The AL-51F1 engine has been described as a transformative upgrade for the Su-57 fighter, enabling it to evade both air-to-air and surface-to-air missiles even when directly visible to the enemy, Russian media reported.

Military expert Yuri Knutov emphasised that the aircraft is equipped with a sensor suite providing the pilot with a complete 360-degree view of the airspace.

He noted that no other aircraft in the world currently possesses such super-manoeuvrability capabilities. Knutov further argued that the Su-57 should be considered more than a multi-role aircraft, calling it an air superiority fighter capable of destroying adversaries while remaining practically invisible.

Open-source data indicates that the AL-51F1 engine delivers a maximum thrust of approximately 11,000 kgf without afterburner and up to 18,000 kgf with afterburner engaged. The engine incorporates a newly designed nozzle that reduces the aircraft’s infrared and radar visibility, enhancing its stealth profile.

Rostec, under its contract with the Russian Ministry of Defence, is set to supply Su-57 aircraft fitted with this second-stage engine, also known as “Product 30.” The AL-51F1 was first publicly presented in July 2023 at a scientific and technical conference on engine-building prospects held at Samara Technical University. During the event, ODK-Kuznetsov identified the second-stage engine for the Su-57 as AL-51F1 on one of its slides.

Analysts in the aviation sector have assessed that the AL-51F1 will generate at least 11,000 kgf of nominal thrust and up to 17,000 kgf in afterburner mode. This performance translates into a thrust-to-weight ratio exceeding one, estimated at 1.15 to 1.2 under normal take-off weight.

By comparison, the current ratio stands at 1.09 with normal take-off weight and 0.97 when fully loaded. Consequently, the Su-57M equipped with the AL-51F1 will achieve a significant increase in supersonic cruising speed, reaching Mach 1.9 to 2.1 without afterburner. Presently, the aircraft achieves Mach 1.6 to 1.7 in similar conditions. This advancement positions the Su-57 as the fastest fighter of its generation.

Beyond speed, the AL-51F1 engine has been optimised for stealth. It features converging-diverging nozzles with serrated flaps designed to reduce radar cross-section.

Estimates suggest that the thrust of the AL-51F1 is about 8% higher than that of the Pratt & Whitney F119 engine powering the American F-22 Raptor.

However, its most notable advantage lies in reduced maintenance requirements and the integration of thrust vector control, which enhances manoeuvrability at low speeds. These attributes collectively strengthen the Su-57’s role as both a stealth platform and a highly agile combat aircraft.

The introduction of the AL-51F1 marks a decisive step in Russia’s efforts to elevate the Su-57’s competitiveness among fifth-generation fighters. With its combination of speed, stealth, and manoeuvrability, the aircraft is positioned to challenge Western and Chinese designs more effectively. 

The engine’s development also underscores Russia’s determination to overcome delays in its next-generation propulsion program and deliver a fighter capable of meeting modern air combat demands.

Agencies