(a) "Recently someone in China anonymously posted performance data for the new Chinese J-31 fighter. This was in the form of a sales brochure (for trade shows) that had not been distributed to the public. So far the manufacturer has been vague about J-31 performance data. This despite the fact that the J-31 has been showing up at Chinese weapons shows. But so far this promotion has been all about looking at the impressive appearance of the J-31, not crunching any numbers.
"It gets more interesting when you realize that the recently posted data ascribes better engine performance than actual engines the Chinese have in service or access to. There were also descriptions of J-31 electronics that sounded more like a Chinese wish list than anything the Chinese have or are known to be developing. Many in the industry see this as some kind of desperate publicity stunt. Efforts to sell the J-31 have not been very successful so far.
(b) "One advantage the J-31 is that it has two engines, compared to one for the 31 ton F-35. In theory this means the J-31 could carry more weapons, but this is less crucial with all the guided weapons available. Moreover the J-31 is seen using Chinese engines, which are less powerful and reliable, even when two are used, compared to the single engine in the F-35C.
Note: "Recently someone in China anonymously posted performance data for the new Chinese J-31 fighter."