{TAIL ~ The total duct system} thus constitutes a fixed intake aperture feeding {HEAD ~ a configurable exhaust aperture} through a volume and volume velocity driven turbine type fan, 3 
{ TAIL ~ The total duct system } thus constitutes a fixed intake aperture feeding { HEAD ~ a configurable exhaust aperture } through a volume and volume velocity driven turbine type fan , 3
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH