After what was a 2025 with no deliveries—or at least no deliveries officially confirmed—the Russian Aerospace Forces (VKS) have received the first batch of new Sukhoi Su-57 stealth fighters. While no further details were provided, the official images and statements released by Rostec and the United Aircraft Corporation (UAC) show that the delivered fifth-generation fighters are fitted with visible upgrades in self-protection systems and avionics.
Throughout last year, even as the delivery of successive Sukhoi-family combat aircraft—both Su-35S fighters and Su-34 fighter-bombers—was confirmed, Russia’s state defense conglomerates did not officially report any Su-57 deliveries.
During that same period, and according to open-source intelligence (OSINT), only the delivery—observed in May 2025—of two aircraft was noted. After leaving the Komsomolsk-on-Amur production line, they were identified with the tail numbers/serials “Red 25” (RF-81796) and “Red 26” (RF-81797).
That said, this secrecy contrasted with a number of officially reported developments that suggested progress both on potential exports of Russia’s most advanced fighter and on ongoing upgrades related to the Su-57’s propulsion and avionics.
From a broader perspective, progress was reported on propulsion systems, with flight tests confirmed for the new Izdeliye 177 engine. Its main characteristics would include 6,000 kgf of thrust with afterburner, along with improvements in service life and more efficient fuel consumption.
Advances were also highlighted in the development and integration of new 2D thrust-vectoring nozzles, which were even presented for promotional purposes at international exhibitions and stands.
For that reason—and despite confirmation of the delivery of a “significant” batch, with no further precision on quantities, and speculation that these could be aircraft delivered at the end of last year in a tranche of between four and six units—specialists took note of Rostec’s own confirmation that these production Su-57s feature a “new technical configuration.”
In the words of UAC CEO Vadim Badeha, he stated: “The fifth-generation Su-57 aviation complex is the best aircraft in its class, but we do not stop at what has been achieved. The fighter has undergone enormous evolution and continues to be refined today: the capabilities of its weapons and aircraft systems are being expanded. Today this makes it possible to solve the most important tasks, demonstrating effectiveness and excellent maneuvering and combat qualities.”
For his part, one of the VKS pilots interviewed referenced this new technical configuration by noting: “The new technical configuration will help expand the tasks in which this type of aircraft is employed. The future capabilities incorporated into the aircraft weapons complex make it possible to use new models of airborne means of destruction.”
In this regard—and thanks to the viral spread of official images released by Rostec and the UAC—it was observed that the new Su-57s delivered to the Russian Aerospace Forces (VKS) feature new head-up display (HUD)-type visualization systems in the cockpit, a new arrangement of formation lights, and what appears to be a greater number of infrared sensors associated with the 101KS electro-optical system, as pointed out by engineer and specialist George N.
The system mentioned, working in conjunction with the Su-57’s radar, provides additional capabilities for passive tracking and detection of aircraft—one of the key current approaches for detecting stealth fighters. This type of equipment is already considered mandatory on fifth-generation aircraft such as the F-35 and the J-20; while in the case of the first aircraft of this generation, the F-22 Raptor, the U.S. Air Force and Lockheed Martin are evaluating solutions to integrate this capability through pods or via direct installation on the aircraft’s fuselage.
Although it is a passive sensor, it remains a key element for increasing the situational awareness of the aircraft–pilot pairing—essential for operating in highly contested environments such as Ukraine, where a wide array of radars, air-defense systems, and other capabilities are deployed across the theater.
Lastly, it should be noted that the conflict in Ukraine provides Russia with a framework to implement continuous improvements derived from operational experience, applied to the updating and maturation of its main weapons systems. The Su-57’s updates—and, in light of efforts to secure a potential export customer for the aircraft—are a clear example of this dynamic.
Photographs: United Aircraft Corporation (UAC).
You may also like: Ukrainian F-16AM Fighting Falcon fighters continue hunting Russian drones with their M61 Vulcan cannons
