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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. The NATO reporting name for this aircraft is 'Firkin'. A distinguishing feature of the aircraft is its forward-swept wing, similar to that of the Grumman X-29. Although the Berkut has been referred to as the Su-47 since 2002, suggesting that it is a ready-for-production warplane, it will more likely be heavily redesigned (as part of the Prospective Air Complex for Tactical Air Forces or PAK FA program) before any series production begins. The Su-47 designation may or may not be reused for the PAK FA design.
History
Originally known as the S-37, Sukhoi redesignated its advanced test aircraft as the Su-47 in 2002. The change reflected the company's decision to market the design as a production fighter rather than as an experimental prototype. Also commonly referred to as the Berkut (Golden Eagle), the S-37 was originally built as Russia's principal testbed for composite materials and sophisticated fly-by-wire control systems. The aircraft makes use of forward-swept wings allowing superb maneuverability and operation at angles of attack up to 45° or more.
The TsAGI has long been aware of the advantages of forward swept wings, with research including the development of the Tsibin LL and study of the captured Junkers Ju 287 in the 1940s. Forward-swept wings offer lower wave drag, reduced bending moments, and delayed stall when compared to more traditional wing shapes. Unfortunately, forward sweep also induces twisting (divergence) strong enough to rip the wings off an aircraft built of conventional materials. Only recently have composite materials made the design of aircraft with forward-swept wings feasible.
Like its western counterpart, the Grumman X-29, the S-37 was primarily a technology demonstrator, one intended to lay the foundation for the next Russian fighter. Such a fighter must not only be as advanced as the US F-22 Raptor and Eurofighter Typhoon, but must also compete for funding with the more conventional MiG 1.42. However, Sukhoi is now attempting to market the S-37 to the Russian military and foreign customers as a production fighter in its own right. Initial reaction was not good, but the aircraft's performance has been so impressive that the Russian government has made funds available for further testing of the design.
Design
The S-37 is of similar dimensions to previous large Sukhoi fighters, such as the Su-35. To reduce development costs, the S-37 borrowed the forward fuselage, vertical tails, and landing gear of the Su-27 family. Nonetheless, the aircraft includes reduced radar signature features (including radar absorbent materials), an internal weapons bay, and space set aside for an advanced radar. Though similar in overall concept to the American X-29 research aircraft of the 1980s, the S-37 is about twice the size and far closer to an actual combat aircraft than the US design.
To solve the problem of wing-twisting, the S-37 makes use of composite materials carefully tailored to resist twisting while still allowing the wing to bend for improved aerodynamic behavior. Due to its comparatively large wingspan, the S-37 is to be equipped with folding wings, in order to fit inside Russian hangars. Like its immediate predecessor, the Su-37, the Berkut is of tandem-triplane layout, with canards ahead of wings and tailplanes. Interestingly, the S-37 has two tailbooms of unequal length outboard of the exhaust nozzles. The shorter boom, on the left-hand side, houses rear-facing RADAR, while the longer boom houses a brake parachute.
Any production S-37 would presumably be able to carry most air-to-air missiles in service with the Russian and Indian Air Forces, including the AA-12 Adder, AA-11 Archer, and AA-10 Alamo. It does not appear to be capable of carrying the Novator KS-172 AAM-L long-range missile, developed for use on the Su-27 series, Mikoyan MiG-31, and MiG 1.44.
General information
Maneuverability
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, and it also retains maneuverability in supersonic flight.Maximum turn rates and the upper and lower limits on air speed for weapon launch are important criteria in terms of combat superiority. The Su-47 aircraft has very high levels of maneuverability with maintained stability and controllability at all angles of attack.
Maximum turn rates are important in close combat and also at medium and long range, when the mission may involve engaging consecutive targets in different sectors of the airspace. A high turn rate of the Su-47 allows the pilot to turn the fighter aircraft quickly towards the next target to initiate the weapon launch.
The swept-forward wing, compared to a swept-back wing of the same area, provides a number of advantages: higher lift to drag ratio; higher capacity in dogfight maneuvers; higher range at subsonic speed; improved stall resistance and anti-spin characteristics; improved stability at high angles of attack; a lower minimum flight speed; and a shorter take-off and landing distance.
Fuselage
The Berkut's fuselage is oval in cross section and the airframe is constructed mainly of aluminium and titanium alloys and 13 per cent by weight of composite materials.The nose radome is slightly flattened at the fore section and has a horizontal edge to optimise the aircraft's anti-spin characteristics.
Wings
The forward swept midwing gives the unusual and characteristic appearance of the Su-47. A substantial part of the lift generated by the forward-swept wing occurs at the inner portion of the wingspan. The lift is not restricted by wingtip stall. 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.The wing panels are constructed of nearly 90% composites. The forward-swept midwing has a high aspect ratio, which contributes to long-range performance. The leading-edge root extensions blend smoothly to the wing panels, which are fitted with deflectable slats on the leading edge; flaps and ailerons on the trailing edge.
The all-moving and small-area trapezoidal canards are connected to the leading-edge root extensions.
The downside of this wing design is that it produces strong rotational forces that try to twist the wings off, especially at high speeds. This twisting necessitates the use of a large amount of composites in order to increase the strength of the wing. Despite this, the plane was initially limited to Mach 1.6. Modifications have raised this limit, but the new limit has not been specified.
Cockpit
The cockpit's design has focused on maintaining a high degree of comfort for the pilot and also on the pilot being able to control the aircraft in extremely high g-load manoeuvres. The aircraft is equipped with a new ejection seat and life support system. The variable geometry adaptive ejection seat is inclined at an angle of 60°, which reduces the impact of high g forces on the pilot. The seat allows dogfight manoeuvres with significantly higher g loadings than can normally be tolerated by the pilot.The pilot uses a side-mounted, low-travel control stick and a tensiometric throttle control.
Specifications (Su-47)
Su-47 in fiction
- The S-37 is featured in the novel Scarecrow by Matthew Reilly as the Black Raven, the primary plane of the Black Knight, Aloysius Knight. However, it was called an S-37 before its name was revealed.
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