MAILPLANE
Mail plane
A mail plane is an aircraft used for carrying mail. Aircraft that were purely mail planes existed almost exclusively prior to World War II. Because early aircraft were too underpowered to carry cargoes, and too costly to run any "economy class" passenger-carrying service, the main civilian role for aircraft was to carry letters faster than previously possible. In 1934, some mail services in the USA were operated by the United States Army Air Corps, soon ending in the Air Mail scandal.The above text is a snippet from Wikipedia: Mail plane
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