Dark Clouds Swirl Over Russia’s Su-35S Flanker Fighter: Brig. Gen. Oleksiy Gromov, a deputy chief attached to the Ukrainian General Staff, had some hot gossip to spill pertaining to the Russian aviation industry in a briefing to the Ukrainian Media Center on August 11.
Reporting that Russia was resorting to using older, retired Sukhoi Su-24M bombers due to combat losses of newer jets, Gromov threw more shade at manufacturer Sukhoi by claiming in passing that only nine of 24 Su-35S twin-engine fighter jets purchased by China for $2.5 billion in 2015 arrived in operational condition due to unspecified defects in their “onboard systems” ie. avionics.
Gromov’s claims pile on to other troubling developments for the Su-35 (codenamed Flanker-E by NATO) over the last year, with no less than three clients refusing or canceling Su-35 exports.
Of course, there’s good reason to take the allegations with a grain of salt, as Ukraine has been invaded by Russia, is being bombed by Sukhoi jets, and has every incentive to release embarrassing information (true or otherwise) that could impact arms deals being negotiated at Russia’s annual ARMY-2022 military expo.
The deputy further claimed 24 Su-35s had been downed in combat by Ukrainian forces. This figure is doubtful, however, as visual media confirm the loss of just one or possibly two Su-35s over Ukraine as of mid-August. Just over 100 Su-35s were in Russian service prior to the invasion.
— 🇺🇦 Ukraine Weapons Tracker (@UAWeapons) April 3, 2022
However, Gromov’s initial claim is not entirely implausible. The Su-35S officially entered service in 2014, and its conceivable aircraft delivered to China in 2016-2018 exhibited teething issues.
Ukraine’s defense industry also has a significant relationship with China—both the PLA Navy’s first aircraft carrier, and its J-15 Flying Shark carrier-based jets are based on hardware transferred from Ukraine. It’s, therefore, possible Ukraine’s industry learned some scuttlebutt about the Su-35’s condition through these connections.
According to Andreas Rupprecht, an expert on Chinese military aviation and author of Red Dragon ‘Flankers’, there’s simply little publicly available information on China’s Su-35s:
“There aren’t many official reports about them and in fact nothing on their capabilities and issues… That’s the essence of my research on China’s Su-35s—we simply don’t know enough.”
Su-35S: Export Blues and Radar Woes
The Su-35S is a twin-engine ‘heavy fighter’ like the F-15 Eagle designed to carry large fuel and weapons loads, attain high maximum speeds and operate over long distances.
The ultimate evolution of the Flanker family of jets began with the Soviet Su-27 which entered service in 1985, the Flanker-E, in theory, poses a significant threat as it’s significantly more maneuverable than an F-15 thanks to its three-dimensional thrust-vectoring engines which tilt the nozzles up/down and sideways to allow high angles of attack beyond the aircraft’s current vector.
This enables stunning maneuvers with application to within-visual range combat and dodging incoming missiles. (However, such maneuvers are a one-off gambit due to a large amount of speed and altitude lost performing them.)
Furthermore, it boasts a powerful Irbis-E passive electronically scanned array (PESA) multi-mode radar with an impressive maximum range of around 250 miles and can carry up to twelve air-to-air missiles versus the F-15C’s eight.
But most modern Western non-stealth fighters, including upgraded F-15s and F-16s, retain one big advantage over the Su-35—frequency-hopping actively scanned array radars (AESA) which not only boast higher fidelity but are highly resistant to jamming and in some cases, much stealthier (a capability known as Low Probability of Intercept).
Thus, while the Irbis-E is powerful and conveys a detection advantage over older fourth-generation fighters and might even detect some stealth aircraft at under 50 miles, using its full power makes a Su-35S highly visible to adversaries, while that’s not so true for AESA-equipped jets.
Furthermore, Western beyond-visual-range (BVR) missiles have greater range and reliability than the 68-mile R-77-1 BVR missile used on Su-35s. To be fair, the Flanker-E can launch exotic R-37M Very-Long Range Air-to-Air missiles out to 250 miles for use against non-fighter aircraft like tankers and airborne early warning aircraft, a weapon type for which Western air forces lack an equivalent—yet. But that is a specialized capability.
