Polikarpov U-2

The Polikarpov U-2 or Po-2 served as a general-purpose Soviet biplane. The reliable, uncomplicated and forgiving aircraft served as a trainer and crop-duster in peacetime as well as a low-cost ground attack, aerial reconnaissance, psychological warfare and liaison aircraft during war, proving to be one of the most versatile light combat types to be built in USSR. It is the second most produced aircraft, and the most produced biplane, in the history of aviation. More than 40,000 Po-2s were built between 1928 and 1953. It remained in production for a longer period of time than any other Soviet-era aircraft.

Polikarpov U-2 in Worldwar
The U-2 was the plane that Ludmila Gorbunova flew throughout her war time service. She found the plane very reliable despite it's obsolescence, as it's small frame, slow speed and low altitude made it harder to spot by the Race Killercraft. She became rather attached to it by the wars end.