{HEAD ~ a cylinder} and {TAIL ~ piston} forming a chamber mounted on a drop vehicle; and 
{ HEAD ~ a cylinder } and { TAIL ~ piston } forming a chamber mounted on a drop vehicle ; and
HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH