Sukhoi Explains the Need for the Su-57 Dual-Seat Variant

In an interview with the Military Acceptance programme on the Zvezda TV channel, Mikhail Strelets, director of the Sukhoi Design Bureau, revealed the following.

The twin-seat Su-57D is primarily intended for two main tasks:

Training pilots to operate the stealth fighter in special modes, something that is not possible using ground-based simulators.

Facilitating the use of sixth-generation technologies, such as operating as an airborne command post for controlling unmanned aerial vehicles. The primary pilot focuses on flying the mission profile, while the second pilot manages highly intelligent systems such as the S-70 Okhotnik, drone swarms and group-control systems.

The Su-57D will also facilitate the development of combat artificial intelligence, which Russia is currently working on.

Operating in Special Modes

One of the reasons stated for developing the Su-57D twin-seat variant is:

“Training pilots to operate the stealth fighter in special modes, something that is not possible using ground-based simulators.”

I am not sure what “special modes” alludes to.

If I were to guess, it would involve the networking of disparate systems that would be difficult to simulate on the ground.

One such mode could involve controlling a stealth drone operating deep in adversary territory, streaming target coordinates — possibly of a moving target — and relaying them to a precision-strike weapon system on the ground, such as the Iskander, or in the air, such as the Su-34.

The second pilot could manage the drone and other highly autonomous systems while the primary pilot concentrates on flying the mission and maintaining situational awareness.

Incidentally, Ukraine's Defence Intelligence Directorate recently reported recovering a Russian S-71M “Monokhrom”, a stealthy unmanned aircraft associated with the Su-57. The S-71 can reportedly perform both reconnaissance and strike missions, with the latter involving a kamikaze variant. The aircraft recovered by the Ukrainians was presumably the strike variant, which would explain why it was not recovered for reuse.

The Ukrainians found an NVIDIA Jetson Orin computer module in the S-71M, which they claim may indicate the use of AI. This provides an interesting indication of the increasingly sophisticated autonomous systems that could potentially be integrated into such a manned-unmanned architecture.

Perhaps this is what “special modes” refers to.

Su-57, S-71 Integration: Lethal Upgrade

On February 9, 2026, Russia's UAC delivered a large batch of Su-57s which, according to a UAC press release, were “in a new technical configuration.”

“The aircraft have received upgraded onboard systems and a new weapons complex.”

It is likely that the fresh batch of Su-57s delivered added the capability to carry the air-launched stealthy combat UAV designated S-71, a weapon first unveiled during Army 2024.

The S-71 is an air-launched UAV that can be tasked with target identification, marking or destruction. Deploying and controlling a Su-57 carrying an S-71 variant would have required an upgrade of its onboard systems.

The S-71 began captive-carry trials in April 2024 at Russia’s Flight Research Centre in Zhukovsky, with test flights involving the Su-57 fighter.

You can read more details about the S-71 in my Thumkar blog post below:

On January 17, 2026, it was reported that an S-71K “Carpet” demonstrated its effectiveness for the first time by successfully destroying the highly mobile M142 HIMARS multiple-launch rocket system.

The cruise missile–drone hybrid has been developed by GosMKB Raduga JSC and can be used by 4++ generation multirole fighters, including the Su-35S and Su-30SM/SM2, as well as Su-34 NVO fighter-bombers.

Decoding the Su-57D’s Tail Marking: A Glimpse Into Russia’s Future Air Combat Concept

Photo from Defence TC

The graphic above, clearly visible on a close-up photograph of the right fin of the Su-57D, published on the "Defence" TC, highlights the role that the twin-seat stealth platform may be equipped to play.

The graphic shows the Su-57D at the center, with four silhouettes positioned at the tips of white spiral markings radiating outward. Each silhouette appears to represent an aerial platform or missile.

According to the Defence TC, the silhouettes represent the S-70 Okhotnik UCAV, an unmanned Su-75, the Kh-69 air-to-surface cruise missile, and the "Izdeliye 810" air-to-air missile — a further evolution of the R-37M.

If true, the graphic illustrates the Su-57D's ability to coordinate attacks by S-70 and Su-75 combat drones while also launching attacks itself using Kh-69 and Izdeliye 810 missiles.

