The Hughes Hercules flying boat, more widely known as the Spruce Goose, was the product of a collaboration between Howard Hughes and Henry J Kaiser. It was conceived at a time when the flying boat was considered by most in the industry to be the preferred solution to the problem of long-range over-water cargo transport, especially to destinations in the South Pacific theater. As the capacities and ranges of land-based transports improved during the war — and the incredible ability of the SeaBees to provide landing strips wherever needed began to be appreciated — interest in cargo-carrying wet-hull planes waned.

The plane famously made its sole flight during what were supposed to be taxiing tests, with Howard Hughes as pilot. At the time of its flight, November, 1947, the Hercules was by a wide margin the largest and heaviest plane that had ever flown. Critics still debate whether it could have climbed out of ground effect.

But the day of the giant flying boat was past. America's other huge flying boat, the Martin Mars, had only seven examples built and they spent little time in revenue service. Of the other large American flying boats – Consolidated's PBY Catalina and PB2Y Coronado and Martin's PBM Mariner – only the PBY, in its postwar myriads, had significant commercial use.