Spruce Goose alights on list of ASME Historic Landmarks

Diane Kaylor
ASME Public Information

The Howard Hughes Flying Boat, better known as the Spruce Goose, is once again standing before the public in full glory at the Evergreen Aviation Museum in McMinnville, Ore.

ASME designated the aircraft an ASME Historic Mechanical Engineering Landmark in July to a large crowd that included the restorers and aviation enthusiasts who offered it a home.

Designed and built by Hughes Aircraft Co., it is the largest wood-constructed and largest wingspan airplane ever built. The design added significantly to what is now known about large-lift capability and power-boost systems.

Originally designated the HK-1 in 1942, the aircraft was designed to transport troops and materials over long distances. Conceived by Henry Kaiser (famous for the production of liberty ships), the flying boat was designed and constructed by Howard Hughes and his staff.

The Spruce Goose is now an ASME Historic Landmark.

Laminated wood — mostly birch — forms the airframe and surface structures of the seaplane, minimizing the use of critical war materials like aluminum. It was powered by eight Pratt & Whitney 3,000-horsepower engines — the most powerful engines available — which required a mammoth fuel storage and supply system to allow for long, over-the-water flights.

The Hughes Flying Boat, later called the H-4 Hercules, is of a single-hull, eight-engine design, with a single vertical tail, fixed wingtip floats, and full cantilever wing and tail surfaces. All primary control surfaces except the flaps are fabric covered.

The Spruce Goose hull is divided into two areas: a flight deck for the operating crew and a large cargo deck. Access between the two decks is provided by a circular stairway. Below the cargo deck are fuel bays divided by watertight bulkheads.

Along the way, the Flying Boat development encountered and dealt with tremendous design and engineering problems. They ranged from the testing of new concepts for large-scale hulls and flying control surfaces, to the incorporation of complex power boost systems, which gave the pilot the power of 100 men in controlling this Hercules, which was born of a critical national need to fly over enemy submarines ravaging shipping lanes during World War II.

On Nov. 2, 1947, in Long Beach Harbor in Los Angeles, Howard Hughes and a small engineering crew piloted the Flying Boat on its only flight and thrilled thousands of onlookers with the unannounced flight. With Hughes at the controls, the Flying Boat lifted 70 feet off
the water, and flew one mile in less than a minute at a top speed of 80 miles per hour before making a perfect landing.

ASME President Susan Skemp presented a bronze plaque to the museum, noting, "We, as a technical community, absolutely rely on people who push the limits of invention — yet we rarely honor them."

Hughes' Flying Boat offers what historian-engineer John H. Lienhard calls "perplexing testimony" to the end of the big flying boats of the World War II era.

For additional information, visit History News at www.asme.org/history/.

 

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