The Object 640 'Black Eagle' next to a T-80UM-1 at Omsktransmash, ~2014.
Object 640 is a fairly mysterious Russian tank designed by the Leningrad Kirov Plant, and later taken up by the KBTM design bureau of Omsktransmash in Omsk, Russia. It first appeared at an arms exposition in Omsk in 1997, and again in June 1999 in Siberia. In both instances, its turret was covered by camo netting, and due to its limited appearances, pictures of it aren't the most clear or numerous.
Nicknamed 'Black Eagle', the vehicle is notable for its stretched T-80U hull with seven road wheels, and for abandoning the traditional carousel-style autoloader in favor of a bustle autoloader akin to Western vehicles like the Leclerc. The advantage of a bustle autoloader not only lies in how it keeps the ready-ammunition stored behind the turret, usually one of the stronger parts frontally of a tank.
Like other modern Russian tanks, the Object 640 retains a 125 mm gun, but doesn't have the same limitations as tanks with the carousel-style design. This is in part due to ammunition length, which can only be so long so as to fit inside the autoloader in the hull, meaning it is limited in capability and penetration, with rounds like the 3VBM22 and 3VBM23 Svinets pushing the limits of the design. With a bustle autoloader, ammunition can be much longer, which is a particular advantage for APFSDS rounds, resulting in better penetration and post-penetration effect.
Despite its seemingly promising design, the Black Eagle hasn't been seen much since. The above picture, taken at Omsktransmash, was one of the latest sightings, the other being in 2022, still at Omsktransmash. As you might be able to tell, the Black Eagle is another one of those promising projects that ultimately never saw service. With that said it's very likely that experience gained from its development has, and will, help with future Russian tank designs, notably highlighting the advantages of the bustle autoloader







