Sukhoi S-37 "Berkut" 5th Generation Russian Fighter
Air superiority/multirole fighter
Sukhoi's
new WIG aircraft projects
Summary of news and estimated technical information.
There was a lot of speculation following the publication of several articles in Russian and international press about the S-37 fighter. The first article to appear was the ITAR-TASS report of October 8, 1997, which informed the public about the test flights of the "S-32" fighter with forward-swept wing design piloted by Sukhoi's test pilot Igor Votintsev. he article mentioned
 Sukhoi S-37 "Berkut", Russia's 5th generation fighter. New in Sukhoi fighters forward-swept wing design integrated into the tandem triplane configuration. Visible in the tail section of the aircraft are two "stingers". One of them may contain a rearward-looking radar and the other - a break parachute. A rather interesting element: the "stingers" are of different length. At first it might appear that this is a perspective optical illusion, however, after a closer examination the difference in length of the "stingers" is obvious. It is reasonable to conclude that the longer "stinger" contains a spin-recovery parachute. However, the difference in size of the "stingers" can be also explained by a possibility of an aft facing radar. |
that the S-32 fighter is designed to use the thrust-vectoring AL-37FU engines, however, during the first test flights was using the more powerful D-30F6 engines from MiG-31, Russia's most advanced high-speed interceptor aircraft.
The next piece of information about the S-32 appeared simultaneously in Russian newspapers Kommersant-Daily and Nezavisimaya Gazeta (October 24, 1997), shortly followed by an Associated Press article. The article in Kommersant-Daily was accompanied by a photo of the S-32 fighter, which was referred to as S-37 "Berkut" (or "Golden Eagle"). The change of name from S-32 to S-37 caused a short-lived confusion whether the "Berkut" is the same S-37 fighter project officially confirmed by Sukhoi in 1991 which later came to a stall due to the lack of funding (its cancellation was never officially confirmed). The original, 1991 S-37 project was a smaller aircraft with a delta wing design and a single AL-41F engine. This apparently was not the case with the 1997 S-37 "Berkut": the new aircraft is significantly larger, it is equipped with two engines, and employs a forward-swept wing design. Thus, the "Berkut", apparently, took the place of the original S-37.
Perhaps one of the most interesting and confusing technical issue about the new Russian fighter is its engines. The Kommersant-Daily mentioned that the combined thrust of S-37's engines is 25 tons, or lb., no make of engine, however, was mentioned. The thrust of lb. is consistent with the two AL-31F engines commonly used on Russian Su-27 fighters. This, however, raised very interesting questions: why the significantly more powerful D-30F6 engines were used during the initial flight tests when there were AL-37FU engines available and why the engine thrust mentioned by the Kommersant-Daily is consistent only with the older AL-31F engines?
The available information suggests that the basic dimensions and weight of the S-37 "Berkut" are similar to those of Su-37 (see table below). While the main advantage of the forward-swept wing design is the improved maneuverability at subsonic speeds and high angles of attack its primary drawbacks are the reduced lift and handling problems at supersonic speeds. A natural way to counter such problems is by using more powerful engines and an advanced thrust-vectoring controls. There is little doubt that the S-37 would require more powerful engines than the AL-31Fs for stable performance. This conclusion is fully supported by the fact that the initial flight tests were conducted with the powerful D-30F6 engines, though there is no knowledge of any thrust-vectoring version of these engines. Considering all these arguments and facts an interesting possibility arises.
The 1991 S-37 project was designed with very powerful AL-41F engines in mind. There is a strong possibility that a thrust-vectoring version of this engine exists. The AL-41F would be able to satisfy the power requirements of the S-37, as well as to explain why MiG-31's D-30F6 engines were used for initial test flights (this was suggested to me by Yevgeniy Chizhikov from rec.aviation.military).
Some of the latest articles about the S-37 Berkut indicate that it is still unclear what engines are being used on this aircraft. As is evident from the latest photos of the S-37 fighter, it has large canards mounted on the intake side, close to the leading edge of the forward-swept wing. It is also apparent that the vertical stabilizers are canted slightly outward, and not inward, as was previously believed. After closer examination of some photos, two large auxiliary intake doors are visible on the center fuselage section. Their purpose is unclear. It previously suggested that the nose section of the S-37 was similar to the one of Su-27 family. However, better photographs showed that it is rather similar to the original S-37 design announced in 1991 and later canceled. It is now clear that the S-37 fighter is intended to be more than just a technology demonstrator, as OKB Sukhoi is pushing this aircraft to become Russia's fifth generation fighter.
Main visual characteristics:
Technical information
Dimensions:
Powerplants:
Weights:
Performance:
Armament (basic):
Copyright © 1996-1997 Venik, All rights reserved