By this time, the politically savvy Hughes had already secured a military contract for the XF-11, a larger, more powerful all-metal version of the D-2. Designed as a 400 mph, high-altitude reconnaissance aircraft, it was powered by a pair of turbo-supercharged Pratt & Whitney R-4360-31s driving two pairs of counter-rotating propellers. "It was a very highly developed, well-thought-out design," Hallion says. "If Hughes hadn't been so wrapped up in the HK-1 [flying boat], that airplane might have entered the inventory."
As it was, the XF-11 wasn't completed until the war ended. On the craft's 1946 maiden test flight, an oil leak caused the right rear propeller to reverse pitch, the engine lost power, and the airplane crashed in Beverly Hills, damaging some houses. Hughes, the only one injured, was pulled from the wreckage in critical condition. While he recuperated, a second XF-11 was assembled with conventional four-blade props. Nine months after the accident, Hughes successfully flew the airplane. It then passed into the hands of the Army Air Forces before being scrapped in 1949.
The Beginning of the End The D-2/XF-11 was an expensive failure, but Hughes' biggest flop'literally'was yet to come. Like many follies, this one initially seemed to make sense: Pair Hughes with industrialist Henry J. Kaiser, creator of the Liberty ships, to build a gargantuan flying boat to ferry 750 troops overseas. To save money and use a non-critical resource, the HK-1 would be constructed of wood, using the Duramold process. A government contract was signed in 1942, but thanks to Hughes' perfectionism and procrastination, the aircraft was still unfinished at war's end. "It dragged on and on and on and on until it was just another useless aircraft," Burk says. "But it sure kept a lot of people busy."
After Kaiser bailed out of the project, the airplane was given several names: H-4, Hercules, Flying Boat. Popularly, it was known as the "Spruce Goose"'a misnomer since most of the wood was birch'or "Flying Lumberyard." In 1947, it was the subject of Senate hearings into allegations of war profiteering. Exonerated, Hughes crowed to the press, "I designed every nut and bolt that went into this airplane…. I have stated that if it fails to fly, I will leave the country. And I mean it."
Accordingly, the largest wooden airplane ever flown'20 percent larger than a 747'taxied into Long Beach Harbor in California later that year. While a crowd watched, Hughes rocked the eight-engine H-4 off the water and flew about a mile at the dizzying altitude of 70 feet. Thereafter, the HK-1 was kept ready to fly in a climate-controlled hangar. After Hughes' death (and torturous negotiations), the H-4 moved to a dome in Long Beach, where it became a tourist attraction. In 1992, it was disassembled and shipped to McMinnville, Oregon, where it was reconstituted as the centerpiece of the Evergreen Aviation Museum.
A Final Flirtation The Flying Boat was the last airplane the Hughes Aircraft Company built. In 1949, Hughes paid $250,000 to Kellett Aircraft for the rights to the XH-17, an experimental heavy-lift helicopter funded by the Air Force. Nicknamed the "Flying Crane" after Hughes Aircraft bought it, it was equipped with a 130-foot, two-blade rotor. Two Allison J-35 jet engines, modified by General Electric to act as compressors and designated TG-180s, fed compressed air through the hollow rotor blades to the tips, where fuel was ignited in burners to produce thrust. The rotors turned at a leisurely 88 rpm, but the effect was monstrous.
"Flames began to shoot out the tip burners, making a gigantic Fourth of July pinwheel," the Los Angeles Times reported in 1952, when Gale Moore made the first official flight off the Hughes runway in Culver City. "From 50 feet away, the whoosh-whoosh of the whirring blades sounded like hundreds of artillery shells in flight…. Then, with a great, bracing quiver, the helicopter raised itself from the ground, its four wheels at the end of its stork-like supports hanging free. The noise was numbing."
Moore accumulated 10 hours of flight time before the program ended in the mid-1950s. Although a follow-on Flying Crane program failed for lack of funds, helicopters turned out to be the key to a profitable future for Hughes Aircraft. Hughes himself, though, had no interest in rotary-wing technology, and the first flight of the XH-17 was the last time he visited the helicopter factory.
Hughes died on April 5, 1976. Fittingly, he was aboard a Learjet 25B at the time.