The Sukhoi Su-57 (; NATO reporting name: Felon) is a twin-engine stealth multirole fighter aircraft developed by Sukhoi. It is the product of the PAK FA (, ) programme, which was initiated in 1999 as a more modern and affordable alternative to the MFI (Mikoyan Project 1.44/1.42). Sukhoi's internal designation for the aircraft is T-50. The Su-57 is the first aircraft in Russian military service designed with stealth technology and is intended to be the basis for a family of stealth combat aircraft. A multirole fighter capable of aerial combat as well as ground and maritime strike, the Su-57 incorporates stealth, supermaneuverability, supercruise, integrated avionics, and substantial internal payload capacity. The aircraft is expected to succeed the MiG-29 and Su-27 in the Russian military service and has also been marketed for export, the fighter is expected to have a service life of up to 35 years. The first prototype aircraft flew in 2010, but the program would experience a protracted development due to various structural and technical issues that emerged during trials, including the destruction of the first production aircraft in a crash before its delivery. After repeated delays, the first Su-57 entered service with the Russian Aerospace Forces (VKS) in December 2020. Development Origins In 1979, the Soviet Union outlined a need for next-generation fighter aircraft intended to enter service in the 1990s. The programme became the I-90 (, ) and required the fighter to be "multifunctional" (i.e. multirole) by having substantial ground attack capabilities, and would eventually replace the MiG-29 and Su-27 in frontline tactical aviation service. Two subsequent projects were designed to meet these requirements: the MFI (, ) and smaller LFI (, ), with conceptual work beginning in 1983. Mikoyan was selected for the MFI and began developing its MiG 1.44/1.42. Though not a participant in the MFI, Sukhoi started its own programme in 1983 to develop technologies for a next-generation fighter, eventually resulting in the forward-swept wing S-32 experimental aircraft, later redesignated S-37 and then Su-47. Due to a lack of funds after the dissolution of the Soviet Union, the MFI was repeatedly delayed and the first flight of the MiG 1.44/1.42 prototype did not occur until 2000, nine years behind schedule. Owing to the high costs, the MFI and LFI were eventually cancelled while the Russian Ministry of Defence began work on a new next-generation fighter programme; in 1999, the ministry initiated the PAK