revision preference src: It was a twin-engined, low-wing monoplane that first flew in 1935. monoplane was the monoplane of the Ilyushin Il-4 (originally designated DB-3F). <SEP> tgt: It was a twin-engined, low-wing monoplane that first flew in 1935. It was the precursor of the Ilyushin Il-4 (originally designated DB-3F).