The ratio between the fixed intake aperture, and the configurable exhaust aperture creates a volume and {HEAD ~ thus a velocity differential} in {TAIL ~ the air mass} on either side of the relatively centrally located in the duct turbine type fan, 3 
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The ratio between the fixed intake aperture , and the configurable exhaust aperture creates a volume and { HEAD ~ thus a velocity differential } in { TAIL ~ the air mass } on either side of the relatively centrally located in the duct turbine type fan , 3
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH