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Hughes H-4 / HK-1 Hercules / Spruce Goose


American shipbuilder Henry Kaiser introduced the Liberty ship but the vessels were being sunk prompting him to think of a massive cargo aircraft. Initially rebuffed by the US Government, Kaiser sought a partnership that would lend credence to his plan. That partner was Howard Hughes. Howard Hughes sponsored the Hughes H-4 Hercules. Made entirely of wood, almost entirely of laminated birch, this eight-engined flying-boat had the greatest wingspan (320 ft; 97.54 m) of any aircraft built to date.

The aircraft was not completed until September 1945. The design problems which Hughes and his team encountered in creating a 183-tonne (180-ton) aircraft from non-strategic materials delayed the project until after the war, assembly began in June 1946.

House movers being engaged to transport its 66.75-m (219-m) laminated plywood hull along specially laid roads from Culver City, California to Terminal Island, Long Beach where final assembly began.


On 2 November 1947 Hughes boarded the Hercules, started the eight 3000‑hp Pratt & Whitney Wasp Major engines and taxied out into the bay, ostensibly for water­ handling tests. Once on the open water, however, Hughes opened up the Spruce Goose's and took off, flying for about 0.6 km (1 mile), for less than a minute, at a height of 70 feet (21 m) at a speed of 80 mph (128 kph).




The Hercules never flew again. It was stored in a specially constructed hangar at Long Beach, where it remains today, heavily guarded by Hughes employees, the largest aircraft ever to fly. Some say that having proved his point that the machine could fly, Hughes simply lost interest; others claim that even in those few brief moments of flight the Hercules creaked and groaned and handled so badly that Hughes never dared fly it again.



Engines: 8 x 3,000 h.p. Pratt & Whitney R-4360-4A radial. Replaced in 1951 by P&W Wasp Major TS13-3Gs.
Propellers: 8 x Hamilton Standard 24F60-35s
Prop diameter: 17ft 2in diameter (Engine No 4 had a 16ft 2in-diameter)
Wingspan: 320ft 0in
Tailplane span: 113ft 6in
Wing area: 11,430 sq.ft
Maximum wing thickness: 11ft 6in
Length: 218ft 6.25in
Height overall: 79ft 3 3/8in
Fuselage height: 30ft 0in
Payload: 180,0001b
Maximum weight: 400,0001b
Internal fuel: 14,000 USgal
Maximum speed: 218 m.p.h.
Cruising speed: 175 m.p.h.
Alighting speed: 78 m.p.h.
Maximum range: 3,500 miles
Service ceiling: 24,000ft (300,0001b gross weight)
Rate of climb: 700ft/min to 1,000ft/min, depending on weight

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