The Naval Aircraft Factory PN was a series of open cockpit American flying boats of the 1920s and 1930s. A development of the Felixstowe F5L flying boat of the First World War, variants of the PN were built for the United States Navy by Douglas, Keystone and Martin.

The twin-engine F5L was one of the Felixstowe F series of flying boats developed by John Cyril Porte at the Seaplane Experimental Station, Felixstowe, England, during the First World War for production in America.