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2023-12-10

Su-57: Superior Stealth, Advanced Avionics

The Sukhoi Su-57 is a multirole fifth-generation fighter jet, engineered to address a broad spectrum of combat missions encompassing air, ground, and maritime targets. Its operational versatility spans day and night operations, even in adverse weather conditions and challenging electromagnetic environments, while effectively countering enemy air defence systems.

Notably, it demonstrates capabilities for both external control and autonomous operation.

The Su-57 made its inaugural flight on January 29, 2010, in Komsomolsk-on-Amur, marking a significant milestone in its development. The completion of Su-57 prototypes by 2017, as part of the 5th generation aviation complex initiative and its associated systems, underscored a pivotal phase in its production cycle.

Extensive testing was conducted across all components, validating its flight performance aligned with tactical and technical requisites. Furthermore, the aircraft’s avionics, weapons systems, and stealth capabilities, crucial even during live combat operations, have been rigorously confirmed.

The outcomes stemming from this exhaustive experimental phase position the Su-57 as a frontrunner in its class.

Blending Innovation

The aircraft has a blended wing body fuselage and incorporates all-moving horizontal and vertical stabilisers; the vertical stabilisers toe inwards to serve as the aircraft’s airbrake.

It incorporates thrust vectoring and has adjustable leading–edge vortex controllers (LEVCONs) designed to control vortices generated by the leading-edge root extensions, and can provide trim and improve the high angle of attack behaviour, including a quick stall recovery if the thrust vectoring system fails.

The advanced flight control system and thrust vectoring nozzles make the aircraft departure-resistant and highly manoeuvrable in both pitch and yaw, enabling the aircraft to perform very high angles of attack manoeuvres such as the Pugachev’s Cobra and the bell manoeuvre, along with doing flat rotations with little altitude loss.

The Su-57 has a climb rate ranging from 330 m/s (1,100 ft/s) to 361 m/s (1,180 ft/s). The aircraft makes extensive use of composites, with the material comprising 25 per cent of the structural weight and almost 70 per cent of the outer surface.

Weaponry is stored in two tandem main weapons bays located between the engine nacelles, complemented by smaller bulged triangular-section bays near the wing root. Internal weapons carriage eliminates drag associated with external stores, resulting in superior performance and heightened stealth capabilities compared to external carriage.

Power Unit

The Su-57’s auxiliary power unit significantly extends deployment autonomy, decreases ground testing fuel consumption, and prolongs the lifespan of its main engines.

An onboard oxygen extraction unit enhances the aircraft’s operational independence. The incorporation of an explosion-proof fuel tank system, designed as a generator-type neutral gas system, synergises with other measures to elevate the aircraft’s combat survivability to an exceptional level.

The Su-57 outperforms foreign counterparts in combat effectiveness while maintaining a lower life cycle cost. This advantage stems from its exceptional manoeuvrability, supersonic cruising capability, cutting-edge avionics, diverse aviation weaponry, and superior stealth features.

Next-gen Engine

The Su-57’s latest tests involve a next-gen engine, offering increased thrust and reduced fuel consumption for future production models. The Defence Ministry contracted the initial Su-57 fighter batch in 2018, with serial production underway since then. The first batch was delivered in 2020.

Su-57 is currently Sukhoi’s most advanced aircraft in the model lineup. Its export version in the future will become one of the main products of the company in the aviation equipment market.

Supersonic Prowess

The Su-57’s aerodynamics and engines enable it to achieve Mach 2 and fly supersonic without afterburners, or supercruise, a significant kinematic advantage over prior generations of aircraft. Combined with a high fuel load, the fighter has a supersonic range of over 1,500 km (930 mi), more than twice that of the Su-27.

The aircraft offers an extendable refuelling probe, expanding its operational range. Sukhoi’s design of the Su-57 addresses perceived limitations of the F-22, including the inability to induce roll and yaw moments using thrust vectoring, lack of space for weapons bays between engines, and potential stall recovery complications in the event of thrust vectoring failure.

Stealth Properties

The Su-57 marks the Russian Air Force’s inaugural deployment of stealth technology in operational aircraft. Like other stealth fighters such as the F-22, its airframe strategically integrates planform edge alignment to diminish radar cross-section (RCS).

This design aligns the leading and trailing edges of wings, control surfaces, and serrated skin panels at precise angles, minimising radar wave reflections by limiting the directions of their propagation.

Internally housed within the airframe, the Su-57’s weapons remain concealed in dedicated bays, preserving the aircraft’s sleek and stealthy form. Antennas are strategically recessed into the skin to maintain the aircraft’s stealth profile. Moreover, the infrared search-and-track sensor’s housing is retracted when inactive, and its rear surface is coated with radar-absorbent material (RAM) to diminish radar reflections.

To mask the significant RCS contribution of the engine face, the walls of the inlet ducts are coated with RAM and the partial serpentine ducts obscure most of the engines’ fan and inlet guide-vanes (IGV); the remaining exposed engine face is masked by a radar blocker similar in principle to that used on the F/A-18E/F.

Fewer Parts

Due to the extensive use of polymeric carbon plastics composites, the aircraft has four times fewer parts compared to the Su-27, weighs less and is easier to mass-produce.

The aircraft canopy is made of composite material and 70-90 nm thick metal oxide layers with enhanced radar wave absorbing to minimise the radar return of the cockpit by 30 per cent and protect the pilot from the impact of ultraviolet and thermal radiation.

The plane’s design emphasises frontal stealth, with RCS-reducing features most apparent in the forward hemisphere; the shaping of the aft fuselage, the seams between parts, and rivets are much less optimised for radar stealth compared to the F-22.

However, during MAKS 2019 the craftsmanship of the fuselage was actually finer than expected and looked smooth despite the rivets. The combined effect of airframe shape and RAM of the production aircraft is estimated to have reduced the aircraft’s RCS to a value 30 times smaller than that of the Su-27.

Sukhoi’s patent for the Su-57’s stealth features cites an average RCS of approximately 0.1 to 1 m2, compared to the Su-27’s of approximately 10 to 15 m2.

Like other stealth fighters, the Su-57’s low observability measures are chiefly effective against high-frequency (between 3 and 30 GHz) radars, usually found on other aircraft.

Unique Features

Su-57 has a number of unique features, combining the functions of a fighter and a strike aircraft. This is equipped with a fundamentally new complex of deeply integrated avionics, which has a high level of automation for combat use and intelligent crew support.

The aircraft’s on-board equipment allows it to perform tasks not only autonomously, but also to exchange data in real time, both with ground control systems and as part of a task force.

It can use a wide range of air-to-air and air-to-surface munitions, allowing it to perform both fighter and strike tasks. It has the ability to carry out covert actions, due to low level of visibility in radar, infrared and visible wavelength ranges.

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