On Saturday afternoon, I saw murky pictures of this new aircraft appearing on Chinese bbs that were supposedly SAC (Shenyang Aircraft Corporation)'s 5th generation fighter jet project. Originally, the picture looked fishy to me and I thought it might be photo shopped from F-35. Since then, we've gotten clearer photos and it does look real.
It's been long speculated that SAC has also been working on a 5th generation design despite loosing the main 5th generation project to CAC (Chengdu Aircraft Corporation). While CAC has been getting all the funding from PLAAF for the J-20 project, SAC's design was more of a self funded project that may or may not have received a PLAAF designation. The Chinese forums have been referring to this project as J-31 after seeing the serial number 31001 on the plane (and 2001/2002 for J-20 project). Regardless, the following of this project has been gathering steam over the past year. The first significant sighting was the unveiling of an export version at the first International UAV Innovation Grand Prix commonly referred to as F-60 as shown below.
A few months ago, we saw this covered up aircraft moved around which many people speculated to be SAC's 5th generation project.
And by Sunday, we've gotten this much clearer photo of the so called "J-31". At this point, there is still plenty of mystery regarding this aircraft. It looks to be much smaller than J-20. If PLA decides to order it at some point, it could form a hi-lo combination with J-20. There has been a lot of speculation that this aircraft will get navalized at some point due to the appearance of twin front landing gear and PLAN's stated desire for a next generation naval fighter jet. It also appears that 2 RD-93s have been fitted for this aircraft initially until the engine designed for this aircraft becomes available (so there won't be the gap with the exhaust).
This aircraft could end up as China's F-35 or it could be a privately funded project that will be competing against something from CAC as the lo part of PLAAF's hi-lo combination or it could be an export project. There is a lot that we certainly don't know yet.