J-20 5th Gen Fighter Thread VI

[kurutoga]

Is it credible? With assumptions of 12000 kg additional weight from fuel and payload, we get 1.07 T/W

It's hard to say. If true it means the current engine is usable and a pair of 18 ton engines will be unreal

 

[latenlazy]

On the veracity of the magazine article, it makes some claims that I'm dubious about. First, it says that the F-22 was designed more for multirole capabilities than the J-20 so it packs more equipment, which then contributes to it being heavier, but I'm not sure if that makes any sense since, as I understand it, the primary difference I can think of for a fighter to be geared more towards multirole capabilities is if they had more sensors, yet every indication we have suggests the J-20 packs more sensors than the F-22. Second, it says the J-20, though slightly longer than the F-22, is not as wide, and has a slightly shorter wingspan. I think we can all be somewhat certain about the wingspan claim, but I'm not as sure about the claim about width (by which I presume they're referring to the fuselage of the plane).

Also, it may just be me, but the writing in the article feels a little less professional than what I'm used to from these sorts of pieces, though that probably doesn't tell us much about how accurate the claims it makes are.

 

[plawolf]

The biggest weight gain contributor for multirole aircraft compared to pure AA is the additional structural strengthening needed to carry bombs many times heavier than the biggest AAMs.

 

[latenlazy]

The biggest weight gain contributor for multirole aircraft compared to pure AA is the additional structural strengthening needed to carry bombs many times heavier than the biggest AAMs.

And that might be what the article is referring to, but 机载设备的安装密度 doesn't sound like it's talking about payload...rather it sounds like it's talking about the standard equipment installed on the plane.

 

[Hyperwarp]

magazine article: J-20 empty weight = 15 metric ton, weight reduction made possible by several new manufacturing technology

15,000 kg? huh? Something doesn't sound right. Just compare to the other 4.5 and 5th gen fighters. Even if one could argue that the F-22 uses older manufacturing tech, the gap is still pretty suspicious.

F-22 - 19,700 kg
Su-35 - 18,400 kg
Su-57 - 18,000 kg (est)
F/A-18E/F - 14,550 kg
F-35A - 13,150 kg
Eurofighter - 11,000 kg

 

[latenlazy]

15,000 kg? huh? Something doesn't sound right. Just compare to the other 4.5 and 5th gen fighters. Even if one could argue that the F-22 uses older manufacturing tech, the gap is still pretty suspicious.

F-22 - 19,700 kg
Su-35 - 18,400 kg
Su-57 - 18,000 kg (est)
F/A-18E/F - 14,550 kg
F-35A - 13,150 kg
Eurofighter - 11,000 kg

It is entirely within the realm of possibility (as plawolf is hinting) that the J-20 is *completely* optimized for air superiority and has at best very meager strike capabilities, so is structurally much lighter than fighters of comparable dimensions (and they may make the frame heavier to expand into more multirole capabilities as better engines become available), but even then 15,000 kg empty is lighter than a flanker, so that seems outlandish. It is also possible, though maybe not plausible, that China has taken the edge on structural engineering and what we're seeing is the state of the art, since they have been investing heavily in this field for decades now. I have some reasons for being skeptical of this article beyond the believability of the claim, but I suppose now we wait to see if other independently derived sources can corroborate.

 

[Quickie]

Is it credible? With assumptions of 12000 kg additional weight from fuel and payload, we get 1.07 T/W and variable wing loading from 346 kg/m^2 to 288 kg/m^2 at 50% fuel / payload, assuming 142 kn engines. The problem is, what we've seen from the J-20's maneuverability is that given high AOA capability, it does not seem to be a low wing-loading aircraft.

One interesting possibility is that if high maneuverability videos are real, the initial videos were based off a lack of afterburner, resulting in a 20% reduction in return rate. I'm not sure if we've seen 24 degree / sec turns, but that translates into 23 degree / sec turns with afterburners, implying that the J-20 is better than Flankers in sustained turns, and puts us at 26 degree per second peak STR going from 142 kn to 180 kn engines.

