The Hughes H-4 Hercules (also known as the HK-1 or "Spruce Goose"; Aircraft registration NX37602) is a prototype heavy transport aircraft designed and built by the Hughes company.
The aircraft made its only flight on November 2, 1947 and the project never advanced beyond the single example produced. Built from wood because of World War II restrictions on the use of aluminium, its critics nicknamed it the "Spruce Goose" despite it being made almost entirely of Birch rather than Spruce. TheHercules 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 Aviaton Museum in McMinnville, Oregon, USA.
Designed as a freighter, the aircraft could carry 700 passengers.
Measuring 218 ft 8 in (66.60 m) in length and 79 ft 4 in (24.10 m) in height, the H-4 had a 319 ft 11 in (97.50 m) wingspan. Power was provided by eight 3,000 hp (2,236 kW) Pratt & Whitney R-4360-4A piston engines, giving the aircraft a maximum speed of 235 mph (378 km/h) at sea level, a cruising speed of 140 mph (225 km/h), estimated service ceiling of 21,000 ft (6,400 m) and range of 1,575 miles (2,535 km)..
- The H-4 was featured in the 1987 Hanna Barbera animated movie "Yogi Bear and The Magical Flight of the Spruce Goose".
- World Aircraft Information Files Aviation Partwork. Midsummer Books Ltd. File 896 Sheet 30 (A-Z of Aircraft:H - Hughes H-4 Hercules (continued) to Hurel-Dubois aircraft)
- WAIF File 896 Sheet 29 (A-Z of Aircraft:H - Henschel Hs 129 (continued) to Hughes H-4 Hercules