Essentially an Allison-powered B-17E, the XB-38 was a project developed by engineers at Lockheed-Vega. The ninth production B-17E 41-2401 had been delivered to Lockheed-Vega to help in setting up a Flying Fortress production line at their Burbank, California facility. This was the aircraft modified as the prototype for the XB-38 design. 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. Design and Development The XB-38 was the result of a modification project undertaken by Vega (a subsidiary of Lockheed) on a Boeing B-17 Flying Fortress to fit it with liquid-cooled Allison V-1710-89 V-12 engines. It was to be an improved B-17, and an alternative if the normally fitted air-cooled Wright R-1820 radial engines became scarce. Completing the modifications took less than a year, and the XB-...