I believe the silhouettes could instead represent the S-70 Okhotnik UCAV, an unmanned Su-75, a MALE reconnaissance and targeting drone, and a tactical ballistic missile such as the Iskander-M.

In that case, the graphic would illustrate the Su-57D's ability to coordinate attacks by S-70 and Su-75 combat drones, as well as assign targets to an Iskander-M battery using coordinates relayed from the MALE drone.

I could be wrong, but my interpretation is based on what appear to be the Su-57D's primary roles — a drone mothership for MUM-T operations and an airborne command post.

It may be noted that, when configured for MUM-T and command-post roles, the Su-57D likely does not carry weapons in its internal bays. I explained the reasons in my earlier blogpost.

You are welcome to share your opinion with a comment below.

Copyright © Vijainder K Thakur. First published on Thumkar.

Su-57D: Russia’s Stealth Fighter Becomes an Airborne Command Post

Su-57D Maiden Flight

On May 19, Russia’s UAC announced that the Su-57D — a two-seat variant of the Su-57 — had undertaken its maiden flight and commenced flight testing.

During the maiden flight, the aircraft was flown by a single pilot, Sergei Bogdan, the chief test pilot of the Sukhoi Design Bureau.

The Su-57 is designed for single-seat operations. Situational awareness, AI decision assist, and automation have been extensively used to allow a single pilot to handle the cockpit workload.

Imperative for Two-Seat Variant

To begin with, Russian forces didn't feel the need for a two-seat variant. However, much has changed since the stealth fighter first flew in 2010. Based on advances in combat aviation technology and the experience of the Russian Aerospace Forces in Ukraine, Russia's Ministry of Defense has now ordered a batch of the twin-seaters.

It is widely understood that a twin-seat variant facilitates speedier pilot training and operational conversion, as well as manned-unmanned teaming (MUM-T) of combat aircraft operating as a drone mothership.

The Su-57D is reportedly capable of teaming up with four S-70 Okhotnik modular drones configured for roles such as SEAD, electronic warfare, reconnaissance, and aerial combat. Notably, the control and coordination demands of MUM-T operations are far beyond what a single pilot can handle, even using sensor fusion and AI assistance.

Following the Su-57D's maiden flight, Bogdan, during his interaction with the Russian press, highlighted yet another important role that would require a second seat. He stated that the co-pilot of the Su-57D would be able to command an air group directly in the air, thousands of kilometers away from base. It is important to understand what Bogdan was alluding to because it highlights another emerging, path-breaking trend in combat aviation.

Important Cues from the Su-57D Patent

In November 2023, Russia's United Aircraft Corporation published a patent for a multifunctional two-seat stealth aircraft, which has now been unveiled as the Su-57D.

Based on a copy of the patent, TASS reported that the two-seat stealth tactical aircraft would be designed to detect and destroy air, surface, and ground targets.

The patent document acquired by TASS referred to the aircraft as “...a multifunctional two-seat stealth tactical aircraft... intended to detect and destroy air, surface, and ground targets at super- and subsonic flight speeds across a wide range of altitudes, as well as act as an airborne command post for network-oriented operations involving mixed groups of aircraft.”

To reiterate, the document noted that the twin-seat variant would retain its ability to destroy targets with guided and unguided weapons. In addition, it would be possible to use the new variant as an air control point with the ability to ensure coordination between aviation and military formations, as well as serve as a control point for unmanned aerial vehicles.

Air Command Role

For several years now, the RuAF has been evaluating the use of the Su-57 for cooperative operations with manned fighters such as the Su-35.

In June 2020, TASS reported that Russia had tested Su-35–Su-57 cooperative operations.

“The experiment was carried out in real combat conditions. A group of Su-35 fighters was involved in the ‘flock’; the role of the command-and-staff aircraft was performed by the Su-57,” a source told TASS.

More recently, as part of the ongoing conflict in Ukraine, Su-57 fighters have teamed up with S-70 Okhotnik UCAVs to strike targets in Ukraine.

Su-57D Redesign

Pivotal to the Su-57D's role as a command post would be long endurance and range, which would necessitate a significant increase in the fuel carried internally by the aircraft.

