19.1 Introduction
This chapter discusses the question of why it took thirty years for
the realisation to set in that direct drive (DD) of a wind turbine is
clearly the better concept, as well as acknowledge the pioneers
and inventors who worked hard to design and implement this
realisation.
Directly driven wind turbines already existed in Persia 3000
years ago. In the Persian–Afghan border region Sistan–Baluchestan
wind turbines are still driving the millstones with vertical axes
(Fig. 19.1).
Historical resources state vertical axes turbines around the
year 644 AD and a description of that construction type ...