{HEAD ~ The trough} has {TAIL ~ width} substantially corresponding to that of the take off location and has a bottom and sidewalls which preferably converge in the shape of a funnel 
has
{ HEAD ~ The trough } has { TAIL ~ width } substantially corresponding to that of the take off location and has a bottom and sidewalls which preferably converge in the shape of a funnel
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