The Early '40s Wind Power Dinosaur Of Vermont

The 1.25 MW Smith-Putnam Wind Machine

More than sixty years ago right here in the U.S. during a little-known chapter of wind energy development history, an engineer named Palmer Coslett Putnam conceived the most powerful electric plant that the wind had ever driven up until then. It ran briefly on a knoll near Rutland, Vermont, to feed current into the whole New England network of transmission lines. Although its sails were visible for twenty-five miles, that great plant was a promptly forgotten victim of the winds from World War II.

Putnam was a 1923 graduate of the Massachusetts Institute of Technology who became a pioneer in energy science when a utility company’s bills for lighting his Cape Cod home shocked him. He thought that the wind should provide all the current that he needed there, and maybe a few more kilowatts for him to send back to the power company for credit. Putnam’s father was a famous New York publisher, and his mother was a noted author and scholar. He had studied at the Technische Hochschule in Munich and at Yale University as well as M.I.T., served with the Royal Flying Corps, traveled widely, and become an enthusiastic yachtsman. Few men were as well acquainted with social and business leaders, and eminent scientists and engineers in Boston and elsewhere.

The wind machines then producing a few watts for some farmers, of course, were much too small to satisfy Putnam. He reviewed the progress made in building windmills. The big sails of Dutch windmills had rarely revolved faster than the wind was blowing. The tips of the blades on American windmills went twice as fast, and with propeller types of blades builders had attained working ratios of five or more. A high number of revolutions per minute was helpful in generating electricity, but no one seemed to have comprehensively determined the most economical dimensions for a very large wind turbine.

Putnam considered the Russians’ approach to the problem bold and practical; they had begun, however, with an induction generator rather than one that could be synchronized with other power plants, and their machine at Yalta was crudely constructed. Roofing metal was used in the Russians’ rotor, and the main gears were wooden. Surely, Putnam thought, with the greater resources in the United States, a better wind turbine could be built here.

Elisha Fales, one of the first experimenters with airfoils on windmills in this country, lent Putnam a small two-bladed rotor that he mounted on a 60-foot tower and used as a kind of gauge to study the wind. Another friend interested him briefly in a Savonius rotor that was being considered for use on windmills on Colonel Henry Huddleston Rogers’ estate on Long Island; but Putnam concluded that long vertical airfoils would be better for his purpose.

The surface exposed must be larger for a wind turbine than for a water turbine because air is thinner than water. Hydroelectric and thermal plants were generating alternating current for the New England utility companies, and Putnam proposed to produce current in phase with them. This meant that both the rotor and a synchronous generator would have to be especially designed for a very large wind turbine on a windy site. So, too, would a structure to support it.

Putnam consulted many of our country’s leading authorities on aerodynamics, electrical generators, structures, meteorology, ecology, and construction costs. With their help he succeeded in launching an unprecedented historic project. Although nothing is left of the great machine that resulted from his efforts, his diagnostic obituary of it is still a timely textbook on an aerogenerator builder’s many problems.

The Smith-Putnam turbine weighed 250 tons and was erected on a 2,000-foot hill called Grandpa’s Knob in the Green Mountains west of Rutland, Vermont. The tower was 110 feet tall, and the operators of the plant rode to and from the control room on an elevator. Up there the wind spun two long bright metal airfoils in a rotor 175 feet in diameter. A specially designed generator came on line when the wind blew 17 m.p.h., and produced 1,250 kilowatts when it reached 30 m.p.h. This was enough for a small town, and machines like this could help lighten the growing loads on the utilities.

A complete roster of the participants in the Smith-Putnam project would be virtually a Who’s Who of the most able scientists and engineers in the 1930s. The dean of engineering who became President Roosevelt’s wartime research director, Vannevar Bush, put Putnam in touch with academic celebrities and the movers and shakers in American industry. The project, as Dr. Bush wrote later, demonstrated “the ability of complex science and technology to focus a score or more of specialized skills on the various aspects of a problem.” This was done, moreover, without any subsidies from federal or other government agencies.

