sin αst

ROTOR THEORY
Figure B.4: Blade pitch angle according to Betz and Schmitz theory. Shown for tip-speed
ratio � = 5, the airfoil lift coefficient Cl = 0.99, number of blade B = 3 and optimal angle of
attach � = 7�
As shown on the above figures the blade design for optimum power production has an
increasingly large chord and pitch angle when approaching the blade root. This makes the
fabrication of the blade difficult and the present blade design, described in section 6.2, is
therefore modified for ease of manufacturing using the optimum blade shape as a guide-
line.
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