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.

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-38 made its first flight on May 19, 1943. Only one was built, and it was modified from a regular production aircraft.

The XB-38 delivered a higher top speed, but its ceiling was lower. After a few flights it was grounded due to exhaust gas leaks from the engine manifolds. Once this had been fixed, testing resumed until the ninth flight on June 16, 1943 when the inboard starboard engine caught fire and the crew bailed out. The XB-38 was destroyed and the project was canceled, in part because the V-1710 engines were in high demand for Lockheed P-38 Lightning, Curtiss P-40 Warhawk and North American P-51A Mustang fighters.

Operators

 * 🇺🇸 United States
 * United States Army Air Forces