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Hughes H-4 Hercules (Spruce Goose)


Heavy-Lift Transport / Flying Boat Prototype


United States | 1945



"The Hughes H-4 Hercules, ridiculed as the Spruce Goose, remains the largest flying boat ever constructed and features the largest wingspan of any aircraft ever made."

Power & Performance
Those special qualities that separate one aircraft design from another. Performance specifications presented assume optimal operating conditions for the Hughes H-4 Hercules Heavy-Lift Transport / Flying Boat Prototype.
8 x Pratt & Whitney 28-cylinder R-4360 propeller engines developing 3,000 horsepower each.
Propulsion
199 mph
320 kph | 173 kts
Max Speed
20,899 ft
6,370 m | 4 miles
Service Ceiling
2,983 miles
4,800 km | 2,592 nm
Operational Range
1,000 ft/min
305 m/min
Rate-of-Climb
Structure
The nose-to-tail, wingtip-to-wingtip physical qualities of the Hughes H-4 Hercules Heavy-Lift Transport / Flying Boat Prototype.
3
(MANNED)
Crew
218.7 ft
66.65 m
O/A Length
320.0 ft
(97.54 m)
O/A Width
79.3 ft
(24.18 m)
O/A Height
396,832 lb
(180,000 kg)
MTOW
Variants
Notable series variants as part of the Hughes H-4 Hercules (Spruce Goose) family line.
HK-1 - Original Design Designation that reflects the collaborative efforts of design and concept from Henry Kaiser and Howard Hughes ("HK").
H-4 - Base Designation with the wihtdrawal of Henry Kaiser from the project.
HFB-1 - Another designation attributed as a recognition of "Hughes Flying Boat - First Design".
Authored By: Staff Writer | Last Edited: 06/28/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site; No A.I. was used in the generation of this content.

This famous Howard Hughes flying boat aircraft - formally designated by Hughes Aircraft as the H-4 "Hercules" - only ever achieved a single flight (with Hughes himself at the controls) and was only produced in a single working example. The folly of the project garnered the H-4 the nickname of "Spruce Goose" and largely termed a failure in the scope of World War 2-era aircraft design. The primary drive behind such a large airframe was in providing the United States military - then committed to war in Europe and the Pacific - with an oversized transport capable of airlifting large quantities of battlefield equipment to the front. This was strengthened by regular losses of Allied shipping from German U-Boats in the Atlantic and elsewhere, taking their toll on vital supplies attempting trying to reach forces in Europe. As such, a military requirement was put forth for a trans-Atlantic freighter-type aircraft capable of a considerable payload.

Despite the seemingly promising nature of the H-4 design, it simply arrived too late in the war to serve much of a purpose, additionally adding to the image of the project as a complete failure for Hughes. The H-4 also suffered from the defense spending drawn down once the war had officially come to a close - many projects were either suspended indefinitely or cancelled outright. Hughes was then forced to appear before a Senate committee to answer for government funds spent on his H-4.

Upon its completion, the H-4 became the world's largest aircraft and largest flying boat ever designed and produced to that point. Power was served through 8 x Pratt & Whitney R-4360 28-cylinder engines developing 3,000 horsepower each. Four engines were fitted to a wing. Each wing was high-mounted in its installation and straight in its general design with the engine nacelles fitted at the leading edges. Each wing itself was the full wingspan of just one competing Boeing B-29 "Superfortress" four-engined heavy bomber. To demonstrate the internal carrying capacity of the H-4, the hold could service up to 700 combat infantry or two M4 Sherman Medium Tanks. Endurance of the aircraft was estimated to be approximately 21 hours of flight time. Its flying boat qualities - aided by its boat-like hull and outboard-mounted pontoon legs - allowed the H-4 to take-off and land from just about any water source. Additionally, the aircraft was constructed of wood (birch) which helped buoyancy and would not require heavy use of metals in its construction (metal proving a critical wartime resource). The wood approach was also spanned into another Hughes wartime project - the D-2 heavy fighter (detailed elsewhere on this site). The "Spruce Goose" ridicule is related to the product's heavy use of wood in its construction.

The initial H-4 concept was drawn up by Henry Kaiser while the direct design was put together by engineer Glenn Odekirk. Howard Hughes served as the project's overseer and would be the hands at the controls during her one and only flight. The one and only prototype was saved in the post-war draw down and can be seen in its full glory at the Evergreen Aviation Museum of McMinnville, Oregon, USA.

As much as aviation technology has advanced to this day (November 2013), the Hughes H-4 Hercules still maintains the largest wingspan of any aircraft ever built, let alone considered for production. This claim to fame includes even the mammoth American Boeing 747 and the Soviet/Russian An-225 Mriya offerings. Additionally, no other flying boat design has bested her dimensions.

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Operators
Global customers who have evaluated and/or operated the Hughes H-4 Hercules (Spruce Goose). Nations are displayed by flag, each linked to their respective national aircraft listing.

Total Production: 1 Units

Contractor(s): Hughes Aircraft - USA
National flag of the United States

[ United States (cancelled) ]
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Going Further...
The Hughes H-4 Hercules (Spruce Goose) Heavy-Lift Transport / Flying Boat Prototype appears in the following collections:
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