Lockheed R6V Constitution

The Lockheed R6V Constitution was a large, propeller-driven, double-decker transport developed in the 1940s by Lockheed as a long-range, high-capacity transport and airliner for the United States Navy and Pan American Airways. It began in 1942 as a joint study, the Lockheed Model 89, for a pressurized aircraft to carry 17,500 pounds of cargo 5,000 miles at 25,000 feet and faster than 250 miles per hour, with tunnels through the thick wings to all four engines. Its double-bubble, figure-eight fuselage gave the strength of a cylinder for pressurization without wasted space. A contract for 50 was cut to two aircraft after VJ Day. The first flew on 9 November 1946 with R-4360 radials and proved underpowered, so the engines were changed, and it made a non-stop flight from Moffett Field in California to Patuxent River in Maryland on 25 July 1948. Only two prototypes were ever built; too large and underpowered for airline use, the Constitution remains the largest fixed-wing aircraft type ever operated by the Navy.