Last week, we got news out of India that they are not happy with the progress of PAK-FA project. The article says that IAF found FGFA (their version of PAK-FA) to be too expensive, not have enough technology sharing with India and use inadequate engine solution. On top of that, IAF has also declared in the most recent meeting that the radar is inadequate and the stealth features badly engineered.
So, what does all of this tell us? It sounds to me that IAF's biggest concern here is with their work share in the project. They are trying to put the pressure on the Russians to share more of the technology that Russia is simply not prepared to share. We've heard similar complaints from India in the past regarding other projects with Russians. The other complaint of escalating costs seems also be a negotiation tactic. Cost overrun seems to be a common issue with all the new military aviation projects. The article itself even mentioned that MMRCA project's escalating costs is part of the reason that IAF is complaining here.
The technical issues are something that I think PLAAF followers should look carefully at. We know that China still depends very heavily on Russia in high performance turbofan engines right now. China invested large amount of resources in the 99M project, which is still lagging in progress to the 117S project used on Su-35. If Russia is having trouble developing and mass producing a new generation of engine for 5th gen aircraft, then one can imagine the stumbling blocks facing WS-15 project and other next generation Chinese turbofan projects. Up to now, all indications are that WS-15 development is going well, but as we've seen from WS-10 project, the mass production version of a new engine takes some time to sort out problems. So, it remains to be seen whether or not WS-15 will be ready by the end of this decade.
The other issue of inadequate radar with PAK-FA is less of an issue with J-20. China is ahead of Russia in electronics and are ready to cost efficiently produce the components needed for AESA radar, whereas Russia is not. I believe that China has even tried to sell AESA radars to Russia. It appears that J-10B and J-16 will be equipped with the 1st and 1.5th generation of AESA radar, so China's AESA technology should be a lot more mature by the time J-20 is in mass production. Even so, one has to look at the whole systems of avionics. F-35 is said to have more than 8 million lines of code to manage all of the weapon and sensory subsystems to give unprecedented situation awareness to the pilot. However with such a complex system, any software engineer can tell you that it would take a long time to test out such a complicated system. There is quite a few articles on issues with the complexity of F-35 code. When it comes to J-20, CAC has smartly been using J-10B as a testbed for a bunch of next generation avionics that will help with J-20's integrated avionics architecture development. I think it partly explains why J-10B took so long to go into production. When it comes to J-20, we are likely to see similar delays due to avionics that we've seen with F-35. My guess is that IAF chief will be complaining a lot about avionics delays on PAK-FA as we get closer to induction time.
Stealth is probably the biggest issue with PAK-FA compared to western definition of 5th generation aircraft. When I look at PAK-FA, it looks to be stealthier than the 4th generation fighter jets, but just can't compare to F-22/35. IAF chief would have known about this all along. Just in my non-professional eyes, J-20 looks to be stealthir than PAK-FA, but is probably closer to PAK-FA in lo technology than F-22/35. Stealth technology is probably the biggest advantage that Lockheed and Boeing have over the Russian and Chinese aircraft companies.
So I find that IAF complaints over PAK-FA just shows how difficult it is to develop 5th generation aircraft. Only US, China and Russia are actively developing these aircraft. And if you ask some Western defense analyst, they would say J-20 and PAK-FA don't qualify as truly lo platforms. These are extremely advanced technologies, so it's not surprising that Russia is reluctant to share them with India. Cost escalations are common. We don't really hear about it on Chinese military aviation projects, but it probably has similar cost escalation as F-35 and PAK-FA. From that, I think it's quite interesting that China can still afford J-20 and J-31 (supposedly will be made official PLAAF project) at the same time.