Boeing XB-38 Flying Fortress 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 Lockheed) on a B-17 Flying Fortress to fit it with liquid-cooled Allison V-1710-89 Vee engine. It was meant as an improved version of the B-17, and a variant that could be used if air-cooled Wright R-1820 radial engines became scarce. Completing
RAF Bomber Command aircrew of World War II aircrew were given the task of flying a required number of operations, an "operational tour", usually of about 30 operations (missions in USAAF terminology). On completion of an operational tour the airman (and often his complete crew as they tended to remain very tight-knit, always flying together) would be "screened" (taken off operational flying) and split up as they received their future postings which would frequently be serving at Operational Training Units or Heavy Conversion Units preparing the next groups of young bomber crews for their postings to operational squadrons. Between March 1943 and the early summer of 1944 the