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The Hughes H-4 Hercules (commonly known as the Spruce Goose; registration NX37602) is a prototype strategic airlift flying boat designed and built by the Hughes Aircraft Company. Intended as a transatlantic flight transport for use during World War II, it was not completed in time to be used in the war. The aircraft made only one brief flight, on November 2, 1947, and the project never advanced beyond the single example produced.

Built from wood (Duramold process) because of wartime restrictions on the use of aluminum and concerns about weight, the aircraft was nicknamed the Spruce Goose by critics, although it was made almost entirely of birch. The Hercules is the largest flying boat ever built, and it had the largest wingspan of any aircraft that had ever flown until the Scaled Composites Stratolaunch first flew on April 13, 2019. The aircraft remains in good condition. After having been displayed to the public in Long Beach, California, from 1980 to 1992, it is now on display at the Evergreen Aviation & Space Museum in McMinnville, Oregon, United States.