This jet was under development since 1970-1980 in Russia. It is only recently, that the materials, required for such design to work perfectly, were created. X-29 was just good-for-nothig toy.

The Su-47 has extremely high agility at subsonic speeds, enabling the aircraft to alter its angle of attack and its flight path very quickly while retaining maneuverability in supersonic flight. The Su-47 has a maximum speed of Mach 2.34 at high altitudes and a greater than 9g capability

Amazing what you can do when you copy someone else's design. Look up (wikipedia) the US X-29 from 25 years ago.