The redesign of the Su-57 airframe to realise the Su-57D is aimed not only at creating space for a second cockpit but also at increasing internal fuel capacity. In other words, the Su-57D variant will carry more fuel internally than the Su-57 fighter. Usually, twin-seat variants carry less fuel than the single-seat fighter because the second seat is fitted while retaining the fighter version's dimensions.

It is clear that, in the case of the Su-57D, Sukhoi has departed from the norm to facilitate its MUM-T and command-post roles.

Optionally, the Su-57D can also carry additional fuel in tanks fitted into the weapon bays normally used for the internal carriage of missiles and bombs.

It is also possible that, by increasing the dimensions, Sukhoi has created additional space for the avionics required to support MUM-T and command-post roles. Perhaps the avionics could also go into the weapon bays?

As such, it is highly likely that the Su-57D can be configured either for a combat role or for a command-post role, but not both simultaneously.

Conclusion

The option to carry additional fuel in the weapons bays of the Su-57 is an interesting innovation that increases the versatility of the stealth fighter.

With the Su-57, Russia appears to be following the same approach that the Soviet Union successfully pursued after developing the Su-27 — continuously reinventing the aircraft to meet the challenges and opportunities emerging from technological advances.

The Su-27, officially inducted into the Soviet Air Force in 1985, evolved into several Su-30 variants, the Su-34, the Su-35, and the J-11, all of which remain in service to this day. The evolved variants of the Su-27 will likely remain in service for at least a couple of decades more.

It is highly likely that Su-57 variants will similarly remain in service for the next 50 years.

Copyright © Vijainder K Thakur. First published on Thumkar.

India Walked Away from the FGFA. The Need for a Twin-Seat Stealth Fighter Did Not!

 The Fifth Generation Fighter Aircraft (FGFA), which India and Russia once planned to co-develop, was envisioned as a two-seat variant of the Su-57.

The IAF’s requirement was never for a stealth fighter — it was, and likely continues to be, for a twin-seat stealth fighter!

It's likely that the IAF’s preference for a twin-seat fighter was based on its experience operating the Su-30MKI. Besides pilot training and operational conversion, a twin-seat fighter could also support multi-role operations benefiting from a second crew member, such as complex strike coordination, electronic warfare/attack roles, and reconnaissance.

The reported reasons for India opting out of the FGFA program — lack of supercruise and unproven operational capability — were always unconvincing, considering that India, as a co-developer of the fighter, would eventually have addressed those shortcomings.

The Rationale for a Twin-Seat Stealth Fighter

All 4th-generation fighter development programs foresaw the eventual need for a twin-seat variant. The initial designs provisioned for a second seat, usually by placing a fuel tank and relocatable electronics behind the cockpit. That space could later be utilized for a second cockpit by moving the electronics and dispensing with the fuel tank.

Stealth fighter development programs for the F-22 and F-35 chose to depart from the twin-seat convention for the following reasons:

1. A twin-seat configuration compromises stealth shaping to some extent.

2. It reduces internal fuel-carrying capacity, thereby compromising range. (Stealth fighters cannot carry fuel externally in drop tanks.)

3. The fighters were primarily designed to penetrate contested airspace; it was believed that sensor fusion would be adequate to enable a single pilot to fly such missions.

In brief, it was believed — with good reason — that twin-seat stealth fighters would add complexity, reduce internal fuel or payload in some cases, and increase radar cross-section.

MUM-T Operations

It has now been clear for several years that the choice of single-seat-only stealth fighters did not anticipate the emergence of the requirement for Manned-Unmanned Teaming (MUM-T) operations.

The Su-57D, for example, is reportedly designed to team up with four S-70 Okhotnik modular drones configured for roles such as SEAD, electronic warfare, reconnaissance, and aerial combat. The control and coordination demands of MUM-T operations far exceed what sensor fusion and AI alone can enable a pilot to manage.

South Korea's KF-21 Boramae Stealth Fighter

South Korea followed a pragmatic approach in developing its KF-21 stealth fighter — an approach that is paying rich dividends in terms of meeting performance and development timeline goals.

