Hughes H-4 Hercules

H-4 Hercules
Role	Heavy transport flying boat
National origin	United States
Manufacturer	Hughes Aircraft
First flight	November 2, 1947
Status	On display
Produced	1947
Number built	1
Unit cost	$2,500,000
Career
Other name(s)	"Spruce Goose"
Registration	NX37602
Flights	1
Preserved at	Evergreen Aviation Museum

The Hughes H-4 Hercules (also known as the "Spruce Goose"; registration NX37602) is a prototype strategic airlift flying boat designed and built by the Hughes Aircraft Company. Intended as a transatlantic flight transport for use during World War II, it was not completed in time to be used in the war. The aircraft made only one brief flight on November 2, 1947, and the project never advanced beyond the single example produced. Built from wood because of wartime restrictions on the use of aluminium and concerns about weight, it was nicknamed by critics the "Spruce Goose", although it was made almost entirely of birch. The Hercules is the largest flying boat ever built and has the largest wingspan of any aircraft in history. It remains in good condition and is on display at the Evergreen Aviation & Space Museum in McMinnville, Oregon, United States.

In 1942, the U.S. War Department needed 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. Wartime priorities meant the aircraft could not be made of strategic materials (e.g., aluminum).

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 carry 150,000 pounds, 750 fully equipped troops or two 30-ton M4 Sherman tanks. The original designation "HK-1" reflected the Hughes and Kaiser collaboration.

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