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