Overall, the lack of AESA radar leaves the Su-35S at a disadvantage in confronting newer Western fighters in BVR combat. This was highlighted in an air-to-air faceoff in 2021 arranged by the Egyptian Air Force, which operates French-built Rafale jets and had begun receiving Su-35s from Russia. The attacking Su-35’s radar was reportedly rendered useless by defensive jamming from the Rafale’s F3R’s SPECTRA electronic warfare suite—admittedly, one of the most formidable of its kind.
The Rafale proceeded to acquire and mock shoot down the Su-35, the Rafale’s RBE2-AA AESA radar undeterred by the Su-35’s L175M Khibiny self-defense jammer.
At least two likely Su-35 customers have passed on the Russian jet in the winter of 2021-2022. Indonesia, which had dangled an order for 11 Su-35s since the mid-2010s ultimately decided to buy Rafale or F-15EX jets instead. And Algeria, long a dedicated customer for Russian arms, passed on the Su-35 in January, citing its radar.
These countries likely feared CAATSA sanctions from the U.S. could have made the jets more trouble than they were worth, especially after U.S. sanctions intensified in 2021 during Russia’s buildup for the invasion of Ukraine.
Sanctions and diplomatic pressure from Washington were also behind Egypt’s decision to cancel its order of 24-30 Su-35 jets from Russia (17 already built) in exchange for likely purchases of F-15s.
That said, as Moscow becomes more isolated, it may see less to lose in selling Su-35s to Iran, which has long pressed for them—perhaps in a swap for drones Iran has sold to Russia for combat use in Ukraine.
Meanwhile, Russian Su-35s are seeing combat in air superiority and air defense suppression roles over Ukraine, inflicting some damage but failing to suppress neither Ukraine’s old fighters nor ground-based batteries.
China’s 24 Su-35s are flown operationally by the PLA Air Force’s 6th Aviation Brigade at Suixi airbase in Guangdong province (southeastern China). Reportedly, these retain Russian-language instrumentation and visibly differ only in the omission of a navigation antenna and the use of a novel electro-optical targeting pod.
China initially wanted to purchase only a few Su-35s, but Moscow—likely recalling China’s history of reverse-engineering earlier Flanker aircraft—insisted on the minimum buy of 24. Thus, it’s widely believed Beijing was primarily motivated to study Su-35 technology—particularly its thrust-vector control engines. Since the Su-35 acquisition, China has tested indigenous thrust-vectoring engines for possible use on its indigenous J-10 and J-20 jets.
However, due to its long range and powerful sensors, the Flanker-E is also well-suited to patrols over the South China Sea or circumnavigating Taiwan. Indeed, in May 2022 China began including Su-35s in large patrols inside Taiwan’s air-defense identification zone (ADIZ), alongside indigenously-built J-11 and J-16 Flanker-derived jets.
One-on-one, the Su-35 overmatches Taiwan’s F-16Cs, as military aviation analyst Justin Bronk told Hushkit.net in 2016: “The [F-16C] Block 50/52 fleet is certainly not capable of meeting the Su-35S on anything like equal terms – losing out to the Russian fighter in kinematics, sensors, weapons loadout and [electronic warfare] capabilities.”
However, that edge will be reduced once Taiwan’s F-16 are fully upgraded to the latest F-16V Block 70/72 standard with APG-83 AESA radars.
Chinese media also claimed, falsely according to Taiwan, that two Su-35s flew “across” the Taiwan Strait during a visit to the island by U.S. speaker Nancy Pelosi on August 2. An Indian article also claims Su-35s successfully jammed the radars of four Taiwanese F-16s.
These unverified stories suggest a mystique attributed to the Flanker-E, but should be considered with skepticism, Rupprecht warned me: “I’m always most careful in taking such reports for real, more often the true intention is not to inform about the topic, but to tell a different story.”
Sébastien Roblin writes on the technical, historical, and political aspects of international security and conflict for publications including The National Interest, NBC News, Forbes.com, War is Boring and 19FortyFive, where he is Defense-in-Depth editor. He holds a Master’s degree from Georgetown University and served with the Peace Corps in China. You can follow his articles on Twitter.