the sukhoi su-47 "berkut" () (nato reporting name firkin), also designated s-32 and s-37 (not to be confused with the twin-engined delta canard design offered by sukhoi in the early 1990s under the designation su-37) during initial development, was an experimental supersonic jet fighter developed by sukhoi aviation corporation. a distinguishing feature of the aircraft was its forward-swept wing that gave the aircraft excellent agility and maneuverability. while serial production of the type never materialized, the sole aircraft produced served as a technology demonstrator prototype for a number of advanced technologies later used in the 4.5 generation fighter su-35bm and current fifth-generation jet fighter sukhoi su-57.