What's in the Name?
The S-32 (do not mix with Su-32!) is an internal Sukhoi OKB designation which is rationalized in terms of commonly used yet controversial indexing originated with Sukhoi Su-7 and Su-9 prototypes. These were designated S-1 and T-1 respectively, with "S" being a first letter of swept wing in Russian "Strelovidnoe krylo" and "T" from the Russian for delta wing "Treugol'noe krylo". Clearly, the "S" in S-32 implies that new Sukhoi has a swept wing but the index conflicts with another S-32 taken by Sukhoi Su-17 prototypes few decades ago. There is a great deal of hints that S-32 is a phony designation and presently a different designation is used in conjunction with new Sukhoi fighter -- S-37 (do not mix with Su-37!). The S-37 index was formerly allocated to a single-engined lightweight multirole combat aircraft broadly similar to French Rafale which was cancelled in 1994. In any event, both S-32 and S-37 are internal bureau designation, and could become Su- anything. Reported name of S-37 is Berkut (Ber-koot) which means golden eagle in Russian.
From Tailless Canard to Tandem Triplane
The fifth-generation Sukhoi fighter features forward-swept wings (FSW), canards and twin outward-canted vertical stabilisers and incorporates low-observable and thrust-vectoring technologies. Comparing blown up photograph of the scale model and early speculative sketches and artist renderings, which appeared in western aviation press, it is clear that S-37's forward-swept wing is closely coupled to canards. Nonetheless, the aircraft retains the horizontal stabilisers, evolving from pure canard to a tandem triplane layout. The first S-37 photographs show that the stabilizer are highly swept (ca 70 deg) and their leading edges appear to extend aft from the wing roots of FSW. This is very different from X-29A strakes which were extensions of the wing roots themselfs ending with a trailing edge flaps.
The tandem triplane configuration was test flown in 1985 on T-10-24 which served as one of the naval Flanker prototypes. The addition of the canards, referred PGO in Russian (Perednee Gorizontal'noe Operenie - Forward Horizontal Stabilizers), solved the control problems encountered at high angle-of-attack (AOA) flight regimes when the tailerons lost their efficiency in the wake of the wing. The PGO's seemed to be a favourite choice for forth-and-a-half generation of Sukhoi's Su-34, -32FN, -35 and Su-37 and fifth-generation S-37 and S-54.
Although the genesis of the S-37 remains unclear, some sources suggested that original layout was much closer to X-29A tailless scheme and that aerodynamic of early S-37 directly benefited from Central Aerohydrodynamics Institute (TsAGI) wind-tunnel tests with X-29A scale models. It is possible that S-32 may be a technology demonstrator, built to examine FSW aerodynamics and composite wing structures or may have started its life as one, but realities of 90's urged Simonov to take this project one step further in attempt to present the S-32 as a genuine contender for a fifth-generation fighter seeked by the Russian air force. This might explain the fact that the S-32 seems to be much too heavy for a research testbed, being a considerably larger aircraft than Northrop F-5 sized X-29A.
In fact, the S-37 is in the class of Su-27 as seen from comparison of its scale model to the advanced Su-27 Flanker model presented at the same meeting. Moscow Aerospace (MAKS 97) provided additional data on S-37 and confirmed that dimensions, performance and tandem triplane layout of the S-37 are similar to that of Su-37. First public photographs of the S-37 suggested that the front part of the fuselage including the "hooded cobra" LERX could have come from the original S-37 canard-delta. If true, this could possibly clear up the origins of the S-37 index.
Forward Swept Wing
The early Soviet designs to feature moderately forward swept wing were Belyaev's DB-LK and Babochka aircraft and Mikoyan Gurevitch PBSh-2 (MiG-6) biplane. Captured at the end of WWII, German FSW Junkers Ju-287 was test flown by German and Russian crews. A six engined EF-131 was build and underwent extensive structural and flight testing until 1947, when theme was closed. At about the same time Pavel Tsybin build several testbeds LL (Letauchaya Laboratoriya) -1, -2 and -3 with stright, swept back and forward swept wings respectively (40 degrees). The LL-1 and LL-3 rocket powered gliders performed number of powered flights and provided TsAGI with much needed FSW data. In one of the flights LL-3 reached Mach 0.97 in dive.
Wingspan: 16.7 m
Length overall: 22.6 m
Height overall 6.40 m
Weight empty, equipped : 24,000 kg (52,910 lb)
Max T-O weight : 34,000 kg (74,960 lb)
Max level speed at height : 2,500km/h (1,350 knots)
Max level speed at S/L : 1,400km/h (756 knots)
Service ceiling : 18,000 m (59,050 ft)
Range with max fuel at height : 1,782 nm (3,300 km/2,050 miles)
Number of hardpoints: 14: 2 wingtip, 6-8 underwing, 6-4 conformal underfuselage
Air-to-air : R-77, R-77PD, R-73, K-74
Air-to-surface: X-29T, X-29L, X-59M, X-31P, X-31A, KAB-500, KAB-1500