Konstantin Fyodorovich Chelpan was a prominent Soviet engineer of Greek background. Head of the Engineering Design Bureau of the Kharkiv Locomotive Factory, chief designer of the T-34 tank engine. Awarded the Order of Lenin, he was politically repressed and executed under a mass persecution ordered by Joseph Stalin, but politically rehabilitated after death.

The T-34 is a Soviet medium tank from World War II. When introduced, its 76.2 mm (3 in) tank gun was more powerful than many of its contemporaries, and its 60-degree sloped armour provided good protection against anti-tank weapons. The T-34 had a profound effect on the conflict on the Eastern Front, and had a long-lasting impact on tank design. The tank was praised by multiple German generals when encountered during Operation Barbarossa, although its armour and armament were surpassed later in the war. Its main strength was its cost and production time, meaning that German panzer forces would often fight against Soviet tank forces several times their size. The T-34 is also a critical part of the mechanized divisions that form the backbone of the Deep Battle Strategy.