Su-57 Felon – Russian stealth multirole fifth-generation fighter [review]
Felon or ‘the Criminal’. Thus, NATO named the newest Russian fighter, Su-57, which by its characteristics is a combat multi-role fighter. The fighter is designed according to the instructions of the Russian Air Force, as part of the PAK-FA program. The Su-57 has not one but two engines. The main goal of the PAK-FA program is to replace the existing Sukhoi Su-27. Nearly three years ago [August, 2017], the new Moscow fighter received its designation Su-57, while the type is more popular as a prototype Sukhoi T-50.
On the basis of the “FGFA program”, a two-seat variant for the Indian Air Force should also be developed. However, India dropped out of the project in spring 2018.
Development – The development of the Su-57 goes back to the tactical-technical requirements from 1998 after the MFI program was canceled in 1997. At the end of 2000, the requirements for the front pilot were specified and in April 2001 the “PAK-FA program” was officially launched on 26th.
Back at 2002 on April, the state authorities transferred system leadership for the development of the new combat aircraft to Sukhoi, in which the OKBs Mikojan-Gurewitsch and Jakowlew are also involved. After completing the preliminary design phase in late 2004, the program was officially launched as T-50 with chief designer Alexander Dawidenko. In 2007, the Indian Hindustan Aeronautics (HAL) entered into a 50:50 financial partnership with Suchoi, which aimed to modify an Indian variant of the T-50, which was called the FGFA project.
In contrast to the Russian version, the Indian version was planned as a two-seater, which corresponded to a specific requirement of the Indian Air Force. Although India contributed half of the cost, it did not get the design details it had originally hoped for, and the division of labor was also reduced.
According to the Indian military, which was not named, India wanted to procure just under 70 instead of the originally planned 127 aircraft to reduce the import quota. Eventually, India dropped out of the project in spring 2018 after repeated budget and schedule overruns. Russia would also sell the aircraft to Algeria and Vietnam in June 2016, according to the Izvestia report, in order to reduce manufacturing costs in this way.
The camouflage fighter was first presented to a broader public in August 2011 at the MAKS international aviation fair in Zhukovsky near Moscow. The two prototypes presented there showed design differences (for example on the rear radar). One of the T-50-1 flights had to be canceled due to engine problems.
The originally planned delivery of 52 aircraft between 2016 and 2020 has been reduced to 12 orders. These 12 aircraft are to be tested by the Air Force, further orders will depend on the financial options.
Back in May 2017, Sergei Schoigu – the Russian defense Minister announced that the Su-57 would not be put into service before 2019 and in July 2018 the order for 12 machines was confirmed. Russian Defense Minister Yuri Borissov said production in large numbers would not be imposed as long as the capabilities of the other Air Force aircraft were sufficient and there was no rush to launch the Su-57.
The first plane should join a pending regiment of the southern defense district in 2019, followed by a second plane in 2020, according some Russian media reports back in April 2019.
On May 15, 2019, the procurement of 76 aircraft instead of just 16 was announced by 2028, which Kommersant considered to be the largest procurement business in Russian aviation; the second series copy is scheduled for delivery in mid-2020.
2. Test program
Test program – January 29, 2010 – Fighter prototype T-50-1 number 51 conducted its first flight, taking off from Dsjomgi Air Base in Komsomolsk on the Amur. The fighter was piloted by Sukhoi test pilot Sergei Bogdan.
On March 3, 2011 – a prototype fighter T-50-2 number 52 made its second test flight, taking off from Komsomolsk on the Amur.
March 14, 2011 – Fighter prototype T-50 reaches supersonic speed during a test flight performed during the week.
November 22, 2011 – a prototype fighter T-50-3 number 53 again performs a test flight, and again it was performed from the airport in Komsomolsk on the Amur.
December 12, 2012 – another test flight was made, but this time with the fourth prototype number 54
October 28, 2013 – the fifth prototype fighter performs its test flight, and on February 21, 2014 it was handed over to the State Air Force Testing Center of the Air Force in Akhtubinsk.
October 20, 2016 it is known that the ninth prototype begins its test flight.
December 5, 2017 – the number 52 fighter or the second prototype makes a 17-minute flight, and its characteristic feature is that the flight was performed with the future standard engine of the Su-57. The engine bears the technical name “Products 30”.
February 21, 2018 – it becomes clear that two fifth-generation Su-57 fighters have landed at the Russian air base in Syria – Hmeimim. Later in March, the Russian Ministry of Defense confirmed this information, supporting it by claiming that the two fighters in question had conducted two-day tests in combat.
Since there is no reliable information about the specifications of the Su-57 so far, only certain requirements are known. The aircraft is designed as a blended wing body. In contrast to the MiG 1.44, no canards were used and instead a classic configuration consisting of delta wings with elevators was chosen. Movable leading edge flaps are integrated in the forward wing roots to increase the maximum angle of attack.
The rudders are in the V position and are designed as a pendulum tailplane analogous to those of the Lockheed F-117, as can be seen from the pictures published so far without a doubt. Part of the armament is carried internally in two 4.6 × 1.1 m weapon shafts to reduce the radar cross-section (RCS) and air resistance of the machine.
For the use of modern air-to-surface missiles and maritime missiles that are not accommodated in the internal weapon shafts, there are obviously two underwing stations available. The suspension points are clearly visible in the published crack drawings. An external weapon guide increases the radar signature. According to official information, this is 0.5 m².
