Moving the receptor fins controls {HEAD ~ the extent} of interleave thereof with the radiator fins, so as to control {TAIL ~ temperature} of the mandrel 
to control
Moving the receptor fins controls { HEAD ~ the extent } of interleave thereof with the radiator fins , so as to control { TAIL ~ temperature } of the mandrel
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH