Just check the tight turn performed by both J-20 and F-22, while the F-22 did use the afterburner, but the J-20 didn't even use the afterburner.
PS, the J-20 did perform a longer vertical climbing than the F-22 without using the afterburner as well.
Also, the J-20 can carry the external fuel twice as much as that of the F-22, so that means the maximum takeoff weight of the J-20 is also significantly greater than that of the F-22.
How the J-20 could achieve this feat with an underpowered AL-31F?
View attachment 363654
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Yup, we can see that on the China Airshow, J-20 performed, without the afterburner, a slow vertical climb that did not slow down at the top. This shows the Dry Trust to Weight Ratio of the engine to the plane is greater than 1.
If the empty weight of J-20 is greater than F-22's 19.6 tons, plus 3 tons of fuel, then its near 23 tons.
If J-20 is using WS-10 which has reach 140kN thrust, Dry Thrust is around 60% of that, which is 85kN per engine. Double than is 170kN or 17.3 tons.
17.3 tons is no where near the 23 tons lift J-20 slowly and vertically.
F-22 has 156kN Max thrust (93kN Dry Thrust) per engine, or 19 ton total dry Thrust.
This is not enough to lift the 23 tons weight (19.6 + 3 tons of fuels) of F-22, vertically without afterburner.
That's why we are seeing the F-22 need to turn on the Afterburner on almost the whole demo.
@Deino ignored this fact by just insisting the demo of J-20 is not that impressive and it doesn't mean anything.
Now, if J-20 is using WS-15 and its maximum thrust is 180kN as stated in the internet, then its dry thrust is (180kn x 0.6 x 2 = 216kN or 22 Ton)
This is just enough to lift vertically the empty weight, 22 tons, of J-20 without afterburner (we supposed is 22 ton, the same as F-22 plus 2 tons more, since its body is 3 meters longer), not including 3-4 tons of fuel needed to fly from a nearby airport to the demo.
Now, we suppose the empty weight of J-20 is 22 tons plus 4 tons of fuels for the demo, then the Dry Thrust required to lift it vertically is 26 tons, or 255kN or 127.5kN per engine. (127kN is only 13kN less than the maximum thrust 140kN of WS-10) To have 127.5kN of dry thrust per engine, the maximum thrust of the engine must be around a whoopping 212kN (60% of 204kN is 127.2kN)
Coincidentally, 212kN is close to the YAK-141's R79-v300 engine's maximum thrust of 206kN.
China has purchased the YAK-141's R79-v300 engine technology, including all the technical blueprints and documents, from Russia in the 1990's.
Of course, my figures are guess-estimate based on the estimate empty weight of J-20, 22 Tons and plus 4 tons of fuels needed for the demo. I would say 4 tons of fuel, or 1/3 of a full tank, is a conservative figures.
If my figure of J-20's empty weight is anywhere close to the truth, the Maximum thrust of WS-15 is closer to +++ 212kN +++, not 180kN as advertised.
Get that number into your head, folks. WS-15's Maximum Thrust is north of 212kN.
No wonder the Chinese government want to keep the mighty WS-15 under tight wrap. It's power is too shocking for the world to digest.
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Su-35's empty weight is 18 tons, plus 4 tons of fuel for the demo then its 22 tons. It's 117S or AL-41F's maximum thrust is 180kN, or total thrust is 360kN, and total Dry Thrust is 216kN, or 22 tons. It's just enough to lift it vertically without afterburner.
This video shows it that is is true. No afterburner is needed. It could hang in mid air and do vertical climb slowly all without the use of afterburner.
The Russian T50 fighter (empty weight 18 tons, using AL-41F engine, same as Su-35) doing spectacular demo, without the use of afterburner.
So in conclusion, there is no doubt in my mind, that the maximum power of WS-15 is much greater than 180kN as advertised, north of 212kN is much more likely.
Eat your heart out, you China bashers. China can't produce a powerful and reliable engine, you say.
however, as long as the expositions are mainly rational and scientific, they are of good reading interests 
cheers!
