Just as russia has bribed(stolen) the plans for stealth technology from american democrats.. American technology is moving to UNmanned stealth fighters.. Thats gotta hurt..
From pictures that I’ve seen of PAK-FA I have to question it’s stealth. The engine intakes are very prominent & it down’t look like they made any effort to ‘hide’ the front face of the engine compressor. That is not stealth by any stretch.