On Monday, Russia’s TASS state news agency reported that the United Aircraft Company was developing a two-seat version of the twin-engine Su-57 stealth fighter (codenamed ‘Felon’ by NATO) that could serve as a control hub for up to four high-end Okhotnik-B (“Hunter”) stealth combat drones at once.

Russia’s defence military declined to confirm or deny the claim, made by an anonymous defence industry source. Reports of work on an Su-57 two-seater are far from new — but the drone-control rationale is. In June, Deputy Prime Minister Yuri Borisov stated “The Defence Ministry and the Sukhoi Design Bureau have plans to develop a two-pilot aircraft that will boost the export demand for this model … and it may create additional demand.”

Going further back, Sukhoi was supposed to develop a customized two-seat variant of the Su-57 called the FGFA for license production in India, but New Delhi pulled out in 2018 due to lack of progress. Whatever work did get done on FGFA may help speed up the new two-seater concept.

Two-seat fighter jets like the F-15E and Rafale-B are inevitably a bit heavier and less agile, but are preferred for training purposes because an instructor can sit in the rear seat and take control if necessary. As a Russian defence official told Interfax in December 2020 “This [Su-57 two-seater] can be in demand in flight personnel’s training to lower the psychological stress of inexperienced pilots, and also to perform lengthy flights over featureless terrain.”

Furthermore, in combat a Weapon Systems Officer (WSO) in the back seat can operate sensors, guided weapons and more exotic payloads like electronic warfare systems and drone command links more effectively while the pilot focuses on flying.

However, there aren’t any two-seater stealth fighters so far because a stretching out a stealth jet while maintaining low-radar-observable geometry is more difficult and costly than it would be for a conventional fighter. Finesse thus will be required to refashion the Su-57 without compromising its stealth characteristics.

A two-seater Su-57B could potentially become the first two-seat stealth fighter in service, though there are rumours China is developing a two-seat version of its Chengdu J-20 stealth fighter too. The Su-57’s role working in tandem with the Okhotnik-B stealth drone has also been forecast for several years. Just a month after the drone made its first fight in August 2019, it was tested in autonomous mode flying in formation with a single-seat Su-57 fighter.

The emphasis on armed drone control also reflects how rapidly Russia is attempting to integrate combat drones into service after lagging behind for years in that domain, with its first armed drones being delivered to operational units in 2021.

Drone-control is becoming a standard feature in next-generation fighter concepts like the U.K.’s Tempest, the Franco-German FCAS and the U.S.’s two NGAD programs.

But how can a pilot flying a single-seat fighter adequately supervise drones while also managing his own aircraft? Likely what’s needed is robust artificial intelligence that could broadly but faithfully interpret simple instructions from said pilot, while reacting autonomously to rapidly developing combat situations. In other words, a robot to help control other robots.

Having a back-seater WSO instead could drastically enhance an Su-57’s viability as a drone controller without requiring a next-generation man-machine interface.

Felon And Hunter: A Stealthy Power Couple?

The Su-57 has walked a long and rocky path prior to entering service in 2020. During the mid-2020s Moscow downsized its order to a mere twelve jets, and the first production-model Su-57 crashed due to a flaw in the flight control system just prior to delivery to the military. The Felon is also still making do with stopgap engines as the desired final model hasn’t entered production yet.

However, serial production of the twin-engine fighter is finally, if slowly, underway with four Su-57s expected for delivery in 2021 towards fulfilling the current order for 76 production aircraft by 2028. Compared to the U.S. F-35 Lightning stealth jet, the Felon is significantly more agile but appears to have a much larger radar cross-section, particularly from the side and rear aspect. Generally, it’s better suited for shallow rather than deep penetration of hostile air space, and shorter-range air-to-air engagements.

The Sukhoi S-70 Okhotnik-B, meanwhile, is a large flying wing stealth drone with a combat radius of around 2,500 miles carrying up to two tons of surface-attack and air-to-air weapons. Sukhoi began flight testing two S-70 prototypes starting in 2019, with entry to service supposedly scheduled for 2024. However, there remains uncertainty as to what extent the production-model S-70 will rectify the non-low-observable characteristics of the prototypes’ engines.

An Su-57 could serve as a command-and-control hub for multiple S-70s, broadening the pilot’s situational awareness and options for scanning or attacking from multiple angles simultaneously. The controller could assign riskier combat tasks to the drones, such as launching weapons or using active radars to search for enemy fighters, ensuring hostile sensors and weapons would detect and engage the drones rather than the manned Su-57 directing their activities.

But unlike ultra-cheap ‘Loyal Wingman’ drones like the XQ-58 Valkyrie, Okhotnik is decidedly large, expensive and non-expendable, so it may be employed in a less self-sacrificing manner.

Consider that while Okhotnik could be pre-programmed to perform missions autonomously, it might still be desirable to have a platform that can stealthily penetrate enemy airspace alongside S-70s and maintain a short-range command link allowing for more flexible employment of the drone and relaying of its surveillance data in event that its satellite-communications link is compromised. Drone-builder Kronshtadt is also proposing a more traditional low-cost Loyal Wingman-style drone called Grom, though this does have the downside of significantly more limited combat radius of around 400 miles.

Export Focus

The two-seat Su-57 undoubtedly remains aimed at export clients, as smaller air forces often prefer fighters that can do double duty as trainers. According to Defence World, the Su-57E will likely cost around $100 million. Russia’s top arms dealer claims five Southeast Asian countries have inquired about purchasing Su-57s. These likely include Indonesia, Malaysia, Myanmar and Vietnam, all operators of Russian jet fighters. Further afield, Algeria and even Turkey have expressed interest in the stealth jet.

However, such prospects remain murky due to uncertainty as to how India will balance its relationships with Washington and Moscow, and the many years before any export-model Su-57s, let alone two-seaters, become available. By then, Ankara and New Delhi may well prefer to spend money on domestic stealth fighter programs instead.

Furthermore, the Su-57E may have to compete with Sukhoi’s cheaper, export-oriented Checkmate single-engine light stealth fighter built using many Su-57 systems—though full development of Checkmate too is far from guaranteed.

Given the concerted public statements and compelling rationales, a two-seat Su-57 seems distinctly possible. However, its development beyond the prototype stage should not be taken for granted due to how financial and industrial base constraints have led to huge delays and dramatically curtailed procurement for so many big-ticket Russian defence programs entering into the 2020s.