From Danregn to Bonus - Wind Power for the World: The Rise of Modern Wind Energy - page 285

10.3 Important Fundamental Rules

Our goal was to make the simplest possible windmill. We visited
Risø, Gedser windmill, Tvind, Økær Vind Energi, Hjerm Elektro,
Folkecenter, Kuriant, whose owner I knew, and many more. And
when someone knew something about windmills—we listened
avidly. Folkecenter had a complete concept for the production of
a windmill. I asked if they could help us by making drawings and
dimensioning for a windmill. The answer was no.
Few days later I called Preben Maegaard and asked him for
help with the major issues and about what we should watch out
for. We would, of course, pay for these services. He answered “I
cannot take a fee, but I am going to Copenhagen next week, then I
can look in for a couple of hours.” During his visits we learnt
about some important fundamental rules, such as don't forget that

• the main shaft should be of good quality and have a thickness
of 10 mm for each rotor diameter

• yawing should only be one degree a second

• the gear must be twice as strong as the generator capacity

• all other parts should be able to stand up to a permanent load
of 120%

• the shaft should be lined up in such a way that it puts a
constant load on the yaw system

10.4 Quite a Good Thing to Be Little

Behindhand

At the outset there were only three persons: Stubkjær Sørensen;
his wife Alice Sørensen, a draughtswoman; and me. We did things
from the end backwards to the beginning, building the wind
turbine piece by piece and made the drawings afterwards from
what we had made. It was a hard time, as we had to hurry
because Nordtank and Vestas were already marketing their wind
turbines.
When our prototype was ready, Risø came to inspect the wind
turbine. I distinctly remember their remarks: this bearing house
will slide, that plate will not stand for the axial loads, etc. Afterwards
we set these things right, and upon their next visit they thought
that things looked very good.