Specifically:

The KF-21 features significant reduction in RF observability rather than all-aspect low observability. (To achieve the latter, it would have required materials that the nation had not yet developed.)

The KF-21 features a twin-engine, semi-stealth design with external weapons carriage (no internal weapons bay in the early blocks).

Of the six prototypes built, two were twin-seat variants.

The first prototype rolled out in April 2021 and flew in July 2022. All prototypes collectively conducted roughly 1,600 sorties over 42 months of incident-free flight testing, achieving supersonic flight, aerial refueling, and weapons integration. System development concluded in early 2026.

The first serial-production KF-21 to roll out in March 2026 was, significantly, a trainer!

Initial deliveries to the ROKAF are slated for the second half of 2026, with 40 Block I aircraft targeted by 2028 and up to 120 total aircraft (including Block II) by 2032.

Block I prioritizes air superiority; Block II will add full multirole air-to-ground and anti-ship capabilities. Block III variants will address stealth shortcomings and include internal weapons bays.

The two-seat variant will play a pivotal role. It will not only accelerate pilot training and operational conversion but also facilitate the development of advanced variants and future concepts such as loyal-wingman operations.

An electronic warfare/attack variant — the KF-21EA — is planned, with a dedicated Electronic Warfare Officer (EWO) station in the rear cockpit.

China's J-20S

Ahead of the KF-21, China’s J-20S — a two-seat variant of the Chengdu J-20 Mighty Dragon — became the world’s first operational twin-seat fifth-generation stealth fighter.

The fighter was unveiled at the 2024 Zhuhai Airshow.

Prototypes first flew in 2021; the aircraft entered, or approached, PLAAF operational service in 2025, with frontline markings appearing by mid-year.

The J-20S is reportedly optimized for combat (MUM-T operations), not training or operational conversion. The second crew member — a Mission Systems Officer — manages MUM-T-related sensor fusion, electronic warfare/jamming, and tactical command and control.

While the pilot focuses on flight and air superiority, the Mission Systems Officer directs loyal-wingman drones for coordinated strikes, reconnaissance, and SEAD (Suppression of Enemy Air Defences).

Su-57D

Russia’s UAC announced on May 19, 2026, that the Su-57D — a two-seat, multifunctional, fifth-generation fighter — had commenced flight testing. The Su-57D is now the third stealth fighter with a twin-seat variant.

Circumstantial evidence suggests that Russia provisioned for a twin-seat variant of the Su-57 from the start of the aircraft’s development.

Reliable Russian social media recently reported that the Su-57D “was converted from the already existing 055 aircraft in the shortest possible time.”

“The Indians wanted such an aircraft, and we customized it for them.”

Converting an existing single-seat airframe into a twin-seater in a short time would not have been possible had Sukhoi not designed the aircraft for such a conversion.

The most likely reason Sukhoi did not develop a twin-seat variant earlier was that the Russian Aerospace Forces never projected the need for one.

However, over the past couple of years, Sukhoi has completed development and operational testing of the S-70 Okhotnik stealth combat drone. Su-57 fighters have successfully carried out operational Su-57 + S-70 MUM-T missions in Ukraine.

The need for a twin-seat variant of the Su-57 has now been firmly established, and Russia’s Ministry of Defense has already ordered a batch of the twin-seaters.

HAL Likely to Offer a Customized Su-57D Variant

Russia has offered to help HAL build a customized variant of the Su-57D for the IAF. The offer reportedly involves ToT and industrial participation, including joint-venture production of components in India, licensed assembly, MRO facilities, and possible avionics customization.

If Rosoboronexport and HAL successfully negotiate the technological and financial terms of their collaboration, HAL is likely to offer the customized Su-57D variant to the IAF.

The HAL–Rosoboronexport tie-up is unlikely to be derailed by any CAATSA sanctions because U.S. leverage over HAL is limited. Any U.S. move to stop the supply of GE F404 or F414 engines to HAL is likely to hurt Boeing as much as it hurts India. From India’s perspective, such sanctions now would be preferable to sanctions imposed when the LCA Mk-2 and AMCA programs are approaching maturity and serial production.

Copyright © Vijainder K Thakur. First published on Thumkar.