The day before, at a meeting in Sochi on military topics, Russian President Vladimir Putin announced plans to conclude a contract for the supply of 76 Su-57 fighters by 2028 and thereby re-equip three aviation regiments of the Russian Aerospace Forces with promising fifth-generation aviation systems.
According to President Vladimir Putin, the state armaments program (GPV) planned to purchase 16 Su-57 fighters by 2027; however, thanks to an agreement with the industry, which reduced the cost of aircraft and weapons by 20%, it was decided “that we will purchase over the same period without increasing the cost 76 of these aircraft. “
In early May, an Interfax source said that a new contract for the serial delivery of fourth-generation Su-57 fighters for the Russian Aerospace Forces is planned to be signed this year, and the first serial Su-57 will enter the troops by November 2021 but delayed due to technical difficulties with the engines and avionics.
The contract is estimated at up to 170 billion rubles, which makes it the largest in the history of aviation and guarantees full utilization of the capacities of the Komsomolsk-on-Amur Aviation Plant (KnAAZ is a branch of Sukhoi, part of the UAC – IF) for at least a decade.
The Su-57 is bigger and heavier than the Flanker variants it borrowed its engines from Su-35 while engines more appropriate to it were under development, reported Interfax news agency. The cockpits for both the Su-35 and Su-57 feature two multi-function displays (MFDs) and a Head-up-display (HUD), making it a class of fourth-generation aircraft.
Failed trial with new engines
The AL-41F engines have a tendency to overheat when pushed to the power levels necessary to operate the plane within its design parameters. This has already had a major impact on marketability. At just the time the Russians were trying to interest India into a co-development contract, one of the prototypes burned up on the runway. It was just one of the factors that caused the Indians to back out, but it was definitely a factor. It turns out developing an engine that runs reliably at the power levels needed and has a chance of maintaining stealth without throwing heat signatures out there that modern IRST units can pick up easily is not an easy thing to do. The Chinese, who either use Russian engines or model those they develop after the Russian designs, have the same problem for Chinese J-20 and J-31 aircraft.
The Su-57 is touted to be fitted with a new AESA radar and engine. In its propaganda brochure, Russia advertised Su-57 with a new N036 Byelka radar system and L402 Himalayas electronic countermeasures (ECM) system. Still, the latest flyer circulated on the internet shows that Russia intends to market Su-57E with N050 radar, OLS-UEM electro-optical targeting system and electronics from MiG-35 also known as MiG-29M2.
Due to the development delay with the izdeliye 30 engine, the Su-57 is powered by a pair of NPO Lyulka-Saturn izdeliye 117, or AL-41F1 turbofans are 100kg overweight than original AL-31 engine. In 2014, the Indian Air Force openly expressed concerns over the reliability and performance of the AL-41F1; during the 2011 Moscow Air Show, a Su-57 suffered a compressor stall that forced the aircraft to abort the takeoff.
N050 failed trials
The N050 AESA radar is the AESA radar mounted on the Russian Sukhoi PAK-FA prototype as an export trial. Apart from Zhuk-AME, N050 is the second AESA radar under development by the Russian design bureau NIIP and NIIR Phazotron. N050 BRLS AFAR/AESA built by Tikhomirov NIIP and based on Tikhomirov NIIP N035 Irbis-E.
It is built of about 1000 transmit/receive modules. The radar is supported by two L-band with frequencies of 1-2 GHz. At those low frequencies, most of the Radar Absorbing Material (RAM) is less effective, but resolution and accuracy are worse than they are with conventional radar frequencies, meaning that it is not possible to provide enough target information for an accurate missile shot. However, they will instead be used as early warning radars to confirm that there is “something out there”. For this reason, Sukhoi delivered one Su-57 with Irbis-E phased array radar to the Russian Air Force.
NIIP has stated that the radar will have a detection range of 350 km in the best case without clutter or jamming situation against a 5 m² target. Thus, the range against a 1 m² target is 268 km, according to India’s HAL proposal to upgrade Su-30MKI aircraft.
FGA-35 failed trials
Sukhoi also trialed FGA-35 AESA radar on Su-57E. The FGA-35 is one of if not the first aircraft mounted AESA designed by Phazotron (a subsidiary of KRET). The design for their FGA-35 and FGA-29 uses ring radiators for the individual t/r elements. The FGA-35 trial ended due to heat issues.
These radiators have higher bandwidth and better antenna gain compared to the patch radiators that had been used in previous Russian electronically scanned arrays. This increases the amount of energy focused in a given direction which thus increases range. However, the design also shows the inexperience of the Russian engineers in designed phased arrays of this type because notched antennas, which Western nations have been using as standard for two decades now, have superior characteristics but aren’t used; that would be because of the difficulty in creating the individual radiators and the voltage feed to run them. They have to be made with high quality materials that do not lose too much of the electrical energy to heat while also being able to handle a large amount of electrical energy being pumped in. The radar is also rather small, having around 900 t/r elements compared to over 1500 for the AN/APG-81.
Zhuk-AME failed trials
Phazontron-NIIR reportedly developed the new Active Electronically Scanned Array (AESA) radar version called Zhuk-A/AM for the fighter. The radar has over 900 solid-state transceiver-receiver modules, Anastasia Kravchenko, MiGs communications director, was quoted as saying by the Tass news agency.
Concern Radio-Electronic Technologies (KRET) showed its Zhuk-AME FGA-50 AESA radar compatible with MiG-35 jet at Airshow China 2016. The radar can detect targets and track up to 30 of them and engage up to 4 targets in the air and 2 on the ground. The Zhuk-AME was removed from export markets due to heat issues and failed several ground test on MiG-35.
The new Zhuk-AME AESA radar was unveiled at MAKS 2019 international air show and later removed from export markets.
Sukhoi Design Bureau plans to fit in working N050 Pulse-Doppler radar, OLS and AL-41F engines to the export variant Su-57E fighter jets.
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