GETTING THE GIANT TOGETHER

The times had seemed propitious. The scars from the Great Depression were healing; economists were debating new theories, and investors were regaining confidence. Putnam got estimates from steel makers and other manufacturers of the probable cost of producing the big aerogenerators he envisioned in lots of 100, and the decision to build an experimental model was made in Boston in 1939. That was the year a world’s fair opened in New York, and also the year that a second world war began in Poland.

Thomas F. Knight, a coastal sailor and vice president of General Electric, had become one of Putnam’s most helpful allies. General Electric agreed to develop and provide a synchronous generator that could be used in conjunction with New England’s hydroelectric and thermal plants. Knight also helped to interest other wealthy and influential companies in the venture. He knew there were few good sites left in New England for hydroelectric plants, that builders of turbines were looking for new markets, and that utility companies were worried about the growing demands on reservoirs from which they were drawing water to generate current.

A leading builder of hydraulic turbines, the S. Morgan Smith Company in Pennsylvania, was a family owned enterprise with an exceptionally able staff of engineers. Walter Wyman, the New England Public Service Company’s president, lived on a windy ridge and was receptive to the idea of developing a new source of power. After considerable study, the Smith company agreed to build a big wind turbine, and Wyman arranged for a Vermont utility company to feed the current that it would generate into transmission lines serving several states.

Professor John B. “Bud” Wilbur, who later headed M.I.T.’s Department of Civil and Sanitary Engineering, became chief engineer for the project. Dr. Theodore von Karman of the California Institute of Technology, and other noted aerodynamicists, helped the designers solve many difficult problems. The famous Norwegian meteorologist, Sverre Petterssen, and fellow scientists at Harvard, M.I.T., and elsewhere, began a thorough study of the wind in the Green Mountains.

The war in Europe distracted and rushed nearly every participant. The S. Morgan Smith Company was soon swamped with war work, but succeeded in assigning completion of the aerogenerator to other experienced builders - including the Budd Company in Philadelphia, which built stainless steel railroad cars; the Wellman Company in Cleveland, which produced heavy materials-handling equipment; and the American Bridge Company, which had erected many huge structures.

The war in Europe went badly; it seemed increasingly certain in 1940 that the United States would be involved. If big forgings for the wind machine were not ordered immediately, it might be impossible to get them made. So they were ordered on the basis of approximate and fairly rough estimates of stresses, before the big turbine had been fully designed. Grandpa’s Knob was likewise chosen as a convenient site to get on with the project, even though the meteorologists did not yet have as much data as they wanted.

The schedule called for cumbersome heavy parts to be hauled up the side of the mountain in bitterly cold weather when the curving road was frozen solid. The main girder with the driving shaft and bearings weighed so many tons when placed on a trailer that two Caterpillar tractors were needed to tug it. At a hairpin turn the girder fell off the trailer and landed upside down under a snowbank in a rocky crevice. Workmen had to struggle for three weeks to get that girder back on the road.

Each one of the two blades for the turbine was 11 feet wide, nearly 70 feet long, and weighed 8 tons. Those blades, the generator, and other heavy parts had to be carefully balanced - like little millhouses on single posts centuries earlier - on top of the tower. After the first blade was attached to the high hub, it had to be held in a fixed position until the second one was attached. But all such challenges to men’s strength and skill were met, almost cheerfully at times.

Palmer Putnam was called to Washington to help Dr. Bush in the Office of Scientific Research and Development before the plant he had proposed was finished. Engineers assigned to test the machine opened a field office in Rutland and escorted many distinguished visitors up to the control room with mechanics and inspectors. A General Electric operator began letting the machine run slowly, and more weeks of testing and tinkering were necessary before it was allowed to run at full speed. Then on Sunday night, October 19, 1941, it fed energy from a gusty 24-mile-per-hour wind into the utility companies’ lines, for the first time that this ever was done in the United States.

