Russia's Su-75 Checkmate remains in the prototype construction stage, with its maiden flight now expected once assembly work, systems integration, and preparatory testing are completed, Russian media reported.

According to Alexey Bogatyrev, head of the Safir analytical centre, the aircraft has not yet progressed to flight testing because development is still focused on building and preparing the prototype airframe for trials.

Bogatyrev contrasted the Su-75's design philosophy with that of the American F-35, noting that while both are single-engine fighters, they have been conceived for different purposes.

In his view, the F-35 was designed primarily as a node within a wider information and communications network, placing heavy emphasis on data sharing, sensor fusion, and network-centric operations.

The Su-75, by contrast, is intended to prioritise lower weight, higher speed, greater operating altitude, and enhanced manoeuvrability. Bogatyrev argued that the aircraft is being developed as an alternative option for customers seeking a lightweight single-engine fighter rather than a platform centred principally on information dominance.

He stated that the Checkmate concept focuses on the aircraft itself and its flying qualities. According to his assessment, the fighter is intended to be faster, more agile, and capable of operating at higher altitudes than competing designs, reflecting a different aerospace engineering philosophy.

Bogatyrev described this as a distinction between two engineering schools. For the F-35, stealth characteristics, onboard computing power, and integration with other assets are the defining features. For the Su-75, the platform's flight performance and manoeuvrability are seen as the primary strengths.

United Aircraft Corporation (UAC) currently lists the Checkmate as a single-engine stealth fighter with a projected maximum speed of Mach 1.8, a range of up to 2,900 km without external fuel tanks, and a combat payload of up to 7,400 kg, equivalent to roughly 7.4 tons.

The company also says the aircraft should be capable of carrying up to five air-to-air missiles within internal weapons bays while maintaining a low-observable configuration. However, all of these figures remain projected performance targets that require validation through ground and flight testing.

The latest developments suggest the programme has moved beyond the concept and mock-up phase that began with its public unveiling at MAKS 2021. Russian aerospace officials have confirmed that construction of a flying prototype is now under way, representing the most significant progress in the program in several years.

The aircraft has experienced repeated schedule changes since its unveiling, with earlier flight targets slipping multiple times as development continued. The transition to physical prototype assembly is therefore being viewed as a critical milestone for the project.

The Su-75 is being marketed as a more affordable fifth-generation fighter option aimed at both export customers and potential domestic procurement. Russian industry officials have also signalled interest in developing both crewed and uncrewed variants of the aircraft.

Earlier reports proposed the use of an unmanned Su-75 operating alongside a two-seat Su-57 and unmanned aerial vehicles. Under this concept, stealth characteristics, automation, and task-sharing across multiple platforms would enable a mixed combat formation capable of conducting more complex missions while distributing operational risk.

If the forthcoming test program proceeds as planned, the first flight will mark the beginning of efforts to verify the aircraft's advertised performance, stealth characteristics, avionics integration, and overall operational viability. Until that point, the Checkmate remains a promising but still unproven platform whose headline specifications exist largely on paper rather than in demonstrated flight performance.

Agencies