Therefore the blades encounter an apparent frontal wind when moving {TAIL ~ downwind}, which is the resultant of the blade speed minus {HEAD ~ the wind speed} 
Therefore the blades encounter an apparent frontal wind when moving { TAIL ~ downwind } , which is the resultant of the blade speed minus { HEAD ~ the wind speed }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD