The PLA's Red Eagle display team flies in close formation. [Photo by ZHANG WEI/CHINA DAILY]

According to Gao, the thrust vector control nozzle on the J-10B is the most complicated and advanced of its kind in the world. However, he said engineers will need to conduct numerous tests and make many modifications before the technology is fully ready for the J-20.

China has designed and constructed two fifth-generation stealth combat aircraft-the J-20 and the FC-31.

The J-20, designated as a future pillar of the PLA Air Force, made its maiden flight in January 2011, and was declassified in November 2016. It was commissioned to the Air Force last year, becoming the world's third stealth fighter to enter service, after the F-22 and the F-35.

The FC-31, which appears to have been developed for export, was first flown in October 2012 and has taken part in several Zhuhai Airshows as well as arms shows overseas. It is believed to be undergoing test flights. It is not known if the FC-31 will use a thrust-vectoring engine.