High Quality Content by WIKIPEDIA articles! The Hughes H-4 Hercules (registration NX37602) ("Spruce Goose") is a prototype heavy transport aircraft designed and built by the Hughes Aircraft company. The aircraft made its only flight on November 2, 1947 and the project was never advanced beyond the single example produced. Built from wood because of wartime raw material restrictions on the use of aluminium, it was nicknamed the "Spruce Goose" by its critics, despite being made almost entirely of birch, rather than spruce. The Hercules is the largest flying boat ever built, and has the largest wingspan of any aircraft in history. It survives in good condition at the Evergreen Aviation Museum in McMinnville, Oregon, USA.