Detailed analysis of the technologies of the Sukhoi SU-57 Felon, Russia’s 5th generation fighter: stealth, sensors, engines, weapons.

The Sukhoi SU-57 Felon represents the most ambitious project for the Russian military aircraft industry since the end of the USSR. Designed to compete with the American F-22 and F-35, this 5th-generation Russian fighter combines several technological advances. However, its development, which began in the 2000s, has suffered structural slowdowns, partly due to industrial and budgetary constraints. Series deliveries of the SU-57 did not begin until 2021, with only a handful of examples operational to date. The official goal of the Russian Ministry of Defense is to have 76 aircraft by 2028.

The SU-57’s appeal lies in three key areas: stealth, advanced detection systems and multi-role capabilities. Unlike the F-35, which benefited from massive funding (over 1,000 billion USD for the entire program), the SU-57 was developed in a more constrained economic context. This reality is reflected in the aircraft’s technological architecture: the choices made favor simplicity of maintenance, sensor versatility and a balance between performance and cost.

The Sukhoi SU-57 Felon airframe: stealth and hybrid aerodynamics

The SU-57 features an airframe designed according to mixed principles. In contrast to the American approach, aerodynamics takes priority over radar signature reduction. The fuselage incorporates composite materials for around 25% of the structure. This results in a weight reduction of around 1,100 kg, while also reducing the radar footprint. The estimated radar surface area of the SU-57 is 0.3 m², compared with 0.001 m² for the F-22. This limits its ability to remain undetected by certain long-range radars.

The air intakes are partially masked, but do not feature an S-duct type engine cowling system, which increases radar retro-detection. On the other hand, the aircraft’s geometry optimizes maneuverability. The swept-back wing, combined with canard planes and movable tailplanes, makes it extremely agile, especially in close combat. The SU-57 is capable of flying at an angle of attack of over 60°, and reaches a maximum speed of Mach 2 (approx. 2,470 km/h). Estimated combat radius is 1,500 km without refueling.

The flight envelope allows high-incidence maneuverability, with a maximum load of 9 G. This performance is designed to outperform 4th-generation fighters in dogfights, while maintaining a supersonic cruising speed (supercruise) of around Mach 1.3.

The reinforced landing gear enables operations on semi-prepared runways, a choice that reflects Russia’s strategic approach to rusticity and dispersal of resources.

Target detection and processing system: sensors and data fusion

The SU-57 is based on a network of sensors integrated around the IMA BK system, a centralized IT architecture. The main N036 Byelka radar, developed by Tikhomirov, uses an AESA (Active Electronically Scanned Array) antenna divided into several modules. This consists of an array of over 1,500 active X-band modules on the nose of the aircraft, complemented by two L-band side radars.

The front radar offers a detection range of 400 km against conventional airborne targets, and around 150 km against targets with low radar signatures. The L-band radar is optimized for detecting stealth aircraft (such as the F-35) at long range, although its resolution is lower. These radars are combined with an IRST optronic system (101KS-V) capable of detecting thermal targets over a range of 50 to 70 km.

The SU-57 also carries an integrated electronic warfare system, including passive radar detection sensors, active decoys and directional jamming. These systems are linked to a real-time processing module that ensures data fusion. The cockpit features a digital interface with three main screens, a head-up display and a helmet-mounted vision system.

The operational objective is passive detection prior to active engagement, thus limiting the aircraft’s electromagnetic visibility in the initial interception phases. This tactical choice is in line with the Russian doctrine of preserving surprise and saturating the enemy’s defenses.

The SU-57’s propulsion: performance and limitations of the Saturn AL-41F1 engine

The SU-57’s main weakness at present lies in its engine. The aircraft is delivered as standard with Saturn AL-41F1 engines, an evolution of the SU-35’s AL-31 engine. This engine develops a thrust of 142 kN with afterburner, giving a thrust-to-weight ratio of around 1.13 for an aircraft in combat configuration.

However, the definitive version of the SU-57 is to be fitted with the Izdeliye 30 engine, currently in the testing phase. This new engine promises 176 kN thrust, greater fuel efficiency, a smaller thermal footprint and enhanced durability. It will also enable the SU-57 to maintain supercruise over longer distances, with fuel consumption reduced by around 20%.

The three-dimensional vector nozzle system enables extreme maneuvers, especially at low speeds, but the entire propulsion unit remains more visible and hotter than the F-22’s engines. The lack of advanced thermal coating is a limiting factor for infrared stealth.

The estimated unit cost of an SU-57 is around 35 million euros, or around 3.5 billion Russian rubles, lower than the cost of an F-35 (around 80 million euros), but with technological compromises that limit its 5th-generation stealth.

On-board weaponry: modularity, long-range engagement and hypersonic missiles

The SU-57 has six internal bunkers and eight external carry points. Basic armament includes the R-77M active radar-guided air-to-air missile, with a range of 160 km, and the R-74M2 short-range missile. These missiles are designed for use from the cargo bay, to maintain a low radar profile.

The aircraft can also fire the Kh-59MK2 air-to-ground missile, with inertial guidance and IR terminal, with a range of 300 km. The SU-57 is compatible with the Kh-47M2 Kinzhal hypersonic missile (speed in excess of Mach 10), although this armament remains limited to certain configurations. A stealth version of the R-37M very long-range air-to-air missile (400 km range) is also being integrated.

The weaponry is modular, depending on the mission: air superiority, ground attack, long-range interception. A remote-controlled drone version of the SU-57 is in joint development with the S-70 Okhotnik-B combat drone. This integration aims to create a man-machine tactical ecosystem, with the SU-57 serving as an advanced coordinator.

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