{HEAD ~ The number} of {TAIL ~ vanes} 56 may vary but they are preferably spaced between 20 degrees and 30 degrees apart around the circumference of the cylindrical wall member 32 
of
{ HEAD ~ The number } of { TAIL ~ vanes } 56 may vary but they are preferably spaced between 20 degrees and 30 degrees apart around the circumference of the cylindrical wall member 32
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH