Chengdu J-20 news and analysis Part III

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Alfa_Particle said:
Except that's not true. The F110 is not derived from the CFM56 but rather the F101. And yes! The WS-10 is quite a sophisticated machine with contra-rotating spools. The core might be vaguely based on the CFM56, but everything else is so different that at this point it's basically a thing of it's own. The vanilla WS-10 is quite comparable to the F110-GE-100 with superior thrust curves before M0.3 and past transonic speeds.
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In fact, this envelope diagram comes from early Chinese imports of the AL-31F engines; however, it has been edited using PS to pass security requirements, meaning its curves—especially the latter half—are completely inaccurate.

I cannot reveal more information; you may choose to receive comments on this selectively.

Furthermore, the paper was published in October 2016. In fact, China had no experience using the AL-31FM2 at that time, and considering that the original paper discussed a twin-engine fighter jet, it could not actually be the AL-31FN series.
 

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Valodyana_80U said:
In fact, this envelope diagram comes from early Chinese imports of the AL-31F engines; however, it has been edited using PS to pass security requirements, meaning its curves—especially the latter half—are completely inaccurate.

I cannot reveal more information; you may choose to receive comments on this selectively.

Furthermore, the paper was published in October 2016. In fact, China had no experience using the AL-31FM2 at that time, and considering that the original paper discussed a twin-engine fighter jet, it could not actually be the AL-31FN series.
Click to expand...
I highly doubt that. It's quite far removed from the baseline performance of the AL-31F. Yes, the thrust curves are indeed not quite accurate, but actually in the nerfed sense (as in the actual installed performance is even better). Source: I had the opportunity to come across a conversation between a Beihang professor (that worked with AECC) and an undergrad. It is a primary source with basically nothing to back it up, so I'm gonna have to take a page out of your playbook:
Valodyana_80U said:
I cannot reveal more information; you may choose to receive comments on this selectively.
Click to expand...

Anyways, the cyrillic in the paper understandably led most people to conclude this is an AL-31F of sorts. But what they're forgetting is that early WS-10s' FADEC systems are heavily based on (some even say more or less directly taken from) the AL-31F.
 
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Alfa_Particle said:
I highly doubt that. It's quite far removed from the baseline performance of the AL-31F. Yes, the thrust curves are indeed not quite accurate, but actually in the nerfed sense (as in the actual installed performance is even better). Source: I had the opportunity to come across a conversation between a Beihang professor (that worked with AECC) and an undergrad. It is a primary source with basically nothing to back it up, so I'm gonna have to take a page out of your playbook:


Anyways, the cyrillic in the paper understandably led most people to conclude this is an AL-31F of sorts. But what they're forgetting is that early WS-10s' FADEC systems are heavily based on (some even say more or less directly taken from) the AL-31F.
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Just to illustrate my point additionally (been meaning to do this for a while), here's the adjusted thrust curves of the so-called "Photoshopped AL-31F" since the way the axes were formatted originally should be a crime against humanity:
Untitled design_20260914_035634_0000_edit_451500518326931.png

And here's the REAL AL-31F (I stretched it a bit):
Untitled design_20260914_035652_0000.png

Overlapping the two gives:
Untitled design_20260914_040623_0000.png
You can see that:
- despite being an entire kilometre higher (3 vs 2 km) it puts out the same/slightly more power from transonic speeds on
- puts out almost 20 kN more at 8 km/M1.5
- puts out at least 30 kN more at M2

"Photoshop" my ass this is a whole damn different engine.

Valodyana_80U said:
Furthermore, the paper was published in October 2016. In fact, China had no experience using the AL-31FM2 at that time, and considering that the original paper discussed a twin-engine fighter jet, it could not actually be the AL-31FN series.
Click to expand...
Good point. So let's think about this! This is an engine that:
- is in the same class as the AL-31F
- in flight testing with the PLAAF during the early 2010s
- uses a Russian or Russian-based FADEC (which still needed minor fine-tuning at the time of writing, i.e. early 2010s)
- used on a new twin-engined fighter that was undergoing airframe-intake integration
- supposedly had significantly better thrust curves than the AL-31F

That rules out the base AL-31F, it can't be the AL-31FN/M1, and the PLAAF haven't taken delivery of the AL-31FM2 at the time.

One engine fits the bill perfectly. Just saying. So pray tell, which is more likely: this is a comically boosted AL-31F thanks to Photoshop, or that this is the WS-10(A) flight testing on the J-16?
 

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