J-20 fighter is now using Russian engines. But according to anonymous sources, the test work of domestic WS-10 engine (Taihang) on J-20 fighters may have been completed. And J-20 fighters are witnessing genuine domestic engines and such versions are about to be mass-produced and delivered to the troops.
As China’s fifth-generation stealth fighter, the J-20 fighter is originally planned to have a domestic WS-15 turbofan engine. From overseas data, the domestic WS-15 engine is comparable or similar to the US F119 turbofan engine. However, the domestic aero-engine industry has not been able to develop such an engine capability. Therefore, the relevant units are adopting a relatively safe approach, using mature engines to allow the first flight and small batch production of J-20 fighter, which is the so-called A-state (J-20A). Then when WS-15 is mature, A-state will be replaced by B-state (J-20B).
J-20 fighter is now using AL-31FN-SER3 turbofan engine, which is an improved version of AL-31FN. The main improvement is to increase the engine thrust to about 13 tons, and to install FADEC system for improved reliability. However, its overall performance can only be said to be medium-to-high in the third-generation turbofan engine, which limits the performance upgrade of J-20 fighter, and its mass production is also limited by Russian production capacity. Therefore, it is widely speculated that J-20 fighters started to be produced in small batches from 2016. The number of equipment should be less than 50, and the average annual production is only about 10.
As F-22 and F-35 fighters spread around China and the region, China’s Air Force faced a sharp rise in pressure. And J-20 also participated in Red Sword confrontation exercise, and in the face of the four-generation fighters, J-20 fighters scored their opponents and let the Chinese Air Force realize that value of the four-generation fighters will decrease rapidly after 2020. The requirements for the five-generation stealth fighters are more than ever
On the other hand, the domestic WS-15 engine is still in the process of development. It takes time to design and test for flight. However, as the domestically produced Taihang WS-10 engine made breakthrough progress, being installed on the J-16 fighter, and passed practical tests, China’s Air Force decided to replace AL-31FN-SER3 with Taihang modified engine to achieve mass production in advance.
In September 2017, J-20 with the Taihang WS-10 engines had its maiden flight. After two years of test flights, the aircraft should have passed the design appraisal and can be put into mass production. The domestic improved Taihang WS-10 engine thrust is about 13.2 tons. This index is the same as or similar to AL-31FN-SER3, so it will not affect the flight and maneuverability of the aircraft after the replacement. In addition, the Taihang modified engine adopts single crystal blades and FADEC. With advanced technologies such as systems, reliability and fuel consumption have also increased significantly, and overall performance is better than the introduction of AL-31FN-SER3 engine. In particular, it is worth mentioning that the Taihang engine is also planned to have enhanced performance. The latter’s maximum thrust is increased to more than 14 tons, and even 15 tons in emergency situations. These indicators are almost the same as the WS-15 engine. It is not excluded that J-20 will have such engines in the future, to improve the performance of J-20, and gain time for WS-15 development.
It is believed that China can produce about 50 four-generation dual-engine heavy fighters in one year, and the output of the Taihang WS-10 engine is more than 100. Chengdu has three J-20 pulse production lines and can produce 36 J-20 fighters per year. Considering the spare engine, 80 Taihang WS-10 engines would be needed, which should be sufficient in terms of engine capacity. Therefore, from 2020 onwards, the Chinese Air Force may be equipped with J-20 fighters in batches, with a speed of up to one aviation brigade per year, and a certain capacity to produce J-16 fighter-bombers.
After 2020, the mass production of the J-10C fighter will also come to an end. And Chengdu should also increase the J-20 production line to further increase production capacity, and J-20 assembly speed will continue to accelerate. As for the WS-15 engine, China’s famous aviation engine expert Jiang Hefu has revealed that WS-15 is close to maturity and it is estimated that it will be put into use in a few years. It can be speculated that the WS-15 engine may be installed onto J-20B around 2020, considering that it takes a period of time for the test flight, and a small batch production trial after the test flight, so the complete state of J-20B fighters can be put into mass production in about 2025, replacing the current J-20A fighters.