I guess the guesser's got guessed out for the time being. So I guess its time for another clue or 2  ?
 
  1 - biplane
  2 - 2 seater
  3 - trainer
  4 - designed and  or built in 1925 
  5 - 32 production machines made over next 3 years. 1925-26-28
  6 - various models/versions used a number of different engines.at least 4 different mfg.
        as far as I can determine.  7 - powered by a water cooled straight 6 cyl. of German descent.  8 - "Z" is not only for Zorro. 
          
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