The T-50/Su-57 prototype first flew on January 29, 2010 and as of March 2018 there are 10 Su-57 prototypes and were renamed Felons that year. This is Russia’s first stealth aircraft and was designed to cope with the F-22 and F-35. The Su-57 is made from extensive use of composite material and radar absorbing material (RAM). The original AL-41F-1 engine is under powered and will be replaced by an Izdelie 30 which is under development. The Felon has super maneuverability, super-cruise, thrust-vectoring nozzles. Russia ordered 76 Su-57s.
The registration RF-81775 was originally used on the 10th and final flight prototype aircraft PAK FA, T-50-11 Bort 511 Blue delivered in 2021. 511 Blue was removed from the aircraft during a brief deployment to Syria. This same aircraft was used in a KnAAZ promotional video with tail number "52" in blue. Later the aircraft became Bort 52 Red, wearing RF-81775 on its tail and is intended for use with the 4th GTsPAP i PVI (4th State Air Personnel Training & Aircraft Evaluation Center) at the “Chkalov” base in Lipetsk.