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