“If this wind-power project proves as successful as engineers working on it believe it will,” the Boston Post had reported that spring, “the vision of thousands of similar stream-lined scientific windmills operating on the wind-swept summits of New England’s mountains and high hills is not too fantastic to contemplate. . . A few well aimed aerial bombs striking New England’s largest power plants would cut off the supply of electricity to a widespread area of this industrial section. But wind turbines, distributed through the hills and camouflaged to blend with the scenery would be much less vulnerable to destructive attack from the air than equivalent generating capacity concentrated in a single large plant.”

HOW A BLADE BROKE

Testing continued after the Japanese attacked Pearl Harbor on December 7, 1941, but fewer people paid attention to what was happening on Grandpa’s Knob. When fully adjusted, the turbine ran smoothly and frequently delivered 1,000 kilowatts. This was a test unit that purposely had not been placed at the point of maximum output in New England lest high continental winds make constructing and testing it too difficult. Yet it once drew 1,500 kilowatts from a 70-m.p.h. wind, and when idle it withstood gales up to 115 m.p.h.

A bearing failure halted use of the machine in the winter of 1943. By then the Allies were demanding that their foes surrender unconditionally, and the war delayed replacement of the bearing. Design analyses had shown that the blade shanks over which the spars of the blades should fit were too small, and the connections permitted greater stress concentrations and more fatigue than the engineers considered acceptable. No one could be sure that the connections would fail, but neither could anyone promise that they would not.

Should the whole project be halted until after the war, when new and larger forgings could be obtained? Or should the testing be resumed? The S. Morgan Smith Company decided to go ahead, with electric strain gauges mounted at certain critical areas.

Another omen of trouble was discovered during the long shutdown caused by the failure of the bearing. The blades were feathered and held vertically then, and hairline cracks appeared at some points on their skins. These apparently resulted from the vibration and shaking of the blades while they were locked in one position. One suggestion was that those cracks be prevented from growing by welding bulkheads near the shank-spar connections, and this was done.

By then everyone realized, Chief Engineer Bud Wilbur recalls, that “we were living on borrowed time.” He recommended that the plant only be run long enough to complete certain tests before discontinuing operations. It could be strengthened more after the war ended. Beauchamp Smith, president of the company responsible, agreed, and the tests were resumed.

The wind was blowing steadily about 20 m.p.h. on a moonlit night in March 1945 when one of the two 70-foot blades left the turbine and landed down the side of the mountain. At six o’clock that morning Bud Wilbur telephoned the man who had conceived and promoted the construction of the great turbine to report: “Put, we’ve had an accident. We’ve lost a blade, but no one is hurt, and the structure is still standing.”

Only one man was aloft in the control room when it happened. The jolt knocked him down, and he fell again when he tried to leap over the 24-inch rotating shaft to stop the mighty machine. But he regained his feet and overrode automatic controls that already were functioning to feather the remaining blade and bring the machine to a full stop in ten seconds.

The Smith-Putnam windmill never ran again, but the wind survey begun before it was built was continued. The meteorologists had placed instruments at many Green Mountain sites, obtained data from balloons, and festooned a 185-foot skeleton steel tower at Grandpa’s Knob with so many gauges that people called it a Christmas tree. Anemometers heated by gas and later by electricity were developed for use on it. Ecologists measured the height and deformation of trees and noted the icing on them. The terrain also was modeled for aerodynamicists to study the effects of air rushing over it in a wind tunnel. This was the most thorough study of the wind in the region that ever had been made, and much was learned from it.

Participants’ memories and published articles have differed about the troubles with the machine. In Dr. Von Karman’s autobiography he likened his experience as a consultant for the project to what happened when a finicky man ordered a steak in a restaurant. “Cut the steak exactly two and a half inches thick,” he told the waiter, “add a pinch of pepper and a half teaspoon of salt. Keep vegetables on the side of the plate. Get it?” The impatient waiter nodded, turned around and yelled to the chef: “Steak and french fries for one."

