{HEAD ~ The side} opposite the skin on the second grid structure is preferably covered by {TAIL ~ a further inner skin}, for example secured by casting or by an adhesive 
is preferably covered by
{ HEAD ~ The side } opposite the skin on the second grid structure is preferably covered by { TAIL ~ a further inner skin } , for example secured by casting or by an adhesive
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH