A large number of engines were considered before settling on the Shvetsov ASh-2K, essentially two air-cooled ASh-82 radial engines paired together and the liquid-cooled Dobrynin VD-4K six-bank inline engine, similar in configuration to the failed German Junkers Jumo 222, for a format of engine/airframe proposed much earlier during World War II's later phases in late July 1943, for the Heinkel firm's "Amerikabomber" never-built contract contender.