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
Military history of the United States during World War II American bomber crew losses were high. One such example was the Schweinfurt-Regensburg mission, which resulted in staggering losses of men and equipment. The introduction of the revered P-51 Mustang, which had enough fuel to make a round trip to Germany's heartland, helped to reduce losses later in the war. In mid-1942, the United States Army Air Forces (USAAF) arrived in the UK and carried out a few raids across the English Channel. The USAAF Eighth Air Force's B-17 bombers were called the "Flying Fortresses" because of their heavy defensive armament of ten to twelve machine guns, and armor plating in