The single 400,000-pound H-4 Hercules flying boat, built by the Hughes Aircraft Co., was the largest flying boat ever built with the widest wingspan. It was built after a U.S. government request in 1942 for a cargo and troop carrier that would not be susceptible to Axis submarines and not use critical wartime materials by substituting wood for metal in its construction.
Originally conceived by Henry J. Kaiser, a steelmaker and builder of Liberty ships, the aircraft was designed and constructed by Howard Hughes and his staff; hence, the original HK-1 Hercules (#NX37602) designation. Kaiser withdrew his support in 1944 because Allied aircraft needs shifted toward bombers and they no longer needed this type of aircraft.
Hughes continued to develop the aircraft under the H-4 designation. The press nicknamed it the "Spruce Goose" -- a name Hughes hated because it insulted its builders and, in fact, the plane was built almost entirely of laminated birch, not spruce.
The cargo-type flying boat was designed to carry 750 fully-equipped troops or two Sherman tanks over long distances. It has a single hull, eight radial engines, a single vertical tail, fixed wingtip floats, and full cantilever wing and tail surfaces. The entire airframe and surface structures are composed of laminated wood and all primary control surfaces, except the flaps, are fabric covered. The aircraft's hull includes a flight deck for the operating crew and a large cargo hold. A circular stairway connects the two compartments. Fuel bays, divided by watertight bulkheads, are below the cargo hold.
By 1947, the U.S. government had spent $22 million on the H-4 and Hughes had spent $18 million of his own money. Finally, on Nov. 2, 1947, Howard Hughes and a small engineering crew fired up the eight radial engines for taxi tests. Hughes lifted the giant aircraft 33 feet off the surface of Long Beach (Calif.) Harbor and flew it for one mile, for less than a minute, remaining airborne 70 feet off the water at a speed of 80 mph before landing.
The H-4 Hercules never flew again. Until he died in 1976, Hughes made sure the HK-1/H-4 was constantly maintained and kept in flight-ready condition. The "Spruce Goose" then found a home with the Aero Club of Southern California, preserved in its own circular building, next to the former ocean liner Queen Mary, at Long Beach, Calif. In 1988, The Walt Disney Co. acquired the location, and Disney's plans for the site did not include the "Spruce Goose." Facing loss of their lease, the Aero Club sold the giant plane to the Evergreen Aviation Museum in 1993, which disassembled the aircraft and moved it by barge to its current home in McMinnville, Ore.
By the mid-1990s, the former Hughes Aircraft buildings in Los Angeles, Calif., including the one where the "Spruce Goose" was built, had been converted into movie sound stages. Scenes from movies such as Titanic have been filmed on location in the 315,000-square-foot airplane hangar where Howard Hughes created the legendary flying boat and other famous Hughes aircraft. In August 2008, the hangars were put up for sale.