Su-35 is useful to PLAAF. It's able to demonstrate what MKI's performance could be like. It could also show some of what Su-57's subsystems are like. PLAAF will be able to find out whether Russian claims of being able to detect stealth fighters are correct with their wing mounted L bands. If Su-35 can detect J-20 at range, Su-57 definitely can therefore Indian FGFA can too. If Su-35 cannot, it doesn't mean Su-57 cannot, but it's unlikely to. It's a way of finding out what the best and near best (for future) is like for RuAF and IAF. Also useful for:
1. Interception of Japanese and US planes without exposing signatures and radar emissions of backbone fighters.
2. Comparing domestic TVC technologies to Russian one. It takes many years if not a decade to nail TVC and if J-10 is being tested with one (assuming tests haven't been done prior to the recent leaks) that means Chinese have been working on TVC on WS-10 for many years already. Some sources indicate since at least 2012.
3. Comparing J-11D after. Since J-11D was not selected, it's either back to the drawing board to come up with something that matches or is superior to Su-35. Otherwise PLAAF has no problem buying more from Russia when domestic equipment doesn't measure up. AL-31 on J-10 is indicative that current WS-10 variants are not reliable enough. It is good to know that what is considered not good enough is not fielded or purchased from Russia where possible. This is promising since most equipment in PLAAF is now Chinese.
4. There's a possibility SAC and other guys will be able to reverse engineer certain parts of Su-35 for future Chinese flanker variants.
5. Good look at 117 engine and most powerful PESA radar on a fighter. Again things to learn from here.
Personally I think the most likely reason is to test the best Russia has to offer against PLAAF inventory without only doing exercises with Russia using J-20 that reveals too much. See if their claims on detecting stealth has merit. Su-57 doctrine is to win WVR fight. Jam, confuse etc enemy missiles until they are exhausted (F-22 only has max of 6 MRAAMs) and win WVR if merged. PLAAF wants to see Russian doctrine based equipment vs their own which follows US method of hide, shoot, run. This is important since Russia and India are the biggest air threats to China outside of USA. Su-35 offers a look into this. If it works, we'll see PLAAF use similar methods to defend against US F-35 and F-22s. Possibly even purchase a squadron or two of Su-57 in a decade. Also offers PLAAF ideas on how to overcome Russian and Indian next gen and workhorse fighters. If they don't already.
1. Interception of Japanese and US planes without exposing signatures and radar emissions of backbone fighters.
2. Comparing domestic TVC technologies to Russian one. It takes many years if not a decade to nail TVC and if J-10 is being tested with one (assuming tests haven't been done prior to the recent leaks) that means Chinese have been working on TVC on WS-10 for many years already. Some sources indicate since at least 2012.
3. Comparing J-11D after. Since J-11D was not selected, it's either back to the drawing board to come up with something that matches or is superior to Su-35. Otherwise PLAAF has no problem buying more from Russia when domestic equipment doesn't measure up. AL-31 on J-10 is indicative that current WS-10 variants are not reliable enough. It is good to know that what is considered not good enough is not fielded or purchased from Russia where possible. This is promising since most equipment in PLAAF is now Chinese.
4. There's a possibility SAC and other guys will be able to reverse engineer certain parts of Su-35 for future Chinese flanker variants.
5. Good look at 117 engine and most powerful PESA radar on a fighter. Again things to learn from here.
Personally I think the most likely reason is to test the best Russia has to offer against PLAAF inventory without only doing exercises with Russia using J-20 that reveals too much. See if their claims on detecting stealth has merit. Su-57 doctrine is to win WVR fight. Jam, confuse etc enemy missiles until they are exhausted (F-22 only has max of 6 MRAAMs) and win WVR if merged. PLAAF wants to see Russian doctrine based equipment vs their own which follows US method of hide, shoot, run. This is important since Russia and India are the biggest air threats to China outside of USA. Su-35 offers a look into this. If it works, we'll see PLAAF use similar methods to defend against US F-35 and F-22s. Possibly even purchase a squadron or two of Su-57 in a decade. Also offers PLAAF ideas on how to overcome Russian and Indian next gen and workhorse fighters. If they don't already.
... and I'm sure the PLAAf known quite well WHY they bought that bird.
