The first Russian effort to create a stealth fighter produced the Su-57. It was not a success and Russia realized the Su-57 was neither effective nor affordable. The Su-57 could not compete with the Americans F-22s and F-35s. These two stealth aircraft have been in combat and succeeded using their stealth and other new capabilities. Since the Su-57 could not compete, Russia tried something new, a more recent stealth design called Checkmate, or the Su-75. This aircraft was meant to avoid the mistakes made in developing the Su-57. So far, the Su-75 is an effort, not an accomplishment and the most optimistic Russian predictions have the aircraft entering service later in the decade.
The Russian invasion of Ukraine resulted in economic sanctions that stalled planned production and deployment of the Su-57. Russia kept trying and that led to a new design. This was revealed in 2021 as a new single engine stealth fighter called Checkmate was revealed. Sukhoi, the developer and manufacturer of the most successful current Russian fighters, displayed a mockup of the new single-engine Checkmate stealth fighter, which was meant to match the capabilities of the American F-35. Checkmate was developed by the same team that designed the Su-57, the Russian effort to match the American F-22. The Su-57 proved to be a failure as an F-22 clone and few are being built, and those only for the Russian Air Force. Export customers cancelled orders and accused Sukhoi and the Russian government of fraud and trying to sell an aircraft that does not work. Checkmate appears as a desperate move to salvage something from all the money spent on developing the Su-57.
So far Russia has revealed few details on Checkmate, and these include things like the aircraft being available in one and two seat versions, with the two-seater used as a trainer or an electronic warfare aircraft. There were also plans for an unmanned version, without a cockpit, and thus cheaper to build. Russia already has the S-70, a UCAV (unmanned combat aircraft) in production. This stealthy, delta wing aircraft has already been tested accompanying manned fighters and production is underway.
Checkmate is shaped more like the American YF-23, the loser in the competition to select a stealth fighter design. The YF-22 won and in 1991 became the F-22. Only two YF-23s were built as development aircraft and, given the amount of data obtained from defense industries by Russian hackers since then, that could have included detailed plans for the YF-23. Moreover, the two YF-23s eventually became museum aircraft and were available for anyone to photograph. Over the years many details of the YF-23 performance were published.
Russia used a similar approach when the U.S. had two competing designs for a new ground attack aircraft. The YA-10 won out over the YA-9 in 1973 and entered service in 1976. Russia adopted the YA-9 design and their Su-25 entered service five years later. The Su-25 was successful and over 1,024 were built, compared to 713 A-10s. Both aircraft were popular with the ground troops and are still in use after undergoing several upgrades.
Checkmate seeks to save a lot of time, effort and money adopting proven design concepts. The Su-57 was an overall disappointment but many of its features were successful, and these are apparently incorporated into the Checkmate design. In one respect Checkmate will not match the F-35 and that is the extensive software and data-fusion systems that all pilots report as remarkable and make the F-35 a truly unique aircraft, giving the pilot unique situational awareness of what is going on around him. The Russians have seen the Israelis F-35s in action and were impressed. They were also dismayed when they realized it would take them a long time to develop something equal to the current F-35 software systems. Meanwhile the Russians will have to improvise.
Despite all the tech Russia has available for Checkmate, they have much less money available to integrate it all into a new aircraft that will approach the F-35 in performance. Then again, Russia may just be trying to salvage what they can from their Su-57 debacle and find some satisfied export customers for their Su-75. Checkmate is expected to be a lot cheaper than the Su-57 and F-35 and, unlike the Su-57, deliver some of what was promised for earlier Russian stealth aircraft.