crazy.

http://www.dean-boys.com/ec-121.htm


Take your time. Learn something. Next time when you try to fool us, do not compare turn rate at 3000 m with that at 4527 m. Do not cite a sped-up video.
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Unread post25 Mar 2017, 18:43

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.


Really I've been wondering how long would it take in order for you to come up with the UHF/VHF radars...

First of all there's the fact that VHF radar have low targeting precision hence why they aren't used to guide missiles (for this task it's used more precise radars such as X-band). Resuming UHF and VHF radars are only good for detection or if you prefer Early Warning. What does this means? It means that even if you detect lets say a F-35 with a UHF/VHF radar you wouldn't or couldn't engage or guide a missile against the F-35 (or any other fighter aircraft for that matter).

Secondly, UHF/VHF are NOT a magical solution against "Stealth" or more precisely against the F-35.
The "best" and most powerful of such radars in existence today and likely for quite some time into the future is the Nebo-M AESA VHF radar which is usually used in conjunction with the S-400 (NATO name: SA-21 Growler) air defence system.
According to the manufacturer (I'll post the Nebo-M brochure below) the Nebo-M is able to detect a 1 square meter RCS target at a distance of 480Km in a circular (360º) scan or alternatively it's able to detect the same 1 square meter RCS target at a distance of 510Km in a sector (90º) scan.
If we assume the F-35 RCS to be 0.001 square meter (which is reportedly lower) it means that the "greatest" and "best" VHF radar in existence today, the Nebo-M is able to detect the F-35 at best at a maximum range 85Km in a circular scan or at a maximum range 90Km in a sector scan and all of this without any EW/ECM/Jamming present.
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".

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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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