Consolidated B-24 Liberator XB-24

The US Army Air Corps awarded Consolidated the XB-24 prototype contract in March 1939, with the requirement that one example be ready before the end of the year. The company finished with two days to spare: the prototype flew on 29 December 1939. The design was simple in concept yet advanced for its time, built around the high-aspect-ratio, low-drag Davis wing that delivered the range the Army wanted.

Testing exposed serious shortfalls. The most important was that the aircraft failed to meet the contracted top speed: as built it reached only 273 mph (439 km/h) instead of the specified 311 mph (501 km/h). The mechanically supercharged R-1830-33s were therefore replaced by turbo-supercharged R-1830s, the tail span was widened by 2 ft (61 cm) and the pitot-static probes were moved from the wings to the fuselage.

With those changes the prototype was redesignated XB-24B, and they became standard on every B-24 built from the B-24C onwards. XB-24B 39-680 ended its career converted into a luxury airliner, with the interior gutted, new windows cut, compartments fitted with two-tier Pullman-style berths, sound-proofing trim and a galley with refrigerator and hot plates.