The Sukhoi Su-47 Berkut (Russian: Су-47 Беркут - Golden Eagle), also designated S-32 and S-37 during initial development, is an experimental supersonic jet fighter developed by Sukhoi Aviation Corporation. A distinguishing feature of the aircraft is its forward-swept wing, similar to that of the Tsybin's LL-3.[1] Its NATO reporting name is "Firkin". The sole aircraft produced is an advanced technology demonstrator prototype and manufacture of a planned second flying prototype is under question due to recent MIG developments of 5th generation Jet fighters.