Test Flight of China’s J-20 with 4 Auxiliary TanksPosted: December 27, 2016
The above photo of test flight of J-20 no. 2012 with four auxiliary tanks is taken from a recent footage by a web user.
Source: mil.huanqiu.com “Seen for the first time! Test flight of a J-20 with 4 auxiliary tanks” (summary by Chan Kai Yee based on the report in Chinese)