J-20 5th Gen Fighter Thread IV (Closed to posting)

[latenlazy]

Maybe. But why develop a PL-12 with cropped fins in the first place then?

Well, looking back, we now know that 200X was not a production design, so the space in the internal bays might not have been optimized. Alternatively, the PL-12 with cropped fins we saw in the J-20 was not a final design (and it probably wasn't a functional missile but a mock up).

 

[TerraN_EmpirE]

Maybe. But why develop a PL-12 with cropped fins in the first place then?

Interim stop gap, export, system updates for other aircraft, fall back program in case of cancellation or technology lag.

 

[Blitzo]

Well, looking back, we now know that 200X was not a production design, so the space in the internal bays might not have been optimized. Alternatively, the PL-12 with cropped fins we saw in the J-20 was not a final design (and it probably wasn't a functional missile but a mock up).

I agree that the space in the internal bays may not have been optimized, but I believe PL-15/PL-12 cropped fins would have been at a reasonably advanced level of development.
After all, it was seen carried by J-11Bs a few years before we saw it on J-20 and likely tested as well.

Interim stop gap, export, system updates for other aircraft, fall back program in case of cancellation or technology lag.

Possibly, but we don't have enough information to suggest those are likely alternatives.
The most likely answer to me sounds like 2001/2 simply had weapon bays which were not designed large enough. Afterall, they skimped out on some other things like round LERX and smaller tails on the first two prototypes as well, I wouldn't put it past them to have designed a less than optimal weapons bay.

I will concede though, that widening the weapons bay is a slightly more challenging task than changing external aerodynamic structures... then again, they only need to widen it by a dozen or so cm each way.

 

[cyan1320]

Did he just lick a finger and stick it in the air?

Bhahahaha that made my day. thanks

 

[Totoro]

The J-20’s weapon arrangement is similar to the F-22, except that the ventral bays are shorter and narrower

This bit is very much not true. Plenty of images are available to size the bays and it is evident the bays are as wide as ones f-22 has, or even a few cm wider. Also, bays are visibly longer (a few tens of cm) than ones f-22 has. Also, seeing how even pl-15 seems a bit wider/longer finned than amraam, it is likely the depth of the bay is also somewhat greater.

Available 2011/2012 images, while not showing the internal configuration of bays, do show the outer door lines, which seem the same as ones on 2001/2002. So, unless there's been some major rework, like deepening of the bays or removal of the middle wall between bays (both are unlikely in my opinion)

All that points to a larger weapons carrying potential than what f-22 has. I say "potential" as right now the larger size of chinese aams and stand off weaponry seems to be negating that potential but that may change with new variants in the future.

 

[siegecrossbow]

A detailed Chinese technical paper published in 2001 by Song Wencong, designer of the Chengdu J-10, points to key aerodynamic features of the J-20. The paper addresses the design of a fighter with a delta wing, canards and leading-edge root extensions (Lerxes), and discusses how the three interact. The J-20, unlike the J-10, has a broad body and the canard and wing are not close-coupled. However, according to the paper, the Lerx and canard, used together and in combination with a high degree of instability, can achieve maximum lift coefficients that are as high if not higher than those from a close-coupled canard.

The paper also discusses the vertical stabilizer design of a stealth configuration with outward-canted surfaces. Fixed, canted tails are exposed to powerful crossflows at high angles of attack, because of the formation of vortices from the wings and canard. The result is that the tails can develop powerful moments, and because the tails are canted, those forces will include pitch-up moments. One way to resolve this, the paper notes, is to use smaller, all-moving surfaces. The J-20 resembles the Sukhoi T-50 in being directionally unstable, and is actively controlled with the all-moving verticals. Song’s paper also says the canard layout provides positive post-stall recovery, without the use of thrust vectoring.

Might be based on my translation!!!!

 

[Air Force Brat]

Might be based on my translation!!!!

Very likely siege, and one more reason I remind all posters to put up your best work, and not to link "junk" up on the forum just because it follows your narrative. In fact after re-reading that, I believe that it was very likely sourced from your "outstanding" translation, one of the reasons I became convinced the J-20 was a very sound airplane, both in concept, design, and execution. Thanks for all your hard work over the years. brat

 

[Verum]

Speaking of the mentioning of J-20 in published scientific journals, has J-20 ever been displayed or unveiled in public?
J-31 has already had its model displayed in the previous Zhuhai airshow, now the prototype/demonstrator arrived too. How about J-20, was it ever in public display or even shown a model?

PS: Been mentioned in daily news doesn't count, unless it's something as formal as CCTV's 7pm news.

 

[latenlazy]

Speaking of the mentioning of J-20 in published scientific journals, has J-20 ever been displayed or unveiled in public?
J-31 has already had its model displayed in the previous Zhuhai airshow, now the prototype/demonstrator arrived too. How about J-20, was it ever in public display or even shown a model?

PS: Been mentioned in daily news doesn't count, unless it's something as formal as CCTV's 7pm news.

No. Because Zhuhai is primarily a show oriented towards exports. The J-31 is being offered for export. The J-20 isn't.

 

[Deino]

Hey ... I have not seen before this image !