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.

pix2258a
Top illustration shows how the lift vector of an airfoil positioned with its curved face to the wind impedes windmill rotation. Bottom illustration shows how the lift vector of an airfoil positioned with it's flat face to the wind aids rotation.
ILLUSTRATION: MOTHER EARTH NEWS STAFF