As of 2017, it is reported that control system, stealth coatings and hull materials, and infrared sensors still have technical issues as does the reliability of its WS-15 engines.
Some prototypes use the 14-ton thrust derivative of the Russian AL-31 or Chinese Shenyang WS-10 turbofan engines as they target 2019-2020 for all J-20s to use the 18–19 ton WS-15 engine. The WS-15 will enable the J20 to super-cruise without using afterburners.
China’s homegrown powerful WS-15 engine for its most advanced stealth fighter J-20. Mil.huanqiu.com photo
A Chinese aviation engineer told China Military Online on March 13,2017 that they are optimistic that the new WS15 engine for the fifth-generation fighter aircraft will be ready soon. The engine’s development is proceeding well. They also have begun to design a next-generation aviation engine with a thrust-to-weight ratio that is much higher than that of current types,” he said.
They were still working are able to develop the two most important components in an advanced engine — the single crystal superalloy turbine blades and powder metallurgy superalloy turbine disks — but in mass production, the products’ quality is not very satisfactory.
There are online reports that China will deploy 4 air regiments of J-20 fighter jets by 2019. There are 96 fighter jets in 4 hinese air force regiments. It takes less than 3 years for China to build that many J-20s. In 2016, China had two J-20 production lines, one producing J-20 with Russian AL-31 engines and the other producing J-20A installed with China’s WS-10B Taihang engines.
A third production line has recently gone into operation to produce J-20A. As each line makes one J-20 a month, their combined production capacity will be 36 a year.
By the end of 2019, there will be a fourth J-20 production line for trial production of J-20B using China’s homegrown WS-15 Emei turbofans.
J-20B is an improved version of J-20 installed with China’s new homegrown powerful WS-15 Emei turbofans. China has already developed WS-15 all-direction vector turbofan with thrust-weight ratio of 10. The turbofan is now undergoing intensive tests and will be ready to be installed in J-20B by 2019, an improved version of J-20.
If the WS-15 meets design goals then J-20B’s cruise speed will be Mach 1.8 and maximum speed exceeds Mach 2.2. Those would equal the US F-22. China will produce 500 J-20B, more than the future total number of other fifth-generation fighter jets in Asia-Pacific.
The US F-22 was in production for 15 years (1996-2011), at a rate of roughly two per month during peak production. China would be about 23 years behind US jet and jet engine technology. China could possibly achieve in 2019 what the US had in 1996). China stole US F22 and F35 designs and technology. Around 2030, China could have 500 J20B and 100 J20 and J20A stealth fighters. The US would have 185 F22 and perhaps 1500 F35s.
The J-20 likely has inferior stealth to the Lockheed Martin F-22 Raptor stealth fighter aircraft or the F-35 Lightning II fighter. The J20 lacks thrust vectoring and is likely less maneuverable than American-made fifth-generation warplanes.
Russia has developed 99M1 to 99M4 improved versions of AL-31F, but China has also developed improved versions of WS-10, named WS-10A and WS-10B better than Russian ones with thrust-weight ratio of 9 than Russia’s 8.
China has a third-generation single-crystal blade used in WS-10B. It is reported to withstand 2000 degrees which enables engine life to be increased from 800 hours to 1,500 hours. This would be close to maintenance overhaul interval of western engines.