On 25 September 1997 the S-37 Berkut (royal eagle) made its maiden flight from the flight test centre airfield at Zhukhovskii. The S-37 (sometimes referred as the Su-47) is being developed by Sukhoi to explore the post-stall maneuverability and supermaneuverability. Although very much a research aircraft and concept demonstrator in its present form, it formed the basis of a fifth generation Russian Sukhoi PAK FA stealthy air superiority fighter.
The most radical aspect of the Berkut is its forward swept wing, 90 per cent of which is of composites construction to ensure adequate torsional stiffness. The very advanced aerodynamic configuration includes strakes, canards, wing leading edge root extensions, tailplanes and twin fins. Combined with extensive use of radar absorbent materials, these are carefully shaped to minimize radar cross section. It is of similar size to the MiG 1.44.
The S-37 shares many components with the Su-27, including the strengthened undercarriage developed for the naval Su-33, tailfins and canopy. It is reported to be fitted with the quadruplex fly-by-wire system of the Su-35/Su-37.
Little hard information regarding the S-37's present or future capabilities has been revealed. Almost certainly, it is not flying with engines representative of a production fighter derivative. It further lacks radar, mission systems or weapons but clearly has provision for their installation, as evidence by the various dielectric panels, and radomes around the airframe as well as mock-up infra-read search and track and exhaust vent for an internal gun.
Weapons carriage is said to be either on conventional pylons or in a semi-conformal arrangement to minimize radar cross-section. The type may also have an internal weapons bay.