N'afọ 1934, United States Army Air Corps rịọrọ maka bọmbụ nke nwere okpukpu abụọ nke bọmbụ bọmbụ na nso nke Martin B-10, nke na-abanye ọrụ dịka onye na-agba bọmbụ nke ndị agha. Na nyocha na Wright Field n'afọ na-esote, Douglas gosipụtara DB-1. Ọ na-asọmpi Boeing Model 299 (mgbe e mesịrị ghọọ Boeing B-17 Flying Fortress) na Martin Model 146. Ajụjụ: Ònye bụ onye asọmpi ha?
Boeing Model 299 (nke e mechara mepụta Boeing B-17 Flying Fortress) na Martin Model 146