Russia's Testing Their New Secret 6th Gen Fighter Will Replace SU-57

The Su-57, code-named T-50 and nicknamed by NATO, "Felon", was conceived as a heavy multi-role fighter capable of replacing the Su-27.
The requirements for the aircraft of the future, as well as the first developments, appeared in the 90s of the last century. Two Soviet design bureaus, Sukhoi and Mikoyan, worked on such projects as the Berkut (Su-47) and MiG 1.44. Both, however, were never completed, mostly due to lack of funding and the rather tense situation in the country. But despite their sad fate, the prototypes have made a significant contribution to the development of the T-50, because it was on them were worked out many of the technologies used today on the fifth generation.