Russia develops new version of its Su-57 Felon fighter

A two-seat variant of Russia’s Su-57 fifth-generation stealth fighter has been photographed conducting ground taxi trials, with Russian military aviation blogger Ilya Tumanov, who operates the widely followed Fighterbomber Telegram channel, confirming the aircraft’s existence on May 16 and describing it as a new two-seat modification of the Felon that completed ground runs as part of initial testing.

The photograph, which appeared in Russian defense media, shows what appears to be a Su-57 airframe with a distinctly elongated forward fuselage section accommodating a second cockpit, consistent with the tandem two-seat configuration used by most Russian combat trainer variants.

Tumanov, whose channel is considered one of the more reliable sources on Russian tactical aviation among open-source monitoring communities, wrote that the aircraft’s final designation remains undecided: “Will it be called Su-57D or Su-57UB, we’ll see. As an option — Su-57ED,” per his post. The uncertainty over nomenclature is typical of a program at early ground testing stage, where official designations are often not finalized until later in the development cycle.

The Su-57, known by its NATO reporting name Felon, is Russia’s most advanced operational combat aircraft, a twin-engine multirole stealth fighter developed by Sukhoi and produced at the Komsomolsk-on-Amur aircraft plant in Russia’s Far East. The aircraft entered limited service with the Russian Aerospace Forces in 2020 after a protracted development program that stretched across more than a decade, with production accelerating gradually as Russia has sought to field the type in operationally meaningful numbers. The Su-57 features low-observable shaping, internal weapons bays, thrust-vectoring engines, and an advanced sensor suite, positioning it as Russia’s answer to the American F-22 Raptor in the air superiority domain, though independent assessments of its actual stealth performance have consistently questioned whether it achieves the radar cross-section reductions that Russian claims suggest.

The significance of a two-seat variant lies primarily in its export potential rather than its operational utility for Russian pilots. Tumanov himself noted this, while the Telegram channel Voyevoda Veshchayet, another Russian military commentary source that discussed the aircraft, stated explicitly that “the two-seat modification is intended primarily for export,” per its post. Single-seat combat aircraft typically require a dedicated two-seat trainer variant for foreign customers whose pilots lack the institutional training pipeline and simulator infrastructure that domestically trained Russian crews can access. Exporting only the single-seat Su-57 to foreign air forces would place an enormous training burden on customer nations that most cannot independently sustain, making a two-seat variant a practical prerequisite for successful export at scale.

In April 2026, Rosoboronexport, Russia’s state arms export agency, announced new foreign contracts for the Su-57, without specifying customers or quantities, according to Russian state newspaper Rossiyskaya Gazeta. The announcement coincided with the emergence of multiple photographs and videos showing Su-57 fighters flying over Africa bearing Algerian Air Force markings, with a first high-quality photograph of an Algerian Su-57 published in April 2026, again per Rossiyskaya Gazeta. Algerian Air Force pilots have apparently been conducting Su-57 familiarization and conversion flights, making Algeria the first confirmed foreign operator of the type, a geopolitically significant development given Algeria’s historical reliance on Russian and Soviet combat aircraft and its position as one of Africa’s largest defense spenders.

The Su-57’s combat record has been complicated by a series of confirmed losses, none of which occurred in air-to-air or surface-to-air engagements. According to open-source tracking by the Oryx blog and Ukrainian military reporting, Russia has lost at least four Su-57 aircraft since the full-scale invasion began, with all confirmed losses occurring on the ground as a result of Ukrainian long-range drone strikes against Russian airbases deep inside Russian territory. The pattern of losses, all attributable to Ukrainian drone strikes rather than air defense intercepts, has raised questions not about the aircraft’s airborne survivability but about Russia’s ability to protect its most advanced combat aircraft from increasingly capable Ukrainian long-range unmanned systems operating hundreds of kilometers inside Russian territory.