Environmental Engineering Reference
In-Depth Information
Hütter's doctorate thesis also builds on Betz's theory. Hütter
was the first to transfer the principle of airfoil aerodynamics of air-
planes to rotors of wind turbines. Until today, the design principles
Hütter derived for the calculation of wind turbines widely subsist.
The fact that Hütter's philosophy was rooted in aircraft
construction had efects on all his constructions and in particular
on rotor blade development. “All things that rotate should be as
light as possible but of course also as solid as necessary,” was his
creed. Even for the smallest systems Hütter took all eforts to
minimise the loads afecting the rotor blade by reducing its weight.
It follows that his basic principle was a consequent lightweight
construction.
As an aircraft designer Hütter paid special attention to the
profiles of the rotor blades and worked hard on their aerodynamic
optimisation. He opted for fast-running machines and high lift
coefficients through the blade profile. “From the aerodynamic point
of view, the profiling is important for high-speed blades, not the
number of blades,” Dörner cites his teacher. “In theory even one
blade alone might be enough for a wind turbine to come close to
the theoretically possible energy yield from the wind.” From today's
perspective he adds: “Two blades were chosen for reasons of weight
symmetry, but because of the alternating loads, this was not too
beneficial for the service life. Therefore in the end three blades have
won.” However there was a long way to go towards this finding.
17.3
Allgaier's Investments
Hütter's search for the perfect concept began shortly after World War
II with the construction of small systems. Together with company
Schempp-Hirth he had developed a small single-blade rotor in
1946. After further experiments, he was able to build a 3-blade
1.3 kW unit for the power supply of a chicken farm in Ohmden
near Kirchheim/Teck only one year later.
Thereupon the entrepreneur Erwin Allgaier from Uhingen near
Göppingen in Wurttemberg recognised the potential of this new
technology for his medium-range mechanical engineering company
Allgaier-Werke. The company that once had been founded as a
workshop for cutting and stamping tools by then was producing
a wide range of metal products, from pots and pans to pumps
for manure.
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