Martin 4-0-4

The Martin 4-0-4 is a pressurized, all-metal, low-wing 40 passenger American airliner built by the Glenn L. Martin Company and introduced in 1951. Derived from the unpressurized Martin 2-0-2, it is 3 feet longer, powered by the same Pratt & Whitney R-2800 Double Wasp-CB16 18-cylinder radial engine, and slightly slower. In addition to commercial airline use initially in the United States, it was used by the United States Coast Guard and United States Navy as the RM-1G.