PUBLISHED on August 11, 2025, 12:20 PM EDT – Key Points and Summary – While Russia’s Su-57 “Felon” has been heavily criticized and its stealth is considered inferior to the F-22 and F-35, it still qualifies as a fifth-generation fighter.
-Russia has taken a balanced approach, prioritizing supermaneuverability alongside stealth.
-Continuous upgrades, including a new engine and improved avionics in the Su-57M1 variant, are steadily closing the technology gap.
-Now reportedly seeing increased and more complex combat action in Ukraine, the Felon is on a similar evolutionary path as China’s J-20.
-Its most significant hurdle is no longer its design but its slow production rate.
Russia’s Su-57 Felon: On the Comeback Trail?
The Sukhoi Su-57 “Felon” is far and away Russia’s most advanced fighter jet.
It incorporates a blend of stealth features, advanced avionics, and supermanuverability. The Su-57 has been the subject of much criticism from Western analysts, with many experts claiming that it isn’t even a fifth-generation fighter jet.
I argue that while the Su-57 doesn’t live up to the F-22 or F-35’s reputation, it still qualifies as a fifth-generation fighter jet.
Evaluating the Su-57’s Stealth Capabilities
The design philosophy behind the Su-57 differs significantly from its Western counterparts. While American fifth-generation fighters prioritize stealth above all else, Russia has taken a more balanced approach, integrating stealth with supermaneuverability, speed, and electronic warfare capabilities.
The Su-57’s airframe features angular surfaces and serrated panel edges, which help deflect radar waves away from the source. These design choices are intended to reduce the aircraft’s radar cross-section (RCS), a key metric in assessing its stealth.
In addition to shaping, the Su-57 utilizes radar-absorbent materials (RAM) to further reduce its detectability. Approximately a quarter of the aircraft’s structure is composed of composite materials, which include RAM coatings designed to absorb radar signals.
The aircraft also stores its weapons internally, avoiding the radar reflections that would result from external pylons. Another notable feature is the addition of a coaxial radial grating to the engine intakes, which obscures the compressor blades —a significant source of radar reflection.
The infrared search-and-track (IRST) sensor, which previously posed a stealth liability, has been modified to rotate backward when not in use, with its rear treated in RAM to reduce its frontal radar signature.
Shortfalls in Stealth
Despite these efforts, the Su-57’s stealth capabilities are generally considered inferior to those of the F-22 and F-35. Western analysts have pointed out that while the Su-57 has made significant strides in reducing its RCS, it remains more detectable than its American counterparts. This is partly due to the aircraft’s design compromises, which favor aerodynamic performance and maneuverability over stealth optimization.
One of the most critical aspects of stealth is the aircraft’s infrared signature, which is influenced by its engine design. The Su-57 currently uses the AL-41F1 engine, a derivative of the Su-35’s powerplant.
This engine initially lacked the stealthy nozzle design and reduced infrared emissions found in the F-22’s F119 engines. Russia plans to upgrade the Su-57 with the Izdeliye 30 engine, which promises improved performance and lower infrared visibility.
New variants of the Su-57 are equipped with these engines as well as upgraded thrust vectoring nozzles, which will enhance the fighter’s maneuverability while reducing its infrared signature.
Avionics
Avionics and sensor fusion are also essential components of fifth-generation fighter capabilities.
The Su-57 is equipped with a comprehensive sensor suite that provides 360-degree coverage, theoretically allowing it to detect threats from any direction. It also features advanced electronic warfare systems designed to jam enemy radar and communications. The IRST system enables passive tracking of targets without emitting radar signals, enhancing the aircraft’s survivability in contested environments.
Experts have criticized the Su-57 for its avionics and electronics lagging behind Western fighter jets. While this is still true, Russia has seen improvements in this area as well. In May 2025, Russia’s United Aircraft Corporation (UAC) unveiled the newest variant of the Su-57, the Su-57M1.
In addition to the improved thrust vectoring nozzles, the aircraft also possesses improved avionics and HUD displays. The new variant also reportedly offers AI integration, assisting with navigation, target acquisition, and system diagnostics, thereby reducing pilot workload and allowing for a focus on tactical decision-making. If true, this is a significant step up from earlier versions of the aircraft.
Su-57 Felon: The Most Combat-Tested Stealth Fighter?
As of 2025, only around 32 Su-57s have been built (according to estimates), with plans to produce 76 by 2028.
Most commentators have claimed that the Su-57 has seen few tests in combat conditions; however, in light of recent news, this is not entirely accurate.
According to reports from both Russian and Ukrainian sources, the Su-57 has seen increased activity in Ukraine in the past months. Sources reported that tactical formations of Russian fifth-generation fighter jets have been conducting both air-to-air and air-to-ground missions. It has long been said that Russia is too afraid to deploy its Su-57s in combat, but this no longer appears to be the case.
In my opinion, the Su-57 is following the path of China’s J-20 stealth fighter. The J-20 started as a decent but underwhelming fighter, especially compared to America’s F-22. However, after numerous upgrades to its engine, avionics, and radar, the J-20 is now significantly more threatening than it was at its release.
The Su-57 is currently heading down a similar path. While it lacks in many areas, and still lacks in the realm of stealth, Russia has been gradually improving and evolving it to meet its needs.
Over the next several years, the Su-57 is expected to receive further upgrades, enhancing its competitiveness against its American counterparts.
Is the Su-57 a Fifth-Generation Fighter?
With all of this in mind, can the Su-57 be called a fifth-generation fighter? I believe that to be the case.
While its avionics, engine, and stealth features were lacking at its release, Russia’s continual upgrades have gradually transformed the Felon into the capable stealth fighter it was first advertised as. Its biggest hurdle at this point is its slow rate of production.
With only around 30 units produced, Russia has the smallest stealth-fighter fleet of either China or the U.S. Despite efforts to ramp up production, delivery remains slow.
International sanctions and Russia’s war economy have likely further harmed fighter production, limiting its effect on the battlefield.
About the Author: Isaac Seitz
Isaac Seitz, a Defense Columnist, graduated from Patrick Henry College’s Strategic Intelligence and National Security program. He has also studied Russian at Middlebury Language Schools and has worked as an intelligence Analyst in the private sector.
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