10/31/2011. Prototype photographed three days before its maiden flight that took place on December 29, 1939, with chief test pilot Bill Wheatley being at the controls. The prototype B-24 design top speed was 311 mph (501 kmh), but was only able to achieve 273 mph (439 kmh).
Subsequently the aircraft was fitted with Pratt & Whitney R-1830-41 Twin Wasp fourteen-cylinder radial engines radials replacing the original R-1830-33 engines. General Electric B-2 turbosuperchargers replaced the original mechanical superchargers, and relocating these and the oil coolers gave the engine nacelles the characteristic elliptic shape that became familiar on the production Liberators.
Redesignated XB-24B the prototype was flown again on February 1, 1941, and the aircraft was able to attain a maximum speed of 310 mph (499 kmh). The aircraft was scrapped at Brookley Field, Alabama on June 20, 1946.