Carl Wilcox References in the Text of Putnam’s Power from the Wind

By Paul Gipe

To further illustrate the role of Carl Wilcox in the Smith-Putnam project, I searched the name index and pulled together specific mentions of him in the text.

There are eight references in the index of Palmer Putnam’s Power from the Wind to Carl J. Wilcox: pages 6, 12, 14, 35, 58, 131, 140 and 141. Putnam’s description of the development of the 1.25 MW Smith-Putnam wind turbine in the early 1940s is one of the seminal books on wind energy in English. The references to Wilcox indicate the important role he played in the project.

Page 6. “The computations were carried out by Carl J. Wilcox, on loan to the S. Morgan Smith Company by the Budd Company.”

Page 12. “One of the most important studies made in this period was a review of loadings by Wilcox, in collaboration with Holley, under the direction of Wilbur.”

Page 14. In reference to a review of the entire project, “studies were carried out by Carl J. Wilcox and Stanton Dornbirer, in collaboration with Jackson and Moreland, and in consultation with George A. Jessop, John B. Wilbur, and Myle J. Holley.”

Page 35. Putnam mentions Wilcox in reference to the re-examination of anemometer measurements. “Unwilling to believe that these low values were characteristic of the western foothills of the Green Mountains, Wilcox studied the trend of the reported velocity records from Blue Hill, East Boston, and Mount Washington (Ref. 9-b), and discovered that, beginning a few months earlier, the velocity on Mount Washington had shown a substantial drop.”

Page 58. Putnam makes further reference to Wilcox and the wind measurement program. “After V-J day, the data of most immediate interest—the direction and velocity measurements—were worked up by Lange, Wilcox, and myself.” V-J refers to Victory over Japan in WWII.

Page 131. In a significant paragraph on the test and operation of the wind turbine, Putnam again cites the role of Wilcox.

“By 1944 enough experience had been obtained, including strain-gauge recordings, to permit a recalculation of loadings. This was carried out by Wilcox, in collaboration with Holley, under the direction of Wilbur, who concluded that the actual loadings were somewhat higher than those which had been used in the design. His anxiety increased about the blade-root sections, which had originally been very highly stressed. Accordingly, in December, 1944, and just before the unit was to go back on the line as a routine generating station, Wilbur proposed to the S. Morgan Smith Company that the test unit be torn down as soon as it had served its purpose. This decision was accepted by [the] S. Morgan Smith Company.”

This was prescient. One blade failed at the root on 26 March 1945.

Page 140. In the chapter on the best size for a large wind turbine, Putnam describes how they arrived at their design, including the shape of their ideal blade.

“Accordingly, following a suggestion by von Kármán, an extension of the classical theory was carried out by Wilcox and Holley. By means of this extension they were able to compute the output of an ideal turbine for various values of the lift-drag ratio.”

Page 141. Continuing his description of how they determined their ideal blades, Putnam refers to multiple iterations of blade calculations. This was in the day of slide rules and all calculations had to be done by hand and it appears this was done by Wilcox and Holley.

“Four blades were designed, the respective maximum efficiencies occurring at four different tip-speed ratios, viz., 4.0, 6.0, 8.0 and 10.0. For each of the four values of the tip-speed ratio, Wilcox and Holley used three values of the lift coefficient, viz., 0.60, 0.80, and 1.20, each held constant from root to tip.”