The Lockheed Model 44 Excalibur was a proposed American airliner designed by Lockheed.[1] The Model 44 was the first four-engined design from the company,[1] a low-wing monoplane with a retractable tricycle landing gear. Originally fitted with twin fins, the design ended up with three fins.[1] It was to be powered by four 1200 hp Pratt & Whitney Twin Wasp radial engines. Pan American Airways was close to ordering the Excalibur when Lockheed abandoned the project to devote its resources into developing the Model 49 Constellation that had been ordered by Trans World Airlines.[1]