The Su-47 Berkut is an experimental aircraft that was designed to evaluate technological, technical, and layout solutions as part of the next-generation fighter development program. The Sukhoi Design Bureau initiated work on this project in 1983 under the provisional code name S-22. The Su-27 fighter’s development, testing, and production had been largely finalized by this point. Mikhail Simonov initiated the initiative to develop an experimental aircraft with forward-swept wings (FSW) in this context. This design was expected to offer numerous benefits, such as the ability to generate high lift at subsonic speeds, the ability to prevent stalling and spinning at high angles of attack, and more.
Eight aerodynamic configurations for the new aircraft were developed in collaboration with TsAGI (Central Aerohydrodynamic Institute) during the initial five years. Detailed design work for one of these configurations was concluded by the Sukhoi team, which also refined the primary aerodynamic parameters. In 1988, the Soviet Air Force authorized the full-scale development of an experimental aircraft that was regarded as a prototype for a fifth-generation fighter and was designed according to the specified configuration.
The “lifting triplane with FSW” configuration was selected for further development. S-32 was the new designation under which the project was continued, and Mikhail Pogosyan was appointed as the principal designer. The preliminary design of the aircraft, which was then referred to as the Su-27KM, was approved in 1989. The design bureau commenced the production of detailed technical documentation and the construction of the aircraft in the early 1990s. Nevertheless, the progress made was significantly impeded by budget reduction in R&D funding. In order to maintain the project, the Sukhoi Design Bureau implemented cost-saving strategies, including the replacement of the planned engines with D-30F production models, the simplification of the onboard systems, and the direct execution of structural testing on the flight-ready airframe, using funds from export contracts.
The aircraft implemented a number of innovative features that had not been implemented in this category of aircraft before, despite the obstacles it faced. This involved the use of composite materials in critical structural components, the use of large-scale milled panels with double curvature, and a high degree of longitudinal static instability. The manufacturing process necessitated a significant amount of collaboration with other Russian aerospace companies. For instance, the Novosibirsk division of NIAT and Chkalov NAPO produced curved panels, IAPO produced wings, and the “Composite” Research Institute in Obninsk produced composite panels.
The airframe was finalized by mid-1996, and the aircraft was subsequently transferred to the assembly stage after passing static tests. Before its public debut in early 1997, the aircraft was assigned a new designation, S-37, and subsequently its official appellation, Su-47. The primary assembly work was finalized by May 1997, and the aircraft was transported to the Sukhoi Design Bureau’s test facility in Zhukovsky in mid-July. In mid-September, Vladimir Bykov was appointed as the head for flight tests, and ground tests commenced.
The Su-47’s inaugural flight was conducted by test pilot Igor Votintsev on September 25, 1997. Sergei Korotkov succeeded Mikhail Pogosyan as the principal designer in 1998, following Pogosyan’s appointment as President of the Sukhoi company. The Su-47 underwent flight tests in phases until 2003, during which time it was featured at numerous MAKS airshows. The Su-47 has been used as a research platform for fifth-generation fighter technologies since 2004.
So why was the Su-47 project discontinued?
The Su-47 used mainly as a testbed for sophisticated technologies, such as fly-by-wire systems and composite materials, following its first flight in 1997. Although its forward-swept wing design was innovative, it was ultimately not pursued for mass production due to performance limitations at supersonic speeds in comparison to traditional aft-swept wings.
Funding for the Su-47 was primarily provided by Sukhoi, as opposed to the Russian military, and only four prototypes were built. The Russian military’s lack of interest in adopting the aircraft for service during the post-Soviet economic struggles was suggested by the limited financial support.
The Sukhoi T-50 (later designated Su-57) had a major influence by the technological advancements that were made during the development of the Su-47. Although it did not evolve into an operational aircraft, the Su-47’s features served as a valuable source of inspiration for the development of future fighter aircraft.
Attention shifted to the development of the T-50 as Russia’s primary fifth-generation fighter in the mid-2000s. Around 2005, the PAK FA program commenced in earnest, leading up to the first prototype flight in 2010. This change was indicative of a strategic decision to pursue more conventional designs that could more effectively address the changing military requirements than the Su-47’s unusual configuration.
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