Douglas XB31 Raidmaster Plus bonus XP55 Ascender, XP56 Black Bullit, XP54 Goose Swoose

In early 1939, the USAAC was alarmed by the wars in Europe and Far East . A special committee was established and was sent to the Luftwaffe bases. The final report convinced the committee that Germany was far ahead of the Allied nations. It led to the USAAC requirement for a "Super Bomber" which could operate at high-speeds, long-range, more bomb load and more defensive armament than the existing B-17 and B-24. In 1940, Douglas submitted Model 423 for the competition, and it received the designation XB-31. The Army also issued contracts for a preliminary design to other three major aircraft companies, which were designated as Boeing XB-29, Lockheed XB-30 and Consolidated XB-32. The Douglas XB-31 was the largest and heaviest of four Super-bomber designs. The pilot and co-pilot were to be seated under separate double bubble canopies that were used were later fitted to the C-74 Globemaster transport and the XB-42 experimental bomber. In September 1941, the Boeing and Consolidated were much further in their designs, and received prototype contacts. The XB-31 and XB-30 were withdrawn from competition.