Russian Su-47 Berkut fighter jet marks 25 years
Su-47 Berkut (Golden eagle) jet, the predecessor of the fifth-generation Su-57, made the maiden flight 25 years ago. first flown on September 25, 1997 by Igor Votintsev, test pilot of the Sukhoi Design Bureau, is considered one of the most unusual aircraft. First of all, due to its main feature - the reverse sweep wing. Not so noticeable externally, but no less advanced technologies in the Su-47 are a digital control system and composite materials.
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Su-47 Berkut showcased during MAKS 2019 (Picture source: Air Recognition)
The flight of the Su-47 did not go into production, the machine was produced in a single copy. However, the technologies used on the Berkut formed the basis of the latest Russian aircraft - the fifth generation Su-57 fighter and the MS-21 airliner .
History of creation
In the late 1970s, Soviet designers began work on the next generation fighter. Leading design bureaus thought about the concept of the new car, offered their own options for the appearance and determined the main characteristics. According to the military, the new multifunctional fighter was supposed to develop supersonic speed in cruising flight modes, conduct all-aspect shelling of air targets in close combat, and also be stealthy for radars. In addition to all this, one of the main requirements was super-maneuverability. It was this feature that determined the futuristic look of the new car. An unusual design solution was to make the fighter more maneuverable - the reverse-swept wing (KOS).
Work on this topic began at the Sukhoi Design Bureau in 1983 under the conditional code S-22. By that time, work on testing and introducing the basic Su-27 fighter into the series had already been basically completed. In this situation, on the initiative of M.P. Simonov, the Sukhoi Design Bureau received an assignment from the Ministry of Aviation Industry of the USSR to create an experimental aircraft with a reverse-swept wing (KOS). Subsequently, after the collapse of the USSR and the subsequent crisis in the aviation industry, funding for the project ceased, and work continued on the initiative of the Sukhoi Design Bureau. It was decided to stop at the construction of one prototype, which received the designation "S-37". The Sukhoi Design Bureau managed not only to build a new machine, but also to implement its flight test program.
Su-47 Berkut in flight (Picture source: Sergey Krivchikov / wikimedia.org)
The aircraft first took to the skies on September 25, 1997. The novelty was presented to the general public at the MAKS air show in 1999 under the name S-37. The fighter received the name Su-47 and the nickname "Berkut" in 2001 - for its ability to quickly change direction or angle of attack.
Airplane wings forward
The Su-47 differed from its contemporaries in more advanced characteristics and was practically approaching the fifth generation. But the main feature of this aircraft is the reverse sweep wing (KOS). If the majority considers the KOS simply as a stylish detail, which, of course, gives the aircraft an unusual look, then the experts have more reasoned justifications.
Aircraft designers began to experiment with such a wing a long time ago. Back in 1944, the German Ju-287 bomber took off for the first time. However, he never made it to the series. Immediately after the war, we began to investigate the KOS in our country. For example, in 1947 a glider was created with a KOS and a powder booster, which reached a speed of 1150 km / h. Similar experiments were carried out by both domestic and foreign designers. Why were they so attracted to models "with wings forward"? Without going into technical details, the following advantages can be noted: less air resistance, good “behavior” at high angles of attack, the leading edge deflected “inward” for better stealth. Supermaneuverability follows from these features, even without the use of engines with a controlled thrust vector.
Su-47 Berkut in flight (Picture source: Sergey Krivchikov / wikimedia.org)
The advantages of a swept-back wing smoothly flow into its main drawback, or rather, into the technical complexity of the design. As the speed increases, the load on the wing increases, and it bends. They tried to cope with such "self-destruction" of the wing by increasing the rigidity, which led to a heavier structure. Here, composites came to the rescue - the wing of the Su-47 is half composed of them. A new technology for joining long composite panels has made it possible to increase the rigidity of the structure without significantly increasing its weight. The Su-47 airframe consists of 13% composites in total, which made it possible to reduce the total weight of the aircraft, as well as its radar visibility.
Thus, the Su-47 "Berkut" became the first domestic prototype of a combat aircraft to receive a "black wing". It was based on the experience gained in the creation of composite products for Buran at the Obninsk Research and Production Enterprise Tekhnologiya. Work on the wing for the Berkut made it possible to subsequently use composites from Obninsk in the creation of the fifth generation Su-57 fighter and the MS-21 airliner.
Despite the fact that Berkut did not go into production, this project can rightly be called successful. Tests of the Su-47 allowed the designers of the Design Bureau. Dry to work out a number of technologies that later appeared in the fifth generation Su-57 fighter.