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