term 5-engined giant most likely means a Zeppelin R.IV or Zeppelin R.V bomber. "German Giants" is the best reference on the subject, but youŽll find quite a bit on them in the net as well...just fire up your fave search engine with words "Zeppelin Staaken" or the type names above...
Coincidentally, just an hour ago I was painting the lozenges to the top wing of my 1/72 R.V

Should be ready in a month or two...