{HEAD ~ Energy} is extracted from {TAIL ~ a free stream fluid flow} of wind or water by means of a multi turn helicoid structure with a relatively small pitch angle 
{ HEAD ~ Energy } is extracted from { TAIL ~ a free stream fluid flow } of wind or water by means of a multi turn helicoid structure with a relatively small pitch angle
HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH