Russia’s fifth-generation Su-57 Felon fighter has begun test flights with a second-stage engine called Izdeliye 30, according to a statement by the state-run Rostec Corporation.

According to the plan, the updated fighter will be put into service with the Russian Aerospace Forces (VKS) within the framework of a contract signed several years ago.

The Su-57 Felon – a multi-role fighter developed by the Sukhoi Design Bureau has now received new weapons and will soon increase its combat capabilities through engine improvements. The second stage engine is expected to improve the aircraft’s performance, meeting the basic requirements for fifth-generation fighters, which are supersonic cruise flight and reducing exposed infrared signals.

The contract for the supply of 76 Su-57 Felon fighters assumes that some fighters of this type will be equipped with first-stage AL-41F1 engines, the rest will receive second-stage engines. The transition to using new generation engines is expected to take place between 2023 and 2025, if tests show positive results.

The Su-57 stealth fighter is designed to perform many different tasks: from destroying air, ground and sea targets; to reconnaissance and suppression of enemy air defense systems and aircraft. Performance improvements thanks to the integration of second-stage engines will significantly expand the capabilities of the fighter within the framework of modern military technical requirements.

Throughout its development and testing phase, the Su-57 relied on an interim powerplant – the NPO Saturn Product 117 engine, derived from the Su-35’s afterburning AL-41F-1S turbofans. The introduction of the Izdeliye 30 engine is anticipated to significantly enhance the fighter’s thrust and fuel efficiency, and simultaneously decrease weight and upkeep needs.

One standout feature of the Izdeliye 30 is its chevron nozzle, renowned for increasing thrust efficiency, stability, maneuverability, and overall performance while cutting down engine noise. Notably, the addition of Chevron exhaust nozzles is likely to deeply influence the aircraft’s infrared and radar footprints. The implementation of these nozzles adjusts the exhaust plume’s temperature distribution and shape, making IR and radar detection and tracking of the plane more difficult, thereby augmenting the jet’s stealth features overall.

The AL-51F-1, also known as Izdeliye 30, is an advanced turbofan engine with a two-shaft, low-bypass, afterburning design. The structure of this powerful engine is composed of a three-stage fan that’s driven by a single-stage lower-pressure turbine, further paired with a five-stage high-pressure compressor that’s propelled by a single-stage high-pressure turbine.

When compared to its predecessor, the AL-41F1, the AL-51F-1 engine exhibits notable improvements. For one, it incorporates glass-fiber plastic IGVs and convergent-divergent nozzles that employ serrated flaps. These features are designed to minimize its radar visibility. Furthermore, the AL-51F-1 boasts a 19% increase in thrust-to-weight ratio, a 6.4% enhancement in specific thrust, and a 9% reduction in specific fuel consumption.

In terms of power, this turbofan engine’s thrust is estimated at 107.9 kN while operating without afterburner, and 166.8 kN with afterburner use. The AL-51F-1 is typically equipped with a full authority digital engine control system, which ups its reliability under different working conditions.


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