Sukhoi Su-47

Su-47 Berkut
The Su-47 at an airshow in June 2007
General information
TypeExperimental aircraft/Technology demonstrator
ManufacturerSukhoi
Designer
StatusCancelled
Primary userRussian Air Force
Number built1
History
First flight25 September 1997; 29 years ago (1997-09-25)
Developed from
Sukhoi Su-37

The Sukhoi Su-47 Berkut (Russian: Сухой Су-47 «Беркут», lit. 'Golden eagle', NATO: Firkin, designated S-32 and S-37 during initial development) is a Russian twin-engine, forward-swept wing, supersonic technology demonstrator developed by the JSC Sukhoi Company.

Powered by two Soloviev D-30 engines, the forward-sweep was intended to give the aircraft increased 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 prototype for a number of technologies later used in Sukhoi's Su-35 fourth-generation fighter, and the Su-57 fifth-generation fighter.

The single model was first flown in 1997, and made regular appearances at Russia's MAKS air show until 2007, after which it made one appearance in 2019.

Development

Originally known as the S-37, Sukhoi redesignated its advanced test aircraft as the Su-47 in 2002. Officially nicknamed Berkut (Russian: Беркут; the Kazakh word for "Eagle"), the Su-47 was originally built as Russia's principal testbed for composite materials and sophisticated fly-by-wire control systems, as well as new airframe technologies.

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. At high angles of attack, the wing tips remain retracted allowing the aircraft to retain aileron control. Conversely to more conventional rear-swept wings, forward sweep geometrically creates increased angle of incidence of the outer wing sections when the wing bends under load. The wings experience higher bending moments, leading to a tendency for the wings to fail structurally at lower speeds than for a straight or aft-swept wing.

The project was launched in 1983 on order from the Soviet Air Force. However after the fall of the USSR, funding from the government was frozen and instead the project continued to be privately funded by Sukhoi. Like its US counterpart, the Grumman X-29, the Su-47 was primarily a technology demonstrator for future Russian fighters such as the Sukhoi Su-57. The forward-swept wing configuration was ultimately not pursued because it was mainly advantageous at transonic speeds while an aft-swept wing was superior at supersonic speeds.

Outline of the Sukhoi Su-47

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, carrying rearward-facing radar and a breaker-chute.

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 while retaining maneuverability in supersonic flight.

The forward-swept wings give the Su-47 an unconventional appearance. The inner portion of the wing generates a substantial part of the lift. This lift is not restricted by wingtip stall, and the lift-induced wingtip vortex generation is thus reduced. The aileron 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 disadvantage of such a forward-swept wing design is that it twists when under load, resulting in greater stress on the wing than occurs with 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 composite wing skins laid-up to twist. The aircraft 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 pursued further.

Thrust vectoring

The thrust vectoring (with PFU engine modification) of ±20° at 30°/second in pitch and yaw was intended to support the agility gained by other aspects of the design.

Status since cancellation

The Su‑47 Berkut was last seen publicly in August 2019 at the MAKS‑2019 air show in Zhukovsky, Russia. This was its first appearance since MAKS‑2007, making it a rare and unexpected sighting.

Specifications (Su-47)

Data from Jane's All the World's Aircraft 2000–01

General characteristics

Performance

1,400 km/h (870 mph; 760 kn) / M1.12 at sea level
458 kg/m2 (94 lb/sq ft) normal (approx.)
1.29 normal take-off weight

Armament

Avionics

See also

Related development

Aircraft of comparable role, configuration, and era

References

  1. ↑ "Su-47 / S-37 Berkut". globalsecurity.org. Retrieved 10 January 2016.
  2. ↑ Russian Aviation Page: Sukhoi S-37 Berkut (S-32) Archived February 13, 2006, at the Wayback Machine
  3. ↑ Mitchel, Gareth (22 July 2009). "What are the advantages of forward-swept wings in aircraft design?". Science focus. BBC. Retrieved 6 July 2024.
  4. ↑ Eastwood, Brent (29 November 2023). "Sukhoi Su-47 'Golden Eagle': Russia's First Stealth Fighter Failure". The National Interest. Center for the National Interest. Retrieved 19 June 2024.
  5. ↑ Butowski, Piotr (2021). Su-57 Felon. Stamford, UK: Key Books. p. 13. ISBN 978-1-913870-44-7.
  6. ↑ Roblin, Sebastien (30 July 2021). "The Original Russian Stealth Fighter: The Su-47". The National Interest. Retrieved 23 August 2023.
  7. ↑ Mitchell, Gareth (22 July 2009). "What are the advantages of forward-swept wings in aircraft design?". Future Technology. BBC Science Focus. Retrieved 2 July 2024.
  8. ↑ Zettlemoyer, Ryan. "WHAT ARE TIP STALLS? HOW DO THEY FORM?". Flite Test. Retrieved 22 June 2024.
  9. ↑ Mann, Michael; Mercer, Charles (November 1986). Forward-Swept-Wing Configuration Designed for High Maneuverability by Use of a Transonic Computational Method (PDF) (Technical report). Nasa Technical Paper. Vol. 2628. Retrieved 1 July 2024.
  10. ↑ "Methods of Reducing Induced Drag". U.S. Centennial of Flight Commission. Retrieved 1 July 2024.
  11. ↑ Demerly, Tom (27 August 2019). "MAKS 2019 Surprise Appearance: The Mysterious Sukhoi Su-47 Berkut Re-emerges". The Aviationist. Retrieved 10 July 2026.
  12. ↑ Jackson, Paul, ed. (2000). Jane's All the World's Aircraft 2000–01 (91st ed.). Coulsdon, Surrey, United Kingdom: Jane's Information Group. pp. 457–458. ISBN 978-0-7106-2011-8.
  13. ↑ "Су-47 (С-37) "Беркут" (Russian)". testpilot.ru. Retrieved 29 August 2020.
  14. ↑ "Su-47 (S-37 Berkut) Golden Eagle Fighter". airforce-technology.com. Retrieved 25 March 2020.

Bibliography