Originally, an engine with about 170 kN thrust was planned for the Su-57, such as the Saturn AL-41F (with thrust vector control) already used in the MiG 1.44. However, this had to be discarded because the engine was too large. There were other reasons against the AL-41F.
The Ministry of Defense wanted the new fighter jet to have an engine with a significantly longer service life and plasma ignition. At MAKS 2009, Alexander Nikolayevich Selin, the commander-in-chief of the Russian Air Force, said on August 20, 2009 that the Su-57 was suffering from engine problems.
Therefore, the Saturn 117 engine (also known as Isdelije 117 or Saturn AL-41F1) will now be installed, which is already used as a simplified version for the Su-35S “Flanker-E” (Saturn-117S or AL-41F1A). For later series machines, Soyuz and NPO Saturn were to develop new engines with up to 190 kN thrust, possibly based on the AL-31FM3 engine.
Due to the use of the smaller and therefore less powerful engine compared to the AL-41, the Su-57 cannot fully utilize its full performance potential for the time being. This would only change with the new engine, which should be available from 2020. Ultimately, NPO Saturn has been developing the new “Isdelije 30” engine (product 30) since 2011 alone.
Although it is slightly longer than the Saturn AL-41F1, it should still be easier and easier to maintain, and it should be possible to install it in the Su-57 without major adjustments to the flight cell. It consists of a three-stage low-pressure compressor, a five-stage high-pressure compressor and only one stage each for the high and low pressure turbines. The thrust without afterburner is 118 kN, with afterburner at 168 kN (older sources indicate 107/176 kN). In November 2016, the new engine completed the first test bench run, followed on December 5 by the first test flight in the prototype T-50-2.
Little is known about avionics. The radar of the Su-57 was shown for the first time at the MAKS 2009. This is the AESA-N050 radar consisting of around 1500 transmitter / receiver modules. It is the second AESA radar of Russian production. All other specifications are still unknown. The complex is said to include antennas still working in the L-band (1–2 GHz) in the leading edge of the wing. Most radar absorbing materials are less effective at frequencies below 2 GHz.
A further development of the 30 mm Grjasew-Schipunow GSch-301 machine gun is used as the on-board cannon. It is installed on the starboard side, weighs only 50 kg and has the GRAY index 9-A1-4071K. Its cadence is 1800 rounds / min.
With a weapon load of 7500 kg in two weapon shafts for short-range air-to-air guided weapons at the LEREX / wing crossing, plus two internal main weapon shafts with an unknown number of internal and six external suspension points, the following armament can be assumed:
Air-to-air guided missile
- 4 × start rails or ejection device for 1 × Wympel R-77 or RWW-AE (AA-12 “Adder”), radar-controlled for long distances
- 2 × start rails or ejection device for 1 × Wympel R-74 or RWW-MD (AA-11 “Archer”), infrared-controlled for short distances
- 2 × start rails or ejection device for 1 × Wympel R-73E (AA-11 “Archer”), infrared-controlled for short distances 
- 2 × start rails or ejection device for 1 × Type 810 each – radar-steered for long distances
Air-to-surface guided missile
- 4 × start rails or ejection device for 1 × Ch-38ME, modular rifle
- 4 × starter rails or ejection device for 1 × Zvezda Ch-35UE “Uranium” (3M24E / AS-20 “Kayak”), cruise missile for fighting ships
- 4 × AKU-58 start rails for 1 × Ch-58USchKE (AS-11 “Kilter”), radar-fighting guided missile 
- 4 × BD-3U suspension for each 1 × region JSC KAB-500L (laser-guided 500 kg bomb)
Planned weapon loading at external suspension points – The Su-57 has two external suspension points per wing and one suspension point on each engine channel.
Air-to-air guided missile
- 4 × Wympel R-73E, infrared controlled for short distances
- 4 × Wympel R-77, radar-steered for long distances 
Air-to-surface guided missile
- 4 × Ch-31P, anti-radar guided missiles
- 6 × 250 kg bombs
- 2 × (possibly 4) additional tanks
5. Technical data
|Type||multi-purpose combat aircraft|
|Wing area||78.80 m²|
|Wing loading||minimal (empty mass): 235 kg / m²|
nominal (normal starting mass): 330 kg / m²
maximum (maximum starting mass): 470 kg / m²
|Empty weight||18.500 kg|
|Normal starting mass||26.000 kg|
|Max. take-off weight||35.480 kg|
|Load multiples||−3 / + 9 g|
|Mach||2+ maximum speed (at optimal flight altitude)|
|Marching speed||Mach 1.22 (at optimal flight altitude)|
|Service summit height||approx. 20,000 m|
|Operating radius||approx. 1200 km|
|Transfer range||approx. 5500 km|
|Radar signature||0.5 m²|
|Max. weapon load||approx. 10,000 kg|
|Engine||two NPO-Saturn-117 / AL-41F1 turbofan engines|
|Thrust||with afterburner: 2 × 147.09 kN|
without afterburner: 2 × 86.29 kN
|Thrust-to-weight ratio||maximum (empty mass): 1.62|
nominal (normal starting mass): 1.15
minimal (maximum starting mass): 0.81
On June 10, 2014, the right air intake of the prototype T-50-5 caught fire during the landing approach, which was quickly extinguished after landing. People were not harmed. The aircraft was later repaired with parts of the prototype T-50-6 that was started and which was not used. This test aircraft was fully equipped.
On December 24, 2019, the first series machine crashed during the acceptance test, and the pilot was able to save himself with the ejection seat. Control failure and subsequent transition to flat spin were reported as the probable cause, and the flight recorders were salvaged.