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