Boeing XB-38 Flying Fortress The XB-38 was destroyed and the project was canceled, in part because the V-1710 engines were needed for other projects such as the Lockheed P-38 Lightning, Bell P-39 Airacobra, Curtiss P-40 Warhawk, North American P-51A Mustang, and Bell P-63 Kingcobra fighters. Boeing XB-38 Flying Fortress The XB-38 Flying Fortress was a single example conversion of a production B-17E Flying Fortress, testing whether the Allison V-1710 V type engine could be substituted for the standard Wright R-1820 radial engine during early World War II. The XB-38 was the result of a modification project undertaken by Boeing and Vega (a subsidiary of
American Theater (World War II) other heavy bomber projects were cancelled. During the final months of World War II, Japan had planned to use plague as a biological weapon against U.S. civilians in San Diego, California, during Operation Cherry Blossoms at Night. The plan was set to launch at night on September 22, 1945. However it was shelved after Yoshijiro Umezu, Chief of the Imperial Japanese Army General Staff, rejected it. Additionally Japan surrendered five weeks before the plan had been intended to take place. These false alarms have generally been attributed to military and civilian inexperience with war and poor radars of the era.