For

`lambdaMin <= lambda <= lambdaMax`

the pitch angle `beta````
is approximated by a polynom
```

beta = sum (lambda^(n-k+1) * p[k] for k in 1:n)

where `n-1`

is the degree of the polynom. The optimum power coefficient is indicated by `beta = betaOpt `

and `lambda = lambdaOpt`

.

The polynominal parameters can be calculated by the Octave script
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