Following World War I propeller aerodynamic design methodology was applied to the development of an efficient windmill for electricity generation in rural areas. H.R. Stuart experimented with combinations of windmills and direct-drive generators; while E.N. Fales, who had worked in aerodynamics at the U.S. Army’s McCook Field, conducted tests of scale-model windmills in wind tunnels.
This type of windmill provides slightly more power than the common multi-blade type while rotating six times faster; thus reducing gearing problems in wind electric power plants.
The artifact, invented and patented by Stuart and Fales, charged a 32-volt storage battery for lighting a farm near Springfield, Ohio beginning in 1922. It produced 230 watts in a 20 mile-per-hour wind (32 km/hr), reaching 1000 watts in higher winds. Similar propeller-driven units appeared subsequently using either direct drive or geared drives in larger sizes.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.