The Sukhoi Su-47 Berkut (Russian: Сухой Су-47 Беркут, lit. 'Golden Eagle') (NATO reporting name Firkin), also designated S-32 and S-37 during initial development, was a Russian experimental supersonic jet fighter developed by the JSC Sukhoi Company. 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 and the configuration was not further pursued, 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-35 and current fifth-generation jet fighter Su-57.
The Su-47 is of similar dimensions to previous large Sukhoi fighters, such as the Su-35. To reduce development costs, the Su-47 borrowed the forward fuselage, vertical tails, and landing gear of the Su-27 family. Nonetheless, the aircraft includes an internal weapons bay, and space set aside for an advanced radar.
Like its immediate predecessor, the Su-37, the Su-47 is of tandem-triple layout, with canards ahead of wings and tailplanes. The Su-47 has two tailbooms of unequal length outboard of the exhaust nozzles. The shorter boom, on the left-hand side, houses an ECM system, while the longer boom houses a rear-facing radar.
The Su-47 has extremely high agility at subsonic speeds, enabling the aircraft to alter its angle of attack and its flight path very quickly while retaining maneuverability in supersonic flight.
The forward-swept midwing gives the Su-47 its unconventional appearance. A substantial part of the lift generated by the forward-swept wing occurs at the inner portion of the wingspan. This inboard lift is not restricted by wingtip stall and the lift-induced wingtip vortex generation is thus reduced. The ailerons—the wing's control surfaces—remain effective at the highest angles of attack, and controllability of the aircraft is retained even in the event of airflow separating from the remainder of the wings' surface.
A downside of such a forward-swept wing design is that it geometrically produces wing twisting as it bends under load, resulting in greater stress on the wing than for a similar straight or aft-swept wing. This requires the wing be designed to twist as it bends—opposite to the geometric twisting. This is done by the use of composites wing skins laid-up to twist. The plane was initially limited to Mach 1.6. Because the forward sweep was primarily beneficial at transonic speed while losing out to aft-swept wing at supersonic speed, it was not further pursued.
The thrust vectoring (with PFU engine modification) of ±20° at 30°/second in pitch and yaw would have greatly supported the agility gained by other aspects of the design.
source text : wikipedia.org
link : https://en.wikipedia.org/wiki/Sukhoi_Su-47