The engineers who built the big turbine had foreseen trouble, and hoped that “modified and cleaned-up” units would be built on other sites in the Green Mountains after the war. This would have required more money, however. The S. Morgan Smith Company had spent about $1.25 million on the project, and its funds were limited. Estimates of the cost of building more wind turbines indicated that large blocks of power could be generated much more economically in other ways.

Nuclear energy was a factor in the decision to dismantle the turbine on Grandpa’s Knob. The bombs that ended the war in Japan suggested that nuclear power could also be used for peaceful purposes. Its potentialities excited both engineers and investors. So Beauchamp and Burwell Smith persuaded Putnam merely to review what had been done in a technical treatise that might be helpful some time where winds were strong and fuel was scarce.

In an introduction to Putnam’s report, Vannevar Bush wrote: “The great wind turbine on a Vermont mountain proved that man could build a practical machine which would synchronously generate electricity in large quantities by means of wind power. It proved also that at some future time homes may be illuminated and factories may be powered by this new means.”

MORE PLANS THAN ACTION

Putnam recommended that a national survey of the wind’s energy be made, and that the government support efforts to use windpower. The War Production Board thought windpower might be most helpful at military bases overseas where there were few other resources, and sponsored studies of aerogenerators for those bases.

New York University engineers then proposed that a 100-kilowatt wind machine be built with more standard components than had been used in the Smith-Putnam giant. Its two blades would be only 2 feet wide and 24 feet long, made of Sitka spruce and held together by an aluminum alloy. That rotor would spin a hollow steel shaft 6 inches in diameter to drive a three-phase 220-volt, 60-cycle induction generator.

A diesel engine would be used to excite and start the generator and pick up the load when the wind died down. The tower would be only 72 feet high, and the machinery could be enclosed in a wooden or sheet steel housing. By building such plants overseas, the designers thought, the government could save fuel oil and reduce shipping costs. But there still seemed to be plenty of oil underground in this country, and the government did not build any aerogenerators.

Percy H. Thomas, another M.I.T. graduate, succeeded Palmer Putnam as this country’s leading proponent of using big turbines to generate electrical current from the wind. Thomas wrote a series of scholarly monographs for the Federal Power Commission that its spokesmen were still quoting in the 1970s. In the first one he suggested that a machine be built to generate five times as many kilowatts as the one on Grandpa’s Knob. In a second report to the commission Thomas continued to favor very large machines, but in a third one he modified his proposals.

Those studies resulted in more hemming and hawing than action in the 1950s. William E. Warne, Assistant Secretary of the Interior, and others who testified at Congressional hearings in 1951, urged that the government construct a 7,500-kilowatt pilot plant. But too many legislators remembered the antics of the little windmills used in the midwestern states, and were loathe to see the taxpayers’ money spent in that way.

The Federal Power Commission did not publish Thomas’ fourth and final monograph on windpower until 1954. Thomas, who had retired by then, proposed a new plan in this report. He conceded that it would be impractical to build a big enough wind machine to deliver, say, 100,000 kilowatts to a network of high-voltage transmission lines. But he pointed out how greatly the wind’s speed often varies within a small area. By combining the output from many generators at different sites, he argued, electrical energy might be generated continuously and economically enough to interest the utility companies and reduce their use of fossil fuels.

Putnam quoted a noted scholar, J. B. S. Haldane, in the final chapter of his book. When writing about the future, Haldane had once said “it was characteristic of the dwellers on the earth that they never looked ahead more than a million years and the amount of energy available was ridiculously squandered.”

In the quarter century after atomic bombs first exploded, few Americans supposed we would ever have to conserve energy. But we must now, and engineers have revived Thomas’s idea of building fleets of aerogenerators to delay exhaustion of other sources of energy.

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