Or, the videos tell you nothing because you don't know *anything* about the particular flight settings and parameters in them. If the plane looks sluggish, maybe they just weren't pushing it that hard? If I recall, a pilot even said as much during an interview for the show they put up during last year's Zhuhai appearance. Or maybe you can't get *any* good measurements because you don't have a fixed point of reference since these videos are pointed at the sky and are moving with the plane all the time?

The 2 J-20s were doing slow speed maneuvers most of time in the Zhuhai appearance. I don't recall the afterburners ever lit up during that time.

 

[ougoah]

It is entirely within the realm of possibility (as plawolf is hinting) that the J-20 is *completely* optimized for air superiority and has at best very meager strike capabilities, so is structurally much lighter than fighters of comparable dimensions (and they may make the frame heavier to expand into more multirole capabilities as better engines become available), but even then 15,000 kg empty is lighter than a flanker, so that seems outlandish. It is also possible, though maybe not plausible, that China has taken the edge on structural engineering and what we're seeing is the state of the art, since they have been investing heavily in this field for decades now. I have some reasons for being skeptical of this article beyond the believability of the claim, but I suppose now we wait to see if other independently derived sources can corroborate.

Makes complete sense for PLAAF to have the first (perhaps only) fielded fifth gen air superiority fighter worthy of that title and completely optimised for air to air combat and nothing else. How many other reliable and high tech platforms are already capable of covering the role of a striker? Let's not forget that the PLA will be focused on a defensive and regional (at a stretch) role for the coming decades. The PLA ground forces alone can take care of many ground targets which need only be supplemented by UAVs and existing strikers or multirole platforms. Superior number of bases and artillery pieces mean there's no need for a fifth gen air superiority to ever be dropping guided munitions. LO strikers are completely unnecessary if you already totally control the air. Denying enemy LO platforms by destroying those targets and their supports, should be the main role of J-20.

When this dynamic changes in a few decades, then they will adapt. For now, I'd be happy if they made J-20 a light weight pure air superiority which is certainly looks like. As opposed to the stupid theories of long fighters not being able to turn and so J-20 must be a striker. Just hoping for WS-15 as soon as it's ready for next block of J-20 upgrades. That's going to make one kickass fighter. Would be the first time China's got a piece of equipment that is clearly better than everyone else's. Su-57 would be hopeless with its relatively massive RCS (if detection methods do not revolutionise) and F-22 would not be active in this region in significant numbers.

 

[siegecrossbow]

Unless the J-20 used some sort of extraterrestrial material or technique during its construction, it is simply impossible for it to have anot empty weight of under 19 metric tons. The J-20 has a longer fuselage than the F-22 and roughly the same cross-sectional area, which implies the same or greater empty weight even accounting for advances in material and manufacturing techniques.

 

[Air Force Brat]

Or, the videos tell you nothing because you don't know *anything* about the particular flight settings and parameters in them. If the plane looks sluggish, maybe they just weren't pushing it that hard? If I recall, a pilot even said as much during an interview for the show they put up during last year's Zhuhai appearance. Or maybe you can't get *any* good measurements because you don't have a fixed point of reference since these videos are pointed at the sky and are moving with the plane all the time?

The J-20 doesn't necessarily "look sluggish", but we haven't really seen an "airshow dispay" of this aircraft like we do of F-15, F-16, F-18s or Su-27s or Su-35s, Mig 29's etc with OVT... So its difficult to say, but what we should be saying is that it appears to be a very high performance aircraft, but I really doubt it has the turn rate of say an SU-35 or SU-57, which each respectively have OVT a huge wing and high output after burning turbines.

I'm sure the J-20 will hold its own, more than that, we really won't know unless China takes it back to Zuhai or some similar venue and "gives it a working over",,, all we've so far are slick higher G turns, but they do not appear to be "maxed out".

So there remains a lot we don't know, but weight, wing loading, and thrust lead us to some very logical conclusions..... the laws of physics don't care if you're Russian, Chinese, or German, they are the same for everybody.