The outer fins 2 wind and extend around {TAIL ~ the outside surface} of {HEAD ~ the tube body} 1 in helical manner 
The outer fins 2 wind and extend around { TAIL ~ the outside surface } of { HEAD ~ the tube body } 1 in helical manner
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH