History: Spruce Goose, Hughes H-4 Hercules

Design and development
In 1942, the U.S. War Department was faced with the need to transport war materiel and personnel to Britain. Allied shipping in the Atlantic Ocean was suffering heavy losses to German U-boats, so a requirement was issued for an aircraft that could cross the Atlantic with a large payload. Due to wartime priorities, the design was further constrained in that the aircraft could not be made of metal.
The aircraft was the brainchild of Henry J. Kaiser, a leading Liberty ship builder. He teamed with aircraft designer Howard Hughes to create what would become the largest aircraft built at that time. It was designed to be capable of carrying 750 fully equipped troops or one M4 Sherman tank. The original designation "HK-1" reflected the Hughes and Kaiser collaboration.