As in the case of conventional airships, the airship 12 accommodates a large volume of a suitable lighter than air gas, {HEAD ~ typically helium}, which renders {TAIL ~ the airship} buoyant in air 
renders
As in the case of conventional airships , the airship 12 accommodates a large volume of a suitable lighter than air gas , { HEAD ~ typically helium } , which renders { TAIL ~ the airship } buoyant in air
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH