Discover the potential flaws in Russian and Chinese stealth aircraft, their technical, structural, and operational vulnerabilities to modern radar, and their real limitations.
The potential flaws in Russian and Chinese stealth aircraft are attracting increasing attention in global air defense. Despite their technological ambitions, these aircraft suffer from vulnerabilities in Russian stealth fighter jets and technical defects in Chinese stealth aircraft. Between engineering difficulties, structural constraints, and radar limitations, it is necessary to analyze in detail the limits of Russian and Chinese fighter stealth, as well as the shortcomings of Russian stealth systems and the shortcomings of Chinese stealth systems.
Design and engineering: fragile facades
Structural and manufacturing quality issues in Russia
The Su-57, intended to be the flagship of fifth-generation Russian aviation, perfectly illustrates the structural weaknesses of Russian stealth aircraft. From its first public appearances, notably at the Zhuhai Air Show in November 2024, several expert observers noted visible anomalies that betrayed a less than perfect industrial finish. These included visible screws protruding from the fuselage, misaligned panels revealing irregular gaps, and cargo and landing gear doors that did not close properly. Each of these flaws may seem minor individually, but when combined, they increase the radar cross section (RCS), compromising the desired electromagnetic stealth. These imperfections, rarely seen on comparable Western aircraft, confirm the design problems of Russian stealth aircraft, revealing both industrial limitations and budgetary constraints weighing on the program.
Technical limitations of Chinese stealth
The Chinese J-20, another major representative of Asian stealth fighters, also suffers from design choices that affect its radar signature. The integration of canard wings at the front, probably intended to improve maneuverability at low speeds, is a compromise that compromises frontal stealth effectiveness. These moving surfaces reflect radar waves at certain angles, increasing the probability of detection by modern systems. Independent analyses estimate that this choice reduces stealth effectiveness against multi-band radars, confirming the limitations of Chinese fighter stealth. In addition, aerodynamic optimization of the aircraft appears to have been prioritized at the expense of maximum SER reduction. This compromise reflects an approach where stealth is not an absolute, but a parameter integrated into a broader set of operational performance requirements, at the risk of making the aircraft more vulnerable to advanced detection systems.
Engines and reliability: a fragile mechanical heart
Russia: engine problems
The Su-57 program, the cornerstone of Russia’s air strategy, has been repeatedly hampered by critical problems with its engines, confirming the technical flaws of Russian stealth aircraft. During testing, a significant incident occurred at the MAKS-2011 air show when a prototype suffered a compressor stall, resulting in a sudden loss of thrust. Three years later, in 2014, another aircraft had one of its engines catch fire during taxiing, revealing serious reliability issues. These failures are not isolated incidents: they reflect the persistent difficulty in producing a new-generation engine capable of combining high performance, low fuel consumption, and reduced infrared signature. The “Izdeliye 30” engine, which was supposed to finally deliver the expected performance, is significantly behind schedule, forcing the aircraft to continue flying with upgraded versions of older engines, to the detriment of its stealth capabilities and strategic autonomy.
China: external dependence and uncertainties
For the J-20, the engine remains a major weakness and illustrates the potential flaws of Chinese stealth aircraft. Despite official announcements about progress on the WS-15 engine, most operational aircraft continue to be equipped with either Russian AL-31F engines or less powerful local WS-10 copies. This external dependence limits China’s ability to guarantee fully independent production and standardize the performance of its fleet. Current engines struggle to match the thrust and reliability of Western models, while generating a larger infrared signature, which reduces stealth in combat. Furthermore, the prolonged absence of a fully operational domestic engine undermines the credibility of the program and reinforces the idea that, despite its aerodynamic advances, the J-20 has not yet achieved the technical maturity required of a leading stealth fighter.
Radar and detection: the illusion of invisibility
Limited stealth against low-frequency radars
Contrary to the image often portrayed, neither the Russian Su-57 nor the Chinese J-20 achieve a level of stealth comparable to the most advanced Western fighters. Their design is more low observable than truly full stealth, which means that their radar signature is reduced but not eliminated. Tests conducted by several air forces and intelligence analyses indicate that the Su-57 remains vulnerable to low-frequency radars, which are often used in long-range surveillance systems. These radars, operating in the VHF or UHF bands, exploit wavelength to circumvent certain shape and coating optimizations. As a result, the stealth of Russian fighter jets loses some of its effectiveness, especially in environments where these sensors are integrated into a multi-layered detection network, combining low-frequency radars for acquisition and high-frequency radars for engagement.
Chinese counter-stealth efforts
China, aware of the limitations of its own stealth capabilities, is investing heavily in counter-detection technologies, particularly to secure its disputed areas. SIAR (Surveillance and Identification at High Resolution) radars have been deployed on the artificial Triton Island in the Paracel archipelago in the South China Sea. These systems, which use multiple frequencies and high transmission power, are designed to detect stealth aircraft at long range, even in adverse weather conditions. This capability is intended both to counter US and allied aircraft and to evaluate the performance of its own fighters, such as the J-20. The very existence of these devices highlights the reduced performance of Chinese stealth aircraft against modern radars: if Beijing is deploying such capabilities, it is because it implicitly recognizes that its aircraft are not completely undetectable. In a strategic context where air superiority depends on surprise and discretion, this reality is a significant handicap.
Operational readiness and human factors
Pilot training in China: an Achilles’ heel
While stealth and technology are essential assets, they are not enough to guarantee air superiority without a strong human component. In the case of the J-20, a notable weakness lies in the training of its pilots. Expert reports and intelligence feedback indicate that the majority of pilots assigned to these aircraft have little real combat experience and are trained in a mainly theoretical setting or during highly supervised exercises. Annual flight hours remain lower than those of Western pilots, limiting their mastery of the complex tactics essential for the optimal operation of a stealth fighter. This shortcoming is sometimes described as an almost “irreparable” deficit, as building tactical culture and operational know-how requires not only years of practice, but also feedback from the field. This often underestimated human factor significantly reduces actual mission effectiveness, even when the aircraft has clear technical advantages.
Lack of close-range weapons on the J-20
Beyond training issues, the very design of the J-20 introduces obvious tactical limitations. Unlike many contemporary fighters, including stealth fighters, it does not have an internal cannon for close combat. This absence reflects a doctrine geared toward long-range interception using air-to-air missiles, but it is a major handicap in dogfights, where maneuverability and immediate firepower are decisive. The inability to effectively engage an opponent in visual combat highlights the operational limitations of Chinese stealth aircraft. In an environment where combat conditions can quickly shift to close range, this shortcoming exposes the aircraft and its pilot to a strategic disadvantage, particularly against trained opponents capable of forcing proximity.
Summary of identified flaws
- Russia (Su-57):
- structural weaknesses (assembly, finish)
- technical defects (unreliable engine)
- radar vulnerabilities (detectable by low-frequency radars)
- China (J-20):
- stealth limitations (canards, design)
- technical flaws (second-hand engines, lack of cannon)
- human shortcomings (insufficient training, lack of experience)
These points illustrate the operational limitations of Russian stealth aircraft and the operational limitations of Chinese stealth aircraft, as well as the vulnerabilities of Russian and Chinese stealth fighter jets.
The potential flaws of Russian and Chinese stealth aircraft are many and varied, ranging from manufacturing defects to tactical or human limitations. The Su-57 exposes the design problems of Russian stealth aircraft, while the J-20 reveals the structural weaknesses of Chinese stealth aircraft and the shortcomings of Chinese stealth systems. Given these challenges, new-generation radars or improved formations could greatly undermine their effectiveness. Finally, monitoring these vulnerabilities is essential to anticipate changes in the balance of air power.
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