{HEAD ~ The craft} is lighter than {TAIL ~ air}, such as a dirigible airship , and has flat projection surfaces on each of its sides 
{ HEAD ~ The craft } is lighter than { TAIL ~ air } , such as a dirigible airship , and has flat projection surfaces on each of its sides
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH