High Quality Content by WIKIPEDIA articles! The Yermolayev Yer-2 was a long-range Soviet medium bomber used during World War II. It was developed from the Bartini Stal-7 prototype airliner before the war. It was used to bomb Berlin from airbases in Estonia after Operation Barbarossa in 1941. Production was terminated in August 1941 to allow the factory to concentrate on building higher-priority Ilyushin Il-2 ground-attack aircraft, but was restarted at the end of 1943 with new, fuel-efficient, Charomskiy ACh-30B aircraft diesel engines.