Originally Posted by
Brat
How many are flying?
I recall in late 2017 there were 10
https://ru.wikipedia.org/wiki/%D0%A1%D1%83-57
It looks like they are delaying serial production because the production lines are busy producing Su-35 and -30 machines as the target numbers from AF are not yet reached. Assume it will be delayed further because even a shallow analysis of the recent conflicts show that "4+" generation planes can do the same job being much cheaper. And in the "armageddon" scenario all such planes do not matter. Thus, better take time for testing, upgrading engines, systems, etc. IMHO.