Su-57 needs to meet the stringent operational requirements of the Russian Air Force, including competing with the F-22 for air supremacy and performing deep penetration ground strike missions. When designing the PAK-FA, the Sukhoi Design Bureau used the F-22 as an imaginary enemy to design the aircraft as a stealth fighter with super maneuverability and super cruise capabilities. The fuselage is made of composite materials. The intention is to lower RCS.
Therefore, the aircraft has applied Russia's most cutting-edge fighter technology in its design and manufacturing, covering stealth, aerodynamics, engines, composite materials, system integration and weapons. Most of the specific design features of the aircraft are strictly confidential, and there are more questions than answers in terms of its true combat capabilities and performance. Therefore, it is difficult to assess whether Sukhoi designers have successfully overcome the rigors of developing high-performance stealth fighters. Challenges such as high agility and maneuverability, sensor fusion and powerful multi-tasking capabilities that combine supersonic cruise performance.
In the overall aerodynamic layout, the Su-57 continues the aerodynamic layout of the lift body wing-body fusion that has been verified by the Su-27. This layout was proposed by the Soviet Central Institute of Aerodynamics at the time, and it was characterized by the fusion of the main wing and the central fuselage into a flat central lift body with an airfoil in the longitudinal section. The two engines are arranged in the form of wide-spaced nacelles on the lower sides to form a "tunnel" in the belly. The lift generated by the lift body can account for up to 20% of the total lift of the aircraft.
Su-57 has a typical lift body aerodynamic layout
lift body aerodynamic layout has the following advantages: large internal space (so that the Su-27 has a huge internal oil, and the Su-57 can have a tandem bomb bay built into the fuselage), eliminating the traditional The aerodynamic interference between the wing and the fuselage is designed to reduce drag. Since the fuselage can also provide considerable lift, the lift-to-drag ratio of the whole aircraft is improved, which is conducive to achieving higher maneuverability. Of course, this layout also has a large infiltration area. Shortcomings.
Because the Su-57 adopts a diamond-shaped fuselage section for stealth, the full-movement vertical tail camber angle is large, and the slanted side wall of the Garrett inlet, so the overall vision is like a flattened Su-27 , Which just reflects the same line of design ideas between the two.
Su-57 and Su-27 frontal comparison
super maneuverability
Su-57 has 12 movable control surfaces, including full-moving flat tail and vertical tail, ailerons, wing leading edge flaps, and flaperons And the adjustable leading edge vortex controller (LEVCON), when both vertical tails are offset inward, it can be used as a speed reducer. The LEVCON in front of the air inlet can control the detachment vortex it generates and provide a certain trim function. LEVCON is a further development of the leading edge strip, which can greatly improve the Su-57's high angle of attack control, and can provide fast stall recovery without using vector thrust.
Su-57 drooping LEVCON
Su-57's landing deceleration state
advanced flight control system and thrust vectoring nozzle make the Su-57 have strong anti-deflection characteristics, and have a high degree of maneuverability on the yaw and pitch axis Due to its flexibility, the aircraft can not only perform ultra-high angle of attack maneuvers such as "Bugachev Cobra" and "Ring the Bell", but also perform horizontal rotation maneuvers with little height loss ("Leaf Gone"). The Su-57's supersonic cruise capability and combat altitude will also give the aircraft a significant increase in advantages over the previous generation fighters.
Su-57's "fallen leaves" maneuver
Su-57 is made of composite materials widely, and 25% of the structural weight and nearly 70% of the skin are composite materials. After testing the static test fuselage and early prototypes, Sukhoi’s designers found that the fuselage structure could not withstand the stresses caused by extreme maneuvers. Therefore, the interior of the Su-57 fuselage was improved to greatly enhance the aircraft. Body structure strength.
Su-57's large-area composite skin
Su-57 manufacturing material ratio: 40-44% aluminum alloy 22-26% composite 18% titanium alloy 10% steel 4% other
second stage fuselage in appearance The biggest difference is: 1. The upper and lower parts of the engine compartment are coated with absorbing paint instead of the exposed titanium alloy heat-resistant skin of the first stage of the fuselage. 2. The exhaust valve on the side of the intake port has been redesignedAnd repositioning, and optimize the serrated shape of the fuselage flap. 3. The tail vertebra is obviously enlarged, and the cross-section shape has been redesigned. The above detailed design will help the Su-57 production model to reduce RCS.
