Howard Hughes's famous HK-1 Hercules (#NX37602) is a cargo-type flying boat
designed to transport men and materials over long distances. Originally conceived by Henry J. Kaiser,
a steelmaker and builder of Liberty ships, the aircraft was designed and constructed by Hughes
and his staff. The original proposal for the enormous, 400,000-pound wooden flying boat, with its
spectacular 320-foot wingspan, came from the U.S. government in 1942. The goal was to build a cargo
and troop carrier that did not require critical wartime materials; in other words, that substituted
wood for metal. Throughout its construction, considerable controversy surrounded its funding. After
a disgruntled U.S. Senator dubbed the HK-1 a "flying lumberyard," the "Spruce Goose" nickname was
coined Hughes despised the name!
The huge flying boat consists of a single hull, eight radial engines, a single
vertical tail, fixed wingtip floats, and full cantilever wing and tail surfaces. The entire airframe
and surface structures are composed of laminated wood (primarily birch, not spruce). All primary
control surfaces, except the flaps, are fabric covered. The aircraft's hull is divided into two
areas: a flight deck for the operating crew and a large cargo hold. Access between the two
compartments is provided by a circular stairway. Below the cargo hold are fuel bays divided by
The Hughes/Kaiser flying boat was to be the largest airplane ever built
(in fact, after its completion, it was three times larger than the largest aircraft built before
it) and probably the most prodigious aviation project of all time. Only the courage and solitary
dedication of Howard Hughes and his small development group caused this project to advance resulting
in its historic first, and only flight. As Hughes kept meddling in the design, making things more
complicated and causing lost time, Kaiser backed out. An urgent government project in 1942, the
wooden flying boat had lost all priority by 1944. Hughes's motives for making things so complicated
are not clear. They seem to have resolved around his idea for an "aerial freighter beyond anything
Jules Verne could have imagined."
Although he thought big, Hughes paid careful attention to the smallest
details. A true eccentric, he would sit for hours in the cockpit of his great aircraft deliberating
the design of the control and instrument panel. Unfortunately, as a perfectionist, he could not make
up his mind, and his many delays finally caused a Senate committee to look into the project. By the
time the aircraft was finally completed in 1947, the U.S. government had spent a whopping $22 million
-- Hughes spent $18 million of his own money!
On 2 November 1947, Howard Hughes and a small engineering crew fired up the eight
radial engines for taxi tests and thrilled thousands of on-lookers with an unannounced
flight. With Hughes at the controls, the flying boat lifted 33 feet off the surface of Los Angeles
Harbor and flew one mile in less than a minute at a top speed of 80 miles per hour before making a
perfect landing. This trial run was simple vindication from the detractors of the program and it is
now looked upon as a great moment in aviation history. Was the flight an accident? When the chief
designer asked Hughes whether he meant to lift it off the water, Hughes replied, "You'll never know."
It is possible he flew it that one time just to prove that something that big could actually fly.
After the historic event, the "Spruce Goose" was returned to its large, specially
designed hangar, never to fly again. As ordered by Hughes, it was constantly maintained and kept in
flight-ready condition, including monthly runups of its engines, until he died in 1976. Over the past
50 years, the aircraft has endured to become a popular cultural artifact telling a remarkable story
of sacrifice, determination, and technological development. The HK-1 was decades ahead of its time
in the 1940s. It revolutionized jumbo flying bodies and large lift capability, shaping modern flight.
The popular wooden flying boat is now appropriately regarded as a true American icon.
After a long period of storage, the HK-1 was presented to the Aero Club of
Southern California and was for many years the star attraction while preserved in its own circular
building, next to the former ocean liner Queen Mary, at Long Beach, California. The aircraft was
in 1992 and now resides in a newly constructed facility at the Evergreen Aviation Educational Center
in McMinnville, Oregon. To this day, it is still the largest aircraft, in terms of wingspan, ever to fly.
Note: The HK-1 designation was derived from the names Hughes and Kaiser.
When Kaiser backed out of the project in 1944, Hughes redesignated the aircraft H-4 and, after the
first flight, changed the tail number from NX37602 to N37602.
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