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Russian Su-57 Spotted With Flat 2D Thrust Vectoring Nozzle

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The new stealthy nozzle has been installed on the left engine of the T-50-2 prototype, the same used to test the new AL-51F engine.

A Russian Su-57 fighter has been finally equipped with a new stealthy flat 2D thrust vectoring nozzle for testing. The aircraft, which appears to be the Felon’s second prototype, T-50-2 “052 Blue”, is the same used to test the AL-51F engine, also known as Izdeliye 30 (Product 30).

It is unclear how long Russia has been testing the new nozzle, as the few images and short videos emerged online only show the aircraft on the ground. It is possible, however, that testing is in the initial stages, as only the left engine has been equipped with the new nozzle. Also, it is unclear when these images were captured.

The new flat nozzle

Together with the images of the nozzle installed on T-50-2, some slides from a presentation were also shared online. These show some images of the testing on a test bench and in a wind tunnel, together with some details.

The slides, attributed to the United Engine Corporation, say that up to 90% of the nozzle demonstrator’s parts have been manufactured using additive manufacturing (also commonly known as 3D printing). Another slide shows that the nozzle’s supersonic shutters are hydraulically actuated, while the body and side walls are fixed.

There are currently two versions circulating online to explain the new development: a further development of the AL-51F or a sixth generation engine. The former is the most likely, as the Russian Air Force mentioned in the past the will to install flat nozzles on the Su-57.

Also, the slides mention the sixth generation engine but don’t state it is the one being tested. In fact, the slide mentions, using drawings for reference, some areas defined as promising for the development of a new sixth gen engine. Among these are ceramic stages for the turbine, discless impellers, new high-performance bearings and seals, flat nozzles, adaptive three-circuit engine technology and new combustors.

The nozzle now installed on the Su-57’s prototype has some resemblance with the one of the American F-22’s F119 engine. A notable difference is the installation itself, as on the F-22 the nozzle moves vertically, while on the Su-57 it moves diagonally.

The AL-51F was initially equipped with “standard” serrated circular nozzles. The new flat nozzle reportedly causes a 6-8% thrust loss, however it might be considered acceptable due to the radar and infrared signature reduction.

A rendering of a Su-57 with the new engine. (Image credit: Russian Internet)

The AL-51F/ Izdeliye 30 engine

The engine that has been initially used for the Su-57 is the NPO Saturn AL-41F-1, also known as Izdeliye 117, derived from the one used by the Su-35. This engine was considered underpowered for the aircraft, however it was never meant as a permanent powerplant, but only an interim one until the final engine is ready.

The new Izdeliye 30 engines increase the Su-57’s thrust to 11,000 kg without afterburner and 18,000 kg in afterburner, according to reports, while the previous engine provided 8,800 kg and 15,000 kg, respectively. The new engine also has reportedly fewer components, with consequent lower maintenance costs and reduced maintenance schedule, and is claimed to have better fuel economy.

As with most modern Russian fighters, the Izdeliye 30 is a thrust-vectored engine and has supercruise capability, enabling the Su-57 to fly at supersonic speeds without afterburner. According to reports, the new engine should be able to give to the jet a top speed in excess of Mach 2 and a supercruise capability at Mach 1.3.

The first successful test flight with an Su-57 using the new Izdeliye-30 took place on Dec. 5, 2017. The 17-minute test flight saw Sukhoi chief test pilot Sergei Bogdan flying the T-50-2 prototype from the M.M. Gromov flight test center, in Zhukovsky.

The fourth prototype of the Su-57s seen at MAKS 2019 with the older AL-41/Izdeliye 117 engines. (Image credit: Tom Demerly/The Aviationist)

Serial production of the Izdeliye 30 engine was expected to start in 2022, with the engine receiving the designation AL-51F in 2023. Initial reports stated that the engine was expected to be ready by 2025, however the deliveries of Su-57s equipped with the new engine reportedly started in 2023.

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