The second-stage fuselage of the Su-57 after stealth refinement. The picture shows the T-50-10 prototype
. The ammunition of the aircraft is installed in the two main tandem bomb bays on the belly between the engine nacelles and the wing roots. There are two triangular raised close-range fighting bomb bays. The built-in weapon can not only maintain the stealth appearance of the aircraft, but also greatly reduce the drag and maintain the high maneuverability of the aircraft. The advanced engine and aerodynamic design of the
enable the Su-57 to achieve continuous supersonic cruise without afterburner. With Ouchi Oil, the supersonic range of the Su-57 exceeds 1,500 kilometers, which is more than twice that of the Su-27. In the Su-57 wide-spacing vector nozzle design, Sukhoi has solved the limitation that the F-22 tail nozzle can only be used for pitch control. The vertical centerline of the left and right nozzle shafts is deflected by 32 degrees to the outside (the right nozzle To the right and the left nozzle to the left), the nozzle can be deflected in a V-shaped intersecting plane. When the two nozzles are deflected asymmetrically, the roll and yaw control torque can be generated. This 3D thrust vector control capability can maintain precise control of the aircraft at low speed even when the control surface fails.
The vector tail nozzle of the Su-57 is exactly the same as the Su-35 and Su-30MKI.
test pilot Sergey Bogdan said that the flight performance of the Su-57 is similar to that of the Su-35, but the supersonic acceleration capability of the aircraft is required. Much tougher, with "rough and wild" acceleration capabilities, he also pointed out that the Su-57 has good controllable spin characteristics and can quickly recover. The
Su-57 continues the tradition of Russian-made fighters taking off and landing on simple runways. It has solid landing gear, front wheel fenders, and air intake grilles, which can effectively prevent the engine from inhaling foreign objects.
Front wheel with fenders
stealth design
Compared with the fourth-generation Russian fighter, the radar cross-sectional area of Su-57 is greatly reduced, especially in the forward direction. The weight of the composite material and radar absorbing material of the aircraft is Up to 25%. But for a long time, the exposed rivets, unmodified bomb bay door, straight-through air intake and engine compartment design of the T-50 prototype have made people question its stealth ability. Although with the evolution of the T-50 prototype, the stealth detail design of the aircraft is gradually optimized, but it can still be seen that the Su-57 has made major compromises in stealth design for high mobility and large belly weapon bays.
The screws of the crashed T-50S-1 production fuselage surface maintenance cover have also undergone stealth treatment.
Su-57 is very different from the F-22 in the stealth design concept. According to the Russian military doctrine published in 2014, the main task of the Russian frontline aviation force is air defense and tactical-level ground support for ground forces. The Su-57 does not need to be threatened by advanced integrated air defense systems like the F-22. Fight for air supremacy in hostile airspace. Therefore, the Su-57 is not an omnidirectional stealth fighter. Its stealth design is mainly aimed at the forward direction. The aircraft can be regarded as an anti-stealth fighter. When encountering F-22, it first relies on multi-face radar and photoelectric system. Launch an over-the-horizon attack at a long distance, and then rely on the advantage of mobility and the directional infrared countermeasure system to win in close-range combat.
So compared with F-22, Su-57 appears careless in the stealth design of the rear fuselage. Through the comprehensive application of stealth shape design and absorbing materials, the RCS of the Su-57 is still significantly lower than that of the Su-27. Sukhoi’s estimate of the radar cross-sectional area of the aircraft in a patent filed in December 2013 is "the average 0.1-1 square meters". Although the Su-57's omnidirectional stealth capability may not be as good as the F-22, F-35, and J-20, even so, the aircraft's RCS is still significantly lower than the four and a half generation fighters, such as the Rafale and Typhoon.
In any case, the Su-57 will still be the first stealth fighter equipped by the Russian Air Force. The plane conforms to the stealth design principle of parallel edges, the front and rear edges of the wings and the control wing, and the serration of the skin cover. The edges are parallel to each other at several specific angles, focusing the radar echoes on reflection in several directions, reducing the probability of being intercepted. In addition, the Su-57’s internal bomb bay and conformal antenna flush with the skin maintain the aircraft’s stealth shape. The infrared search and tracking (IRST) ball in front of the windshield will turn to the rear when not in use.Out of the shell made of RAM material to reduce its radar echo. The intake of Su-57 is difficult to hide the strong reflection source on the front of the engine. The production aircraft can completely solve the biggest defect of the straight-through intake in the hidden body after switching to the "Product 30" engine. The surface of the Su-57 fuselage is widely used with absorbing materials, and the windshield and cockpit cover glass are treated with indium tin oxide coating to minimize the radar reflection inside the cockpit.
can also be seen from the straight-through air intake design of the Su-57 that the aircraft has compromised
sensor fusion
Su-57’s avionics and sensor systems are all accessed and controlled through a central computer. The aircraft’s avionics was integrated by the Sukhoi company itself, breaking the conventions of the Soviet era. In the past, instrument manufacturers were responsible for the fire control and flight navigation systems of new fighter jets. For Sukhoi Design Bureau, the integration work was generally entrusted to the Ramenskoye Instrument Design Bureau (RPKB).
