Given the only difference between the interim and final version of FWS15 is the materials used in the engine parts, and taking into account of the latest Chinese breakthrough in new material and process technique,it is not too optimistic to expect the J-20 powered by the final version of FWS15 coming out around 2018. Now the 78271 has deployed to the Brigade170/172 at FTTC, it will take around one year for J-20 to become IOC or 形成战斗力 in Chinese terms like J-10 did back in 2003. So everything seems to point to that direction.
I have the feeling the authorities has decided to declassify some info about J-20 as there are more these materials are being made public. For instance I found this <<Research on the development strategy of Chinese fighter aircraft>> on the net ,which outlines the whole process of the J-20's development. Viewing at hindsight, It clearly clear out many of the questions about J-20 from the outsiders like us. It makes me more confident about my belief that J-20 is powered by the Chinese engines based on one simple reason:J-20 must have turned out as planned in terms of its engine,radar,stealth,weapons, etc;otherwise the authorities would not publish its original plan to embarrass themselves.
Note under the <<Research on the development strategy of Chinese fighter aircraft>>, J-20 would use Taihang engine from day one.
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