The Thomas-Morse MB-4 was a prototype American mailplane of the 1920s. It was of unusual design being a biplane with two main fuselages housing the crew of two and a central nacelle which carried the aircraft's twin engines in a push-pull configuration. It was a failure having extremely poor flying characteristics and being described as the worst thing on wings and saw no service.
Made by Thomas-Morse Aircraft.
It is the successor of the Thomas-Morse MB-3 .