Su-57 cockpit simulator early version
At the Moscow Air Show in 2019, Russia showed the latest single large-screen display of the Su-57
Su-57 equipped with Tikhminov Instrument Manufacturing Institute (NIIP) Tikhomirov's newly developed Sh121 multifunctional integrated radio electronic system (MIRES), its core components are the N036 "Squirrel" active phased array radar system and the L402 "Himalayan" electronic countermeasure system.
N036 "Squirrel" is probably the fighter radar system with the largest number of antenna arrays, except for the N036-1-01 X-band active phased array antenna (1552 T/R modules) installed in the Su-57 nose radome The aircraft also installed two N036B-1-01 X-band active phased array side-view antennas (each with 358 T/R modules) on both sides of the nose to increase the scanning angle of the radar system, which can scan the front half of the aircraft. The airspace of the ball is 270 degrees (135 degrees on the left and right).
This is not over yet. The Su-57 also installed two sets of N036L-1-01 L-band active phased array antennas on the leading edge of the wing, which were not only used as the transmitting and receiving antennas of the N036Sh "Reaper" identification friend or foe system. Unconfirmed news, Su-57's airborne N036UVS computer can comprehensively process the radar signals obtained by the above-mentioned X and L band antenna arrays to obtain the ability to detect stealth fighters.
N036 "Squirrel" radar system
This is because modern fighter radar stealth technology is mainly effective for S-band and X-band fire control radars, and has little effect on L-band radars, so the latter can detect stealth targets. However, the detection range and accuracy of the L-band radar cannot meet the fire control requirements. Therefore, the N036L-1-01 is only referred to as the "identification friend or foe system" by Russia. This is probably a Su-57 specifically for F-22 and F The -35's avionics can also be seen as a compensation for the significantly higher RCS of the Su-57, which will help the long-range detection of Western stealth fighters. The
L402 "Himalayan" electronic countermeasure kit was developed by the Radio Engineering Research Institute (KNIRTI) near Kaluga. The system has its own active phased array antenna located in the tail cone between the engines, but when the system works in the same way as the radar When the frequency is higher, the N036 antenna array is used.
The active phased array antenna of the L402 "Himalayan" system
101KS "Atoll" photoelectric system in the tail cone was developed by the Lal Optics and Machinery Plant (UOMZ) in Yekaterinburg and consists of five subsystems. The first is 101KS-V, an infrared search and tracking (IRST) turret installed in front of the cockpit for detecting, identifying and tracking air targets. The second is the 101KS-O Directional Infrared Countermeasures (DIRCM) turret installed under the back of the aircraft and the front fuselage, which emits modulated lasers to interfere with the infrared guidance heads of incoming missiles. The Su-57 is the world’s first equipment equipped with this equipment. fighter. The third is the 101KS-U Ultraviolet Missile Approach Warning Sensor (MAWS), which can be used in conjunction with the DIRCM turret. The Su-57 fuselage is equipped with four sensors to achieve full coverage. The fourth is 101KS-P high resolutionHigh-speed thermal imaging camera, used for low-altitude and night flight, the two sensors of the system are installed in the front of the wing root short-range air-to-air missile cabin. The last 101KS-N navigation and aiming pod, mounted under the air inlet, is used for target recognition and aiming for ground missions.
101KS "Atoll" photoelectric system installation location diagram
directional infrared countermeasure system
101KS-O makes the Su-57 the world's first fighter equipped with a laser directional infrared countermeasure system. In the past, this system was only used to equip military helicopters, transport aircraft and On passenger planes, shoulder-fired anti-aircraft missiles used to interfere with incoming attacks. The Su-57 equipped with this system shows that Russia has made great progress in the development of the laser directional infrared countermeasure system. The modulated lasers it emits may have been able to destroy the tracking mechanism of modern infrared imaging guided air-to-air missiles (such as AIM-9X). This is the first in the world. It also reflects the main design concept of the Su-57: relying on high mobility, limited stealth capabilities, and modern electronic warfare and optoelectronic countermeasures systems to avoid attacks by air-to-air missiles beyond the visual range and visual range. The two bubble laser turrets of
101KS-O are installed on the upper back of the Su-57 cockpit and the lower jaw under the cockpit. There are built-in laser transmitter reflector components, which respectively form 360 degrees on the upper and lower hemispheres of the fuselage. Full coverage. After the 101KS-U MAWS detects the incoming missile, the self-defense system will automatically control the 101KS-O to aim at the direction of the missile's attack, and automatically continue to emit modulated lasers until the guidance head is blinded and the missile deviates from the aircraft. The installation location of
101KS-O component
101KS-O
In a sense, the 101KS-O equipped with Su-57 may become a "game changer" in future air combat within the line of sight. If the device is indeed effective, it will greatly reduce the effectiveness and lethality of modern infrared imaging air-to-air missiles, thereby offsetting the advantages of Western fighters over Russia in combat bombs. The installation of DIRCM system on fighter aircraft is unprecedented. As a pioneer in this regard, Su-57 is likely to lead the development trend of fighter aircraft DIRCM.
