Windpower Principles by NG Calvert

The wind is free. For thousands of years, people have been using it as a source of power. The major use in the past was (and probably is still today) ship and yacht propulsion. The windmill also has for hundreds of years provided a local, relatively small, but invaluable source of shaft power, but with the coming of electricity and the internal combustion engine, had all but died out by the middle of the twentieth century.

But the wind, although free and environmentally benign, is also unpredictable and uncontrollable. Extracting power usefully and safely from it is an art as well as a science. Only recently, has large scale power production from the wind become either technically feasible or economically viable.

Geoff Calvert had a lifelong interest in windpower, and carried out experimental, theoretical and historical research on it for many years. This book (first published in 1979) is the summarised outcome of that work as regards small scale windmills. It guides the reader through the principles of how windmills work, how to design, build and operate them economically and safely, and in particular, what it is and is not reasonable to expect of a small wind plant. Particular emphasis is placed on the author's favourite design, the Cretan sail mill, but many other types are covered as well.

NG Calvert served an engineering apprenticeship, and then spent many years at the University of Liverpool passing on his enthusiasm for all things mechanical to generations of students. His particular enthusiasm for water, steam, boats and wind comes through strongly in this book and its companion, Steam Engine Principles: their application on the small scale. He died in 1984.