The Hughes H-4 Hercules was a prototype heavy transport aircraft designed and built by the Hughes Aircraft company. The aircraft made its first and only flight on November 2, 1947. Built from wood due to wartime raw material restrictions on the use of aluminum, it was nicknamed the "Spruce Goose" by its critics. The Hercules is the largest flying boat ever built, and has the largest wingspan and height of any aircraft in history. It survives in good condition at the Evergreen Aviation Museum in McMinnville, Oregon, USA.
Due to wartime restrictions on the availability of metals, the H-4 was built almost entirely of laminated birch, not spruce as its nickname suggests. The Duramold process, a form of composite technology, was used in the laminated wood construction. The aircraft was considered a technological tour de force. It married flying boats to a massive wooden airframe that required some ingenious engineering innovations to function.
Ultimately, the plane was not finished in time for use in the war and never advanced beyond the single prototype produced.
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For More Information: Spruce Goose: History and Description