High Quality Content by WIKIPEDIA articles! The Sukhoi Su-47 Berkut (Russian: Су-47 Беркут - Golden Eagle) (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 5th generation fighter prototype Sukhoi PAK FA.