Sukhoi S-37 Berkut

The S-37 is a demonstration-experimental aircraft intended to try out new key technological solutions in aerodynamics, flight control systems, and aircraft flight dynamics. The salient feature of this aircraft is its forward-swept wing (FSW) configuration. The choice of this configuration is the result of the Bureau’s efforts to find new approaches to enhancing aircraft aerodynamics, primarily maneuverability.

The S-37, however, is almost twice the size of the X-29, with a markedly different configuration. It has a length of 74 ft. and a wingspan of 54 ft. 10 in., with a maximum takeoff weight of just under 75,000 pounds. Power comes from two Aviadvigatel (Perm) D-30F6 turbofans, each developing 34,177 pounds of static thrust with afterburners—but without a thrust-vector ring. Together the engines give the S-37 a respectable, if unspectacular, top speed of around Mach 1.6. The aircraft may be re-engined with Sukhoi's preferred option of two Lyulka (Saturn) AL-41F turbofans with thrust vectoring, when these formidable engines—which pour out 39,350 pounds of static thrust with afterburners—become available.

For the first time in developing such a complex aircraft, the Sukhoi Design Bureau has introduced a unique technique of nondestructive testbed structural testing. The technique enabled the developer to start build-ing the flying prototype at once. A large num-ber of innovative technical solutions were employed, which allowed the same airframe to be used for both static and flight trials. In developing the S-37, innovative techniques have been devised ensuring accurate extrapo-lation of the design's ultimate structural loadings based on the testbed-shown operational loadings and structural stresses, i.e. without damaging the aircraft in the tests. This resulted in a significant reduction in the program costs and terms.

The flight trials confirmed the estimated advantages the forward-swept wing aircraft enjoy. With the S-37 going supersonic, the Sukhoi Design Bureau completed the major test phase. The results produced have surpassed the designers' preliminary estimates. The aircraft retains its stability and controllability at very high angles of attack in subsonic modes, with its maneuverability being far superior to that of the Su-27. According to test pilot Igor Votintsev, while travelling at supersonic speed the S-37 shows no specific peculiarities and is controlled just as other supersonic aircraft, with its stability and ease of control remaining as good as in subsonic modes.

Specifications:
wingspan: 16.7
lenght overall: 22.6
heigth overall: 6,4
Maximum speed (km/h): at height= 2500; at S/L= 1400
Weight empty (kg): 24'000
Engine: D30F6/AL-31FU
Thrust: 2 x 15'500 kg
Service ceiling: 18000 m
Range (km): 3300
Number of hardpoints: 14: 2 wingtip; 6-8 underwing; 6-4 conformal underfus. + GSh-301
Air-to-air missiles: KS-172 (AA, range=400km), RVV-AE, R-77; R-77PD; R-73; K-74
Air-to-Surface: X-29T; X-29L; X-59M; X-31P/A; KAB-500/1500