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Stanford engineers involved in America's Cup contender design
STANFORD -- For the second competition in a row, Stanford engineers have participated in the design and construction of one of the contenders in the America's Cup race, which is currently under way.
This year, the hull that has benefited from Stanford expertise is that of the Mighty Mary, the contender crewed almost exclusively by women and financed by the America3 (America Cubed) syndicate, headed by Bill Koch, director of Koch Enterprises, a Wichita oil and gas company.
The principal Stanford engineers involved are Research Professor Stephen W. Tsai, Associate Professor Ilan M. Kroo and visiting scientist Min Qiuling Wang, all from the Department of Aeronautics and Astronautics.
"Koch puts more emphasis on science and technology than the other contenders. He says that the secret to winning is 60 percent boat speed, 25 percent crew and 15 percent luck," Tsai said.
This year, Koch had not intended to enter the competition until the concept of an all-women team came up. As a result, his syndicate was one of the last to throw its hat in the ring.
By that time, a number of the scientific groups that had worked with America3 in 1992 already were working with other syndicates. But the Stanford group was uncommitted, and so was available to provide their expertise in structural optimization modeling and in advanced composite materials, complex materials made from special fibers and resins that are stronger and lighter than most metal alloys.
The properties of composite materials have allowed the America's Cup syndicates to build racing yachts that are about 10 feet longer and 33 percent lighter, spread 50 percent more sail area and sail 25 percent faster than the traditional 12-meter class boats used in Cup racing between 1958 and 1987, Tsai said.
"Our first task was to test three commercially available composite materials for the syndicate. We graded two as superior and one as inferior," Tsai said.
Next, working with a Belgian company that created a structural modeling program called SAMCEF, the Stanford researchers helped the America3 design team assemble a detailed structural model of the sailboat.
"The outsides of the boats are all about the same. But the insides, that is very difficult and it is a free-for-all," Tsai said. The otherwise detailed regulations do not put any restrictions on the yacht's internal structure. This structure is critical because the two parts of the boat that bear by far the greatest load are the mast and the keel, and the manner in which they are connected depends on the internal structure.
"If you shave too much off the structure in order to save weight, then you risk the hull breaking in two, which appears to have happened with the Australian entry that sank several weeks ago," he said.
The Stanford researchers also came up with a unique design for the yacht's underbody. But because of America3's late entry into the competition, they didn't have enough time to work out all the bugs, Tsai said.
Nevertheless, "the syndicate thinks that our boat is two boat lengths faster around the course. That may not sound like much, but if one boat can get ahead early in the race, it can do a lot to control events," said the engineer, who hopes to attend one of the races this week.
Tsai first got involved in America's Cup boat design in the early '80s, before he came to Stanford, after an Australian team beat the United States for the first time and took the cup to Freemantle.
The San Francisco-based St. Francis Syndicate recruited Tsai because of his expertise in composites. Their entrant, USA, was the first to incorporate these materials into an America's Cup yacht design.
"Unfortunately, the syndicate was underfinanced and the yacht reached Freemantle too late for them to fine-tune it," Tsai recalled. As a result, USA only reached the semifinals in the 1986-87 competition.
Tsai's next venture into yacht racing was the 1992 competition in San Diego. By that time he was at Stanford, and he recruited a team consisting of Wang, Professor George Springer of aeronautics and astronautics, and several graduate students to work with America3, which fielded four high-tech yachts. Due at least in part to the best efforts of both the Stanford and MIT teams that consulted on their designs, America3 successfully defended the Cup, overcoming the experience and tenacity of San Diego's Stars and Stripes, headed by Dennis Conner, and defeating the Italian challenger Il Moro di Venezia.
According to Tsai, being involved in the high-stakes world of America's Cup racing is an exhilarating experience, much different from normal research in which projects can stretch over years.
"It's very exciting. We say we are in the Federal Express business. If we decide to do something, we do it overnight! And we can do that with composite materials. It would be impossible with metals."
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