Stanley Hiller, who died Thursday at 81, was a boy-genius pioneer and helicopter inventor whose dream of pervasive helicopter commuting didn’t quite work out.

But along the way, he made a number of key helicopter innovations, such as metal blades and the first military helicopter, the H-23A, deployed in Korea to evacuate the wounded.

Hiller’s first version was a “co-axial” device, meaning it had two sets of blades spinning in opposite directions. This eliminated the torque problem that conventional helicopters encounter with the small rear rotor.

On August 31, 1944, the day before the 19-year-old Hiller was set to be drafted, he demonstrated his prototype before representatives of the Army and Navy; he received an immediate deferral. At a demonstration in San Francisco a few weeks later, Hiller taught a shipbuilder and steel tycoon, Henry Kaiser, to fly his contraption, which he dubbed the “Hiller-copter,” in just five minutes. Kaiser offered financing for what became the XH-44, the first helicopter ever produced west of New York. One of them is now in the collection of the Smithsonian National Air and Space Museum.

For technical reasons, Hiller’s co-axial design proved less than ideal, and his subsequent helicopters mostly utilized rear-mounted props for stability, although one model featured a high-powered jet instead. A stream of ideas and prototypes began to emerge from the Hiller Aviation Company’s Palo Alto skunk works. There was the flying platform, a “ducted fan” device that hovered at low altitude. An advanced version in 1959, dubbed the “Coleopter,” resembled the flying saucers besieging drive-ins around that time. The company created the Rotorcycle, a collapsible helicopter small enough to be transported on the luggage rack of a car. More practical yet way-out ideas included flying jeeps and cranes and bridges. Hiller Aviation also produced an early prototype of a vertical take-off and lift airplane with engines that pivoted so that it would first hover and then fly like a plane.

Pursuing the dream of widespread helicoptering, Hiller in 1949 chartered a cross-country barnstorming tour, in which he and two other pilots hop-scotched from San Francisco to New York via 30 cities, demonstrating the helicopter to some 1,500 passengers, such as oil prospectors and crop dusters. Demand boomed, relatively speaking – and Hiller boasted that he sold more commercial helicopters in 1949 and 1950 than all other manufacturers combined. But it was a very small market, and despite consumer-friendly inventions like ramjets on the end of the blades and a $5,000 price tag (expensive in 1950, but not prohibitively so), Hiller never did succeed in cracking the commuter market. Nobody else has, either. By 1960, Hiller told the Christian Science Monitor that he was convinced that pursuing the commuter market was a waste of time. Instead, he concentrated on the more reliable military and commercial markets.

In 1964, Hiller Aviation was acquired by Fairchild Stratos, and Hiller stayed on as executive vice president, in charge of the company’s bid to win a big Pentagon contract for light observation helicopters for Vietnam. The bidding was eventually won by Hughes Tool’s Aircraft Division while a nasty row over improper underbidding went on between the two companies. Hiller resigned in disgust. He later acknowledged in testimony before Congress that he had hired a private detective, whom a Hughes executive accused of ransacking his office.

Hiller then abandoned the aviation business, and in a career transformation worthy one of his flashier inventions, re-engineered himself as a corporate turnaround artist, who rescued dying companies. He claimed to have successfully turned around some 30 companies, including Bekins movers, Bristol Compressors, Reed Tool, and York International – the oldest air conditioner firm in the nation. In the early 1980s, he led a consortium of investors in bidding for troubled Kaiser Steel, which would have been an interesting full-circle transaction, had it occurred.

After achieving moderate success in salvaging Keytronic, Hiller retired in the mid-1970s and founded the Hiller Aviation Institute and Museum, in San Carlos, Calif., with over 40 aircraft on display. He occasionally went out in his yacht, the Bah Humbug.

Stanley Hiller, Jr., was raised in Berkeley. His father was a pilot and inventor, and owner of a large shipping firm. Young Hiller was mechanically precocious, and at age 8 figured out how to power a go-cart using a gas drier engine. In 1940, when he was 16, Hiller founded a company to produce powered toy racecars and water guns. In his first year, he had revenues of $100,000, and the government approached him to manufacture parts for combat aircraft.

Hiller became interested in helicopters after he matriculated at the University of California at Berkeley at age 16. He eventually became so busy with his engineering business that he dropped out, although he retained friendly contacts with the university. When the engine on his prototype of the XH-44 sucked out the skylight windows on his workshop, the university let him do subsequent testing at its football stadium. He took numerous test flights, and even wooed his future wife by taking her aloft. On one such flight, he made an emergency landing at a filling station halfway between San Francisco and Sacramento. Goggle-eyed onlookers had never seen anything like the bright-yellow Hiller-copter.

Stanley Hiller Jr.

Born November 15, 1924, in San Francisco; died Thursday of complications of Alzheimer’s disease; survived by his wife, Carolyn; sons, Jeffrey and Stephen, and seven grandchildren.