Historical Development of the Windmill - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 33

The American Windmill
For this history of the American windmill, we lean heavily on A Field Guide to
American Windmills by T. Lindsay Baker [1985]. This is not a pocket handbook like the
well-known ield guides on birds, lowers, and so on, but a remarkable, large-page topic of
more than 500 pages. It is certainly the most comprehensive catalog of American windmills
and their makers, culled largely from manufacturers' literature and from periodicals of the
farm implement industry, in considerable detail where available. The “ield guide” part is
preceded by some 100 pages of history, development, and general information about the
industry and its technology. It is concerned only with the period from the introduction of
a prototype unit by Halladay in 1854 to the essential end of production of these machines
in the 1930s.
Figure 1-17, from Baker, shows many of the different designs of the American
windmill. Dozens of manufacturers erected windmills at the World's Columbian Exposition
in Chicago in 1893, with every conceivable coniguration competing for recognition and
scrambling to get a piece of the market; an excellent photograph of this event is reproduced
in Torrey [1976].
First, let us give consideration to the origin of the design and function of the American
windmill. Daniel Halladay is credited with the invention of the irst commercially success-
ful, self-governing windmill in 1854; although there were some previous ventures, the
Halladay Standard came to be the archetypal American model. It was intended as a small
unit (2 to 5 m in diameter) for pumping, as were most other American mills. The output
of a mill 5 m in diameter in a 7-m/s wind was about a horsepower or so, quite adequate for
a “water pumper” on farms all over the country. In later years, some much larger ones (up
to about 18 m in diameter) were built for industrial and railroad water-supply systems.
Sectional Wheels: The Halladay Standard
The Halladay mill initially had four rotatable, lat wooden blades joined to an iron shaft
with a crank at its opposite end. A solid wooden tail vane attached to the shaft and set
perpendicularly to the plane of the wheel provided the winding, and a centrifugal governor
changed the blade-setting angle according to the wind speed. Within a few years, the four
paddle-type blades were replaced with a large number of thin, wooden blades nailed to
wood rims. These blades were grouped in perhaps a dozen sections of a half-dozen blades
each; each section was mounted on a hinged casting. This method allowed the groups of
blades to be pivoted backward and forward like an umbrella, controlled by wind pressure
or centrifugal effect, with weights or springs for reverse action. Rotors of this sort were
called sectional wheels , and constituted one of the two main styles of American windmills
in use throughout the nineteenth century. One variant of the sectional mill did not have a
tail vane, in which case the wheel would become a free-swinging, downwind type, called
vaneless sectional (the far-left machine in Figure 1-17). It had a speed control akin to that
of the vaned, upwind model.
Solid Wheels: The Eclipse
The second major style of the American windmill was that of the solid wheel , as
opposed to the sectional wheel. Blades were mounted together in a single rigid section, and
control was effected by moving the whole wheel to some angle to the wind commensurate
with the wind speed. The restraint or return motion was effected in a variety of ways. The
prototype of the solid wheel was introduced in 1866 by a Reverend Leonard R. Wheeler