Figure 13.3 Prototype 2-bladed ECO-RA water brake windmill (left); 3-
bladed ECO-RA version (right).
Figure 13.4 The 3-bladed ECO-RA water brake windmill (left); ECO-RA
water brake windmill built by Ib Grosser, Odder (right).
In 1978, Ib Grosser from Odder used this construction manual
of 12
m (Fig. 13.4 right). It ran very well and the pitch regulation
could keep the rotation speed nearly constant. After four years
of operation it was taken down for revision and was not put up
again. Also other windmills were built in accor