A prototype of Russia’s Sukhoi Su-57 Felon fighter jet has begun flight testing with a new flat nozzle, according to a report by Militarnyi.
The tests are being conducted on the second prototype of the Su-57, designated “052,” which has been equipped with the new nozzle design.
Details about the purpose of these tests remain unclear. Initially, flat nozzles were intended for Russia’s S-70 “Okhotnik” unmanned combat aerial vehicle (UCAV). However, prototypes of the S-70 have been seen with conventional nozzles, leaving the application of this flat nozzle technology uncertain.
Flat nozzles are not new to advanced fighter designs. The U.S. F-22 Raptor employs a similar feature through its Pratt & Whitney F119 engines, which use thrust vectoring to enhance low-speed maneuverability and reduce radar cross-section. The application of flat nozzles on the Su-57 could be aimed at improving stealth characteristics and flight performance.
Reports from 2021 suggested that the narrow nozzle from the first “Okhotnik” prototype would be installed on the Su-57, but it remains unclear whether the current tests are part of this plan or tied to a separate development effort.
Russia’s defense industry has also been working on a new engine for the Su-57, known as the second-stage “Izdeliye 30” engine. This upgrade is expected to enhance the aircraft’s flight performance and reduce its detectability. However, both prototypes and production models of the Su-57 currently rely on the AL-41F1/S engine, which is also used on heavy fighters like the Su-35.
The development of advanced nozzle and engine technology highlights ongoing efforts by Russia to enhance the Su-57’s capabilities and maintain its position as a next-generation fighter.