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