Feedback on Sencenbaugh's O2 Delight: Windmill Blade Design

A reader in Romayor, Texas questions the efficiency of the windmill blade design Jim Sencenbaugh used in his O2 Delight windmill. Jim Sencenbaugh explains his decision and comments on current and future refinements he's planning.

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Illustrations showing shape of pressure envelope around an airfoil and its relationship to effective pitch angle.
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