Week of October 27, 1997

Sukhoi Can't Hide Its 5th Generation Fighter, The S-37

By Vovick Karnozov

Two prominent Russian newspapers - the Commersant Daily and the Nezavisimaya Gazeta (Independent Newspaper) - published the first aerial photos of the S-37 "Berkut" fighter, the latest model from Sukhoi design bureau. The aircraft is depicted at the airport of Gromov's Flight Test and Research Institute in Zhukovsky, where it is undergoing flight testing. The pictures, provided by the Sukhoi design bureau, show a Su-27-sized twin-engined single-seater with canards, forward- swept wings, stabilisers and two outward-canted vertical fins. Unlike the F-117 and F-22, the Russian aircraft has round engine nozzles.

Describing the S-37 as a "super-agile supersonic stealth fighter," the Commersant Daily newspaper gives the following data on the aircraft - length 22.6 m, wing span 16.7 m, typical take-off weight 24 t, maximum speed 2,200 km/h, powerplant of two engines developing a 25-t thrust.

Just to compare - the previous model from Sukhoi, the Su-30MKI for the Indian Air Force, is 22 m in length, with a wing span of 14.7 m and typical take-off weight of 24,000 kg. Remarkably, its two Lulka-Saturn AL-31FU engines also develop a thrust of 25 t. It is believed, therefore, that the powerplant of the two types is the same. There is no information, however, that the S-37 first prototype, Number "01," is fitted with thrust-vectoring nozzles.

Sukhoi stresses that the S-37 had its maiden flight two weeks after its US rival, the Lockheed-Martin/Boeing F-22 Raptor. Now, once the pictures of both aircraft have been revealed, it is possible to draw a comparison between them.

At first glance, the Russian fighter promises to do better in a combat dogfight. Big canards and extensive fuselage extensions to the backward-swept wing should give the S-37 a higher critical angle of attack in comparison with the Raptor, which features a classic aerodynamic layout. There is no doubt that the F-22 is capable of high-alpha flying, but US fighter- designers have yet to prove that their designs can perform the Cobra, Hook, Chakra and other maneuvers invented by Sukhoi pilots. Although combat worthy of these maneuvers is often questioned, the very ability to perform them says a lot about performance of aircraft and engines.

In its turn, the US fighter looks more "stealthy" for short-wave radars. At the same time, the F-22 is physically bigger, and, therefore is seen better at the screens of long-wave stationary surveillance radars, like the 1R13 and 55Zh6 models in production at Nizhny Novgorod. These work in VHF band, where "stealth" aircraft lose their invisibility.

Two Pratt & Whitney F-119 engines on the Raptor produce a thrust of about 32 t, some 7 t more that the S-37's powerplant. This suggests that the heavier US fighter has higher thrust/weight ratio. In dogfight this possible advantage is fully compensated for by the S-37's integral tri-plane layout and wide-spread wings. This combination offers better lift/weight ratio, especially at high-alpha, than the classic aerodynamic layout.

Press reports say that aluminium parts account for 16% of the Raptor's structural weight, and titanium ones for 39%. The share of composites is 24%. The S-37 is believed to have more composites and less of metals.

Despite being very advanced, the F-22 is not the most dangerous enemy for the S-37. Mikoyan design bureau is known to be finishing preparation of its MFI (for Multi-Functional Fighter, and also known as Article 1.42) for the long-awaited first flight.

The MFI has two 20-t Lulka-Saturn AL-41 engines, which give the fighter a very high thrust/weight ratio. According to specialists working at the Central Aerohydrodynamics Institute (TsAGI), the MFI is so aerodynamically advanced as to easily win the title "King of Fighters." In the anticipated battle between the MFI and S-37 for a Russian Air Force order, however, the advantage in aerodynamics will hardly be of any importance. The most important factor will be personal relations between heads of the competing design offices with generals, financiers and political leaders.

[Editor's musings: Somewhere over the north Atlantic two pilots wait, each in their country's latest, hottest bad boy fighter. Watching on long-range radar, each plots out the ideal engagement, then powers toward the adversary.

It seems highly unlikely this high-drama scenario will ever get played out in a mock aerial combat arena. Too bad.]

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