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Luftfahrt - Russia’s Stealth Fighter SU-57

20.01.2021

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An Su-57 in production at Sukhoi's Komsomolsk-on-Amur Aircraft Factory.

SUKHOI

Ten years after it first flew, Russia’s Su-57 Felon stealth fighter is a mess. Its radar signature is at least 10 times greater than that of an American F-22 Raptor. Its radars might not work. And it’s not clear that Moscow can afford to buy all 86 copies that Russian president Vladimir Putin insisted the country should buy.

Those are the sobering conclusions that Justin Bronk, an air-power expert at the London-based Royal United Services Institute, came to in an October study. “There are significant doubts about the scale of Su-57 production and the funding required to mature the aircraft’s sensors, avionics and dedicated weapons systems,” Bronk wrote.

Russian plane-maker Sukhoi developed the twin-engine Su-57 in response to the development by American aerospace giant Lockheed Martin LMT -0.7% of the F-22. The Raptor entered service in 2005. Some 185 of the twin-engine F-22s are in service.

Owing to its high degree of all-around stealth, hard-to-pinpoint radar and high-altitude performance, the F-22 is capable of “completely over-matching all existing Russian combat aircraft,” Bronk wrote.

“Russia was well aware of the F-22 development program and the Su-57 is the result of their efforts to develop a broadly comparable fighter aircraft,” he continued. “The Su-57 is a heavily modified derivative of the [Su-27] Flanker airframe, shaped to minimize frontal-aspect X-band [radar cross-section] while retaining super-maneuverability.”

But it’s not clear how successful the design is. The type’s stealthiness in particular is questionable. “Notable sources of radar-reflections include the unusual fully moving leading-edge root extension control surfaces and actuators, cockpit canopy design, ram air intakes at the base of the canted vertical stabilizers, [infrared] sensor in front of the canopy and the only partially shrouded jet engine turbine faces,” Bronk explained.

“The latter is due to the ‘flattened Flanker’ blended wing-body shape, coupled with two large central weapons bays between the intake trunks, leaving insufficient space for a full ‘S-curve’ to hide the turbine faces as used on the F-22. These features are likely a result of comparative Russian inexperience in designing and building stealth aircraft, coupled with budgetary limitations.”

The same constraints could impact the Su-57’s sensors. The Felon has a unique radar layout—an electronically-scanned-array X-band radar in the nose plus smaller X-band arrays on the nose that extend coverage to the fighter’s flanks.

But the Su-57’s novel X-band radar layout, in combination with low-band arrays that Sukhoi plans to add to the plane’s wings, poses an integration risk. “Russian industry has suffered from a lack of high-end micro-electronic components since the imposition of Western sanctions in response to the annexation of Crimea, increasing the difficulties inherent in developing such a complex fused multiple-array sensor suite to a level of maturity where it can be considered ready for front-line service,” Bronk warned.

The Su-57’s problems could weigh on the Kremlin as it struggles to fulfill Putin’s 2019 edict that the air force acquire 76 Su-57s in addition to the 10 prototype models that already are flying. The Kremlin reportedly has set aside $2.6 billion for initial production, but as Bronk noted, that’s just $34 million per plane—hardly enough to cover a full airframe with sensors and engines.

“As such, the $2.63 billion is likely to only cover an initial tranche—with the remainder of the 76 having to compete for stretched funding within the overall Russian military modernization budget.”

“Even if all 76 airframes announced by Putin are ordered, the [Russian air force] will operate significantly fewer than 100 Su-57s by the end of the 2020s, and the likelihood that the sensors, avionics and engines will be mature is questionable.”

Quelle: Forbes

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